WO2025156421A1

WO2025156421A1 - Systems and methods for demodulation reference signal (dmrs) capacity enhancement

Info

Publication number: WO2025156421A1
Application number: PCT/CN2024/085773
Authority: WO
Inventors: Junli Li; Nan Zhang; Wei Cao; Fangyu CUI
Original assignee: ZTE Corp
Current assignee: ZTE Corp
Priority date: 2024-04-03
Filing date: 2024-04-03
Publication date: 2025-07-31
Anticipated expiration: 2026-10-03

Abstract

Presented are systems and methods for demodulation reference signal (DMRS) capacity enhancement. A wireless communication device may determine a configuration message related to a demodulation reference signal (DMRS) transmission. The configuration message may indicate at least one of: one or more parameters for the DMRS transmission, one or more parameters for a physical uplink shared channel (PUSCH) transmission, or a sequence configuration for the DMRS transmission or the PUSCH transmission. The wireless communication device may perform the DMRS transmission according to the configuration message.

Description

SYSTEMS AND METHODS FOR DEMODULATION REFERENCE SIGNAL (DMRS) CAPACITY ENHANCEMENT

TECHNICAL FIELD

The disclosure relates generally to wireless communications, including but not limited to systems and methods for demodulation reference signal (DMRS) capacity enhancement.

BACKGROUND

The standardization organization Third Generation Partnership Project (3GPP) is currently in the process of specifying a new Radio Interface called 5G New Radio (5G NR) as well as a Next Generation Packet Core Network (NG-CN or NGC) . The 5G NR will have three main components: a 5G Access Network (5G-AN) , a 5G Core Network (5GC) , and a User Equipment (UE) . In order to facilitate the enablement of different data services and requirements, the elements of the 5GC, also called Network Functions, have been simplified with some of them being software based, and some being hardware based, so that they could be adapted according to need. Communication via satellite is one of the typical scenarios of the non-terrestrial networks in 3GPP standardization.

SUMMARY

The example embodiments disclosed herein are directed to solving the issues relating to one or more of the problems presented in the prior art, as well as providing additional features that will become readily apparent by reference to the following detailed description when taken in conjunction with the accompany drawings. In accordance with various embodiments, example systems, methods, devices and computer program products are disclosed herein. It is understood, however, that these embodiments are presented by way of example and are not limiting, and it will be apparent to those of ordinary skill in the art who read the present disclosure that various modifications to the disclosed embodiments can be made while remaining within the scope of this disclosure.

At least one aspect is directed to a system, method, apparatus, or a computer-readable medium of the following. A wireless communication device (e.g., a user equipment (UE) ) may determine a configuration message related to a demodulation reference signal (DMRS) transmission. The configuration message may indicate at least one of: one or more parameters for the DMRS transmission, one or more parameters for a physical uplink shared channel (PUSCH) transmission, or a sequence configuration for the DMRS transmission or the PUSCH transmission. The wireless communication device may perform the DMRS transmission according to the configuration message. In some embodiments, the wireless communication device may receive the configuration message from a wireless communication node (e.g., a base station (BS) ) .

In some embodiments, at least one of the one or more parameters or the sequence configuration may indicate at least one of: an index of an orthogonal cover code (OCC) sequence, a length of the OCC sequence, an index of a cyclic shift, a repetition number, the number of repetitions of identical slots for PUSCH (e.g., ) , or an index of an antenna port. The following information can be indicated in the configuration message (e.g., parameters for DMRS transmission, or PUSCH transmission, or sequence configuration) .

In some embodiments, the wireless communication device may determine a sequence set of an orthogonal cover code (OCC) sequence corresponding to a length of the OCC sequence. The wireless communication device may determine a sequence of the OCC sequence according to an index (e.g., identifier) of the OCC sequence and the sequence set. The wireless communication device may apply the sequence of the OCC sequence to the DMRS transmission.

In some embodiments, the wireless communication device may apply the OCC sequence to the DMRS transmission, wherein a unit of applying OCC sequence is across at least one of: a plurality of repetitions; a plurality of slots; a plurality of sets of slots (e.g., Nslots unit) ; or a plurality of resource units (RUs) . In some embodiments, if the OCC sequence is applied across at least one of the plurality of repetitions or slots or sets of slots or RUs, a sequence of the DMRS transmission to apply the OCC sequence can be same across the plurality of repetitions or slots or sets of slots or RUs.

