WO2025200032A1

WO2025200032A1 - Devices and methods for nprach transmission

Info

Publication number: WO2025200032A1
Application number: PCT/CN2024/085084
Authority: WO
Inventors: Yue Zhou; Gang Wang
Original assignee: NEC Corp
Current assignee: NEC Corp
Priority date: 2024-03-29
Filing date: 2024-03-29
Publication date: 2025-10-02
Anticipated expiration: 2026-09-29

Abstract

Embodiments of the present disclosure provide a solution for narrowband physical random access channel (NPRACH) transmission enhancement. In a solution, a terminal device determines a NPRACH symbol group comprising a plurality of symbol subgroups based on a code domain multiplexing capability of the terminal device, wherein the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group; and transmit, to a network device, an NPRACH signal comprising the NPRACH symbol group.

Description

DEVICES AND METHODS FOR NPRACH TRANSMISSION

FIELDS

Example embodiments of the present disclosure generally relate to the field of communication techniques and in particular, to devices and methods for narrowband physical random access channel (NPRACH) transmission enhancement.

BACKGROUND

A non-terrestrial network (NTN) refers to a network or segment of networks using radio frequency (RF) resources on board a satellite or unmanned aircraft system (UAS) platform. The NTN could provide ubiquitous and resilient wireless service beyond the terrestrial network coverage. The 3rd Generation Partnership Project (3GPP) has started the standardization of NTN since the fifth generation (5G) communication system. NTN is expected to be fully integrated with TN in the sixth generation (6G) . In NTN, a relatively large number of terminal devices are served in a cell.

SUMMARY

In a first aspect, there is provided a terminal device comprising: a processor configured to cause the terminal device to: determine a narrowband physical random access channel (NPRACH) symbol group comprising a plurality of symbol subgroups based on a code domain multiplexing capability of the terminal device, wherein the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group; and transmit, to a network device, an NPRACH signal comprising the NPRACH symbol group.

In a second aspect, there is provided a terminal device comprising: a processor configured to cause the terminal device to: spread a narrowband physical random access channel (NPRACH) symbol group within an NPRACH repetition in a time-domain manner, wherein a spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier; and transmit, to a network device, an NPRACH signal comprising the NPRACH symbol group and the spreading result.

In a third aspect, there is provided a terminal device comprising: a processor configured to cause the terminal device to: spread a first narrowband physical random access channel (NPRACH) symbol group and a second NPRACH symbol group within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group, wherein a spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, or wherein a spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group; and transmit, to a network device, an NPRACH signal comprising the first NPRACH symbol group, the first spread symbol group, the second NPRACH symbol group and the second spread symbol group.

In a fourth aspect, there is provided a network device comprising: a processor configured to cause the network device to: receive, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising an NPRACH symbol group, wherein the NPRACH symbol group comprises a plurality of symbol subgroups determined based on a code domain multiplexing capability of the terminal device, the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group.

In a fifth aspect, there is provided a network device comprising: a processor configured to cause the network device to: receive, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising an NPRACH symbol group and a spreading result of the NPRACH symbol group, wherein the NPRACH symbol group is spread within an NPRACH repetition in a time-domain manner, the spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier.

In a sixth aspect, there is provided a network device comprising: a processor configured to cause the network device to: receive, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising a first NPRACH symbol group, a first spread symbol group, a second NPRACH symbol group and a second spread symbol group, the first NPRACH symbol group and a second NPRACH symbol group being spread within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group, wherein a spreading result of the first NPRACH symbol group comprises the first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises the second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, or wherein a spreading result of the first NPRACH symbol group comprises the first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises the second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group.

In a seventh aspect, there is provided a communication method performed by a terminal device. The method comprises: determining a narrowband physical random access channel (NPRACH) symbol group comprising a plurality of symbol subgroups based on a code domain multiplexing capability of the terminal device, wherein the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group; and transmitting, to a network device, an NPRACH signal comprising the NPRACH symbol group.

In an eighth aspect, there is provided a communication method performed by a terminal device. The method comprises: spreading a narrowband physical random access channel (NPRACH) symbol group within an NPRACH repetition in a time-domain manner, wherein a spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier; and transmitting, to a network device, an NPRACH signal comprising the NPRACH symbol group and the spreading result.

In a ninth aspect, there is provided a communication method performed by a terminal device. The method comprises: spreading a first narrowband physical random access channel (NPRACH) symbol group and a second NPRACH symbol group within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group, wherein a spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, or wherein a spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group; and transmitting, to a network device, an NPRACH signal comprising the first NPRACH symbol group, the first spread symbol group, the second NPRACH symbol group and the second spread symbol group.

In a tenth aspect, there is provided a communication method performed by a network device. The method comprises: receiving, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising an NPRACH symbol group, wherein the NPRACH symbol group comprises a plurality of symbol subgroups determined based on a code domain multiplexing capability of the terminal device, the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group.

In an eleventh aspect, there is provided a communication method performed by a network device. The method comprises: receiving, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising an NPRACH symbol group and a spreading result of the NPRACH symbol group, wherein the NPRACH symbol group is spread within an NPRACH repetition in a time-domain manner, the spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier.

In a twelfth aspect, there is provided a communication method performed by a network device. The method comprises: receiving, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising a first NPRACH symbol group, a first spread symbol group, a second NPRACH symbol group and a second spread symbol group, the first NPRACH symbol group and a second NPRACH symbol group being spread within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group, wherein a spreading result of the first NPRACH symbol group comprises the first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises the second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, or wherein a spreading result of the first NPRACH symbol group comprises the first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises the second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group.

In a thirteenth aspect, there is provided a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to carry out the method according to the seventh, eighth, ninth, tenth, eleventh, or twelfth aspect.

Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Through the more detailed description of some example embodiments of the present disclosure in the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become more apparent, wherein:

FIG. 1 illustrates an example communication environment in which example embodiments of the present disclosure can be implemented;

FIG. 2A and FIG. 2B illustrate schematic diagrams of non-terrestrial network scenarios with different payload types in accordance with some embodiments of the present disclosure;

FIG. 3 illustrates different schemes for applying orthogonal codes;

FIG. 4A illustrates examples of symbol groups for NPRACH;

FIG. 4B illustrates an example hopping pattern in frequency domain;

FIG. 5 illustrates example multiplexing schemes between different NPRACH coverage levels;

FIG. 6 illustrates a signaling flow of a NPRACH transmission in accordance with some embodiments of the present disclosure;

FIG. 7A to 7G illustrate schematic diagrams of patterns of NPRACH symbol group (s) in accordance with some embodiments of the present disclosure, respectively;

FIG. 8 illustrates a signaling flow of a NPRACH transmission in accordance with some embodiments of the present disclosure;

FIG. 9A and 9B illustrate schematic diagrams of spreading patterns in accordance with some embodiments of the present disclosure, respectively;

FIG. 10 illustrates a signaling flow of a NPRACH transmission in accordance with some embodiments of the present disclosure;

FIG. 11A illustrates a schematic diagram of spreading patterns in accordance with some embodiments of the present disclosure;

FIG. 11B illustrates another schematic diagram of spreading patterns in accordance with some embodiments of the present disclosure;

FIG. 12 illustrates a flowchart of a method implemented at a terminal device according to some example embodiments of the present disclosure;

FIG. 13 illustrates a flowchart of a method implemented at a terminal device according to some example embodiments of the present disclosure;

FIG. 14 illustrates a flowchart of a method implemented at a terminal device according to some example embodiments of the present disclosure;

FIG. 15 illustrates a flowchart of a method implemented at a network device according to some example embodiments of the present disclosure;

FIG. 16 illustrates a flowchart of a method implemented at a network device according to some example embodiments of the present disclosure;

FIG. 17 illustrates a flowchart of a method implemented at a network device according to some example embodiments of the present disclosure; and

FIG. 18 illustrates a simplified block diagram of an apparatus that is suitable for implementing example embodiments of the present disclosure.

Throughout the drawings, the same or similar reference numerals represent the same or similar element.

DETAILED DESCRIPTION

Principle of the present disclosure will now be described with reference to some example embodiments. It is to be understood that these embodiments are described only for the purpose of illustration and help those skilled in the art to understand and implement the present disclosure, without suggesting any limitation as to the scope of the disclosure. Embodiments described herein can be implemented in various manners other than the ones described below.

In the following description and claims, unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this disclosure belongs.

As used herein, the term ‘terminal device’ refers to any device having wireless or wired communication capabilities. Examples of the terminal device include, but not limited to, user equipment (UE) , personal computers, desktops, mobile phones, cellular phones, smart phones, personal digital assistants (PDAs) , portable computers, tablets, wearable devices, internet of things (IoT) devices, Ultra-reliable and Low Latency Communications (URLLC) devices, Internet of Everything (IoE) devices, machine type communication (MTC) devices, devices on vehicle for V2X communication where X means pedestrian, vehicle, or infrastructure/network, devices for Integrated Access and Backhaul (IAB) , Space borne vehicles or Air borne vehicles in Non-terrestrial networks (NTN) including Satellites and High Altitude Platforms (HAPs) encompassing Unmanned Aircraft Systems (UAS) , eXtended Reality (XR) devices including different types of realities such as Augmented Reality (AR) , Mixed Reality (MR) and Virtual Reality (VR) , the unmanned aerial vehicle (UAV) commonly known as a drone which is an aircraft without any human pilot, devices on high speed train (HST) , or image capture devices such as digital cameras, sensors, gaming devices, music storage and playback appliances, or Internet appliances enabling wireless or wired Internet access and browsing and the like. The ‘terminal device’ can further has ‘multicast/broadcast’ feature, to support public safety and mission critical, V2X applications, transparent IPv4/IPv6 multicast delivery, IPTV, smart TV, radio services, software delivery over wireless, group communications and IoT applications. It may also incorporate one or multiple Subscriber Identity Module (SIM) as known as Multi-SIM. The term “terminal device” can be used interchangeably with a UE, a mobile station, a subscriber station, a mobile terminal, a user terminal or a wireless device.

The term “network device” refers to a device which is capable of providing or hosting a cell or coverage where terminal devices can communicate. Examples of a network device include, but not limited to, a Node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , a next generation NodeB (gNB) , a transmission reception point (TRP) , a remote radio unit (RRU) , a radio head (RH) , a remote radio head (RRH) , an IAB node, a low power node such as a femto node, a pico node, a reconfigurable intelligent surface (RIS) , and the like.

The terminal device or the network device may have Artificial intelligence (AI) or Machine learning capability. It generally includes a model which has been trained from numerous collected data for a specific function, and can be used to predict some information.

The terminal or the network device may work on several frequency ranges, e.g., FR1 (e.g., 450 MHz to 6000 MHz) , FR2 (e.g., 24.25GHz to 52.6GHz) , frequency band larger than 100 GHz as well as Tera Hertz (THz) . It can further work on licensed/unlicensed/shared spectrum. The terminal device may have more than one connection with the network devices under Multi-Radio Dual Connectivity (MR-DC) application scenario. The terminal device or the network device can work on full duplex, flexible duplex and cross division duplex modes.

