WO2025213432A1

WO2025213432A1 - Random access channel transmission in subband non-overlapping full duplex

Info

Publication number: WO2025213432A1
Application number: PCT/CN2024/087351
Authority: WO
Inventors: Karim KASAN; Nhat-Quang NHAN; Guillermo POCOVI; Youngsoo Yuk; Jingyuan Sun; Jie Gao
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy; Nokia Technologies Oy
Priority date: 2024-04-11
Filing date: 2024-04-11
Publication date: 2025-10-16
Anticipated expiration: 2026-10-11

Abstract

Example embodiments of the present disclosure relate to apparatuses, methods and computer readable storage medium for random access channel (RACH) transmission in subband non-overlapping full duplex (SBFD). In a method, configuration information for random access channel, RACH, transmissions is received from a second apparatus by a first apparatus. A RACH configuration is determined by the first apparatus based on the configuration information. A metric indicates a coverage state of the first apparatus. Further, a random access preamble is transmitted to the second apparatus by the first apparatus based on the determined RACH configuration.

Description

RANDOM ACCESS CHANNEL TRANSMISSION IN SUBBAND NON-OVERLAPPING FULL DUPLEX

FIELD

Various example embodiments of the present disclosure generally relate to the field of telecommunication and in particular, to apparatuses, methods and computer readable storage medium for random access channel (RACH) transmission in subband non-overlapping full duplex (SBFD) .

BACKGROUND

Currently, the new radio (NR) supports two duplexing modes: Frequency Division Duplex (FDD) for paired bands and Time Division Duplex (TDD) for unpaired bands. In TDD, the time domain resource is split between downlink and uplink. Consequently, the allocation time duration is limited for the uplink in TDD, resulting in reduced coverage, increased latency, and reduced capacity.

To address the challenges above, a study on the evolution of duplexing operation in NR has been initiated. Subband non-overlapping full duplex (SBFD) has been proposed as a scheme of an enhanced duplex operation. In the SBFD, simultaneous downlink (DL) transmission and uplink (UL) reception at a new radio (NR) NodeB (also referred to as a gNB) on different physical resource blocks (PRBs) within an unpaired wideband NR cell is allowed. This duplexing scheme is also referred to as cross-division duplexing (xDD) or Flexible Duplexing (FDU) .

SUMMARY

In a first aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises at least one processor; and at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to: receive, from a second apparatus, configuration information for random access channel, RACH, transmissions; determine a RACH configuration based on the configuration information and a metric indicating a coverage state of the first apparatus, the determined RACH configuration being associated with a first preamble transmission duration or a second preamble transmission duration greater than the first preamble transmission duration; and transmit, to the second apparatus, a random access preamble based on the determined RACH configuration.

In a second aspect of the present disclosure, there is provided a method. The method comprises: receiving, from a second apparatus, configuration information for random access channel, RACH, transmissions; determining a RACH configuration based on the configuration information and a metric indicating a coverage state of the first apparatus, the determined RACH configuration being associated with a first preamble transmission duration or a second preamble transmission duration greater than the first preamble transmission duration; and transmitting, to the second apparatus, a random access preamble based on the determined RACH configuration.

In a third aspect of the present disclosure, there is provided a first apparatus. The first apparatus comprises means for receiving, from a second apparatus, configuration information for random access channel, RACH, transmissions; means for determining a RACH configuration based on the configuration information and a metric indicating a coverage state of the first apparatus, the determined RACH configuration being associated with a first preamble transmission duration or a second preamble transmission duration greater than the first preamble transmission duration; and means for transmitting, to the second apparatus, a random access preamble based on the determined RACH configuration.

In a fourth aspect of the present disclosure, there is provided a computer readable medium. The computer readable medium comprises instructions stored thereon for causing an apparatus to perform at least the method according to the second aspect.

It is to be understood that the Summary section is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

Some example embodiments will now be described with reference to the accompanying drawings, where:

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

FIG. 1B illustrates a block of example duplexing modes;

FIG. 1C illustrates a block of SBFD resources and non-SBFD resources;

FIG. 2A illustrates a 4-step RACH procedure;

FIG. 2B illustrates a 2-step RACH procedure;

FIG. 3 illustrates a diagram of an example of time-domain resource determination for RACH occasions (ROs) ;

FIG. 4A illustrates an example diagram of long or short PRACH ROs configuration alternatives;

FIG. 4B illustrates an example diagram of PRACH long format overhead;

FIG. 4C illustrates an example diagram of PRACH short format overhead;

FIG. 5 illustrates a signaling flow of RACH transmissions in accordance with some example embodiments of the present disclosure;

FIG. 6 illustrates a diagram of example zones in accordance with some example embodiments of the present disclosure;

FIG. 7A illustrates an example RACH configuration for a short format in accordance with some example embodiments of the present disclosure;

FIG. 7B illustrates two example RACH configurations for a short format in accordance with some example embodiments of the present disclosure;

FIG. 7C illustrates an example RACH configuration for a long format in accordance with some example embodiments of the present disclosure;

FIG. 7D illustrates two example RACH configurations for a long format in accordance with some example embodiments of the present disclosure;

FIG. 8A illustrates an example diagram of UEs located in the first zone;

FIG. 8B illustrates an example diagram of UEs located in two different zones;

FIG. 9A illustrates a common RACH configuration in accordance with some example embodiments of the present disclosure;

FIG. 9B illustrates an example PCI table in accordance with some example embodiments of the present disclosure;

FIG. 9C illustrates another example PCI table in accordance with some example embodiments of the present disclosure;

FIG. 9D illustrates an example diagram of a mapping between time durations and long formats in accordance with some example embodiments of the present disclosure;

FIG. 10A illustrates a flowchart of a first algorithm in accordance with some example embodiments of the present disclosure;

FIG. 10B illustrates a signaling flow of an example process of RACH transmission in SBFD in accordance with some example embodiments of the present disclosure;

FIG. 11A illustrates a flowchart of a second algorithm in accordance with some example embodiments of the present disclosure;

FIG. 11B illustrates a signaling flow of an example process of RACH transmission in SBFD in accordance with some example embodiments of the present disclosure;

FIG. 12A illustrates a flowchart of a third algorithm in accordance with some example embodiments of the present disclosure;

FIG. 12B illustrates a signaling flow of an example process of RACH transmission in SBFD in accordance with some example embodiments of the present disclosure;

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

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

FIG. 15 illustrates a simplified block diagram of a device that is suitable for implementing example embodiments of the present disclosure; and

FIG. 16 illustrates a block diagram of an example computer readable medium in accordance with some 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.

References in the present disclosure to “one embodiment, ” “an embodiment, ” “an example embodiment, ” and the like indicate that the embodiment described may include a particular feature, structure, or characteristic, but it is not necessary that every embodiment includes the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

It shall be understood that although the terms “first, ” “second, ” …, etc. in front of noun (s) and the like may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another and they do not limit the order of the noun (s) . For example, a first element could be termed a second element, and similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

As used herein, “at least one of the following: <a list of two or more elements>” and “at least one of <a list of two or more elements>” and similar wording, where the list of two or more elements are joined by “and” or “or” , mean at least any one of the elements, or at least any two or more of the elements, or at least all the elements.

As used herein, unless stated explicitly, performing a step “in response to A” does not indicate that the step is performed immediately after “A” occurs and one or more intervening steps may be included.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. 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. It will be further understood that the terms “comprises” , “comprising” , “has” , “having” , “includes” and/or “including” , when used herein, specify the presence of stated features, elements, and/or components etc., but do not preclude the presence or addition of one or more other features, elements, components and/or combinations thereof.

As used in this application, the term “circuitry” may refer to one or more or all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) combinations of hardware circuits and software, such as (as applicable) :

(i) a combination of analog and/or digital hardware circuit (s) with software/firmware and

(ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as a mobile phone or server, to perform various functions) and

(c) hardware circuit (s) and or processor (s) , such as a microprocessor (s) or a portion of a microprocessor (s) , that requires software (e.g., firmware) for operation, but the software may not be present when it is not needed for operation.

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example and if applicable to the particular claim element, a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in server, a cellular network device, or other computing or network device.

As used herein, the term “communication network” refers to a network following any suitable communication standards, such as New Radio (NR) , Long Term Evolution (LTE) , LTE-Advanced (LTE-A) , Wideband Code Division Multiple Access (WCDMA) , High-Speed Packet Access (HSPA) , Narrow Band Internet of Things (NB-IoT) and so on. Furthermore, the communications between a terminal device and a network device in the communication network may be performed according to any suitable generation communication protocols, including, 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) , 5.5G, the sixth generation (6G) communication protocols, and/or any other protocols either currently known or to be developed in the future. Embodiments of the present disclosure may be applied in various communication systems. Given the rapid development in communications, there will of course also be future type communication technologies and systems with which the present disclosure may be embodied. It should not be seen as limiting the scope of the present disclosure to only the aforementioned system.

As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP) , for example, a node B (NodeB or NB) , an evolved NodeB (eNodeB or eNB) , an NR NB (also referred to as a gNB) , a Remote Radio Unit (RRU) , a radio header (RH) , a remote radio head (RRH) , a relay, an Integrated Access and Backhaul (IAB) node, a low power node such as a femto, a pico, a non-terrestrial network (NTN) or non-ground network device such as a satellite network device, a low earth orbit (LEO) satellite and a geosynchronous earth orbit (GEO) satellite, an aircraft network device, and so forth, depending on the applied terminology and technology. In some example embodiments, radio access network (RAN) split architecture comprises a Centralized Unit (CU) and a Distributed Unit (DU) at an IAB donor node. An IAB node comprises a Mobile Terminal (IAB-MT) part that behaves like a UE toward the parent node, and a DU part of an IAB node behaves like a base station toward the next-hop IAB node.