In some embodiments, the wireless communication device may apply a first OCC sequence to the DMRS transmission that is determined by an application of a second OCC sequence for the PUSCH transmission. The first OCC sequence can be same with the second OCC sequence or configured by signaling. The DMRS transmission corresponds to the PUSCH transmission. In some embodiments, the determining indicates at least one of: application of the first OCC sequence to the DMRS transmission is via/using a slot-level OCC when the application of the second OCC sequence to the PUSCH transmission is via/using a slot-level OCC; the application of the first OCC sequence to the DMRS transmission is via/using the slot-level OCC when the application of the second OCC sequence to the PUSCH transmission is via/using a symbol-level OCC; the application of the first OCC sequence to the DMRS transmission is via/using the slot-level OCC when the application of the second OCC sequence to the PUSCH transmission is via/using a resource unit (RU) -level OCC; the application of the first OCC sequence to the DMRS transmission is via/using the RU-level OCC when the application of the second OCC sequence to the PUSCH transmission is via/using the RU-level OCC; the application of the first OCC sequence to the DMRS transmission is via/using a repetition-level OCC when the application of the second OCC sequence to the PUSCH transmission is via/using the repetition-level OCC; or the application of the first OCC sequence to the DMRS transmission is via/using the slot-level OCC when the application of the second OCC sequence to the PUSCH transmission is via/using the repetition-level OCC.

In some embodiments, if the OCC sequence is applied across the plurality of slots for performing single-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence is repeated a number of times in a number of slots equal to a length of the OCC sequence. In some embodiments, if the OCC sequence is applied across the plurality of slots for performing single-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of slots equal to a repetition number. In some embodiments, if the OCC sequence is applied across the plurality of slots for performing multi-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of slots equal to a length of the OCC sequence.

In some embodiments, if the OCC sequence is applied across the plurality of slots for performing multi-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of slots equal to a repetition number. In some embodiments, if the OCC sequence is applied across the plurality of sets of slots for performing multi-tone (e.g., across a number of different frequencies/bands) repetition, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of sets of slots equal to a length of the OCC sequence. In some embodiments, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of sets of slots equal to the number of repetitions of identical slots for PUSCH. The number of identical slots can be smaller than a length of the OCC sequence.

In some embodiments, the wireless communication device may determine the index of the OCC sequence to be a value mapped to the index of the antenna port. The wireless communication device may perform the DMRS transmission corresponding to the index of the antenna port. In some embodiments, the wireless communication device may determine the index of the OCC sequence to be a value mapped to the index of the cyclic shift or at least one value of a plurality of cyclic shifts. The wireless communication device may perform the DMRS transmission corresponding to the index of the cyclic shift or the at least one value of a plurality of cyclic shifts.

In some embodiments, the wireless communication device may determine the index of the OCC sequence to be a value mapped to the index of the cyclic shift or at least one value of a plurality of cyclic shifts. A number of cyclic shifts for performing the DMRS transmission of multi-tone repetition can be configured as/in a list of multiple values (e.g., {cyclicShift value1, cyclicShift value2, cyclicShift value3, cyclicShift value4} ) .

In some embodiments, the wireless communication device may determine to perform an enhanced DMRS transmission when a condition is satisfied. The condition may include at least one of: the wireless communication device is capable of supporting capacity enhancement; an orthogonal cover code (OCC) sequence index is configured for the wireless communication device; a threshold is configured, and a measured reference signal received power (RSRP) is higher than the threshold; a modulation coding scheme (MCS) index is lower than a specific MCS configuration; or a channel condition is higher than a specific threshold configuration. In some embodiments, performing the DMRS transmission can be used both for a legacy DMRS transmission and an enhanced DMRS transmission. The above condition may be for the enhanced DMRS transmission.

In some embodiments, a wireless communication node (e.g., a base station (BS) ) may send a configuration message to a wireless communication device (e.g., a user equipment (UE) ) . The wireless communication device may determine the configuration message related to a demodulation reference signal (DMRS) transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

Various example embodiments of the present solution are described in detail below with reference to the following figures or drawings. The drawings are provided for purposes of illustration only and merely depict example embodiments of the present solution to facilitate the reader's understanding of the present solution. Therefore, the drawings should not be considered limiting of the breadth, scope, or applicability of the present solution. It should be noted that for clarity and ease of illustration, these drawings are not necessarily drawn to scale.