The embodiments of the present disclosure may be performed in test equipment, e.g., signal generator, signal analyzer, spectrum analyzer, network analyzer, test terminal device, test network device, channel emulator. In some embodiments, the terminal device may be connected with a first network device and a second network device. One of the first network device and the second network device may be a master node and the other one may be a secondary node. The first network device and the second network device may use different radio access technologies (RATs) . In some embodiments, the first network device may be a first RAT device and the second network device may be a second RAT device. In some embodiments, the first RAT device is eNB and the second RAT device is gNB. Information related with different RATs may be transmitted to the terminal device from at least one of the first network device or the second network device. In some embodiments, first information may be transmitted to the terminal device from the first network device and second information may be transmitted to the terminal device from the second network device directly or via the first network device. In some embodiments, information related with configuration for the terminal device configured by the second network device may be transmitted from the second network device via the first network device. Information related with reconfiguration for the terminal device configured by the second network device may be transmitted to the terminal device from the second network device directly or via the first network device.

As used herein, the singular forms ‘a’ , ‘an’ and ‘the’ are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term ‘includes’ and its variants are to be read as open terms that mean ‘includes, but is not limited to. ’ The term ‘based on’is to be read as ‘at least in part based on. ’ The term ‘one embodiment’ and ‘an embodiment’ are to be read as ‘at least one embodiment. ’ The term ‘another embodiment’ is to be read as ‘at least one other embodiment. ’ The terms ‘first, ’ ‘second, ’ and the like may refer to different or same objects. Other definitions, explicit and implicit, may be included below.

In some examples, values, procedures, or apparatus are referred to as ‘best, ’ ‘lowest, ’ ‘highest, ’ ‘minimum, ’ ‘maximum, ’ or the like. It will be appreciated that such descriptions are intended to indicate that a selection among many used functional alternatives can be made, and such selections need not be better, smaller, higher, or otherwise preferable to other selections.

As used herein, the term “resource, ” “transmission resource, ” “uplink resource, ” or “downlink resource” may refer to any resource for performing a communication, such as a resource in time domain, a resource in frequency domain, a resource in space domain, a resource in code domain, or any other resource enabling a communication, and the like. In the following, unless explicitly stated, a resource in both frequency domain and time domain will be used as an example of a transmission resource for describing some example embodiments of the present disclosure. It is noted that example embodiments of the present disclosure are equally applicable to other resources in other domains.

As used herein, the term “NRPACH with code domain multiplexing (CDM) ” may refer to an NRACH with a preamble transmission performed by multiplexing in code domain.

As used herein, the term “CDM capable terminal device” may refer to a terminal device with a capability for NPRACH with CDM, or in other words supporting NPRACH with CDM. In the following, some example embodiments may be described by taking a CDM capable UE as an example of the CDM capable terminal device.

As used herein, the term “legacy terminal device” may refer to a terminal device without the capability for NPRACH with CDM. As such, an NPRACH transmission for the legacy terminal device is performed without CDM. In the following, some example embodiments may be described by taking a legacy UE as an example of the legacy terminal device.

FIG. 1 illustrates a schematic diagram of an example communication environment 100 in which example embodiments of the present disclosure can be implemented. In the communication environment 100, a network device 120 may a plurality of terminal devices 110-1, 110-2 and 110-3, which are collectively referred to as terminal devices 110 or individually referred to as a terminal device 110. In an example of FIG. 1, the terminal device 110 may be an UE and the network device 120 may be a base station serving the UE.

It is to be understood that the number of devices and their connections shown in FIG. 1 is only for the purpose of illustration without suggesting any limitation. The communication environment 100 may include any suitable number of devices configured to implement example embodiments of the present disclosure. Although not shown, it would be appreciated that one or more additional devices may be deployed in the communication environment 100.

In some embodiments, the communication between the terminal device 110 and the network device 120 may operate in a narrowband (NB) , for example in the case of NB IoT. In these embodiments, a random access procedure may be performed over a NPRACH.

In the following, for the purpose of illustration, some example embodiments are described with the terminal device 110 operating as a UE and the network device 120 operating as a gNB. However, in some example embodiments, operations described in connection with a terminal device may be implemented at a network device or other device, and operations described in connection with a network device may be implemented at a terminal device or other devices.

A link from the network device 120 to the terminal device 110 is referred to as a downlink (DL) , while a link from the terminal device 110 to the network device 120 is referred to as an uplink (UL) . In DL, the network device 120 is a transmitting (TX) device (or a transmitter) and the terminal device 110 is a receiving (RX) device (or a receiver) . In UL, the terminal device 110 is a TX device (or a transmitter) and the network device 120 is a RX device (or a receiver) . In communication, the terminal device 110 may perform uplink transmission with the network device 120, for example PUSCH transmission. DMRS bundling may be needed for transmission occasions of the uplink transmission.

The communications in the communication environment 100 may conform to any suitable standards including, but not limited to, Global System for Mobile Communications (GSM) , Long Term Evolution (LTE) , LTE-Evolution, LTE-Advanced (LTE-A) , New Radio (NR) , Wideband Code Division Multiple Access (WCDMA) , Code Division Multiple Access (CDMA) , GSM EDGE Radio Access Network (GERAN) , Machine Type Communication (MTC) and the like. The embodiments of the present disclosure may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G) , the second generation (2G) , 2.5G, 2.75G, the third generation (3G) , the fourth generation (4G) , 4.5G, the fifth generation (5G) communication protocols, 5.5G, 5G-Advanced networks, or the sixth generation (6G) networks.

In some embodiments, the communication environment 100 may be implemented in the NTN. The NTN may have different payload types. FIG. 2A and FIG. 2B illustrate schematic diagrams of NTN scenarios with different payload types. The NTN of FIG. 2A is based on a transparent payload, and the NTN of FIG. 2B is based on a regenerative payload.

In some example embodiments, a satellite or UAS platform may implement either a transparent or a regenerative (with onboard processing) payload. The satellite or UAS platform may generate beams (for example, typically generate several beams) over a given service area bounded by its field of view 260. The footprints 250 of the beams are typically of an elliptic shape. The field of view of a satellite or UAS platform depends on the on-board antenna diagram and the minimum elevation angle. Table 1 shows some parameters for some example platforms.

Table 1

As shown in FIG. 2A, in a transparent payload scenario, a UE 210 may communicate with the satellite 220 or UAS platform through a service link, and the satellite 220 or UAS platform may communicate with a gateway 230 having connection with a data network 240 through a feeder link. In this scenario, the satellite 220 or UAS platform may perform RF filtering, frequency conversion and amplification, therefore a waveform signal repeated by the payload may be unchanged. Based on the transparent payload, the UE 210 may have a connection with the data network 240. The round-trip time (RTT) in this case reflects the time for data to transmit from the UE 210 through the satellite 220 or UAS platform to a gNB (which is on the ground) .

As shown in FIG. 2B, in a regenerative payload scenario, the UE 210 may communicate with a satellite 220-1 or UAS platform through a service link. The satellite 220-1 or UAS platform may communicate with a satellite 220-2 or UAS platform through Inter-Switch Link (ISL) , and the satellite 220-2 or UAS platform may communicate with the gateway 230 having a connection with the data network 240 through a feeder link. If ISL is not available, the satellite 220 or UAS platform may communicate with the gateway 230 having a connection with a data network 240 through a feeder link. In this scenario, the satellite 220-1 and 220-2 (or UAS platform) may perform RF filtering, frequency conversion and amplification, demodulation/decoding, switch and/or routing, and coding/modulation which is effectively equivalent to having all or part of base station (for example, gNB) functions on the satellite or UAS platform. Based on the regenerative payload, the UE 210 may have a connection with the data network 240. The RTT in this case reflects the time for data to transmit from the UE 210 to the gNB (which is on the satellite or UAS platform) .

The Orthogonal Cover Code (OCC) is a coding technique used in wireless communication systems to mitigate interference and improve overall system performance. OCC is particularly effective in scenarios where multiple UEs or devices are transmitting simultaneously, such as in cellular networks or wireless local area networks (WLANs) . Thus, OCC is a Code Domain Multiplexing (CDM) technique. In OCC, there may be two types of basic operations: spreading of the modulation symbols and multiplexing of the orthogonal codes.

In coding theory, orthogonal codes refer to sets of binary sequences that have desirable properties. These codes have the property that their inner product is zero, except when two identical sequences are multiplied together, in which case the inner product is equal to the length of the sequence.

FIG. 3 illustrates different schemes for applying orthogonal codes. A scheme in which the OCC is applied in time domain (TD) is referred to as TD-CDM. A scheme in which the OCC is applied in frequency domain (FD) is referred to as FD-CDM, for example, the pattern shown as “FD-CDM2” in FIG. 3. A scheme in which the OCC is applied in both TD and FD is referred to as FD-TD-CDM, for example the pattern shown as “FD2-TD2-CDM4” in FIG. 3 and the pattern shown as “FD2-TD4-CDM8” in FIG. 3.

In some solutions, OCC may be used for a Physical Uplink Control Channel (PUCCH) and demodulation reference signal (DM-RS) multiplexing to provide additional DM-RS ports.

For uplink, for example NB IoT Uplink, the waveform may be Single-carrier Frequency-Division Multiple Access (SC FDMA) , which benefits the Peak to Average Power Ratio (PAPR) and results in good coverage. The NPRACH may be of single tone with a subcarrier spacing (SCS) of 3.75 kHz and a Cyclic Prefix (CP) of 66.7 us or 266.7us.

The NPRACH transmission may include a plurality of preamble repetitions. The number of preamble repetitions may be one in the set {1, 2, 4, 8, 16, 32, 64, 128} . Each preamble repetition may contain P symbol groups, each of which may contain one CP and N symbols. FIG. 4A shows an example symbol group 410 (format 0) and another example symbol group 420 (format 1) . These two symbol groups have the same number of symbols but different CP lengths. As shown, the CP length of the symbol group 410 is 2048 Ts and the CP length of the symbol group 410 is 8192 Ts, where the length of a symbol in the symbol group is 8192 Ts. Ts is the sample duration for a communication system under subcarrier spacing equals to 15KHz and with FFT point equals to 2048. The value of Ts is 32.552 ns. Thus, for the symbol group 420, the length of the CP is equal to the length of a symbol.

The NPRACH may be configured with hopping in frequency domain, which is also referred to as frequency hopping. FIG. 4B shows an example pattern of frequency hopping for preamble format 0 /1 in frame structure type 1. The frequency hopping may include level 1 hopping, which is hopping of one subcarrier between the 1 ^st symbol group 401 and 2^nd symbol group 402, and between the 3^rd symbol group 403 and 4^th symbol group 404. The frequency hopping may include level 2 hopping, which is hopping of 6 subcarriers between the 2^nd symbol group 402 and 3^rd symbol group 403. The frequency hopping may include level 3 hopping, which is hopping within 12 contiguous subcarriers between repetitions in a pseudo-random fashion.

The NPRACH may have different coverage levels, for example, coverage level 0, coverage level 1 and coverage level 2. System information block (SIB) , for example SIB2 may indicate resources for different coverage levels. FIG. 5 shows example multiplexing schemes between different NPRACH coverage levels. Specifically, FIG. 5 shows a TDM scheme 510, an FDM scheme 520 and a TDM and FDM scheme 530. In some cases, for every 64 repetitions, there is a UL gap of 40 ms.