The term “terminal device” refers to any end device that may be capable of wireless communication. By way of example rather than limitation, a terminal device may also be referred to as a communication device, user equipment (UE) , a Subscriber Station (SS) , a Portable Subscriber Station, a Mobile Station (MS) , or an Access Terminal (AT) . The terminal device may include, but not limited to, a mobile phone, a cellular phone, a smart phone, voice over IP (VoIP) phones, wireless local loop phones, a tablet, a wearable terminal device, a personal digital assistant (PDA) , portable computers, desktop computer, image capture terminal devices such as digital cameras, gaming terminal devices, music storage and playback appliances, vehicle-mounted wireless terminal devices, wireless endpoints, mobile stations, laptop-embedded equipment (LEE) , laptop-mounted equipment (LME) , USB dongles, smart devices, wireless customer-premises equipment (CPE) , an Internet of Things (IoT) device, a watch or other wearable, a head-mounted display (HMD) , a vehicle, a drone, a medical device and applications (e.g., remote surgery) , an industrial device and applications (e.g., a robot and/or other wireless devices operating in an industrial and/or an automated processing chain contexts) , a consumer electronics device, a device operating on commercial and/or industrial wireless networks, and the like. The terminal device may also correspond to a Mobile Termination (MT) part of an IAB node (e.g., a relay node) . In the following description, the terms “terminal device” , “communication device” , “terminal” , “user equipment” and “UE” may be used interchangeably.

As used herein, the term “resource, ” “transmission resource, ” “resource block, ” “physical resource block” (PRB) , “uplink resource, ” or “downlink resource” may refer to any resource for performing a communication, for example, a communication between a terminal device and a network device, 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 combination of the time, frequency, space and/or code domain 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 discussed above, the SBFD technology has been proposed to enhance the duplexing operation. For SBFD operation at gNB side within a TDD carrier, objectives are as follows. Semi-static indication of time location of SBFD subbands to UEs in RRC_CONNECTED mode is specified and indication of time location of SBFD subbands in system information block (SIB) is not precluded. Semi-static indication of frequency domain location of SBFD subbands to UEs in RRC_CONNECTED mode is specify and indication of frequency domain location of SBFD subbands in SIB is not precluded. SBFD operation to support random access in SBFD symbols by UEs in RRC_CONNECTED mode is specified. SBFD operation to UE in RRC_IDLE/INACTIVE mode for random access is studied and specified if justified and whether to proceed normative work is checked. UE transmission, reception and measurement behavior and procedures in SBFD symbols and/or non-SBFD symbols for SBFD aware UE are specified.

Further objectives include configurations for SRS, PUCCH and physical uplink shared channel (PUSCH) on SBFD symbols and non-SBFD symbols, e.g., resources, frequency hopping parameters, UL power control parameters and/or beam/spatial relation and collision handling between DL reception in DL subband (s) and UL transmission in UL subband in a SBFD symbol.

As used herein, the term “SBFD-aware UE” refers to a UE which is capable of understanding/applying a SBFD-related configuration.

In the context of the present discourse, a physical random-access channel (PRACH) occasion (RO) in uplink symbol (s) may be referred to as uplink RO and an RO in SBFD symbol (s) may be referred to as SBFD RO for brevity.

In the context of the present disclosure, a preamble transmission duration may be referred to a length in time domain for transmitting a random access preamble. Different preamble transmission durations may be associated with different preamble lengths, or different preamble formats. In the following, for purpose of illustration without any limitation, if a preamble transmission duration is longer than another preamble transmission duration, the preamble transmission duration may be also referred to as a PRACH long format or a long format and the other preamble transmission duration may be also referred to as a PRACH short format or a short format.

FIG. 1A illustrates an example communication environment 100A in which example embodiments of the present disclosure can be implemented. The communication environment 100A includes a first apparatus 110 and a second apparatus 120. A serving area provided by the second apparatus 120 is called a cell. The second apparatus 120 can provide one or more cells, for example, a cell 102 as illustrated in FIG. 1A.

In some example embodiments, the first apparatus 110 may be or may be comprised in a terminal device (for example, a UE) and the second apparatus 120 may be or may be comprised in a network device (which may be shorted as network) serving the terminal device.

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

In some example embodiments, if the first apparatus 110 is a terminal device and the second apparatus 120 is a network device, a link from the second apparatus 120 to the first apparatus 110 is referred to as a downlink (DL) , while a link from the first apparatus 110 to the second apparatus 120 is referred to as an uplink (UL) . In DL, the second apparatus 120 is a transmitting (TX) device (or a transmitter) and the first apparatus 110 is a receiving (RX) device (or a receiver) . In UL, the first apparatus 110 is a TX device (or a transmitter) and the second apparatus 120 is a RX device (or a receiver) .

Communications in the communication environment 100 may be implemented according to any proper communication protocol (s) , comprising, but not limited to, cellular communication protocols of the first generation (1G) , the second generation (2G) , the third generation (3G) , the fourth generation (4G) , the fifth generation (5G) , the sixth generation (6G) , and the like, wireless local network communication protocols such as Institute for Electrical and Electronics Engineers (IEEE) 802.11 and the like, and/or any other protocols currently known or to be developed in the future. Moreover, the communication may utilize any proper wireless communication technology, comprising but not limited to: Code Division Multiple Access (CDMA) , Frequency Division Multiple Access (FDMA) , Time Division Multiple Access (TDMA) , Frequency Division Duplex (FDD) , Time Division Duplex (TDD) , Multiple-Input Multiple-Output (MIMO) , Orthogonal Frequency Division Multiple (OFDM) , Discrete Fourier Transform spread OFDM (DFT-s-OFDM) and/or any other technologies currently known or to be developed in the future.

Multiple duplexing modes may be supported in communication environment 100A. Reference is now made to FIG. 1B, which illustrates a block 100B of three example duplexing modes, i.e., TDD, FDD and SBFD.

The FDD may be used for paired bands and TDD may be used for unpaired bands. In TDD, the time domain resource is split between downlink and uplink. Allocation of a limited time duration for the uplink in TDD would result in reduced coverage, increased latency, and reduced capacity. The SBFD may be considered as an evolution of duplexing operation in NR. In particular, the SBFD may allow simultaneous DL and UL transmission on different physical resource blocks (PRBs) /sub-bands within an unpaired wideband NR cell, as illustrated in FIG. 1B.

Further, different duplexing modes may be used interactively. For better understanding, reference is now made to FIG. 1C, which illustrates a block 100C of SBFD resources and non-SBFD resources.

In SBFD slots, a guard band is expected to be placed between DL and UL resource blocks (RBs) . This provides better isolation between UL and DL transmissions and is expected to be essential for reducing the impact of the self-interference (due to the DL transmissions of the gNB and the UL reception of the gNB) as well as cross-link interference (CLI) between UE-to-UE links, and gNB to gNB links.

In the example of FIG. 1C, it may be observed that there are two slot/symbol types exist for both DL and UL transmissions as shown in FIG. 1C, namely, SBFD slots/symbols, during which the non-overlapping DL sub-bands and UL sub-band (s) both exist, and Non-SBFD slots/symbols, during which the entire band is used for DL or UL (i.e., legacy/full DL/UL slots) .

In the wireless communication system, UE needs to perform random access (RA) procedure to access the network.

In 5G NR, two contention based random access (CBRA) procedures are supported, namely 4-step random access channel (RACH) (Rel-15) and 2-step RACH (Rel-16) and one contention-free random-access procedure (CFRA) . A step in all these procedures is the transmission of a suitable message by the UE to NW (the nature of the message changes depending on which procedure is executed, but the first action is always for the UE) . In this disclosure, the 4-step RACH procedure is focused on, given its larger relevance in practical deployments, and for its better suitability for illustration purpose and simplicity. However, the proposed concept is equally applicable to all three procedures.

FIG. 2A illustrates a 4-step RACH procedure 200A. As shown in FIG. 2A, the 4-step RACH procedure 200A may be summarized as follows below. Message 1/Msg1 (also known as PRACH) indicates that the UE (as an example of the first apparatus 110) sends a specific preamble to the gNB (as an example of the second apparatus 120) via PRACH using a specific resource called RACH occasion (RO) , mapped to one or more synchronization signal block (SSB) beams according to a certain pattern. Message 2/Msg2 (also known as Random access response, RAR) indicates that the gNB replies with an RAR message, which includes the detected preamble ID, the time-advance command, a temporary cell (TC) -radio network temporary identifier (RNTI) , and UL grant for the transmission of Message 3/Msg3 on physical uplink shared channel (PUSCH) . Message 3/Msg3 (also known as radio resource control (RRC) request) indicates that the UE responds to Msg2 over the scheduled PUSCH with an ID for contention resolution. Further, Message 4/Msg4 (also known as. RRC setup) indicates that the gNB transmits the contention resolution message with the contention-resolution ID.

Upon reception of Msg4, the UE sends an acknowledgement (ACK) on a physical uplink control channel (PUCCH) if its contention-resolution ID is carried by Msg4. This completes the 4-step RACH. It is worth noting that prior to Msg1, there is also a preliminary step of sending and receiving the SSB, i.e., DL beam sweeping, which is not formally part of the RACH procedure. As a result of this preliminary step, the UE selects the index of the preferred SSB beam and decodes the associated PBCH for master information block (MIB) , system information block (SIB) and so on. This index is also used by UE to identify a suitable RO for the preamble transmission (Msg1) , according to the SSB-to-RO mapping conveyed by SIB1.

FIG. 2B illustrates a 2-step RACH procedure 200B which is similar to 4-step RACH presented above. Specifically, Msg1 and Msg3 in the 4-step RACH are combined in a MsgA and sent out without waiting for feedback from the UE in between (i.e., Msg2 in the 4-step RACH) . Similarly, the gNB combines Msg2 and Msg4 in the 4-step RACH into MsgB.

The information element (IE) RACH-ConfigGeneric is used to specify the random-access parameters both for regular random access as well as for beam failure recovery. An example of the IE RACH-ConfigGeneric is shown in Table 1.

Table 1

The fields highlighted in bold in the IE RACH-ConfigGeneric are used to signal the time and frequency allocation of the RACH occasions (ROs) to the UE. The parameter prach-ConfigurationIndex maps to the tables in technical specification (TS) 38.211, which, among others, give the time domain resources and other important RACH parameters. The parameter msg1-FDM shows how many ROs are frequency multiplexed in one instance, and the parameter msg1-FrequencyStart gives an offset of lowest PRACH transmission occasion in frequency domain with respective to PRB0.