FIG. 1 illustrates an example cellular communication network in which techniques disclosed herein may be implemented, in accordance with an embodiment of the present disclosure;

FIG. 2 illustrates a block diagram of an example base station and a user equipment device, in accordance with some embodiments of the present disclosure;

FIG. 3 illustrates an example implementation of non-terrestrial networks (NTN) communication, in accordance with some embodiments of the present disclosure;

FIG. 4 illustrates an example implementation for DMRS capacity enhancement, in accordance with some embodiments of the present disclosure;

FIG. 5 illustrates an example implementation for DMRS capacity enhancement, in accordance with some embodiments of the present disclosure;

FIG. 6 illustrates an example implementation for DMRS capacity enhancement, in accordance with some embodiments of the present disclosure;

FIG. 7 illustrates an example implementation for DMRS capacity enhancement, in accordance with some embodiments of the present disclosure;

FIG. 8 illustrates an implementation for DMRS capacity enhancement, in accordance with some embodiments of the present disclosure;

FIG. 9 illustrates an example implementation for DMRS capacity enhancement, in accordance with some embodiments of the present disclosure; and

FIG. 10 illustrates a flow diagram of an example method for demodulation reference signal (DMRS) capacity enhancement, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION

1. Mobile Communication Technology and Environment

FIG. 1 illustrates an example wireless communication network, and/or system, 100 in which techniques disclosed herein may be implemented, in accordance with an embodiment of the present disclosure. In the following discussion, the wireless communication network 100 may be any wireless network, such as a cellular network or a narrowband Internet of things (NB-IoT) network, and is herein referred to as “network 100. ” Such an example network 100 includes a base station 102 (hereinafter “BS 102” ; also referred to as wireless communication node) and a user equipment device 104 (hereinafter “UE 104” ; also referred to as wireless communication device) that can communicate with each other via a communication link 110 (e.g., a wireless communication channel) , and a cluster of cells 126, 130, 132, 134, 136, 138 and 140 overlaying a geographical area 101. In Figure 1, the BS 102 and UE 104 are contained within a respective geographic boundary of cell 126. Each of the other cells 130, 132, 134, 136, 138 and 140 may include at least one base station operating at its allocated bandwidth to provide adequate radio coverage to its intended users.

For example, the BS 102 may operate at an allocated channel transmission bandwidth to provide adequate coverage to the UE 104. The BS 102 and the UE 104 may communicate via a downlink radio frame 118, and an uplink radio frame 124 respectively. Each radio frame 118/124 may be further divided into sub-frames 120/127 which may include data symbols 122/128. In the present disclosure, the BS 102 and UE 104 are described herein as non-limiting examples of “communication nodes, ” generally, which can practice the methods disclosed herein. Such communication nodes may be capable of wireless and/or wired communications, in accordance with various embodiments of the present solution.

FIG. 2 illustrates a block diagram of an example wireless communication system 200 for transmitting and receiving wireless communication signals (e.g., OFDM/OFDMA signals) in accordance with some embodiments of the present solution. The system 200 may include components and elements configured to support known or conventional operating features that need not be described in detail herein. In one illustrative embodiment, system 200 can be used to communicate (e.g., transmit and receive) data symbols in a wireless communication environment such as the wireless communication environment 100 of Figure 1, as described above.

System 200 generally includes a base station 202 (hereinafter “BS 202” ) and a user equipment device 204 (hereinafter “UE 204” ) . The BS 202 includes a BS (base station) transceiver module 210, a BS antenna 212, a BS processor module 214, a BS memory module 216, and a network communication module 218, each module being coupled and interconnected with one another as necessary via a data communication bus 220. The UE 204 includes a UE (user equipment) transceiver module 230, a UE antenna 232, a UE memory module 234, and a UE processor module 236, each module being coupled and interconnected with one another as necessary via a data communication bus 240. The BS 202 communicates with the UE 204 via a communication channel 250, which can be any wireless channel or other medium suitable for transmission of data as described herein.