NB-IoT NTN is already being deployed live currently. In these early and upcoming deployments, it is clearly emerging that IoT-NTN, in particular NB-IoT, will have to support massive capacity in terms of number and types of UEs, some of which with worse characteristics than others (e.g. low-cost devices, wearables, etc) . Given that, more than one UEs may transmit random access preambles to the network by using the same physical resources or overlapped physical resources. In these cases, the network would have to distinguish the preambles from different UEs.

In view of the above, there is a need to enhance random access channel capacity to support the preamble transmissions from different UEs, in particular for NTN where a relatively large number of users (for example, terminal devices) are served in a cell. As an example, multiplexing of UEs by usage of OCC for NPRACH should therefore be studied and if beneficial being specified. An objective is to support capacity enhancements for uplink, for example enhancements to enable multiplexing of multiple UEs (e.g. up to the min of 4 and the maximum allowed by the existing UL and DL signalling) in a single 3.75 kHz or 15 kHz subcarrier via OCC for NPUSCH format 1 and NPRACH. Multi-tone support for 15 kHz SCS should also be considered.

The example embodiments of the present disclosure propose a solution for preamble transmission enhancement, in particular for NTN NPRACH enhancement. In the solution, preamble transmission from a terminal device to a network device is performed based on CDM. Several aspects regarding the NPRACH with CDM will be described below with respect to different embodiments.

FIG. 6 illustrates a signaling flow 600 of a NPRACH transmission in accordance with some embodiments of the present disclosure. For purpose of discussion, the signaling flow 700 will be discussed with reference to FIG. 1, for example, by using the terminal device 110 and the network device 120. It is to be understood that although one terminal device 110 is illustrated in FIG. 7, the signal flow 700 may involves a plurality of terminal devices.

As shown, the terminal device 110 determines (610) a NPRACH symbol group comprising a plurality of symbol subgroups based on a code domain multiplexing capability of the terminal device. The symbol subgroups are used for a plurality of terminal device groups. A symbol subgroup may include one or more symbols. For example, each of the plurality of symbol subgroups contains symbol (s) for NPRACH transmission of a terminal device group. Each terminal device group may include one or more terminal devices.

The plurality of terminal device groups at least comprise two terminal device groups. At least one terminal device group in the plurality of terminal device groups supports NPRACH multiplexing in the code domain.

In some embodiments, the plurality of terminal device groups include a first terminal device group and a second terminal device group, and both the first terminal device group and the second terminal device group support NPRACH multiplexing in the code domain. In this case, the plurality of symbol subgroups may be applied with a first codeword set for the first terminal device group and applied with a second codeword set different from the first codeword set for the second terminal device group.

Specifically, in a case where the NPRACH symbol group includes a first symbol subgroup and a second symbol subgroup, the first symbol subgroup may be applied with a first codeword in the first codeword set and the second symbol subgroup may be applied with a second codeword in the first codeword set for the first terminal device group. Meanwhile, the first symbol subgroup may be applied with a first codeword in the second codeword set and the second symbol subgroup may be applied with a second codeword in the second codeword set for the second terminal device group. More details in this regard will be discussed with reference to FIG. 7A and FIG. 7D.

In embodiments of the present disclosure, a codeword set may include 2 codewords, 4 codewords, or other suitable number of codewords. Table 2 shows an example of two codeword sets, each of them including 2 codewords, where n = 0 or 1, and w_n indicate the n^th codeword set.

Table 2

Table 3 shows an example of 4 codeword sets, each codeword set including 4 codewords. In Table 3, n = 0, 1, 2 or 3, and w_n indicate the n^th codeword set.

Table 3

In addition to the example of codeword sets in Table 3, Table 4 shows another example of 4 codeword sets, each codeword set including 4 codewords. In Table 4, n = 0, 1, 2 or 3, and w_n indicate the n^th codeword set.

Table 4

It is to be understood that the codeword sets illustrated in Tables 2 to 4 are applicable to embodiments of the present disclosure. Some of them may be discussed for example, rather than suggesting any limitation. Other suitable codeword set (s) are also applicable.

In an implementation, the first codeword set is [+1 -1] and the second codeword set is [+1 +1] . Thus, the first symbol subgroup may be applied with the first codeword “+1” in the first codeword set, and the second symbol subgroup may be applied with the second codeword “-1” in the first codeword set. Meanwhile, the first symbol subgroup may be applied with the first codeword “+1” in the second codeword set and the second symbol subgroup may be applied with the second codeword “+1” in the second codeword set. More details in this regard will be discussed with reference to FIG. 7B and FIG. 7E below.

In contrast, in some example embodiments, the second terminal device group does not support NPRACH multiplexing in the code domain, and only the first terminal device group supports NPRACH multiplexing in the code domain. In this case, the plurality of symbol subgroups may be applied with a first codeword set for the first terminal device group, while no codeword set is applied to the plurality of symbol subgroups for the second terminal device group. In an example, the first codeword set may be [+1 -1] . More details related to this will be discussed with reference to FIG. 7C and FIG. 7F below.

In some example embodiments, in addition to the first and second terminal device groups, the plurality of terminal device groups may further include a third terminal device group. Among them, the first, second and third terminal device groups all support NPRACH multiplexing in the code domain. In such case, the plurality of symbol subgroups are applied with a first codeword set for the first terminal device group, applied with a second codeword set for the second terminal device group, and applied with a third codeword set for the third terminal device group. The first codeword set, the second codeword set and the third codeword set are different from each other.

Specifically, in an implementation, the first symbol subgroup may be applied with a first codeword in the first codeword set, the second symbol subgroup may be applied with a second codeword in the first codeword set, and the third symbol subgroup may be applied with a third codeword in the first codeword set. Meanwhile, the first symbol subgroup is applied with a first codeword in the second codeword set and the second symbol subgroup is applied with a second codeword in the second codeword set, and the third symbol subgroup is applied with a third codeword in the second codeword set. Furthermore, the first symbol subgroup is applied with a first codeword in a third codeword set for the third terminal device group, the second symbol subgroup is applied with a second codeword in the third codeword set, and the third symbol subgroup is applied with the third codeword in the third codeword set. More details in this regard will be discussed with reference to FIG. 7G below.

In some example embodiments, the NPRACH symbol group may have several formats. In a first format, the NPRACH symbol group comprises a single Cyclic Prefix (CP) and a plurality of symbol subgroups, in which all of the plurality of symbol subgroups follow the CP. For example, the NPRACH symbol group may include 1 CP and 5 symbols, and the 5 symbols are divided into two symbol subgroups, one symbol subgroup including, e.g., 2 symbols, and the other symbol subgroup including, e.g., 3 symbols. It is to be understood that the number of symbols in each symbol subgroup is discussed for example, rather than suggesting any limitations.

FIGS. 7D to 7F illustrate the NPRACH symbol group in the first format, which will be discussed in details below.

In a second format, the NPRACH symbol group comprises a plurality of Cyclic Prefixes (CPs) and the plurality of symbol subgroups. Each symbol subgroup immediately follows a corresponding CP and all of the plurality of symbol subgroups have the same number of symbols. For example, the NPRACH symbol group may include 2 CPs and 4 symbols, and the 4 symbols may be divided into two symbol subgroups, each symbol subgroup including 2 symbols. Thus, the second format of the NPRACH symbol group may be illustrated as below:
1 CP + 2 symbols + 1CP + 2symbols.

FIGS. 7A to 7C illustrate the NPRACH symbol group in the second format discussed above, and more details in this regard will be discussed below.

Alternatively, in some embodiments, the NPRACH symbol group of the second format may include 3 CPs and 3 symbols, and the3 symbols are divided into 3 symbol subgroups, each symbol subgroup including 1 symbol. Accordingly, the second format of the NPRACH symbol group may be illustrated as below:
1 CP + 1symbol + 1 CP + 1symbol + 1 CP + 1symbol.

FIG. 7G illustrates the NPRACH symbol group in the aforesaid second format, and more details in this regard will be discussed below.

In some embodiments, the terminal device 110 may determine its own terminal device group and find a codeword set that is to be applied. In some example embodiments, the terminal device 110 may determine, from the plurality of terminal device groups, a target terminal device group to which the terminal device belongs. Then the terminal device 110 may determine whether a codeword set is to be applied to the plurality of symbol subgroups based on the target terminal device group. If yes, the terminal device 110 may determine, from a plurality of codeword sets, the codeword set that is to be applied. The determined codeword set is different from a codeword set that is applied to the plurality of symbol subgroups for a further terminal device. By applying the codeword set, the NPRACH symbol group may be determined (610) .

Then, the terminal device 110 transmits (620) an NPRACH signal comprising the determined NPRACH symbol group to the network device 120. By applying respective codewords to different terminal devices, terminal devices with and without code domain multiplexing capability can multiplex with each other for NPRACH transmission.

The network device 120 receives (630) the NPRACH signal from the terminal device 110, and then may spread and detect (640) the NPRACH signal. If the network device 120 has successfully detected the terminal device 110, it may transmit to the terminal device 120 a response indicating the successful detection.

In some cases, the network device 120 may receive overlapped NPRACH signals from multi-terminal devices and may spread and detect the overlapped NPRACH signals. Likewise, the network device 120 may transmit response (s) if it has successfully detected one or more the terminal devices.

With the proposed solution, terminal devices (e.g., UEs) with code domain multiplexing capabilities could multiplex each other for NPRACH transmission and double the network’s initial access capacities. Moreover, UEs with and without code domain multiplexing capability could multiplex with each other for NPRACH transmission and double the network’s initial access capacities.

FIGS. 7A to 7G illustrates schematic diagrams of patterns of NPRACH symbol group (s) in accordance with some embodiments of the present disclosure, respectively. Embodiments of FIGS. 7A to 7G are all relevant to how to insert the CP for symbol group level multiplexing.

In the following discussion, the terminal device 110 is discussed with the example of UE, and the terminal device group is discussed as UE group in some cases.

In general, the NPRACH symbol groups illustrated in FIGS. 7A to 7G each includes 6 symbols, in which the first symbol is CP (denoted as CP 1) and there are 5 remaining symbols after the CP, as illustrated by the symbol group 420 in FIG. 4A. As shown, the length of the CP 1 (or a symbol) is 8192 Ts. Ts is the sample duration for a communication system under subcarrier spacing equals to 15KHz and with FFT point equals to 2048. The value of Ts is 32.552 ns. In some embodiments of FIGS. 7A to 7C, the third (3^rd) symbol in the 5 remaining symbols may function as a further cyclic prefix (denoted as CP 2) or a normal symbol.

In embodiments of FIGS. 7A to 7C, the 3^rd symbol functions as a cyclic prefix, the 1^st symbol and the 2^nd symbol in the 5 remaining symbols may be consider as a first symbol subgroup and multiplexed with the first codewords in a codeword set. The 4^th symbol and the 5^th symbol in the 5 remaining symbols may be consider as a second symbol subgroup and multiplexed with the second code words in the codeword set.