With the parameter prach-ConfigurationIndex indicated by the network, the UE determines the preamble format for PRACH and applies the procedure specified in TS 38.211 (clause 5.3.2) to find the ROs in time-domain.

FIG. 3 illustrates a diagram 300 of an example of time-domain resource determination for RACH occasions. As shown in FIG. 3, the parameter prach-ConfigurationIndex is 251. With this index indicated, the UE determines the following. Preamble format C2 should be used and ROs are allocated at the system frame numbers (n_SFN) that satisfy n_SFN mod 1=0. In addition, within each of the determined SFNs, ROs are allocated at subframe number 2 and 7. Within each of the determined subframes, the remaining parameters in the considered row indicate ROs will start at symbol number 0, 6, 14, 20. The symbol number is continuously counted regardless of the number of slots within the subframe, which depends on the sub-carrier spacing configured for PRACH. ROs duration is 6 symbols (although the actual duration of the preamble format can be less than that) .

In 5G NR carriers/band operating in TDD mode, a predefined “TDD-pattern” is broadcast by the gNB, to inform the TDD UE in which slots UL and DL symbols are to be expected/used. This pattern for RRC-Idle mode is encoded in system information block 1 (SIB1) , which may be the ServingCellConfigCommonSIB as shown in Table 2. For RRC connected mode, the TDD-UL-DL-ConfigCommon is one of the RRC parameters.

Table 2

It is to be noted that there are 3 types of slots: downlink (D) slots, uplink (U) slots, and flexible (F) slots, also referred to as SBFD slots. Flexible is used, if a slot contains both symbols for UL and DL. Such “special” slots often offer downlink data symbols in the beginning, an DL/UL switching gap, and few UL symbols for quick HARQ feedback.

For long sequence, four preamble formats with a preamble length of 839, are designed mainly for big cell deployment scenarios. These long preambles are configured with 1.25 or 5 kHz subcarrier spacing and are restricted to frequency range 1 (FR1) . PRACH preamble formats are shown in table 3 as follows. Table 3 is an example from Table 6.3.3.1-1: PRACH preamble formats for L_RA=839 and Δf_RA∈ {1.25, 5} kHz in TS 38.211.

Table 3

For short sequence, NR introduced nine different short format preambles with a length of 139. This format was mainly introduced to target the small/normal cell and indoor deployment scenarios. The short preamble formats can be used in FR1 with a subcarrier spacing of 15 or 30 kHz and FR2 with a subcarrier spacing of 60 or 120 kHz. Preamble formats are shown in table 4 as follows. Table 4 is an example from Table 6.3.3.1-2: Preamble formats for L_RA∈ {139, 571, 1151} and Δf_RA=15·2^μ kHz where μ∈ {0, 1, 2, 3, 5, 6} in TS 38.211.

Table 4

Cell radius supported by different preamble formats is shown in table 5 as follows.

Table 5

A link budget study shows that a mid-band TDD using a 3.65 GHz spectrum (n78) could support a UL coverage greater than 20km. However, due to the limitation of the PRACH preamble design, the maximum achievable cell range is 4.6 km for a short preamble format (C2) in initial access. This cell range could be increased with the long format preamble to reach a maximum of ～57.4 km (long preamble format 1) , but in mid-band TDD, this is not feasible due to the limitation on the time duration of the uplink (e.g., 0.5ms in DDDSU pattern) and a preamble format 1 require a time duration greater than 1ms. To overcome this limitation, using multiple consecutive SBFD slots can support a longer RACH occasion without modifying the TDD pattern. Hence, longer preamble formats can be applied with the support of the SBFD symbols in initial access.

Two options for RACH configuration of SBFD-aware UE in RRC CONNECTED state are proposed. For random access operation for SBFD-aware UEs in RRC CONNECTED state, the following options may be at least considered. Option a is to use one single RACH configuration with possible enhancement. The ROs within UL subband in SBFD symbols can be valid for SBFD-aware UE and further details are for further study. Option b is to use two separate RACH configurations, including one legacy RACH configuration and one additional RACH configuration. The ROs within UL subband in SBFD symbols configured by the additional RACH configuration can be valid for SBFD-aware UE.

Furthermore, for Option a, the only possible PRACH format is the PRACH short format, since the only format supported for the legacy UEs in a DDDU TDD pattern is the short format.

Legacy RO resource configuration with possible enhancement may be reused for Option a. Regarding possible enhancements, new ROs are introduced relative to already existing ROs. One such solution is that SBFD ROs would be related to legacy ROs based on a time and/or frequency offset such that the SBFD RO would be allowed to be in the SBFD slot and in UL subband. Regarding RO validation, for SBFD aware UE, the ROs within UL subband in SBFD symbols can be valid, but whether the ROs in non-SBFD symbols are valid or not can be further discussed. Regarding SSB-RO mapping, if SBFD-aware UE can use the ROs in non-SBFD symbols, consider the following options for SSB-RO mapping for SBFD-aware UE. Option 1-1 indicates separate SSB-RO mapping between ROs in SBFD symbols and ROs in non-SBFD symbols. Option 1-2 indicates joint SSB-RO mapping for ROs in SBFD symbols and ROs in non-SBFD symbols. The advantage is less signalling overhead. The disadvantage is time or frequency domain resource configuration flexibility restriction, which can only support the same PRACH preamble format for SBFD aware UE and non-SBFD aware UE.

In addition, three different alternatives for PRACH long format ROs design have been proposed. The three different alternatives may be shown in FIG. 4A which illustrates an example diagram 400A of long or short PRACH ROs configuration alternatives. For all three alternatives, the long and the short format are supported at the same time. In Alt. 1 410, only one RACH configuration is required, with separate preamble format (short and long) . Since only one RACH configuration is indicated, the legacy ROs frequency location is constraint by the UL subband of the SBFD symbols. In Alt. 2 320 and Alt. 3 330, two RACH configurations required, one for the short preamble and one for the long preamble. Since each format has its own RACH configuration, the legacy ROs are not constraint by the UL subband of the SBFD symbols. Each preamble format may have its own frequency domain resource allocation.

As previously mentioned, the SBFD random access in RRC-Idle mode is under study. For minimizing specification impacts, SBFD random access in RRC-Idle and RRC-connected should have a unified solution. Therefore, Option b (i.e., using two separate RACH configurations, including one legacy RACH configuration and one additional RACH configuration) is not preferred since it will create a considerable overhead in SIB for RRC-Idle mode. In contrast, although Option a appears to be a better option, a challenge with Option a is how to support a single RACH configuration for configuring both long and PRACH short formats simultaneously.

Reference is now made to FIG. 4B to describe the reason that the alternatives shown in R1-2401218 cannot solve the issue, especially Alt. 1, which aligns with Option a (single RACH configuration) . FIG. 4B illustrates an example diagram 400B of PRACH long format overhead. As shown in FIG. 4B, a case where the UE is in the PRACH short format range is presented. In this case, all the long-format ROs are not needed. Therefore, all three alternatives present some overhead. FIG. 4C illustrates an example diagram 400C of PRACH short format overhead. As shown in FIG. 4C, a case where this time the UE is in the PRACH long format range is presented. In this case, all the short-format ROs are not needed. Therefore, all three alternatives present some overhead.

Example embodiments of the present disclosure propose a solution for RACH transmission in SBFD. In this solution, a first apparatus (for example, a UE) may receive from a second apparatus (for example, a gNB) configuration information for RACH transmissions associated with a first preamble transmission duration or a second preamble transmission duration greater than the first preamble transmission duration. The first apparatus may determine a RACH configuration based on the configuration information and a metric indicating a coverage state of the first apparatus, the determined RACH configuration being associated with the first preamble transmission duration or the second preamble transmission duration. The first apparatus transmits, to the second apparatus, a random access preamble based on the determined RACH configuration. In some example embodiments, the solution may be used for TDD patterns with only one uplink (U) slot.

In this way, an optimal RACH configuration may be determined based on the coverage state of the first apparatus. As such, a RACH configuration suitable for the coverage state can be applied, thereby improving initial access, decreasing latency and collision.

The main idea of the present disclosure is to enable the PRACH long format alongside the PRACH short format. In some example embodiments, this can be achieved by having only one RACH configuration (which is compliance with Option a) . It is to be noted that PRACH long format is any PRACH format has a time span larger than the PRACH short format’s time span. Some example embodiments are now described to illustrate the main idea.

Reference is made to FIG. 5, which illustrates a signaling flow 500 of RACH transmissions in accordance with some example embodiments of the present disclosure. The signaling flow 500 involves the first apparatus 110 and the second apparatus 120 in FIG. 1A. The first apparatus 110 may be or may be comprised in a terminal device, and the second apparatus 120 may be or may be comprised in a network device.

For the purposes of discussion, following embodiments will be discussed with reference to FIG. 1A, for example, by using the first apparatus 110 and the second apparatus 120, where the first apparatus 110 may function as a terminal device and the second apparatus 120 may function as a network device. Further, the first apparatus 110 may be configured with SBFD resources in a time domain and a frequency domain.

It is to be understood that the operations at the first apparatus 110 and the second apparatus 120 should be coordinated. In other words, the second apparatus 120 and the first apparatus 110 should have common understanding about configurations, parameters and so on. Such common understanding may be implemented by any suitable interactions between the second apparatus 120 and the first apparatus 110 or both the second apparatus 120 and the first apparatus 110 applying the same rule/policy.

In the following, although some operations are described from a perspective of the first apparatus 110, it is to be understood that the corresponding operations should be performed by the second apparatus 120. Similarly, although some operations are described from a perspective of the second apparatus 120, it is to be understood that the corresponding operations should be performed by the first apparatus 110. Merely for brevity, some of the same or similar contents are omitted here.