As would be understood by persons of ordinary skill in the art, system 200 may further include any number of modules other than the modules shown in Figure 2. Those skilled in the art will understand that the various illustrative blocks, modules, circuits, and processing logic described in connection with the embodiments disclosed herein may be implemented in hardware, computer-readable software, firmware, or any practical combination thereof. To clearly illustrate this interchangeability and compatibility of hardware, firmware, and software, various illustrative components, blocks, modules, circuits, and steps are described generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware, or software can depend upon the particular application and design constraints imposed on the overall system. Those familiar with the concepts described herein may implement such functionality in a suitable manner for each particular application, but such implementation decisions should not be interpreted as limiting the scope of the present disclosure

In accordance with some embodiments, the UE transceiver 230 may be referred to herein as an "uplink" transceiver 230 that includes a radio frequency (RF) transmitter and a RF receiver each comprising circuitry that is coupled to the antenna 232. A duplex switch (not shown) may alternatively couple the uplink transmitter or receiver to the uplink antenna in time duplex fashion. Similarly, in accordance with some embodiments, the BS transceiver 210 may be referred to herein as a "downlink" transceiver 210 that includes a RF transmitter and a RF receiver each comprising circuity that is coupled to the antenna 212. A downlink duplex switch may alternatively couple the downlink transmitter or receiver to the downlink antenna 212 in time duplex fashion. The operations of the two transceiver modules 210 and 230 may be coordinated in time such that the uplink receiver circuitry is coupled to the uplink antenna 232 for reception of transmissions over the wireless transmission link 250 at the same time that the downlink transmitter is coupled to the downlink antenna 212. Conversely, the operations of the two transceivers 210 and 230 may be coordinated in time such that the downlink receiver is coupled to the downlink antenna 212 for reception of transmissions over the wireless transmission link 250 at the same time that the uplink transmitter is coupled to the uplink antenna 232. In some embodiments, there is close time synchronization with a minimal guard time between changes in duplex direction.

The UE transceiver 230 and the base station transceiver 210 are configured to communicate via the wireless data communication link 250, and cooperate with a suitably configured RF antenna arrangement 212/232 that can support a particular wireless communication protocol and modulation scheme. In some illustrative embodiments, the UE transceiver 210 and the base station transceiver 210 are configured to support industry standards such as the Long Term Evolution (LTE) and emerging 5G standards, and the like. It is understood, however, that the present disclosure is not necessarily limited in application to a particular standard and associated protocols. Rather, the UE transceiver 230 and the base station transceiver 210 may be configured to support alternate, or additional, wireless data communication protocols, including future standards or variations thereof.

In accordance with various embodiments, the BS 202 may be an evolved node B (eNB) , a serving eNB, a target eNB, a femto station, or a pico station, for example. In some embodiments, the UE 204 may be embodied in various types of user devices such as a mobile phone, a smart phone, a personal digital assistant (PDA) , tablet, laptop computer, wearable computing device, etc. The processor modules 214 and 236 may be implemented, or realized, with a general purpose processor, a content addressable memory, a digital signal processor, an application specific integrated circuit, a field programmable gate array, any suitable programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof, designed to perform the functions described herein. In this manner, a processor may be realized as a microprocessor, a controller, a microcontroller, a state machine, or the like. A processor may also be implemented as a combination of computing devices, e.g., a combination of a digital signal processor and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a digital signal processor core, or any other such configuration.

Furthermore, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in firmware, in a software module executed by processor modules 214 and 236, respectively, or in any practical combination thereof. The memory modules 216 and 234 may be realized as RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. In this regard, memory modules 216 and 234 may be coupled to the processor modules 210 and 230, respectively, such that the processors modules 210 and 230 can read information from, and write information to, memory modules 216 and 234, respectively. The memory modules 216 and 234 may also be integrated into their respective processor modules 210 and 230. In some embodiments, the memory modules 216 and 234 may each include a cache memory for storing temporary variables or other intermediate information during execution of instructions to be executed by processor modules 210 and 230, respectively. Memory modules 216 and 234 may also each include non-volatile memory for storing instructions to be executed by the processor modules 210 and 230, respectively.