In embodiments of FIGS. 7D to 7F, the 3^rd symbol functions as a normal symbol, the 1^st symbol and the 2^nd symbol in the 5 remaining symbols may be considered as a first symbol subgroup and multiplexed with the first codeword in a codeword set. The 3^rd symbol, the 4^th symbol and the 5^th symbol in the 5 remaining symbols may be considered as a second symbol subgroup and multiplexed with the second code word in the codeword set.

In embodiments of FIGS. 7A, 7B, 7D and 7E, two terminal device groups (also referred to as “UE groups” for purpose of discussion) may both have code domain multiplexing capabilities and may adopt different codewords sets. For example, the two UE groups may adopt a codeword set [+1 -1] and another codeword set [+1 +1] . In this way, symbols for different UE groups may be encoded in an orthogonal way.

In embodiments of FIGS. 7C and 7F, a terminal device with code domain multiplexing capability may adopts the codeword set [+1 -1] . No codeword or codeword set will be applied to a terminal device without the code domain multiplexing capability.

FIG. 7A illustrate first examples of a NPRACH symbol group for different UE groups, UE group A and UE group B. The NPRACH symbol group includes two CPs, that is, CP1 and CP2.

As shown in the UE group A Format 1, the UE in the first UE group (UE group A)The UE in the first UE group (UE group A) adopts a codeword (A1) from the first codeword set for the 1^st preamble symbol (S1) and 2^nd preamble symbol (S2) , and adopts a codeword (A2) from the first codeword set for the 4^th preamble symbol (S4) and 5^th preamble symbol (S5) , respectively.

As shown in the UE group B Format 1, the UE in the second UE group (UE group B) adopts a codeword (B1) from the second codeword set for the 1^st and 2^nd preamble symbols, and adopts another codeword (B2) from the second codeword set for the 4^th and 5^th preamble symbols, respectively.

Thus, in embodiments of FIG. 7A, for NPRACH multiplexing in the code domain, the third preamble symbol functions as a cyclic prefix (CP2) . For UE supports NPRACH multiplexing in the code domain, they belong to two separate UE groups based on their UE IDs.

For UEs in UE group A, they adopt the codewords in codeword set A, which includes codeword A1 and codeword A2, for code domain multiplexing. For UEs in UE group B, they adopt the codewords in codeword set B, which includes codeword B1 and codeword B2, for code domain multiplexing.

UEs belonging to different UE groups might randomly transmit NPRACH preambles in the same physical resources and overlap with each other.

In some embodiments, the network device 120 may indicate the support of NPRACH multiplexing in the code domain. Thus, the terminal device 110 may know the multiplexing supporting capability of the network device 120.

the network device 120, upon receiving the NPRACH signal including the NPRACH symbol group as shown in FIG. 7A, and may despread and detect the overlapped NPRACH signal from multi-terminals, as well as transmit the response if successfully detected the terminal (s) .

FIG. 7B illustrate second examples of a NPRACH symbol group for different UE groups, UE group A and UE group B. The embodiments shown in FIG. 7B are similar as those in FIG. 7A. Differently, in embodiments of FIG. 7B, the UE group A and the UE group B adopt [+1 -1] and [+1 +1] , respectively.

As shown in FIG. 7B, a UE in the first UE group adopts “+1” for the 1^st and 2^nd preamble symbols (S1 and S2) , and “-1” for the 4^th and 5^th preamble symbols (S4 and S5) , respectively. A UE in the second UE group adopts “+1” for the 1^st and 2^nd preamble symbols (S1 and S2) , and “+1” for the 4^th and 5^th preamble symbols (S4 and S5) , respectively.

FIG. 7C illustrate third examples of a NPRACH symbol group for different UE groups, UE group A and UE group B. In the embodiments of FIG. 7C, for NPRACH multiplexing in the code domain, the third preamble symbol functions as a cyclic prefix. For a UE supports NPRACH multiplexing in the code domain, it may adopt codeword +1 and codeword -1 for code domain multiplexing.

As shown in FIG. 7C, the UE with code domain multiplexing capabilities adopts “+1” for the 1^st and 2^nd preamble symbols, and “-1” for the 4^th and 5^th preamble symbols, respectively. The UE without code domain multiplexing capability and UE with code domain multiplexing capability can transmit the PRACH in the same physical resource.

For UE not supporting NPRACH multiplexing in the code domain and UE supporting NPRACH multiplexing in the code domain, they might randomly transmit NPRACH preambles in the same physical resources and overlap with each other.

FIG. 7D illustrate fourth examples of a NPRACH symbol group for different UE groups, UE group A and UE group B.

The UE in the first UE group adopts the codewords from the first codeword sets for the 1^st and 2^nd preamble symbol, and the 3^rd, 4^th and 5^th preamble symbol, respectively. The UE in the second UE group adopts the codewords from the second codeword sets for the 1^st and 2^nd preamble symbol, and the 3^rd , 4^th and 5^th preamble symbol, respectively.

In embodiments of FIG. 7D, for NPRACH multiplexing in the code domain, the first and second symbols (S1 and S2) are multiplexed with one codeword, and the third, fourth and fifth symbols (S4, S5 and S6) are multiplexed with another codeword.

For UE supports NPRACH multiplexing in the code domain, they belong to two separate groups based on their UE IDs. For UEs in group A, they adopt the codewords in codeword A, which includes codeword A1 and codeword A2, for code domain multiplexing. For UEs in group B, they adopt the codewords in codeword B, which includes codeword B1 and codeword B2, for code domain multiplexing.

In some implementations, the terminal device 110 (e.g., UE) determines its UE group by its UE ID. For UE within the UE group A, the first symbol and the second symbol of a PRACH symbol group multiplex with codeword A1; the third symbol, fourth symbol and fifth symbol of a PRACH symbol group multiplex with codeword A2.

For UE within the UE group B, the first symbol and the second symbol (S1 and S2) are multiplexed with codeword B1. The third symbol, fourth symbol and fifth symbol (S1, S2 and S3) are multiplexed with codeword B2.

FIG. 7E illustrate fifth examples of a NPRACH symbol group for different UE groups, UE group A and UE group B. The embodiments shown in FIG. 7E are similar as those in FIG. 7D. Differently, in embodiments of FIG. 7E, the UE group A and the UE group B adopt [+1 -1] and [+1 +1] , respectively. For UEs in group A, they adopt the codewords in codeword A, which includes codeword +1 and codeword -1, for code domain multiplexing. For UEs in group B, they adopt the codewords in codeword B, which includes codeword +1 and codeword -1, for code domain multiplexing.

Specifically, the UE in the first UE group adopts “+1” for the 1^st and 2^nd preamble symbols (S1 and S2) , and adopts “-1” for the 3^rd, 4^th and 5^th preamble symbols (S4, S5 and S6) , respectively. The UE in the second UE group adopts “+1” for the 1^st and 2^nd preamble symbol (S1 and S2) , and “+1” for the 3^rd, 4^th and 5^th preamble symbols (S4, S5 and S6) , respectively.

FIG. 7F illustrate sixth examples of a NPRACH symbol group for different UE groups, UE group A and UE group B. For NPRACH multiplexing in the code domain, the first and second symbols are multiplexed with the same codeword, and the third, fourth and fifth symbols are multiplexed with the same codeword. For UE supports NPRACH multiplexing in the code domain, they adopt codeword +1 and codeword -1 for code domain multiplexing.

Specifically, the UE with code domain multiplexing capabilities adopts “+1” for the 1^st and 2^nd preamble symbols (S1 and S2) , and “-1” for the 3^rd, 4^th and 5^th preamble symbols (S3, S4 and S5) , respectively. The UE without code domain multiplexing capability and UE with code domain multiplexing capability can transmit the PRACH in the same physical resource.

FIG. 7G illustrate seventh examples of a NPRACH symbol group for three different UE groups, UE group A, UE group B and UE group C. In embodiments of FIG. 7G, for NPRACH multiplexing in the code domain, in addition to the first CP (CP1) in the beginning of an NPRACH symbol group, the 2^nd symbol and 4^th symbol of the remaining 5 symbols may be function as a cyclic prefix. As shown, there may be three CPs in one NPRACH symbol group, that is, CP1, CP2, and CP3.

For UE which supports NPRACH multiplexing in the code domain, it may access the network by sending preambles in NPRACH format 1 with the 2^nd symbol and 4^th symbol of a PRACH symbol group functions as a cyclic prefix. The first symbol (S1) , third symbol (S3) , and fifth symbol (S5) may be multiplexed with indicated or predefined codewords.

In some implementations, the first symbol (S1) may be applied with a first codeword (A1) in the first codeword set for UE group A, the second symbol (S2) may be applied with a second codeword (A2) in the first codeword set, and the third symbol (S3) may be applied with a third codeword (A3) in the first codeword set.

In addition, the first symbol (S1) may be applied with a first codeword (B1) in the second codeword set for UE group B, the second symbol (S1) may be applied with a second codeword (B2) in the second codeword set, and the third symbol subgroup (S3) may be with a third codeword (B3) in the second codeword set.

Furthermore, the first symbol subgroup (S1) may be applied with a first codeword (C1) in the third codeword set for the UE group C and the second symbol (S2) may be applied with a second codeword (C2) in the third codeword set, and the third symbol (S3) may be applied with a third codeword (C3) in the third codeword set.

FIG. 8 illustrates a signaling flow 800 of a NPRACH transmission in accordance with some embodiments of the present disclosure. For purpose of discussion, the signaling flow 800 will be discussed with reference to FIG. 1, for example, by using the terminal device 110 and the network device 120. It is to be understood that although one terminal device 110 is illustrated in FIG. 8, the signal flow 800 may involves a plurality of terminal devices.

As shown, the terminal device 110 spreads (810) a NPRACH symbol group within an NPRACH repetition in a time-domain manner. The spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier.

Then, the terminal device 110 transmits (820) , to the network device 120, an NPRACH signal comprising the NPRACH symbol group and the spreading result.

The network device 120 receives (830) the NPRACH signal from the terminal device 110, and then may spread and detect (840) the NPRACH signal. If the network device 120 has successfully detected the terminal device 110, it may transmit to the terminal device 120 a response indicating the successful detection.

In some example embodiments, the NPRACH symbol group and the at least one symbol group in the spread result may be applied with respective codewords in a codeword set.

The codeword set may include 2 codewords, 4 codewords, or other suitable number of codewords. The number of the at least one symbol group immediately after the first NPRACH symbol group may be 1, 3, or other suitable number. For example, if the codeword set includes 2 codewords, the number of the at least one symbol group immediately after the first NPRACH symbol group may be 1. In another example, if the codeword set includes 4 codewords, the number of the at least one symbol group immediately after the first NPRACH symbol group may be 3.

In contrast to the conventional case where a symbol group in the occupied time duration is predetermined to be transmitted in a subcarrier adjacent to the subcarrier of the NPRACH symbol group, with the proposed solution, the transmission of a symbol group in the occupied time duration is skipped. As a result, the hop between the two symbol groups does not need any more.

FIG. 9A and 9B illustrate schematic diagrams of spreading patterns in accordance with some embodiments of the present disclosure, respectively.

FIG. 9A shows an example of spreading the 1^st symbol group and the 3^rd symbol group in the time domain without changing tones. Skip the 2^nd and the 4^th symbol group transmission. Each symbol group is spread with a code length =2.