In operation, the second apparatus 120 transmits (505) configuration information for RACH transmissions associated with a first preamble transmission duration or a second preamble transmission duration greater than the first preamble transmission duration. The first apparatus 110 receives (510) the configuration information from the second apparatus 120. In the following, the first preamble transmission duration may be referred to as a short transmission duration, and the second preamble transmission duration may be referred to as a long transmission duration.

For example, an IE RACH-ConfigGeneric used for both the short and long transmission durations may be provided by the second apparatus 120. For another example, an IE RACH-ConfigGeneric with two PCIs may be provided to the second apparatus 120, where one of the two PCI is used for the short transmission duration and the other PCI is used for the long transmission duration. For a further example, two IEs RACH-ConfigGeneric used for the short and long transmission durations respectively may be provided by the second apparatus 120. Some example embodiments of the configuration information will be discussed in detail in the following.

After receiving the configuration information, the first apparatus 110 determines (515) a RACH configuration (also referred to as PRACH configuration option or candidate) based on the configuration information and a metric indicating a coverage state of the first apparatus 110. The determined RACH configuration is associated with the first preamble transmission duration or the second preamble transmission duration. In an example, the first apparatus 110 may select a RACH configuration from a plurality of RACH configurations based on the metric indicating the coverage state of the first apparatus 110. The plurality of RACH configurations may comprise at least one RACH configuration associated with the first preamble transmission duration and at least one RACH configuration associated with the second preamble transmission duration.

The coverage state of the first apparatus 110 may be indicated by any suitable metric, or in other words, the first apparatus 110 may estimate its coverage state based on any suitable metric. In some example embodiments, the metric may comprise a radio link quality based on a measurement on a signal from the second apparatus. In an example, the radio link quality may include reference signal receiving power (RSRP) , received signal strength indication (RSSI) , reference signal receiving quality (RSRQ) , etc.

In addition, or alternatively, in some example embodiments, the metric may comprise a distance from the first apparatus 110 to the second apparatus 120. The first apparatus 110 may obtain the distance in any suitable manner. Embodiments of the present disclosure are not limited in this regard.

By way of example, the coverage area of a cell provided by the second apparatus 120 may be divided into different zones and a RACH configuration may be used for or corresponding to a zone. Based on the metric, the first apparatus 110 may estimate the zone it locates in and select a RACH configuration corresponding to the estimated zone. FIG. 6 illustrates a diagram 600 of example zones in accordance with some example embodiments of the present disclosure. As shown in FIG. 6, there are four zones, that is, the first zone 610, the second zone 620, the third zone 630 and the fourth zone 640. Specifically, the first zone 610 may indicate good coverage for PRACH short format. The first zone 620 may indicate short coverage for PRACH short format. The third zone 630 may indicate good coverage for PRACH long format. The fourth zone 640 may indicate short coverage for PRACH long format. A new rule or policy may be used by SBFD- aware UEs to select the best PRACH configuration option based on the UE location (i.e., different zones) .

In some example embodiments, the determined RACH configuration may comprise a configuration for transmitting a preamble of the first preamble transmission duration with a first transmit power in a time window comprising a SBFD time period (for example, a SBFD slot) and an uplink only time period (for example, an uplink only slot) . FIG. 7A illustrates an example RACH configuration 700A for a short format in accordance with some example embodiments of the present disclosure. The RACH configuration 700A (also referred to as Option 1) may be used for or corresponding to the first zone 610. The UEs (as an example of the first apparatus 110) are located in the PRACH short format range in the center of the cell. In this scenario, the primary objective of the cell is to increase the capacity of the ROs as much as possible so that the gNB (as an example of the second apparatus 110) may reduce the delay and the collision between the UEs in the initial access phase. As shown in FIG. 7A, many PRACH short format ROs are provided in the RACH configuration 700A. In this way, initial access may be provided, and latency and the collision may be decreased.

In some example embodiments, the determined RACH configuration may comprise a configuration for transmitting a preamble of the first preamble transmission duration in a time window comprising an uplink only time period, or a configuration for transmitting a preamble of the first preamble transmission duration with a second transmit power lower than the first transmit power in a time window comprising an SBFD time period and an uplink only time period. FIG. 7B illustrates two example RACH configurations for a short format in accordance with some example embodiments of the present disclosure. These two configurations may be used for or corresponding to the second zone 620. The UEs are located in the PRACH short format range, but this time on the edge of the cell (in case PRACH short format is used, cell range can be increased using PRACH long formats) . In this scenario, the UEs may be in coverage shortage. Therefore, the primary objective of the cell is to provide an initial access connection to the UEs while maintaining the minimum amount of CLI between the UL ROs and the DL symbols of the neighbor UEs (aiming at minimizing the CLI of the PRACH transmissions to the neighboring UEs, which are also in this zone and thus may also be sensitive to CLI due to coverage issue) .

As shown in FIG. 7B, two RACH configuration options, that is, the RACH configuration 700B-1 (also referred to as Option 2.1) and the RACH configuration 700B-2 (also referred to as Option 2.2) are possible for this scenario. In the RACH configuration 700B-1, only the ROs in the UL-only slot are validated for transmission. Thus, no CLI between the UL ROs and the DL symbols since the used ROs are located on the UL-Only slot and consequently no need for a limit on the maximum transmitted power (UEs on the edge of the cell require more transmission power) . In the RACH configuration 700B-1, the maximum power of UL transmission on the UL ROs is reduced, and the PRACH repetition is enabled. Therefore, less CLI between the DL symbols and the UL ROs since the maximum power used for the PRACH transmission is reduced. PRACH repetition is enabled to compensate for this power reduction, a feature introduced in Rel-18 to improve the coverage of the UEs located in coverage shortage. In this way, initial access may be provided and CLI may be decreased.

In some example embodiments, the determined RACH configuration may comprise a configuration for transmitting a preamble of the second preamble transmission duration with a first transmit power in a time window comprising at least an SBFD time period. FIG. 7C illustrates an example RACH configuration 700C for a long format in accordance with some example embodiments of the present disclosure. The RACH configuration 700C (also referred to as Option 3) may be used for or corresponding to the third zone 630. The UEs are located in the PRACH long format range in the center of the cell (in case PRACH long format is used) . In this scenario, the primary objective of the cell is to increase the capacity of the ROs as much as possible while using the PRACH long format ROs so that the gNB can reduce the delay and the collision between the UEs in the initial access phase. As shown in FIG. 7C, many PRACH long format ROs (corresponding to the preamble of the second preamble transmission) are provided in the SBFD time period and the uplink time period in the PRACH configuration 700C. In this way, initial access may be provided with cell range extension, and latency and the collision may be decreased.

In some example embodiments, the determined RACH configuration may comprise a configuration for transmitting a preamble of the second preamble transmission duration in a time window extending from an SBFD time period to an uplink only time period, or a configuration for transmitting a preamble of the second preamble transmission duration with a second transmit power in a time window comprising at least an SBFD time period. FIG. 7D illustrates two example RACH configurations for a long format in accordance with some example embodiments of the present disclosure. These two RACH configurations may be used for or corresponding to the fourth zone 640. The UEs are located in the PRACH long format range, but this time on the edge of the cell. In this scenario, the UEs may be in coverage shortage. Therefore, similar to the second zone 620 (with extended cell range) , the primary objective of the cell is to provide an initial access connection to the UEs while maintaining the minimum amount of CLI between the UL ROs and the DL symbols of the neighbor UEs.

As shown in FIG. 7D, two RACH configuration options, that is, the RACH configuration 700D-1 (also referred to as Option 4.1) and the RACH configuration 700D-2 (also referred to as Option 4.2) are possible for this scenario. In the RACH configuration 700D-1, only the ROs crossing the UL-only slot are validated for transmission and thus partial CLI between the UL ROs and the DL symbols since part of the used ROs are located on the UL-Only slot. A slight reduction on the maximum transmitted power may improve the CLI. In the configuration RACH 700D-2, all the ROs are validated for transmission but with reduced maximum transmission power, and the PRACH repetition is enabled. Therefore, less CLI between the DL symbols and the UL ROs since the maximum power used for the PRACH transmission is reduced. PRACH repetition is enabled to compensate for this power reduction. In this way, initial access may be provided with cell range extension and minimal CLI may be guaranteed.

Some example embodiments are now described with respect to determination or selection of the PRACH configuration to be applied.

In some example embodiments, each of the plurality of RACH configurations may correspond to one of a plurality of metric value ranges indicating different coverage states respectively.

In some example embodiments, the first apparatus 110 may determine a metric value range comprising the metric from a plurality of metric value ranges and determine a RACH configuration corresponding to the determined metric value range. In order to select a RACH configuration option, the UE should be able to estimates its zone location. A new rule, for example a threshold on the RSRP/RSSI/RSRQ may be defined. A threshold is defined for each zone, for example, if the RSRP/RSSI/RSRQ ≥ th_A (as an example of the metric value range) , the first zone 610 is selected and the above mentioned Option 1 may be applied. If th_A ≥ the RSRP/RSSI/RSRQ ≥ th_B, the second zone 620 is selected and the Option 2.1 or 2.2 may be applied. Similarly, the rule is applied for the third zone 630 and fourth zone 640. FIG. 8A illustrates an example diagram 800A of UEs located in the first zone 610. As shown in FIG. 8A, UEs are located in the first zone 610 and thus these UEs may select Option 1 based on their zone location (as an example of the determined metric value range) . In this way, a UE may easily select the best PRACH configuration option based on the zone location using the defined threshold in the function of the SS-RSRP and/or the NR-RSSI.

However, the RSRP/RSSI/RSRQ are power estimates, not position estimates. Still referring to FIG. 8A, the UE 805 is located in the first zone 610 but in coverage shortage (e.g., UE in a basement underfloor) . For this UE, the RSRP/RSSI/RSRQ estimate that the UE 805 is in the third zone 630 (or the fourth zone 640) , and consequently, the UE 805 selects Option 3, Option 4.1 or Option 4.2) , but the best option in this scenario is Option 2.1 or 2.2. An alternative solution may be provided to overcome this issue.