The network communication module 218 generally represents the hardware, software, firmware, processing logic, and/or other components of the base station 202 that enable bi-directional communication between base station transceiver 210 and other network components and communication nodes configured to communication with the base station 202. For example, network communication module 218 may be configured to support internet or WiMAX traffic. In a typical deployment, without limitation, network communication module 218 provides an 802.3 Ethernet interface such that base station transceiver 210 can communicate with a conventional Ethernet based computer network. In this manner, the network communication module 218 may include a physical interface for connection to the computer network (e.g., Mobile Switching Center (MSC) ) . The terms “configured for, ” “configured to” and conjugations thereof, as used herein with respect to a specified operation or function, refer to a device, component, circuit, structure, machine, signal, etc., that is physically constructed, programmed, formatted and/or arranged to perform the specified operation or function.

The Open Systems Interconnection (OSI) Model (referred to herein as, “open system interconnection model” ) is a conceptual and logical layout that defines network communication used by systems (e.g., wireless communication device, wireless communication node) open to interconnection and communication with other systems. The model is broken into seven subcomponents, or layers, each of which represents a conceptual collection of services provided to the layers above and below it. The OSI Model also defines a logical network and effectively describes computer packet transfer by using different layer protocols. The OSI Model may also be referred to as the seven-layer OSI Model or the seven-layer model. In some embodiments, a first layer may be a physical layer. In some embodiments, a second layer may be a Medium Access Control (MAC) layer. In some embodiments, a third layer may be a Radio Link Control (RLC) layer. In some embodiments, a fourth layer may be a Packet Data Convergence Protocol (PDCP) layer. In some embodiments, a fifth layer may be a Radio Resource Control (RRC) layer. In some embodiments, a sixth layer may be a Non Access Stratum (NAS) layer or an Internet Protocol (IP) layer, and the seventh layer being the other layer.

Various example embodiments of the present solution are described below with reference to the accompanying figures to enable a person of ordinary skill in the art to make and use the present solution. As would be apparent to those of ordinary skill in the art, after reading the present disclosure, various changes or modifications to the examples described herein can be made without departing from the scope of the present solution. Thus, the present solution is not limited to the example embodiments and applications described and illustrated herein. Additionally, the specific order or hierarchy of steps in the methods disclosed herein are merely example approaches. Based upon design preferences, the specific order or hierarchy of steps of the disclosed methods or processes can be re-arranged while remaining within the scope of the present solution. Thus, those of ordinary skill in the art will understand that the methods and techniques disclosed herein present various steps or acts in a sample order, and the present solution is not limited to the specific order or hierarchy presented unless expressly stated otherwise.

2. Systems and Methods for Demodulation Reference Signal (DMRS) Capacity Enhancement

To address the conflict between limited resources and larger number of user equipments (UEs) , one approach is to improve the uplink capacity. Moreover, non-terrestrial networks (NTN) can be supported. A satellite communication system can cover a wider variety and quantity of UEs due to its wide coverage. For example, a narrowband internet of things (NB-IoT) NTN can be deployed. In deployments, a system, such as for NB-IoT, may have to support massive capacity in terms of number and types of UE, some of which have worse characteristics than others (e.g., low cost devices, or wearables) . Therefore, what has also clearly emerged by capacity analysis is that the current UL system capacity is limited.

The methods to expand physical uplink shared channel (PUSCH) capacity in terrestrial networks /non-terrestrial networks (TN/NTN) are disclosed herein. Demodulation reference signal (DMRS) in IoT may not support multiple UEs multiplexed on same time-frequency resource. To support capacity enhancement, the function of DMRS can be enhanced. In the present disclosure, the methods to enhance DMRS capacity is discussed.

FIG. 3 illustrates an example implementation of non-terrestrial networks (NTN) communication, in accordance with some embodiments of the present disclosure. The structure of a transparent NTN is illustrated in FIG. 3. A link between a UE and a satellite can be a service link. A link between a BS and a satellite can be a feeder link and may be common for all UEs within the same cell.