In some embodiments, the network device 120 may indicate NPRACH multiplexing in code main with an inter-symbol group manner. The terminal device 110 may spread the 1st symbol group 901 and 3rd symbol group 903 of each repetition. The 1st and 3rd symbol may be both spread with the 1st and 2nd codeword in a codeword set. The spread result 902 of the 1st symbol group 901 and the spread result 904 of the 3rd symbol group 903 include spread symbols that take the time slot of each repetition's 2nd and 4th symbol group. The level-1 frequency hopping (hopping between two adjacent subcarriers) may be removed due to the spread operation.

Upon receiving the NPRACH signal including the NPRACH symbol group and the spreading result, the network device 120 may despread and detect the overlapped NPRACH signal from multi-terminals, and transmit the response if successfully detected any of the terminal (s) .

In this way, the time duration of each preamble repetition remains the same as legacy methods. Thus, the Level 1 hopping is skipped. The network can achieve the same accurate time of arrival estimation of the preambles due to no changes in other related frequency hopping, e.g., Level 2 hopping and Level 3 hopping.

As used herein, Level 1 Hopping may refer to a one subcarrier hopping, e.g. the hopping between the 1st and 2nd symbol group, and the 3rd and 4th symbol group. Level 2 Hopping may refer to a 6 subcarriers hopping, e.g. the hopping between the 2nd and 3rd symbol group. Level 3 Hopping may refer to a hopping between each repetition in a pseudo-random fashion within 12 contiguous subcarriers.

FIG. 9B shows another example of spreading the 1^st symbol group and the 3^rd symbol group in the time domain without changing tones. In the embodiments of FIG. 9B, the 2^nd and the 4^th symbol group transmissions are skipped. Each symbol group is spread with a code length =4.

Similar as FIG. 9A, in embodiments of FIG. 9B, the network device 120 may indicate NPRACH multiplexing in code main with an inter-symbol group manner. The terminal device 110 may spread the 1st symbol group 911 and 3rd symbol group 921 of each repetition. The spreading result of the symbol group 911 including symbol groups 912, 913 and 914. The spreading result of the symbol group 921 including symbol groups 922, 923 and 924.

The 1st symbol group 911 and 3rd symbol group 921 may be both spread with the 1st , 2nd , 3rd and 4th codeword in a codeword set. The 2nd symbol group and 4th symbol group of each repetition are removed. Each repetition of a spread preamble transmission takes twice the time duration of the original time duration.

In this way, the level-1 frequency hopping is removed due to the spread operation, and 4 times NPRACH capacity can be achieved. The network could achieve the same accurate time of arrival estimation of the preambles due to no changes in the level-2 and level-3 frequency hopping.

FIG. 10 illustrates a signaling flow 1000 of a NPRACH transmission in accordance with some embodiments of the present disclosure. For purpose of discussion, the signaling flow 1000 will be discussed with reference to FIG. 1, for example, by using the terminal device 110 and the network device 120. It is to be understood that although one terminal device 110 is illustrated in FIG. 10, the signal flow 1000 may involves a plurality of terminal devices.

As shown, terminal device 110 spreads (1010) a first narrowband physical random access channel (NPRACH) symbol group and a second NPRACH symbol group within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group.

In one case, the spreading result of the first NPRACH symbol group includes a first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group. Meanwhile, the spreading result of the second NPRACH symbol group includes a second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group.

Alternatively, in another case, the spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and the spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group.

The terminal device 110 transmits (1020) , to the network device 120, an NPRACH signal comprising the first NPRACH symbol group, the first spread symbol group, the second NPRACH symbol group and the second spread symbol group.

The network device 120 receives (1030) the NPRACH signal from the terminal device 110, and then may spread and detect (1040) the NPRACH signal. If the network device 120 has successfully detected the terminal device 110, it may transmit to the terminal device 120 a response indicating the successful detection.

In some example embodiments, there are a plurality of NPRACH transmission patterns overlapped with each other in an orthogonal sequence domain. The plurality of NPRACH transmission patterns may at least include a first NPRACH transmission pattern associated with a first number of terminal device groups and a second NPRACH transmission pattern associated with a second number of terminal device groups.

In some implementations, the first NPRACH symbol group and the second NPRACH symbol group may be spread based on one of the plurality of NPRACH transmission patterns. This NPRACH transmission pattern may be associated with a first terminal device group to which the terminal device belongs, and thus may be determined from the plurality of NPRACH transmission patterns based on information (such as identification ID) of the terminal device.

In some example embodiments, the terminal device 110 may determine a terminal device group (also referred to as “first terminal device group” for purpose of discussion) to which the terminal device belongs. Next, it may determine a target NPRACH transmission pattern corresponding to the first terminal device group , from the plurality of NPRACH transmission patterns. The terminal device 110 then may spread the NPRACH symbol group based on the target NPRACH transmission pattern.

In some example embodiments, codewords may be applied to the first NPRACH symbol group, the second NPRACH symbol group and their spreading results in various ways. In an example, the first NPRACH symbol group and the first spread symbol group may be applied with a first codeword and a second codeword in a codeword set respectively, and the second NPRACH symbol group and the second spread symbol group may be applied with the first codeword and the second codeword in the same codeword set respectively. The codeword set used in this case may at least comprise 2 codewords, for example, 2 or 4 codewords.

In another example, a codeword set including 4 codewords may be applied. Specifically, this codeword includes a first codeword, a second codeword, a third codeword, and a fourth codeword. The first NPRACH symbol group and the first spread symbol group may be applied with the first codeword and the second codeword, respectively. In the meanwhile, the second NPRACH symbol group and the second spread symbol group may be applied with the third codeword and the fourth codeword, respectively.

As such, the symbol group can be spread in both the time and frequency domain manner and transmit the preambles in two adjacent tones, which can double or quadruple the initial access capacity. FIG. 11A illustrates a schematic diagram of spreading patterns in accordance with some embodiments of the present disclosure. FIG. 11A shows 12 UE groups (UEG #0 to UEG #1) for purpose of discussion.

In FIG. 11A, the preamble transmission is spread into two subcarriers (also referred to as “tones” ) .

In some embodiments, the network device 120 may indicate NPRACH multiplexing in code main with an inter-symbol group manner.

The terminal device 110 may chooses the preamble for initial access by random selection or network indication. The chosen preamble may correspond to a subcarrier for its first preamble symbol group transmission in the first transmission.

For example, if the subcarrier is an even number (e.g. 0, 2, 4, 6, 8, 10) , the UE uses the Layer-1 NPRACH transmission pattern (UEG#0, 2, 4, 6, 8, 10) , which is also referred to as a Layer-1 pattern, indicated by “Layer-1” in FIG. 11A. If the subcarrier is an odd number (e.g. 1, 3, 5, 7, 9, 11) , the UE uses the Layer-2 NPRACH transmission pattern (UEG#1, 3, 5, 7, 9, 11) , which is also referred to as Layer-2 pattern, indicated by “Layer-2” in FIG. 11A. The Layer-1 pattern and the Layer-2 pattern as shown in FIG. 11A may be overlapped to each other in an orthogonal sequence domain.

Each symbol group may be spread in a time/frequency domain manner. In the frequency-domain, the 1st symbol group of one repetition is spread into the subcarrier of the 2nd symbol group of the same repetition. The 2nd symbol group of one repetition is spread into the subcarrier of the 1st symbol group of the same repetition. The 3rd symbol group of one repetition is spread into the subcarrier of the 4th symbol group of the same repetition. The 4th symbol group of one repetition is spread into the subcarrier of the 3rd symbol group of the same repetition.

In the time-domain, the 1st symbol group of one repetition is spread into the time slots of the 2nd symbol group of the same repetition. The 2nd symbol group of one repetition is spread into the time slots of the 1st symbol group of the same repetition. The 3rd symbol group of one repetition is spread into the time slots of the 4th symbol group of the same repetition. The 4th symbol group of one repetition is spread into the time slots of the 3rd symbol group of the same repetition.

As shown in FIG. 11A, in some embodiments, a first NPRACH symbol group 1101 and a second NPRACH symbol group 1104 are spread. Either the first NPRACH symbol group or second NPRACH symbol group includes 6 symbols, one CP and 5 symbols for transmission. The second NPRACH symbol group 1104 occupies a time duration immediately after the first NPRACH symbol group 1104 and an adjacent subcarrier (that is, subcarrier 1) to the subcarrier (that is, subcarrier 0) of the first NPRACH symbol group 1104. The spreading result of the first NPRACH symbol group 1101 may include a first spread symbol group 1102 occupying a time duration of the second NPRACH symbol group 1104 and a subcarrier (that is, subcarrier 0) of the first NPRACH symbol group 1101. The spreading result of the second NPRACH symbol group may include a second spread symbol group 1103 occupying a time duration of the first NPRACH symbol group 1101 and a subcarrier (that is, subcarrier 1) of the second NPRACH symbol group 1104.

Alternatively, in some embodiments, a first NPRACH symbol group 1101 and a second NPRACH symbol group 1102 are spread. The spreading result of the first NPRACH symbol group 1101 may include a first spread symbol group 1103, and the spreading result of the second NPRACH symbol group may include a second spread symbol group 1104.

The spreading length may be vary, for example, there may be length-2 spreading, length-4 spreading, and so son. As to the length-2 spreading, it involves the 1st symbol group and 2nd symbol group of one repetition can spread using the same codewords (length 2 spreading, e.g. A and B ) . The 3rd symbol group and 4th symbol group of one repetition can spread using the same codewords (length 2 spreading, e.g. A1 and B1 ) .

As to the length-4 spreading, it includes the 1st symbol group and 2nd symbol group of one repetition spread with 4 different codewords (length 4 spreading, e.g. A, B for the 1st symbol group, and C, D for the 2nd symbol group) ; and the 3rd symbol group and 4th symbol group of one repetition with 4 different codewords (length 4 spreading, e.g. A, B for the 3rd symbol group, and C, D for the 4th symbol group) .

As shown in FIG. 11A, assuming that the first NPRACH symbol group is the symbol group 1101 and the first spread symbol group is the symbol group 1102, they may be applied with a first codeword (A1) and a second codeword (A2) in a codeword set (A) , where the codeword set A comprises the two codewords A1 and A2. The second NPRACH symbol group 1104 and the second spread symbol group 1103 may be applied with the first codeword (A1) and the second codeword (A2) in the same codeword set.

In another example where the codeword set comprises 4 codewords (A1, A2, A3, A4) , the first NPRACH symbol group 1101 and the first spread symbol group 1102 may be applied with a first codeword (A1) and a second codeword (A2) in the codeword set, and the second NPRACH symbol group 1104 and the second spread symbol group 1103 may be applied with a third codeword (A3) and a fourth codeword (A4) in the same codeword set.

In this way, two times or four times NPRACH capacity can be achieved. The network may achieve the same accurate time of arrival estimation of the preambles due to no changes in the level-2 and level-3 frequency hopping.