In some example embodiments, the first apparatus 110 may determine whether the metric is within a first metric value range or a second metric value range. The first metric value range indicates a better coverage state than the second metric value range. If the metric is within the first metric value range, the first apparatus 110 may determine a RACH configuration associated with the first preamble transmission duration and corresponding to the first metric value range. If the metric is within the second metric value range, the first apparatus 110 may determine a RACH configuration associated with the first preamble transmission duration and corresponding to the second metric value range.

FIG. 8B illustrates an example diagram 800B of UEs located in two different zones. As shown in FIG. 8B, zones are divided into the good coverage zone 810 and coverage shortage zone 820. The good coverage zone 810 is the same as the first zone 610 and the best option for this zone is Option 1 (as an example of the RACH configuration associated with the first preamble transmission duration and corresponding to the first metric value range) . The UE selects this zone if the RSRP/RSSI/RSRQ ≥ th_A. The coverage shortage zone 820 covers the second, third and fourth zone. The UE selects this zone if any of the three threshold is reached {th_B, th_C, th_D} , or if the RSRP/RSSI/RSRQ <th_A. Any UE located in this zone will select Option 2.1 or 2.2 (as an example of RACH configuration associated with the first preamble transmission duration and corresponding to the second metric value range) as a first step. The UE will proceed to the second step under a condition. The condition is that the UE failed to establish an initial access to the cell after a number X of attempts. If the condition is satisfied, the UE moves to the second step. In the second step, the UE switch to Option 4.1 or 4.2. In this way, the abovementioned issue where the UE is in the first zone with coverage shortage may be solved.

In some example embodiments, the first apparatus 110 may determine whether the metric is within a first metric value range or a second metric value range, the first metric value range indicating a better coverage state than the second metric value range. If the metric is within the first metric value range, the first apparatus 110 may determine a RACH configuration with the first preamble transmission duration. If the metric is within the second metric value range, the first apparatus 110 may determine a RACH configuration with the second preamble transmission duration.

In such example embodiments, the UE may rely on the RSRP/RSSI/RSSQ threshold (coverage condition) to select whether it should use PRACH long or short format. In an example, if the RSRP/RSSI/RSRQ ≥ th_A (indicates that the metric is within the first metric value range) , the UE may select the PRACH short format. If the RSRP/RSSI/RSRQ < th_A (indicates that the metric is within the second metric value range) , the UE may select the PRACH long format.

In the above, example RACH configuration candidates and the example ways to select the RACH configuration based on the coverage state are described above. Some example embodiments regarding the configuration information and the determination of ROs and preamble formats are described now.

In some example embodiments, the configuration information may comprise one or more frequency domain parameters common to the first and second preamble transmission durations. The first apparatus 110 may determine a frequency domain resource of at least one RACH occasion based on the one or more frequency domain parameters and determine a preamble format of the random access preamble and a time domain resource of the at least one RACH occasion based on a RACH configuration index comprised in the configuration information. A common RACH configuration may be used so that an SBFD-aware UE may determine the necessary configuration for each PRACH configuration option. Only one RACH configuration may be required to be provided from a gNB to the UE. Based on the UE location, the UE may deduce the best RACH configuration option from the received RACH configuration.

FIG. 9A illustrates a common RACH configuration 900A in accordance with some example embodiments of the present disclosure. As shown in FIG. 9A, the configuration 900A may support deriving all the previously mentioned RACH configuration options. The frequency domain resource allocation for ROs (e.g., the frequency domain parameters Msg1-FDM 905 and msg1-FrequencyStart) is used for all options. Other frequency configurations may also be possible. In the time domain resource allocation for ROs (also referred to as the time domain parameters) , all different formats of ROs (Long, short) have the same starting symbol position 915. To this end, some rules may be required to the PRACH configuration index (PCI) . It is to be noted that for simplicity all alternatives consider Msg1-FDM=1 and the same msg1-FrequencyStart. In this way, PRACH short and PRACH long formats may be alternated while using only one RACH configuration and without breaking the behavior of legacy UEs.

In some example embodiments, the preamble format of the random access preamble and the time domain resource may be determined based on the RACH configuration index from a first table for a plurality of RACH configuration indices. The first table may comprise information for mapping the RACH configuration index to: a preamble format with the first preamble transmission duration, a preamble format with the second preamble transmission duration, and a location in time domain. The first table may comprise a column for PCIS, a column for preambles formats of the first preamble length, a column for preamble formats of the second preamble length, and one or more columns for defining time domain locations of ROs. In the following, these example embodiments may be referred to as Alternative 1.

FIG. 9B illustrates an example PCI table 900B in accordance with some example embodiments of the present disclosure. As shown in FIG. 9B, the PCI table 900B (as an example of the first table) includes a PRACH configuration index column 915 (as an example of the RACH configuration index) and a preamble format column 920 (indicating the preamble format with the first preamble transmission duration) . An additional column (indicating the preamble format with the second preamble transmission duration) in the PCI table 900B is introduced to indicate a new format (long) to be used by the SBFD-aware UE. An example new column, SBFD Preamble format 925 may be added at the end of the PCI table. The SBFD-aware UE uses this column to configure the PRACH long format “0” on the same start RO position “Starting symbol” of the legacy short preamble format “A2” . The other columns are only used to configure the short preamble format “A2” since only one long preamble RO can be supported in one subframe "4 and 9" .

In some example embodiments, the preamble format of the random access preamble and the time domain resource may be determined based on the RACH configuration index from a second table for a plurality of RACH configuration indices. The second table may comprise information for mapping the RACH configuration index to: a combination of a preamble format with the first preamble transmission duration and a preamble format with the second preamble transmission duration, and one or more locations in time domain. The second table may comprise a row for mapping the RACH configuration index to a combination of a preamble format of the first preamble length and a preamble format of the second preamble length. The second table may be a table specified for the SBFD aware UEs. Alternatively, the second table may be a table with rows for the legacy UEs and rows for the SBFD aware UEs. In the following, these example embodiments may be referred to as Alternative 2.

FIG. 9C illustrates another example PCI table 900C in accordance with some example embodiments of the present disclosure. As shown in FIG. 9C, a new PCI index is added to the table 900C (as an example of the second table) , which can be a combination of two legacy PCIs. In the table 900C, an example of a new PCI row is created from the combination of row index “6” for long format “0” and row index “94” for short format “A2” . The new configuration is indicated by the index number “X. ” The SBFD-aware UE will consider only the starting symbol column for the long format “0” and all the columns for the short preamble format “A2” .

In some example embodiments, the determined RACH configuration may be associated with the second preamble transmission duration. A time duration and one or more locations in time domain may be associated with the first preamble transmission duration is determined based on the PRACH configuration index. The preamble format of the random access preamble may be determined based on a mapping between different time durations and preamble formats with the second preamble transmission duration. The time domain resource of the at least one RACH occasion may be determined based on the one or more locations in time domain associated with the first preamble transmission duration. In the following, these example embodiments may be referred to as Alternative 3.

For example, a new rule is defined, e.g., depend on the time duration “t” between two consecutive ROs configured in the configuration information (for example, the IE RACH-ConfigGeneric, the long format may be enabled by the SBFD-aware UE. FIG. 9D illustrates an example diagram 900 D of a mapping between time durations and long formats in accordance with some example embodiments of the present disclosure. As shown in FIG. 9D, three different ROs configurations with three different time duration “t₀, t₁, t₂” are presented. Each of the time duration will map to a specific PRACH long format (indicated by the table 930) , e.g., t₂ maps to long format Y where Y could be any number from the PRACH long format numbers {0, 1, 2, 3} and this long format Y can replace the two consecutive legacy ROs with a new long format Y RO with the same starting (left RO) /ending (right RO) of the RO.

In some example embodiments, two RACH configurations for the long and short transmission durations respectively may be provided by the second apparatus 120. For example, the configuration information comprises one or more first parameters for a RACH configuration associated with the first preamble transmission duration, and one or more second parameters for a RACH configuration associated with the second preamble transmission duration. For example, two IEs RACH-ConfigGeneric may be provided by the second apparatus 120, with one IE for the PRACH short format and the other IE for the PRACH long format.

After determining the RACH configuration, the first apparatus 110 transmits (520) to the second apparatus 120, a random access preamble on the determined RACH configuration. The second apparatus 120 monitors (525) a plurality of RACH occasions based on the configuration information. Further, the second apparatus 120 receives (530) the random access preamble.

In some example embodiments, if the PRACH configuration applied is associated with the first preamble transmission duration, a switch to the second preamble transmission duration may occur in case of failed random access. Specifically, in response to a failure in receiving a response to the random access preamble, the first apparatus 110 may determine (535) a further RACH configuration associated with the second preamble transmission duration. For example, if the initial access fails after a certain number (X) times of attempts, the first apparatus 110 may switch to a PRACH long format. Then, the first apparatus 110 may transmit (540) , to the second apparatus 120, a further random access preamble based on the further RACH configuration.

An example process of RACH transmission in SBFD will be described in detail below with reference to FIG. 10A and FIG. 10B.

FIG. 10A illustrates a flowchart of a first algorithm 1000A in accordance with some example embodiments of the present disclosure. As shown in 1000A, at block 1002, whether a UE is a SBFD aware UE may be determined. If the UE is not a SBFD aware UE, at block 1004, the UE may use the RACH configuration and apply the legacy rule to determine valid ROs. Only ROs on UL-only symbols are valid. If the UE is a SBFD aware UE, at block 1006, the UE may determine the zone of operation (as an example of the coverage state) based on RSRP/RSSI/RSRQ (as an example of the metric) .

Based on different zones, the UE may select different PRACH configuration options. For example, if the UE is located in the second zone, at block 1008, the UE may select PRACH configuration option 2.1 or 2.2 (as an example of the RACH configuration associated with the first preamble length) .

At block 1010, whether initial access failed after X times of attempts may be determined. If the initial access does not fail, the first algorithm 1000A may be terminated. If the initial access fails, the UE may consider itself located in the third zone and apply the PRACH configuration of Option 3 (as an example of the RACH configuration associated with the second preamble length) or consider itself located in the fourth zone and apply the PRACH configuration of Option 4.1 or 4.2 (as an example of the RACH configuration associated with the second preamble length) .