A frequency unit of a narrow band physical uplink shared channel (NPUSCH) can be a subcarrier. A NPUSCH can be configured with different DMRS signals for different numbers of consecutive subcarriers in an UL resource unit for NB-IoT. In a time-domain, there can be one orthogonal frequency-division multiplexing (OFDM) symbol in each slot as the OFDM symbol corresponding to the uplink demodulation reference signal for NPUSCH format 1. There can be three OFDM symbols in each slot as the OFDM symbol corresponding to the uplink demodulation reference signal for NPUSCH format 2. In frequency-domain, the number of subcarriers corresponding to the uplink demodulation reference signal can be the same as the data.

When consecutive subcarrier is 1 (e.g., single-tone) , a length of DMRS sequence can be 16 which may correspond to 16 slots respectively. When consecutive subcarriers are 3 or 6, the length of a DMRS sequence can be 3 or 6 which may correspond to 3 (e.g., three-tones) or 6 (e.g., six-tones) subcarriers in each slot. Due to the short length of the DMRS sequence and the limited number of available root sequences, cyclic shift can be introduced to expand the available sequences. When the configuration is three-tone, the cyclic shift can be configured as one of {0, 2π/3, 4π/3} . When the configuration is six-tone, the cyclic shift can be configured as one of {0, 2π/2, 4π/4, 8π/6} . When the consecutive subcarriers are 12, the length of DMRS sequence is 12 which may correspond to 12 subcarriers in each slot. The cyclic shift for preconfigured uplink resource (PUR) NPUSCH can be configured as 2πn_cs/12, n_cs can be configured as one of {0, 6} through a high layer signaling. For other NPUSCH, the cyclic shift can be set as 0.

FIG. 4 illustrates an example implementation/approach for DMRS capacity enhancement, in accordance with some embodiments of the present disclosure. FIG. 4 illustrates a NPUSCH DMRS structure for NPUSCH format 1 single-tone when enable/disable group hopping. FIG. 5 illustrates an example implementation/approach for DMRS capacity enhancement, in accordance with some embodiments of the present disclosure. FIG. 5 illustrates a NPUSCH DMRS structure for NPUSCH format 1 multi-tone when enable group hopping.

For a DMRS sequence of single tone (e.g., single frequency/band) , the base sequence index of DMRS sequence can be related to the cell ID, which may mean/indicate that the DMRS sequences of each UE in the same cell on the same resource can be the same (e.g., this can be because the IoT system uses frequency division to expand system capacity during design) , so existing DMRS sequence of single-tone may not support code domain based capacity enhancement on the same time-frequency resource.

For a DMRS sequence of multi tone, the base sequence index of DMRS sequence can be configured by a high layer signaling or can be related to a cell identity (ID) (if not configured by the high layer signaling) . The cyclic shifts of 3-tone and 6-tone can be configured by one or more high-level parameters, with 3-tone supporting 3 values and 6-tone supporting 4 values. For 12-tone, if NPUSCH is PUR NPUSCH, the cyclic shift can be implicitly determined by the high-level parameter configuration. At this time, 12-tone may support 2 values. If it is not PUR NPUSCH, the cyclic shift may default to 0. The purpose of the cyclic shift defined can be to expand the number of sequences rather than UE multiplexing. Therefore, the DMRS sequences of each UE in the same cell on the same time-frequency resource can be the same. Therefore, DMRS sequence of multi-tone may not support code domain based capacity enhancement on the same time-frequency resource.

In order to enhance the capacity of NPUSCH, applying an orthogonal cover code (OCC) to the NPUSCH signal can be one approach. Due to the current DMRS sequence not supporting capacity expansion, it can be necessary to enhance the current DMRS sequence to avoid affecting the capacity enhancement of NPUSCH signals. Therefore, the following methods can be considered.

Implementation Example 1: Apply OCC to DMRS sequence

A wireless communication device (e.g., a user equipment (UE) ) may determine a configuration message related to a demodulation reference signal (DMRS) transmission. The configuration message may indicate at least one of: one or more parameters for the DMRS transmission, one or more parameters for a physical uplink shared channel (PUSCH) transmission, or a sequence configuration for the DMRS transmission or the PUSCH transmission. The wireless communication device may perform the DMRS transmission according to the configuration message. In some embodiments, the wireless communication device may receive the configuration message from a wireless communication node (e.g., a base station (BS) ) .