FIG. 11B illustrates another schematic diagram of spreading patterns in accordance with some embodiments of the present disclosure. Most embodiments of FIG. 11B are similar as those in FIG. 11A, which are thus not repeated here. The main difference lies in that the patterns are described in terms of UE groups or UEs. In FIG. 11A, there are totally 12 UE groups (UEG#0 –UEG#11) , each UE group may include 2 UEs. For each UE group, 2 UEs can be multiplexed with each other orthogonally in the code domain. Differently, in FIG. 11B, there illustrates totally 24 UEs (UE#0 –UE#23) . In the case where the spreading length is 2, two of the 24 UEs may be multiplexed with each other orthogonally in the code domain.

FIG. 12 illustrates a flowchart of a communication method 1200 implemented at a terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1200 will be described from the perspective of the terminal device 110 in FIG. 1.

At block 1210, the terminal device 110 determines a narrowband physical random access channel (NPRACH) symbol group comprising a plurality of symbol subgroups based on a code domain multiplexing capability of the terminal device, wherein the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group.

At block 1220, the terminal device 110 transmits, to a network device, an NPRACH signal comprising the NPRACH symbol group.

In some example embodiments, the second terminal device group supports NPRACH multiplexing in the code domain, and the plurality of symbol subgroups are applied with a first codeword set for the first terminal device group and are applied with a second codeword set different from the first codeword set for the second terminal device group.

In some example embodiments, the plurality of symbol subgroups comprise a first symbol subgroup and a second symbol subgroup, the first symbol subgroup is applied with a first codeword in the first codeword set and the second symbol subgroup is applied with a second codeword in the first codeword set for the first terminal device group, and the first symbol subgroup is applied with a first codeword in the second codeword set and the second symbol subgroup is applied with a second codeword in the second codeword set for the second terminal device group.

In some example embodiments, the first codeword set is [+1 -1] and the second codeword set is [+1 +1] .

In some example embodiments, the second terminal device group does not support NPRACH multiplexing in the code domain, the plurality of symbol subgroups are applied with a first codeword set for the first terminal device group, and the first codeword set is [+1 -1] , and wherein no codeword set is applied to the plurality of symbol subgroups for the second terminal device group.

In some example embodiments, the plurality of terminal device groups further comprise a third terminal device group, the second terminal device group and the third terminal device group both support NPRACH multiplexing in the code domain, and the plurality of symbol subgroups are applied with a first codeword set for the first terminal device group, applied with a second codeword set different from the first codeword set for the second terminal device group, and applied with a third codeword set different from the first and second codeword sets for the third terminal device group.

In some example embodiments, the first symbol subgroup is applied with a first codeword in the first codeword set, the second symbol subgroup is applied with a second codeword in the first codeword set, and the third symbol subgroup is applied with a third codeword in the first codeword set. The first symbol subgroup is applied with a first codeword in the second codeword set and the second symbol subgroup is applied with a second codeword in the second codeword set, and the third symbol subgroup is applied with a third codeword in the second codeword set. The first symbol subgroup is applied with a first codeword in a third codeword set for the third terminal device group, the second symbol subgroup is applied with a second codeword in the third codeword set, and the third symbol subgroup is applied with the third codeword in the third codeword set.

In some example embodiments, the NPRACH symbol group is of a first format in which the NPRACH symbol group comprises a single Cyclic Prefix (CP) and the plurality of symbol subgroups, and wherein all of the plurality of symbol subgroups follow the CP.

In some example embodiments, the NPRACH symbol group is of a second format in which the NPRACH symbol group comprises a plurality of Cyclic Prefixes (CPs) and the plurality of symbol subgroups, and wherein each symbol subgroup immediately follows a corresponding CP and all of the plurality of symbol subgroups have the same number of symbols.

In some example embodiments, the terminal device is further caused to: determine, from the plurality of terminal device groups, a target terminal device group to which the terminal device belongs; determine whether a codeword set is to be applied to the plurality of symbol subgroups based on the target terminal device group; and in accordance with a determination that a codeword set is to be applied to the plurality of symbol subgroups, determine, from a plurality of codeword sets, the codeword set that is different from a codeword set applied to the plurality of symbol subgroups for a further terminal device.

FIG. 13 illustrates a flowchart of a communication method 1300 implemented at a terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1300 will be described from the perspective of the terminal device 110 in FIG. 1.

At block 1310, the terminal device 110 spreads a narrowband physical random access channel (NPRACH) symbol group within an NPRACH repetition in a time-domain manner, wherein a spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier.

At block 1320, the terminal device 110 transmits, to a network device, an NPRACH signal comprising the NPRACH symbol group and the spreading result.

In some example embodiments, transmission of a symbol group in the occupied time duration, which is predetermined to be performed in a subcarrier adjacent to the subcarrier of the NPRACH symbol group, is skipped.

In some example embodiments, the NPRACH symbol group and the at least one symbol group in the spread result are applied with respective codewords in a codeword set.

In some example embodiments, the codeword set comprises 2 or 4 codewords, and the number of the at least one symbol group immediately after the first NPRACH symbol group is 1 or 3.

FIG. 14 illustrates a flowchart of a communication method 1400 implemented at a terminal device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1400 will be described from the perspective of the terminal device 110 in FIG. 1.

At block 1410, the terminal device 110 spreads a first narrowband physical random access channel (NPRACH) symbol group and a second NPRACH symbol group within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group. A spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group. Alternatively, a spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group.

At block 1440, the terminal device 110 transmits, to a network device, an NPRACH signal comprising the first NPRACH symbol group, the first spread symbol group, the second NPRACH symbol group and the second spread symbol group.

In some example embodiments, the first NPRACH symbol group and the second NPRACH symbol group are spread based on a NPRACH transmission pattern associated with a first terminal device group to which the terminal device belongs, and the NPRACH transmission pattern belongs to a plurality of NPRACH transmission patterns overlapped with each other in an orthogonal sequence domain.

In some example embodiments, the plurality of NPRACH transmission patterns at least comprise a first NPRACH transmission pattern associated with a first number of terminal device groups and a second NPRACH transmission pattern associated with a second number of terminal device groups.

In some example embodiments, the terminal device is further caused to: determine a first terminal device group to which the terminal device belongs; determine, from the plurality of NPRACH transmission patterns, a target NPRACH transmission pattern corresponding to the first terminal device group; and spread the NPRACH symbol group based on the target NPRACH transmission pattern.

In some example embodiments, the first NPRACH symbol group and the first spread symbol group are applied with a first codeword and a second codeword in a codeword set respectively, and the second NPRACH symbol group and the second spread symbol group are applied with the first codeword and the second codeword in the same codeword set respectively, and wherein the codeword set at least comprises 2 codewords.

In some example embodiments, the codeword set comprises 4 codewords, the first NPRACH symbol group and the first spread symbol group are applied with a first codeword and a second codeword in a codeword set respectively, and the second NPRACH symbol group and the second spread symbol group are applied with a third codeword and a fourth codeword in the same codeword set respectively.

FIG. 15 illustrates a flowchart of a communication method 1500 implemented at a network device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1500 will be described from the perspective of the network device 120 in FIG. 1.

At block 1510, the network device 120 receives, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising an NPRACH symbol group. The NPRACH symbol group comprises a plurality of symbol subgroups determined based on a code domain multiplexing capability of the terminal device, the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group.

In some example embodiments, the network device is further caused to: determine, from the plurality of terminal device groups, a target terminal device group to which the terminal device belongs; determine, from a plurality of codeword sets, a codeword set corresponding to the target terminal device group; and decode the NPRACH signal based on the determined codeword set.

FIG. 16 illustrates a flowchart of a communication method 1600 implemented at a network device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1600 will be described from the perspective of the network device 120 in FIG. 1.

At block 1610, the network device 120 receives, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising an NPRACH symbol group and a spreading result of the NPRACH symbol group. The NPRACH symbol group is spread within an NPRACH repetition in a time-domain manner, the spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier.

FIG. 17 illustrates a flowchart of a communication method 1700 implemented at a network device in accordance with some embodiments of the present disclosure. For the purpose of discussion, the method 1700 will be described from the perspective of the network device 120 in FIG. 1.

At block 1710, the network device 120 receives, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising a first NPRACH symbol group, a first spread symbol group, a second NPRACH symbol group and a second spread symbol group, the first NPRACH symbol group and a second NPRACH symbol group being spread within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group. A spreading result of the first NPRACH symbol group comprises the first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises the second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group. Alternatively, a spreading result of the first NPRACH symbol group comprises the first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises the second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group.

In some example embodiments, the network device is further caused to: determine a first terminal device group to which the terminal device belongs; determine, from the plurality of NPRACH transmission patterns, a target NPRACH transmission pattern corresponding to the first terminal device group; and decode the NPRACH symbol group based on the target NPRACH transmission pattern.

FIG. 18 is a simplified block diagram of a device 1800 that is suitable for implementing embodiments of the present disclosure. The device 1800 can be considered as a further example implementation of any of the devices as shown in FIG. 1. Accordingly, the device 1800 can be implemented at or as at least a part of the terminal device 110 or the network device 120.

As shown, the device 1800 includes a processor 1810, a memory 1820 coupled to the processor 1810, a suitable transceiver 1840 coupled to the processor 1810, and a communication interface coupled to the transceiver 1840. The memory 1820 stores at least a part of a program 1830. The transceiver 1840 may be for bidirectional communications or a unidirectional communication based on requirements. The transceiver 1840 may include at least one of a transmitter 1842 and a receiver 1844. The transmitter 1842 and the receiver 1844 may be functional modules or physical entities. The transceiver 1840 has at least one antenna to facilitate communication, though in practice an Access Node mentioned in this application may have several ones. The communication interface may represent any interface that is necessary for communication with other network elements, such as X2/Xn interface for bidirectional communications between eNBs/gNBs, S1/NG interface for communication between a Mobility Management Entity (MME) /Access and Mobility Management Function (AMF) /SGW/UPF and the eNB/gNB, Un interface for communication between the eNB/gNB and a relay node (RN) , or Uu interface for communication between the eNB/gNB and a terminal device.

The program 1830 is assumed to include program instructions that, when executed by the associated processor 1810, enable the device 1800 to operate in accordance with the embodiments of the present disclosure, as discussed herein with reference to FIGS. 1 to 17. The embodiments herein may be implemented by computer software executable by the processor 1810 of the device 1800, or by hardware, or by a combination of software and hardware. The processor 1810 may be configured to implement various embodiments of the present disclosure. Furthermore, a combination of the processor 1810 and memory 1820 may form processing means 1850 adapted to implement various embodiments of the present disclosure.

The memory 1820 may be of any type suitable to the local technical network and may be implemented using any suitable data storage technology, such as a non-transitory computer readable storage medium, semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. While only one memory 1820 is shown in the device 1800, there may be several physically distinct memory modules in the device 1800. The processor 1810 may be of any type suitable to the local technical network, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1800 may have multiple processors, such as an application specific integrated circuit chip that is slaved in time to a clock which synchronizes the main processor.

According to embodiments of the present disclosure, a terminal device comprising a circuitry is provided. The circuitry is configured to: determine a narrowband physical random access channel (NPRACH) symbol group comprising a plurality of symbol subgroups based on a code domain multiplexing capability of the terminal device, wherein the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group; and transmit, to a network device, an NPRACH signal comprising the NPRACH symbol group. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the terminal device as discussed above.