FIG. 10B illustrates a signaling flow of an example process 1000B of RACH transmission in SBFD in accordance with some example embodiments of the present disclosure. In this example, a UE 1020 operates as an example implementation of the first apparatus 110 in FIG. 1A and a gNB 1030 operates as an example implementation of the second apparatus 120 in FIG. 1A.

In the process 1000B, at step 1032, the SBFD-aware UE 1020 receives a single RACH config from the gNB 1030. This RACH configuration contains the frequency domain resource allocation (e.g., Msg1-FDM and msg1-FrequencyStart) and the time domain resource allocation (PCI) of the ROs which are required for an SBFD-aware UE to configure any of the ROs option. For the time domain resources, the RACH configuration contains one of three alternatives. Alternative 1 indicates an additional column in the PCI table is introduced to tell a new format (long) to be used by the SBFD-aware UE. Alternative 2 indicates a PCI covering the long and the PRACH short format time resource allocation is indicated. Alternative 3 indicates only the legacy PCI is indicated. The SBFD-aware UE 1020 will deduce the PRACH long format configuration from the time duration between two consecutive legacy ROs.

At step 1034, the SBFD-aware UE 1020 runs the first algorithm 1000A to estimates its zone location. If the RSRP/RSSI/RSRQ ≥th_A, the first zone is selected, and the SBFD-aware UE 1020 considers the PRACH configuration of Option 1. If the RSRP/RSSI/RSRQ ≥th_B, the second zone is selected, and the SBFD-aware UE 1020 considers the PRACH configuration of Option 2.1 or 2.2. If the RSRP/RSSI/RSRQ ≥th_C, the third zone is selected, and the SBFD-aware UE 1020 considers the PRACH configuration of Option 3. If the RSRP/RSSI/RSRQ ≥th_D, the fourth zone is selected, and the SBFD-aware UE 1020 considers the PRACH configuration of Option 4.1 or 4.2.

At step 1036, the SBFD-aware UE 1020 transmits the preamble at least on one of the valid ROs based on the selected option. For the case of the SBFD-aware UE located in the second zone, if the UE failed to receive Msg2 (RAR) from the gNB for X number of times, the SBFD-aware UE 1020 may consider itself located in the third zone and apply the PRACH configuration of option 3.

At step 1038, the gNB 1030 monitors all the ROs (Long and short format) in the configured PRACH slots including the ones that overlap with the DL symbols.

Another example process of RACH transmission in SBFD will be described in detail below with reference to FIG. 11A and FIG. 11B.

FIG. 11A illustrates a flowchart of a second algorithm 1100A in accordance with some example embodiments of the present disclosure. As shown in 1100A, at block 1102, whether a UE is a SBFD aware UE may be determined. If the UE is not a SBFD aware UE, at block 1104, the UE may use the RACH configuration and apply the legacy rule to determine valid ROs. Only ROs on UL-only symbols are valid. If the UE is a SBFD aware UE, at block 1106, the UE may determine the zone of operation (as an example of the coverage state) based on RSRP/RSSI (as an example of the metric) .

Based on different zones, the UE may select different PRACH configuration options. For example, if the UE is located in the coverage shortage zone, at block 1108, the UE may select PRACH configuration option 2.1 or 2.2 (as an example of the RACH configuration associated with the first preamble length) .

At block 1110, whether initial access failed after X times of attempts may be determined. If the initial access does not fail, the second algorithm 1100A may be terminated. If the initial access fails, at block 1112, the UE apply the PRACH configuration of option 3, 4.1 or 4.2 (as an example of the RACH configuration associated with the second preamble length) .

FIG. 11B illustrates a signaling flow of an example process 1100B of RACH transmission in SBFD in accordance with some example embodiments of the present disclosure. In this example, a UE 1120 operates as an example implementation of the first apparatus 110 in FIG. 1A and a gNB 1130 operates as an example implementation of the second apparatus 120 in FIG. 1A.

In the process 1100B, at step 1132, the SBFD-aware UE 1120 receives a single RACH config from the gNB 1130. This RACH configuration contains the frequency domain resource allocation (e.g., Msg1-FDM and msg1-FrequencyStart) and the time domain resource allocation (PCI) of the ROs which are required for an SBFD-aware UE to configure any of the ROs option. For the time domain resources, the RACH configuration contains one of three alternatives. Alternative 1 indicates an additional column in the PCI table is introduced to tell a new format (long) to be used by the SBFD-aware UE. Alternative 2 indicates a PCI covering the long and the PRACH short format time resource allocation is indicated. Alternative 3 indicates only the legacy PCI is indicated. The SBFD-aware UE 1020 will deduce the PRACH long format configuration from the time duration between two consecutive legacy ROs.

At step 1134, the SBFD-aware UE 1120 runs the first algorithm 1100A to estimates its zone location. If the RSRP/RSSI/RSRQ ≥th_A, the good coverage zone is selected, and the SBFD-aware UE 1120 considers the PRACH configuration of Option 1. If the RSRP/RSSI/RSRQ ＜th_A, the short coverage zone is selected, and the SBFD-aware UE 1120 considers the PRACH configuration of Option 2.1 or 2.2.

At step 1136, the SBFD-aware UE 1120 transmits the preamble at least on one of the valid ROs based on the selected option. For the case of the SBFD-aware UE located in short coverage zone, if the UE 1120 failed to receive Msg2 (RAR) from the gNB for X number of times, the SBFD-aware UE 1120 may switch its PRACH configuration to option 4.1 or 4.2.

At step 1038, the gNB 1130 monitors all the ROs (Long and short format) in the configured PRACH slots including the ones that overlap with the DL symbols.

A further example process of RACH transmission in SBFD will be described in detail below with reference to FIG. 12A and FIG. 12B.

FIG. 12A illustrates a flowchart of third algorithm 1200A in accordance with some example embodiments of the present disclosure. As shown in 1200A, at block 1202, whether a UE is a SBFD aware UE may be determined. If the UE is not a SBFD aware UE, at block 1204, the UE may use the RACH configuration and apply the legacy rule to determine valid ROs. Only ROs on UL-only symbols are valid. If the UE is a SBFD aware UE, at block 1206, the UE may determine the zone of operation (as an example of the coverage state) based on RSRP/RSSI (as an example of the metric) .

At block 1208, whether RSRP/RSSI/RSRQ ≥ th_A may be determined. If RSRP/RSSI/RSRQ is greater than or equal to th_A, at block 1210, the UE may select the PRACH short format. If RSRP/RSSI/RSRQ is less than th_A, at block 1212, the UE may select PRACH long format.

After selecting the PRACH short format, at block 1214, whether initial access failed after X times of attempts may be determined. If the initial access does not fail, the third algorithm 1200A may be terminated. If the initial access fails, the UE may consider selecting the PRACH long format.

FIG. 12B illustrates a signaling flow of an example process 1200B of RACH transmission in SBFD in accordance with some example embodiments of the present disclosure. In this example, a UE 1220 operates as an example implementation of the first apparatus 110 in FIG. 1A and a gNB 1230 operates as an example implementation of the second apparatus 120 in FIG. 1A.

In the process 1200B, regardless of how long and short formats are configured, UE will rely on the RSRP/RSSI threshold (coverage condition) to select whether it should use long or short format. At step 1 1232, the SBFD-aware UE 1220 receives [one, two] RACH configuration from the gNB 1230. These RACH configurations contain the frequency domain resource allocation (e.g., Msg1-FDM and msg1-FrequencyStart) and the time domain resource allocation (PCI) of the ROs which are required for an SBFD-aware UE to configure any of the ROs option.

At step 1234, the SBFD-aware UE 1220 runs the third algorithm 1200A to select the preamble format. If the RSRP/RSSI/RSRQ ≥th_A, the PRACH short format is selected. If the RSRP/RSSI/RSRQ ＜th_A, the PRACH long format is selected.

At step 1236, the SBFD-aware UE 1220 transmits the preamble at least on one of the valid ROs. For the case of the SBFD-aware UE 1220 with the short preamble format, if the UE 1220 failed to receive Msg2 (RAR) from the gNB 1230 for X number of times, the SBFD-aware UE 1220 may switch to the long preamble format.

At step 1238, the gNB 1230 monitors all the ROs (Long and short format) in the configured PRACH slots including the ones that overlap with the DL symbols.

FIG. 13 shows a flowchart of an example method 1300 implemented at a first apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1300 will be described from the perspective of the first apparatus 110 in FIG. 1A.

At block 1310, the first apparatus 110 receives, from a second apparatus, configuration information for random access channel, RACH, transmissions.

At block 1320, the first apparatus 110 determines a RACH configuration based on the configuration information and a metric indicating a coverage state of the first apparatus, the determined RACH configuration being associated with a first preamble transmission duration or a second preamble transmission duration greater than the first preamble transmission duration.

At block 1330, the first apparatus 110 transmits, to the second apparatus, a random access preamble based on the determined RACH configuration.

In some example embodiments, the method 1300 further comprises: determining whether the metric is within a first metric value range or a second metric value range, the first metric value range indicating a better coverage state than the second metric value range; in accordance with a determination that the metric is within the first metric value range, determining a RACH configuration with the first preamble transmission duration; and in accordance with a determination the metric is within the second metric value range, determining a RACH configuration with the second preamble transmission duration.

In some example embodiments, the method 1300 further comprises: determining whether the metric is within a first metric value range or a second metric value range, a first metric value range indicating a better coverage state than the second metric value range; in accordance with a determination that the metric is within the first metric value range, determining a RACH configuration associated with the first preamble transmission duration and corresponding to the first metric value range; and in accordance with a determination that the metric is within the second metric value range, determining a RACH configuration associated with the first preamble transmission duration and corresponding to the second metric value range.

In some example embodiments, the method 1300 further comprises: determining a metric value range comprising the metric from a plurality of metric value ranges indicating different coverage states respectively; and determining a RACH configuration corresponding to the determined metric value range.