In some embodiments, at least one of the one or more parameters or the sequence configuration may indicate at least one of: an index (e.g., identifier) of an orthogonal cover code (OCC) sequence, a length of the OCC sequence, an index of a cyclic shift, a repetition number, the number of repetitions of identical slots for PUSCH (e.g., ) , or an index of an antenna port. The following information can be indicated in the configuration message (e.g., parameters for DMRS transmission, or PUSCH transmission, or sequence configuration) . In some embodiments, the wireless communication device may apply the OCC sequence to the DMRS transmission, wherein a unit of applying OCC sequence is across at least one of: a plurality of repetitions; a plurality of slots; a plurality of sets of slots (e.g., Nslots unit) ; or a plurality of resource units (RUs) .

Regardless of whether the group hopping is enabled or disabled for single-tone, the DMRS in different slots can be different. When group hopping is enabled, the DMRS in different slots can be different for multi-tone. Therefore, in these cases, when applying OCC to the DMRS, the following method can be considered.

Case-1: If the OCC sequence is applied across at least one of the plurality of repetitions, a sequence of the DMRS transmission to apply the OCC sequence can be same across the plurality of repetitions. For example, the element of an OCC sequence can be applied across repetitions. Existing RV cycle remain unchanged, as shown in FIG. 6. The scheme can also be applied to multi-tone transmission, as shown in FIG. 7. The DMRS sequence in the repetition to apply OCC can remain the same. FIG. 6 illustrates an example implementation/approach for DMRS capacity enhancement, in accordance with some embodiments of the present disclosure. FIG. 6 illustrates a NPUSCH DMRS structure for single-tone inter-repetition OCC. FIG. 7 illustrates an example implementation/approach for DMRS capacity enhancement, in accordance with some embodiments of the present disclosure. FIG. 7 illustrates a NPUSCH DMRS implementation/approach for multi-tone inter-repetition OCC.

Case-2: If the OCC sequence is applied across at least one of the plurality of slots, a sequence of the DMRS transmission to apply the OCC sequence can be same across the plurality of slots. For example, the element of an OCC sequence can be applied across slots. Existing RV cycle can remain unchanged, for single-tone, and the mapping of DMRS sequence can be modified. The mapping of DMRS sequence to resource elements can be in increasing order of first frequency domain resource (e.g., k subcarrier) , then time-domain resource (e.g., l symbol) , and finally the slot number.

Option-1: If the OCC sequence is applied across the plurality of slots for performing single-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of slots equal to a length of the OCC sequence. For example, after mapping to the first slot, the DMRS in the slot can be repeated (occLength-1) additional times before continuing the mapping of DMRS sequence to the following slot. After the full DMRS sequence (e.g., slots) has been repeated occLength times. The DMRS sequence can be regenerated and the procedure is then repeated once to complete the mapping ofas shown in FIG. 8. FIG. 8 illustrates an example implementation/approach for DMRS capacity enhancement, in accordance with some embodiments of the present disclosure. FIG. 8 illustrates a NPUSCH DMRS structure for single-tone inter-slot OCC.

Option-2: If the OCC sequence is applied across the plurality of slots for performing single-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of slots equal to a repetition number. For example, after mapping to the first slot, the DMRS in the slot can be repeated (repetiitonNum-1) additional times before continuing the mapping of DMRS sequence to the following slot.

For multi-tone, the similar scheme can also be applied. The mapping of DMRS sequence can be modified. The mapping of DMRS sequence to resource elements can be in increasing order of first frequency domain resource (e.g., k subcarrier) , then time-domain resource (e.g., l symbol) , finally the slot number.

Option-3: If the OCC sequence is applied across the plurality of slots for performing multi-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of slots equal to a length of the OCC sequence. For example, after mapping to the first slot, the DMRS in the slot can be repeated (occLength-1) additional times before continuing the mapping of DMRS sequence to the following slot. After the full DMRS sequence (e.g., occLength slots) has been repeated occLength times. In some embodiments, the DMRS sequence can be regenerated and the procedure can be then repeated once to complete the mapping ofslots, as shown in FIG. 9. FIG. 9 illustrates an example implementation/approach for DMRS capacity enhancement, in accordance with some embodiments of the present disclosure. FIG. 9 illustrates a NPUSCH DMRS implementation/approach for multi-tone inter-slot OCC.