According to embodiments of the present disclosure, a terminal device comprising a circuitry is provided. The circuitry is configured to: spread a narrowband physical random access channel (NPRACH) symbol group within an NPRACH repetition in a time-domain manner, wherein a spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier; and transmit, to a network device, an NPRACH signal comprising the NPRACH symbol group and the spreading result. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the terminal device as discussed above.

According to embodiments of the present disclosure, a terminal device comprising a circuitry is provided. The circuitry is configured to: spread a first narrowband physical random access channel (NPRACH) symbol group and a second NPRACH symbol group within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group, wherein a spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, or wherein a spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group; and transmit, to a network device, an NPRACH signal comprising the first NPRACH symbol group, the first spread symbol group, the second NPRACH symbol group and the second spread symbol group. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the terminal device as discussed above.

According to embodiments of the present disclosure, a network device comprising a circuitry is provided. The circuitry is configured to: receive, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising an NPRACH symbol group, wherein the NPRACH symbol group comprises a plurality of symbol subgroups determined based on a code domain multiplexing capability of the terminal device, the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the network device as discussed above.

According to embodiments of the present disclosure, a network device comprising a circuitry is provided. The circuitry is configured to: receive, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising an NPRACH symbol group and a spreading result of the NPRACH symbol group, wherein the NPRACH symbol group is spread within an NPRACH repetition in a time-domain manner, the spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the network device as discussed above.

According to embodiments of the present disclosure, a network device comprising a circuitry is provided. The circuitry is configured to: receive, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising a first NPRACH symbol group, a first spread symbol group, a second NPRACH symbol group and a second spread symbol group, the first NPRACH symbol group and a second NPRACH symbol group being spread within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group, wherein a spreading result of the first NPRACH symbol group comprises the first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises the second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, or wherein a spreading result of the first NPRACH symbol group comprises the first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises the second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group. According to embodiments of the present disclosure, the circuitry may be configured to perform any method implemented by the network device as discussed above.

The term “circuitry” used herein may refer to hardware circuits and/or combinations of hardware circuits and software. For example, the circuitry may be a combination of analog and/or digital hardware circuits with software/firmware. As a further example, the circuitry may be any portions of hardware processors with software including digital signal processor (s) , software, and memory (ies) that work together to cause an apparatus, such as a terminal device or a network device, to perform various functions. In a still further example, the circuitry may be hardware circuits and or processors, such as a microprocessor or a portion of a microprocessor, that requires software/firmware for operation, but the software may not be present when it is not needed for operation. As used herein, the term circuitry also covers an implementation of merely a hardware circuit or processor (s) or a portion of a hardware circuit or processor (s) and its (or their) accompanying software and/or firmware.

According to embodiments of the present disclosure, a terminal apparatus is provided. The terminal apparatus comprises means for determining a narrowband physical random access channel (NPRACH) symbol group comprising a plurality of symbol subgroups based on a code domain multiplexing capability of the terminal device, wherein the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group; and means for transmitting, to a network device, an NPRACH signal comprising the NPRACH symbol group. In some embodiments, the first apparatus may comprise means for performing the respective operations of the method 1200. In some example embodiments, the first apparatus may further comprise means for performing other operations in some example embodiments of the method 1200. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

According to embodiments of the present disclosure, a terminal apparatus is provided. The terminal apparatus comprises means for spreading a narrowband physical random access channel (NPRACH) symbol group within an NPRACH repetition in a time-domain manner, wherein a spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier; and means for transmitting, to a network device, an NPRACH signal comprising the NPRACH symbol group and the spreading result. In some embodiments, the second apparatus may comprise means for performing the respective operations of the method 1300. In some example embodiments, the second apparatus may further comprise means for performing other operations in some example embodiments of the method 1300. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

According to embodiments of the present disclosure, a terminal apparatus is provided. The terminal apparatus comprises means for spreading a first narrowband physical random access channel (NPRACH) symbol group and a second NPRACH symbol group within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group, means for wherein a spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, or means for wherein a spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group; and means for transmitting, to a network device, an NPRACH signal comprising the first NPRACH symbol group, the first spread symbol group, the second NPRACH symbol group and the second spread symbol group. In some embodiments, the third apparatus may comprise means for performing the respective operations of the method 1400. In some example embodiments, the third apparatus may further comprise means for performing other operations in some example embodiments of the method 1400. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

According to embodiments of the present disclosure, a network apparatus is provided. The network apparatus comprises means for receiving, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising an NPRACH symbol group, means for wherein the NPRACH symbol group comprises a plurality of symbol subgroups determined based on a code domain multiplexing capability of the terminal device, the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group. In some embodiments, the fourth apparatus may comprise means for performing the respective operations of the method 1500. In some example embodiments, the fourth apparatus may further comprise means for performing other operations in some example embodiments of the method 1500. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

According to embodiments of the present disclosure, a network apparatus is provided. The network apparatus comprises means for receiving, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising an NPRACH symbol group and a spreading result of the NPRACH symbol group, means for wherein the NPRACH symbol group is spread within an NPRACH repetition in a time-domain manner, the spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier. In some embodiments, the fifth apparatus may comprise means for performing the respective operations of the method 1600. In some example embodiments, the fifth apparatus may further comprise means for performing other operations in some example embodiments of the method 1600. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

According to embodiments of the present disclosure, a network apparatus is provided. The network apparatus comprises means for receiving, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising a first NPRACH symbol group, a first spread symbol group, a second NPRACH symbol group and a second spread symbol group, the first NPRACH symbol group and a second NPRACH symbol group being spread within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group, means for wherein a spreading result of the first NPRACH symbol group comprises the first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises the second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, or means for wherein a spreading result of the first NPRACH symbol group comprises the first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises the second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group. In some embodiments, the sixth apparatus may comprise means for performing the respective operations of the method 1700. In some example embodiments, the sixth apparatus may further comprise means for performing other operations in some example embodiments of the method 1700. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In summary, embodiments of the present disclosure provide the following aspects.

In an aspect, it is proposed a terminal device comprising: a processor configured to cause the terminal device to: determine a narrowband physical random access channel (NPRACH) symbol group comprising a plurality of symbol subgroups based on a code domain multiplexing capability of the terminal device, wherein the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group; and transmit, to a network device, an NPRACH signal comprising the NPRACH symbol group.

In some embodiments, the second terminal device group supports NPRACH multiplexing in the code domain, and the plurality of symbol subgroups are applied with a first codeword set for the first terminal device group and are applied with a second codeword set different from the first codeword set for the second terminal device group.

In some embodiments, the plurality of symbol subgroups comprise a first symbol subgroup and a second symbol subgroup, the first symbol subgroup is applied with a first codeword in the first codeword set and the second symbol subgroup is applied with a second codeword in the first codeword set for the first terminal device group, and the first symbol subgroup is applied with a first codeword in the second codeword set and the second symbol subgroup is applied with a second codeword in the second codeword set for the second terminal device group.

In some embodiments, the first codeword set is [+1 -1] and the second codeword set is [+1 +1] .

In some embodiments, the second terminal device group does not support NPRACH multiplexing in the code domain, the plurality of symbol subgroups are applied with a first codeword set for the first terminal device group, and the first codeword set is [+1 -1] , and wherein no codeword set is applied to the plurality of symbol subgroups for the second terminal device group.

In some embodiments, the plurality of terminal device groups further comprise a third terminal device group, the second terminal device group and the third terminal device group both support NPRACH multiplexing in the code domain, and the plurality of symbol subgroups are applied with a first codeword set for the first terminal device group, applied with a second codeword set different from the first codeword set for the second terminal device group, and applied with a third codeword set different from the first and second codeword sets for the third terminal device group.

In some embodiments, the first symbol subgroup is applied with a first codeword in the first codeword set, the second symbol subgroup is applied with a second codeword in the first codeword set, and the third symbol subgroup is applied with a third codeword in the first codeword set. The first symbol subgroup is applied with a first codeword in the second codeword set and the second symbol subgroup is applied with a second codeword in the second codeword set, and the third symbol subgroup is applied with a third codeword in the second codeword set. The first symbol subgroup is applied with a first codeword in a third codeword set for the third terminal device group, the second symbol subgroup is applied with a second codeword in the third codeword set, and the third symbol subgroup is applied with the third codeword in the third codeword set.

In some embodiments, the NPRACH symbol group is of a first format in which the NPRACH symbol group comprises a single Cyclic Prefix (CP) and the plurality of symbol subgroups, and wherein all of the plurality of symbol subgroups follow the CP.

In some embodiments, the NPRACH symbol group is of a second format in which the NPRACH symbol group comprises a plurality of Cyclic Prefixes (CPs) and the plurality of symbol subgroups, and wherein each symbol subgroup immediately follows a corresponding CP and all of the plurality of symbol subgroups have the same number of symbols.

In some embodiments, the terminal device is further caused to: determine, from the plurality of terminal device groups, a target terminal device group to which the terminal device belongs; determine whether a codeword set is to be applied to the plurality of symbol subgroups based on the target terminal device group; and in accordance with a determination that a codeword set is to be applied to the plurality of symbol subgroups, determine, from a plurality of codeword sets, the codeword set that is different from a codeword set applied to the plurality of symbol subgroups for a further terminal device.

In an aspect, it is proposed a terminal device comprising: a processor configured to cause the terminal device to: spread a narrowband physical random access channel (NPRACH) symbol group within an NPRACH repetition in a time-domain manner, wherein a spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier; and transmit, to a network device, an NPRACH signal comprising the NPRACH symbol group and the spreading result.

In some embodiments, transmission of a symbol group in the occupied time duration, which is predetermined to be performed in a subcarrier adjacent to the subcarrier of the NPRACH symbol group, is skipped.

In some embodiments, the NPRACH symbol group and the at least one symbol group in the spread result are applied with respective codewords in a codeword set.

In some embodiments, the codeword set comprises 2 or 4 codewords, and the number of the at least one symbol group immediately after the first NPRACH symbol group is 1 or 3.

In an aspect, it is proposed a terminal device comprising: a processor configured to cause the terminal device to: spread a first narrowband physical random access channel (NPRACH) symbol group and a second NPRACH symbol group within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group, wherein a spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, or wherein a spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group; and transmit, to a network device, an NPRACH signal comprising the first NPRACH symbol group, the first spread symbol group, the second NPRACH symbol group and the second spread symbol group.

In some embodiments, the first NPRACH symbol group and the second NPRACH symbol group are spread based on a NPRACH transmission pattern associated with a first terminal device group to which the terminal device belongs, and the NPRACH transmission pattern belongs to a plurality of NPRACH transmission patterns overlapped with each other in an orthogonal sequence domain.

In some embodiments, the plurality of NPRACH transmission patterns at least comprise a first NPRACH transmission pattern associated with a first number of terminal device groups and a second NPRACH transmission pattern associated with a second number of terminal device groups.

In some embodiments, the terminal device is further caused to: determine a first terminal device group to which the terminal device belongs; determine, from the plurality of NPRACH transmission patterns, a target NPRACH transmission pattern corresponding to the first terminal device group; and spread the NPRACH symbol group based on the target NPRACH transmission pattern.