In some example embodiments, the method 1300 further comprises: in response to a failure in receiving a response to the random access preamble, determining a further RACH configuration associated with the second preamble transmission duration; and transmitting, to the second apparatus, a further random access preamble based on the further RACH configuration.

In some example embodiments, the determined RACH configuration comprises one of: a configuration for transmitting a preamble of the first preamble transmission duration with a first transmit power in a time window comprising a subband full duplex, SBFD, time period and an uplink only time period, a configuration for transmitting a preamble of the first preamble transmission duration in a time window comprising an uplink only time period, or a configuration for transmitting a preamble of the first preamble transmission duration with a second transmit power lower than the first transmit power in a time window comprising an SBFD time period and an uplink only time period, a configuration for transmitting a preamble of the second preamble transmission duration with a first transmit power in a time window comprising at least an SBFD time period, a configuration for transmitting a preamble of the second preamble transmission duration in a time window extending from an SBFD time period to an uplink only time period, or a configuration for transmitting a preamble of the second preamble transmission duration with a second transmit power in a time window comprising at least an SBFD time period.

In some example embodiments, the metric comprises a radio link quality based on a measurement on a signal from the second apparatus.

In some example embodiments, the method 1300 further comprises: determining a frequency domain resource of at least one RACH occasion based on the one or more frequency domain parameters; and determining a preamble format of the random access preamble and a time domain resource of the at least one RACH occasion based on a RACH configuration index comprised in the configuration information.

In some example embodiments, the preamble format of the random access preamble and the time domain resource are determined based on the RACH configuration index from a first table for a plurality of RACH configuration indices, and the first table comprises information for mapping the RACH configuration index to: a preamble format with the first preamble transmission duration, a preamble format with the second preamble transmission duration, and a location in time domain.

In some example embodiments, the preamble format of the random access preamble and the time domain resource are determined based on the RACH configuration index from a second table for a plurality of RACH configuration indices, and the second table comprises information for mapping the RACH configuration index to: a combination of a preamble format with the first preamble transmission duration and a preamble format with the second preamble transmission duration, and one or more locations in time domain.

In some example embodiments, the determined RACH configuration is associated with the second preamble transmission duration, and a time duration and one or more locations in time domain associated with the first preamble transmission duration is determined based on the RACH configuration index; the preamble format of the random access preamble is determined based on a mapping between different time durations and preamble formats with the second preamble transmission duration, and the time domain resource of the at least one RACH occasion is determined based on the one or more locations in time domain associated with the first preamble transmission duration.

In some example embodiments, the configuration information comprises: one or more first parameters for a RACH configuration associated with the first preamble transmission duration; and one or more second parameters for a RACH configuration associated with the second preamble transmission duration.

In some example embodiments, the first apparatus is or is comprised in a terminal device, and the second apparatus is or is comprised in a network device.

FIG. 14 shows a flowchart of an example method 1400 implemented at a second apparatus in accordance with some example embodiments of the present disclosure. For the purpose of discussion, the method 1400 will be described from the perspective of the second apparatus 120 in FIG. 1A.

At block 1410, the second apparatus 120 transmits, to a first apparatus, configuration information for random access channel, RACH, transmissions associated with a first preamble transmission duration or a second preamble transmission duration greater than the first preamble transmission duration.

At block 1420, the second apparatus 120 monitors a plurality of RACH occasions based on the configuration information.

At block 1430, the second apparatus 120 receives, from the first apparatus, a random access preamble using a RACH configuration associated with the first preamble transmission or the second preamble transmission.

In some example embodiments, the configuration information comprises one or more frequency domain parameters common to the first and second preamble transmission durations, and the first apparatus.

In some example embodiments, a first apparatus capable of performing any of the method 1300 (for example, the first apparatus 110 in FIG. 1A) may comprise means for performing the respective operations 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. The first apparatus may be implemented as or included in the first apparatus 110 in FIG. 1A.

In some example embodiments, the first apparatus comprises means for receiving, from a second apparatus, configuration information for random access channel, RACH, transmissions; means for determining a RACH configuration based on the configuration information and a metric indicating a coverage state of the first apparatus, the determined RACH configuration being associated with a first preamble transmission duration or a second preamble transmission duration greater than the first preamble transmission duration; and means for transmitting, to the second apparatus, a random access preamble based on the determined RACH configuration.

In some example embodiments, the first apparatus further comprises: means for determining whether the metric is within a first metric value range or a second metric value range, the first metric value range indicating a better coverage state than the second metric value range; means for in accordance with a determination that the metric is within the first metric value range, determining a RACH configuration with the first preamble transmission duration; and means for in accordance with a determination the metric is within the second metric value range, determining a RACH configuration with the second preamble transmission duration.

In some example embodiments, the first apparatus further comprises: means for determining whether the metric is within a first metric value range or a second metric value range, a first metric value range indicating a better coverage state than the second metric value range; means for in accordance with a determination that the metric is within the first metric value range, determining a RACH configuration associated with the first preamble transmission duration and corresponding to the first metric value range; and means for in accordance with a determination that the metric is within the second metric value range, determining a RACH configuration associated with the first preamble transmission duration and corresponding to the second metric value range.

In some example embodiments, the first apparatus further comprises: means for determining a metric value range comprising the metric from a plurality of metric value ranges indicating different coverage states respectively; and means for determining a RACH configuration corresponding to the determined metric value range.

In some example embodiments, the first apparatus further comprises: means for in response to a failure in receiving a response to the random access preamble, determining a further RACH configuration associated with the second preamble transmission duration; and means for transmitting, to the second apparatus, a further random access preamble based on the further RACH configuration.

In some example embodiments, the first apparatus further comprises: means for determining a frequency domain resource of at least one RACH occasion based on the one or more frequency domain parameters; and means for determining a preamble format of the random access preamble and a time domain resource of the at least one RACH occasion based on a RACH configuration index comprised in the configuration information.

In some example embodiments, a second apparatus capable of performing any of the method 1400 (for example, the second apparatus 120 in FIG. 1A) may comprise means for performing the respective operations 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. The second apparatus may be implemented as or included in the second apparatus 120 in FIG. 1A.

In some example embodiments, the second apparatus comprises means for transmitting, to a first apparatus, configuration information for random access channel, RACH, transmissions associated with a first preamble transmission duration or a second preamble transmission duration greater than the first preamble transmission duration; means for monitoring a plurality of RACH occasions based on the configuration information; and means for receiving, from the first apparatus, a random access preamble using a RACH configuration associated with the first preamble transmission or the second preamble transmission.

FIG. 15 is a simplified block diagram of a device 1500 that is suitable for implementing example embodiments of the present disclosure. The device 1500 may be provided to implement a communication device, for example, the first apparatus 110 or the second apparatus 120 as shown in FIG. 1A. As shown, the device 1500 includes one or more processors 1510, one or more memories 1520 coupled to the processor 1510, and one or more communication modules 1540 coupled to the processor 1510.

The communication module 1540 is for bidirectional communications. The communication module 1540 has one or more communication interfaces to facilitate communication with one or more other modules or devices. The communication interfaces may represent any interface that is necessary for communication with other network elements. In some example embodiments, the communication module 1540 may include at least one antenna.

The processor 1510 may be of any type suitable to the local technical network and may include one or more of the following: general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on multicore processor architecture, as non-limiting examples. The device 1500 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.

The memory 1520 may include one or more non-volatile memories and one or more volatile memories. Examples of the non-volatile memories include, but are not limited to, a Read Only Memory (ROM) 1524, an electrically programmable read only memory (EPROM) , a flash memory, a hard disk, a compact disc (CD) , a digital video disk (DVD) , an optical disk, a laser disk, and other magnetic storage and/or optical storage. Examples of the volatile memories include, but are not limited to, a random-access memory (RAM) 1522 and other volatile memories that will not last in the power-down duration.

A computer program 1530 includes computer executable instructions that are executed by the associated processor 1510. The instructions of the program 1530 may include instructions for performing operations/acts of some example embodiments of the present disclosure. The program 1530 may be stored in the memory, e.g., the ROM 1524. The processor 1510 may perform any suitable actions and processing by loading the program 1530 into the RAM 1522.

The example embodiments of the present disclosure may be implemented by means of the program 1530 so that the device 1500 may perform any process of the disclosure as discussed with reference to FIG. 2 to FIG. 14. The example embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

In some example embodiments, the program 1530 may be tangibly contained in a computer readable medium which may be included in the device 1500 (such as in the memory 1520) or other storage devices that are accessible by the device 1500. The device 1500 may load the program 1530 from the computer readable medium to the RAM 1522 for execution. In some example embodiments, the computer readable medium may include any types of non-transitory storage medium, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like. The term “non-transitory, ” as used herein, is a limitation of the medium itself (i.e., tangible, not a signal) as opposed to a limitation on data storage persistency (e.g., RAM vs. ROM) .

FIG. 16 shows an example of the computer readable medium 1600 which may be in form of CD, DVD or other optical storage disk. The computer readable medium 1600 has the program 1530 stored thereon.

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, and other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. Although various aspects of embodiments of the present disclosure are illustrated and described as block diagrams, flowcharts, or using some other pictorial representations, it is to be understood that the block, apparatus, system, technique or method 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.

Some example embodiments of the present disclosure also provide at least one computer program product tangibly stored on a computer readable medium, such as a non-transitory computer readable medium. The computer program product includes computer-executable instructions, such as those included in program modules, being executed in a device on a target physical or virtual processor, to carry out any of the methods as described above. 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. The program code 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 code, 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.

In the context of the present disclosure, the computer program code or related data may be carried by any suitable carrier to enable the device, apparatus or processor to perform various processes and operations as described above. Examples of the carrier include a signal, computer readable medium, and the like.

The computer readable medium may be a computer readable signal medium or a computer readable storage medium. A computer 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 computer 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, although 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, although 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. Unless explicitly stated, certain features that are described in the context of separate embodiments may also be implemented in combination in a single embodiment. Conversely, unless explicitly stated, various features that are described in the context of a single embodiment may also be implemented in a plurality of embodiments separately or in any suitable sub-combination.