In some embodiments, the first NPRACH symbol group and the first spread symbol group are applied with a first codeword and a second codeword in a codeword set respectively, and the second NPRACH symbol group and the second spread symbol group are applied with the first codeword and the second codeword in the same codeword set respectively, and wherein the codeword set at least comprises 2 codewords.

In some embodiments, the codeword set comprises 4 codewords, the first NPRACH symbol group and the first spread symbol group are applied with a first codeword and a second codeword in a codeword set respectively, and the second NPRACH symbol group and the second spread symbol group are applied with a third codeword and a fourth codeword in the same codeword set respectively.

In an aspect, it is proposed a network device comprising: a processor configured to cause the network device to: receive, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising an NPRACH symbol group, wherein the NPRACH symbol group comprises a plurality of symbol subgroups determined based on a code domain multiplexing capability of the terminal device, the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group.

In some embodiments, the network device is further caused to: determine, from the plurality of terminal device groups, a target terminal device group to which the terminal device belongs; determine, from a plurality of codeword sets, a codeword set corresponding to the target terminal device group; and decode the NPRACH signal based on the determined codeword set.

In an aspect, it is proposed a network device comprising: a processor configured to cause the network device to: receive, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising an NPRACH symbol group and a spreading result of the NPRACH symbol group, wherein the NPRACH symbol group is spread within an NPRACH repetition in a time-domain manner, the spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier.

In an aspect, it is proposed a network device comprising: a processor configured to cause the network device to: receive, from a terminal device, a narrowband physical random access channel (NPRACH) signal comprising a first NPRACH symbol group, a first spread symbol group, a second NPRACH symbol group and a second spread symbol group, the first NPRACH symbol group and a second NPRACH symbol group being spread within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group, wherein a spreading result of the first NPRACH symbol group comprises the first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises the second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, or wherein a spreading result of the first NPRACH symbol group comprises the first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises the second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group.

In some embodiments, the network device is further caused to: determine a first terminal device group to which the terminal device belongs; determine, from the plurality of NPRACH transmission patterns, a target NPRACH transmission pattern corresponding to the first terminal device group; and decode the NPRACH symbol group based on the target NPRACH transmission pattern.

In an aspect, a terminal device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the terminal device discussed above.

In an aspect, a network device comprises: at least one processor; and at least one memory coupled to the at least one processor and storing instructions thereon, the instructions, when executed by the at least one processor, causing the device to perform the method implemented by the network device discussed above.

In an aspect, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the terminal device discussed above.

In an aspect, a computer readable medium having instructions stored thereon, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the network device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the terminal device discussed above.

In an aspect, a computer program comprising instructions, the instructions, when executed on at least one processor, causing the at least one processor to perform the method implemented by the network device discussed above.

Generally, various embodiments of the present disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representation, it will be appreciated that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The present disclosure also provides at least one computer program product tangibly stored on a non-transitory computer readable storage medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor, to carry out the process or method as described above with reference to FIGS. 1 to 18. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, or the like that perform particular tasks or implement particular abstract data types. The functionality of the program modules may be combined or split between program modules as desired in various embodiments. Machine-executable instructions for program modules may be executed within a local or distributed device. In a distributed device, program modules may be located in both local and remote storage media.

Program code for carrying out methods of the present disclosure may be written in any combination of one or more programming languages. These program codes may be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the processor or controller, cause the functions/operations specified in the flowcharts and/or block diagrams to be implemented. The program code may execute entirely on a machine, partly on the machine, as a stand-alone software package, partly on the machine and partly on a remote machine or entirely on the remote machine or server.

The above program code may be embodied on a machine readable medium, which may be any tangible medium that may contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine readable medium may be a machine readable signal medium or a machine readable storage medium. A machine readable medium may include but not limited to an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing. More specific examples of the machine readable storage medium would include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a random access memory (RAM) , a read-only memory (ROM) , an erasable programmable read-only memory (EPROM or Flash memory) , an optical fiber, a portable compact disc read-only memory (CD-ROM) , an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

Further, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In certain circumstances, multitasking and parallel processing may be advantageous. Likewise, while several specific implementation details are contained in the above discussions, these should not be construed as limitations on the scope of the present disclosure, but rather as descriptions of features that may be specific to particular embodiments. Certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment may also be implemented in multiple embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in language specific to structural features and/or methodological acts, it is to be understood that the present disclosure defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

A terminal device comprising:

a processor configured to cause the terminal device to:

determine a narrowband physical random access channel (NPRACH) symbol group comprising a plurality of symbol subgroups based on a code domain multiplexing capability of the terminal device, wherein the symbol subgroups are used for a plurality of terminal device groups, and the plurality of terminal device groups at least comprise a first terminal device group supporting NPRACH multiplexing in the code domain and a second terminal device group; and

transmit, to a network device, an NPRACH signal comprising the NPRACH symbol group.
The device of claim 1, wherein the second terminal device group supports NPRACH multiplexing in the code domain, and the plurality of symbol subgroups are applied with a first codeword set for the first terminal device group and are applied with a second codeword set different from the first codeword set for the second terminal device group.
The device of claim 2, wherein the plurality of symbol subgroups comprise a first symbol subgroup and a second symbol subgroup,

the first symbol subgroup is applied with a first codeword in the first codeword set and the second symbol subgroup is applied with a second codeword in the first codeword set for the first terminal device group, and

the first symbol subgroup is applied with a first codeword in the second codeword set and the second symbol subgroup is applied with a second codeword in the second codeword set for the second terminal device group.
The device of claim 2 or 3, wherein the first codeword set is [+1 -1] and the second codeword set is [+1 +1] .
The device of claim 1, wherein the second terminal device group does not support NPRACH multiplexing in the code domain, the plurality of symbol subgroups are applied with a first codeword set for the first terminal device group, and the first codeword set is [+1 -1] , and

wherein no codeword set is applied to the plurality of symbol subgroups for the second terminal device group.
The device of claim 1, wherein the plurality of terminal device groups further comprise a third terminal device group,

the second terminal device group and the third terminal device group both support NPRACH multiplexing in the code domain, and

the plurality of symbol subgroups are applied with a first codeword set for the first terminal device group, applied with a second codeword set different from the first codeword set for the second terminal device group, and applied with a third codeword set different from the first and second codeword sets for the third terminal device group.
The device of claim 6, wherein the first symbol subgroup is applied with a first codeword in the first codeword set, the second symbol subgroup is applied with a second codeword in the first codeword set, and the third symbol subgroup is applied with a third codeword in the first codeword set,

the first symbol subgroup is applied with a first codeword in the second codeword set and the second symbol subgroup is applied with a second codeword in the second codeword set, and the third symbol subgroup is applied with a third codeword in the second codeword set, and

the first symbol subgroup is applied with a first codeword in a third codeword set for the third terminal device group, the second symbol subgroup is applied with a second codeword in the third codeword set, and the third symbol subgroup is applied with the third codeword in the third codeword set.
The device of any of claims 1 to 7, wherein the NPRACH symbol group is of a first format in which the NPRACH symbol group comprises a single Cyclic Prefix (CP) and the plurality of symbol subgroups, and wherein all of the plurality of symbol subgroups follow the CP.
The device of any of claims 1 to 7, wherein the NPRACH symbol group is of a second format in which the NPRACH symbol group comprises a plurality of Cyclic Prefixes (CPs) and the plurality of symbol subgroups, and wherein each symbol subgroup immediately follows a corresponding CP and all of the plurality of symbol subgroups have the same number of symbols.
The device of any of claims 1 to 9, wherein the terminal device is further caused to:

determine, from the plurality of terminal device groups, a target terminal device group to which the terminal device belongs;

determine whether a codeword set is to be applied to the plurality of symbol subgroups based on the target terminal device group; and

in accordance with a determination that a codeword set is to be applied to the plurality of symbol subgroups, determine, from a plurality of codeword sets, the codeword set that is different from a codeword set applied to the plurality of symbol subgroups for a further terminal device.
A terminal device comprising:

a processor configured to cause the terminal device to:

spread a narrowband physical random access channel (NPRACH) symbol group within an NPRACH repetition in a time-domain manner, wherein a spreading result of the NPRACH symbol group occupies a time duration of at least one symbol group immediately after the NPRACH symbol group, and the spreading result and the NPRACH symbol group are in the same subcarrier; and

transmit, to a network device, an NPRACH signal comprising the NPRACH symbol group and the spreading result.
The device of claim 11, wherein transmission of a symbol group in the occupied time duration, which is predetermined to be performed in a subcarrier adjacent to the subcarrier of the NPRACH symbol group, is skipped.
The device of claim 11, wherein the NPRACH symbol group and the at least one symbol group in the spread result are applied with respective codewords in a codeword set.
The device of claim 13, wherein the codeword set comprises 2 or 4 codewords, and the number of the at least one symbol group immediately after the first NPRACH symbol group is 1 or 3.
A terminal device comprising:

a processor configured to cause the terminal device to:

spread a first narrowband physical random access channel (NPRACH) symbol group and a second NPRACH symbol group within an NPRACH repetition, the second NPRACH symbol group occupying a time duration immediately after the first NPRACH symbol group and an adjacent subcarrier to the first NPRACH symbol group,

wherein a spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH

symbol group, or

wherein a spreading result of the first NPRACH symbol group comprises a first spread symbol group occupying a time duration of the first NPRACH symbol group and a subcarrier of the second NPRACH symbol group, and a spreading result of the second NPRACH symbol group comprises a second spread symbol group occupying a time duration of the second NPRACH symbol group and a subcarrier of the first NPRACH symbol group; and

transmit, to a network device, an NPRACH signal comprising the first NPRACH symbol group, the first spread symbol group, the second NPRACH symbol group and the second spread symbol group.
The device of claim 15, wherein the first NPRACH symbol group and the second NPRACH symbol group are spread based on a NPRACH transmission pattern associated with a first terminal device group to which the terminal device belongs, and the NPRACH transmission pattern belongs to a plurality of NPRACH transmission patterns overlapped with each other in an orthogonal sequence domain.
The device of claim 16, wherein the plurality of NPRACH transmission patterns at least comprise a first NPRACH transmission pattern associated with a first number of terminal device groups and a second NPRACH transmission pattern associated with a second number of terminal device groups.
The device of claim 16 or 17, wherein the terminal device is further caused to:

determine a first terminal device group to which the terminal device belongs;

determine, from the plurality of NPRACH transmission patterns, a target NPRACH transmission pattern corresponding to the first terminal device group; and

spread the NPRACH symbol group based on the target NPRACH transmission pattern.
The device of any of claims 15 to 18, wherein the first NPRACH symbol group and the first spread symbol group are applied with a first codeword and a second codeword in a codeword set respectively, and the second NPRACH symbol group and the second spread symbol group are applied with the first codeword and the second codeword in the same codeword set respectively, and

wherein the codeword set at least comprises 2 codewords.
The device of claim 19, wherein the codeword set comprises 4 codewords,

the first NPRACH symbol group and the first spread symbol group are applied with a first codeword and a second codeword in a codeword set respectively, and the second NPRACH symbol group and the second spread symbol group are applied with a third codeword and a fourth codeword in the same codeword set respectively.