Although the present disclosure has been described in languages 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 first apparatus comprising:

at least one processor; and

at least one memory storing instructions that, when executed by the at least one processor, cause the first apparatus at least to:

receive, from a second apparatus, configuration information for random access channel, RACH, transmissions;

determine a RACH configuration based on the configuration information and a metric indicating a coverage state of the first apparatus, the determined RACH configuration being associated with a first preamble transmission duration or a second preamble transmission duration greater than the first preamble transmission duration; and

transmit, to the second apparatus, a random access preamble based on the determined RACH configuration.
The first apparatus of claim 1, wherein the first apparatus is caused to:

determine whether the metric is within a first metric value range or a second metric value range, the first metric value range indicating a better coverage state than the second metric value range;

in accordance with a determination that the metric is within the first metric value range, determine a RACH configuration with the first preamble transmission duration; and

in accordance with a determination the metric is within the second metric value range, determine a RACH configuration with the second preamble transmission duration.
The first apparatus of claim 1, wherein the first apparatus is caused to:

determine whether the metric is within a first metric value range or a second metric value range, a first metric value range indicating a better coverage state than the second metric value range;

in accordance with a determination that the metric is within the first metric value range, determine a RACH configuration associated with the first preamble transmission duration and corresponding to the first metric value range; and

in accordance with a determination that the metric is within the second metric value range, determine a RACH configuration associated with the first preamble transmission duration and corresponding to the second metric value range.
The first apparatus of claim 1, wherein the first apparatus is caused to:

determine a metric value range comprising the metric from a plurality of metric value ranges indicating different coverage states respectively; and

determine a RACH configuration corresponding to the determined metric value range.
The first apparatus of any of claims 1 to 4, wherein the determined RACH configuration is associated with the first preamble transmission duration, and the first apparatus is caused to:

in response to a failure in receiving a response to the random access preamble, determine a further RACH configuration associated with the second preamble transmission duration; and

transmit, to the second apparatus, a further random access preamble based on the further RACH configuration.
The first apparatus of any of claims 1 to 5, wherein the determined RACH configuration comprises one of:

a configuration for transmitting a preamble of the first preamble transmission duration with a first transmit power in a time window comprising a subband full duplex, SBFD, time period and an uplink only time period,

a configuration for transmitting a preamble of the first preamble transmission duration in a time window comprising an uplink only time period, or

a configuration for transmitting a preamble of the first preamble transmission duration with a second transmit power lower than the first transmit power in a time window comprising an SBFD time period and an uplink only time period,

a configuration for transmitting a preamble of the second preamble transmission duration with a first transmit power in a time window comprising at least an SBFD time period,

a configuration for transmitting a preamble of the second preamble transmission duration in a time window extending from an SBFD time period to an uplink only time period, or

a configuration for transmitting a preamble of the second preamble transmission duration with a second transmit power in a time window comprising at least an SBFD time period.
The first apparatus of any of claims 1 to 6, wherein the metric comprises a radio link quality based on a measurement on a signal from the second apparatus.
The first apparatus of any of claims 1 to 7, wherein the configuration information comprises one or more frequency domain parameters common to the first and second preamble transmission durations, and the first apparatus is caused to:

determine a frequency domain resource of at least one RACH occasion based on the one or more frequency domain parameters; and

determine a preamble format of the random access preamble and a time domain resource of the at least one RACH occasion based on a RACH configuration index comprised in the configuration information.
The first apparatus of claim 8, wherein the preamble format of the random access preamble and the time domain resource are determined based on the RACH configuration index from a first table for a plurality of RACH configuration indices, and

the first table comprises information for mapping the RACH configuration index to:

a preamble format with the first preamble transmission duration,

a preamble format with the second preamble transmission duration, and

a location in time domain.
The first apparatus of claim 8, wherein the preamble format of the random access preamble and the time domain resource are determined based on the RACH configuration index from a second table for a plurality of RACH configuration indices, and

the second table comprises information for mapping the RACH configuration index to:

a combination of a preamble format with the first preamble transmission duration and a preamble format with the second preamble transmission duration, and

one or more locations in time domain.
The first apparatus of claim 8, wherein the determined RACH configuration is associated with the second preamble transmission duration, and

a time duration and one or more locations in time domain associated with the first preamble transmission duration is determined based on the RACH configuration index;

the preamble format of the random access preamble is determined based on a mapping between different time durations and preamble formats with the second preamble transmission duration, and

the time domain resource of the at least one RACH occasion is determined based on the one or more locations in time domain associated with the first preamble transmission duration.
The first apparatus of any of claims 1 to 7, wherein the configuration information comprises:

one or more first parameters for a RACH configuration associated with the first preamble transmission duration; and

one or more second parameters for a RACH configuration associated with the second preamble transmission duration.
The first apparatus of any of claims 1 to 12, wherein the first apparatus is or is comprised in a terminal device, and the second apparatus is or is comprised in a network device.
A method comprising:

receiving, at a first apparatus from a second apparatus, configuration information for random access channel, RACH, transmissions.

determining a RACH configuration based on the configuration information and a metric indicating a coverage state of the first apparatus, the determined RACH configuration being associated with a first preamble transmission duration or a second preamble transmission duration greater than the first preamble transmission duration.

transmitting, to the second apparatus, a random access preamble based on the determined RACH configuration.
The method of claim 14, wherein determining the RACH configuration comprises:

determining whether the metric is within a first metric value range or a second metric value range, the first metric value range indicating a better coverage state than the second metric value range;

in accordance with a determination that the metric is within the first metric value range, determining a RACH configuration with the first preamble transmission duration; and

in accordance with a determination the metric is within the second metric value range, determine a RACH configuration with the second preamble transmission duration.
The method of claim 14, wherein determining the RACH configuration comprises:

determining whether the metric is within a first metric value range or a second metric value range, a first metric value range indicating a better coverage state than the second metric value range;

in accordance with a determination that the metric is within the first metric value range, determining a RACH configuration associated with the first preamble transmission duration and corresponding to the first metric value range; and

in accordance with a determination that the metric is within the second metric value range, determining a RACH configuration associated with the first preamble transmission duration and corresponding to the second metric value range.
The method of claim 14, wherein determining the RACH configuration comprises:

determining a metric value range comprising the metric from a plurality of metric value ranges indicating different coverage states respectively; and

determining a RACH configuration corresponding to the determined metric value range.
The method of any of claims 14 to 17, wherein the determined RACH configuration is associated with the first preamble transmission duration, and the method further comprises:

in response to a failure in receiving a response to the random access preamble, determining a further RACH configuration associated with the second preamble transmission duration; and

transmitting, to the second apparatus, a further random access preamble based on the further RACH configuration.
The method of any of claims 14 to 18, wherein the determined RACH configuration comprises one of:

a configuration for transmitting a preamble of the first preamble transmission duration with a first transmit power in a time window comprising a subband full duplex, SBFD, time period and an uplink only time period,

a configuration for transmitting a preamble of the first preamble transmission duration in a time window comprising an uplink only time period, or

a configuration for transmitting a preamble of the first preamble transmission duration with a second transmit power lower than the first transmit power in a time window comprising an SBFD time period and an uplink only time period,

a configuration for transmitting a preamble of the second preamble transmission duration with a first transmit power in a time window comprising at least an SBFD time period,

a configuration for transmitting a preamble of the second preamble transmission duration in a time window extending from an SBFD time period to an uplink only time period, or

a configuration for transmitting a preamble of the second preamble transmission duration with a second transmit power in a time window comprising at least an SBFD time period.
The method of any of claims 14 to 19, wherein the metric comprises a radio link quality based on a measurement on a signal from the second apparatus.
The method of any of claims 14 to 20, wherein the configuration information comprises one or more frequency domain parameters common to the first and second preamble transmission durations, and determining the RACH configuration:

determining a frequency domain resource of at least one RACH occasion based on the one or more frequency domain parameters; and

determining a preamble format of the random access preamble and a time domain resource of the at least one RACH occasion based on a RACH configuration index comprised in the configuration information.
The method of claim 21, wherein the preamble format of the random access preamble and the time domain resource are determined based on the RACH configuration index from a first table for a plurality of RACH configuration indices, and

the first table comprises information for mapping the RACH configuration index to:

a preamble format with the first preamble transmission duration,

a preamble format with the second preamble transmission duration, and

a location in time domain.
The method of claim 21, wherein the preamble format of the random access preamble and the time domain resource are determined based on the RACH configuration index from a second table for a plurality of RACH configuration indices, and

the second table comprises information for mapping the RACH configuration index to:

a combination of a preamble format with the first preamble transmission duration and a preamble format with the second preamble transmission duration, and

one or more locations in time domain.
The method of claim 21, wherein the determined RACH configuration is associated with the second preamble transmission duration, and

a time duration and one or more locations in time domain associated with the first preamble transmission duration is determined based on the RACH configuration index;

the preamble format of the random access preamble is determined based on a mapping between different time durations and preamble formats with the second preamble transmission duration, and

the time domain resource of the at least one RACH occasion is determined based on the one or more locations in time domain associated with the first preamble transmission duration.
The method of any of claims 14 to 20, wherein the configuration information comprises:

one or more first parameters for a RACH configuration associated with the first preamble transmission duration; and

one or more second parameters for a RACH configuration associated with the second preamble transmission duration.
The method of any of claims 14 to 25, wherein the first apparatus is or is comprised in a terminal device, and the second apparatus is or is comprised in a network device.
A first apparatus comprising:

means for receiving, from a second apparatus, configuration information for random access channel, RACH, transmissions;

means for determining a RACH configuration based on the configuration information and a metric indicating a coverage state of the first apparatus, the determined RACH configuration being associated with a first preamble transmission duration or a second preamble transmission duration greater than the first preamble transmission duration; and

means for transmitting, to the second apparatus, a random access preamble based on the determined RACH configuration.
A computer readable medium comprising instructions stored thereon for causing an apparatus at least to perform the method of any of claims 14-26.