Option-4: If the OCC sequence is applied across the plurality of slots for performing multi-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of slots equal to a repetition number. Option 4 can be same with Option-2.

Option-5: If the OCC sequence is applied across the plurality of sets of slots for performing multi-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of sets of slots equal to a length of the OCC sequence. For example, after mapping to the N_slots slot, the DMRS in the N_slots slot can be repeated (occLength-1) additional times before continuing the mapping of DMRS sequence to the following slot. After occLength*N_slots slots, the full DMRS sequence may have been repeated occLength times. In some embodiments, the DMRS sequence can be regenerated and the procedure can be then repeated once to complete the mapping ofslots.

Case-3: A sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of sets of slots equal to the number of repetitions of identical slots for PUSCH (e.g., ) . The number of identical slots can be smaller than a length of the OCC sequence. In addition to defining occLength number of slots to apply OCC, existing parameterscan also be reused for the mapping of DMRS. When>=occLength, the mapping of DMRS can be same with the procedure defined in Case-2 (e.g., replace the occLength by) . When<occLength, after the full DMRS has been repeatedtimes, the procedure can then be repeated until the number of identical slots = occLength. Then the DMRS sequence can be regenerated and the procedure repeated to complete the mapping ofslots. The same mechanism can be used both for single-tone and multi-tone approaches.

Besides the repetition unit and slot unit to apply OCC, the Nslots unit, RU unit can also be used to apply OCC. The OCC can be applied inter-Nslots and/or inter-RU. The above procedure can also be used to achieve inter-Nslots OCC and inter-RU OCC mechanism.

The parameter occLength can be the length of OCC sequence, representing the number of multiplexed-UE. For example, the length of OCC sequence [W0, W1] can be 2. The length of OCC sequence and sequence index can be configured through a signaling (e.g., high layer signaling or downlink control information (DCI) signaling) or equal to the length of OCC sequence and sequence index for data part (no additional signaling for DMRS) . In some examples, for a specific UE, the OCC sequence for DMRS can be same as the OCC sequence for data (e.g., data portion as opposed to the DMRS portion) , the OCC sequence for data is determined by the specific OCC sequence index corresponding to each UE. In some examples, the granularity of applying OCC for data and DMRS can be same or different. For example, when the granularity of data to apply OCC is slot, the granularity of DMRS to apply OCC can be slot. When the granularity of data to apply OCC is symbol, the granularity of DMRS to apply OCC can be slot. In some embodiments, application of the first OCC sequence to the DMRS transmission is via/using a slot-level OCC when the application of the second OCC sequence to the PUSCH transmission is via/using a slot-level OCC; the application of the first OCC sequence to the DMRS transmission is via/using the slot-level OCC when the application of the second OCC sequence to the PUSCH transmission is via/using a symbol-level OCC; the application of the first OCC sequence to the DMRS transmission is via/using the slot-level OCC when the application of the second OCC sequence to the PUSCH transmission is via/using a resource unit (RU) -level OCC; the application of the first OCC sequence to the DMRS transmission is via/using the RU-level OCC when the application of the second OCC sequence to the PUSCH transmission is via/using the RU-level OCC; the application of the first OCC sequence to the DMRS transmission is via/using a repetition-level OCC when the application of the second OCC sequence to the PUSCH transmission is via/using the repetition-level OCC; or the application of the first OCC sequence to the DMRS transmission is via/using the slot-level OCC when the application of the second OCC sequence to the PUSCH transmission is via/using the repetition-level OCC.

When group hopping is disabled, the DMRS in different slots can be same for multi-tone implementation. Therefore, in this case, an existing mapping rule can be reused, e.g., when applying OCC to the DMRS, the following method can be considered. The set of sub-carriers used in the mapping process can be identical to the corresponding NPUSCH transmission. The mapping to resource elements can be in increasing order of first k, then l, and finally the slot number. The OCC can be applied to DMRS transmission across slots, or repetitions, or RUs, or Nslots.

Implementation Example 2: Enhance DMRS capacity via DMRS ports or cyclic shift enhancement

Case-1: The wireless communication device (e.g., UE) may determine the index of the OCC sequence to be a value mapped to the index of the antenna port. The wireless communication device may determine the DMRS transmission corresponding to the index of the antenna port. For example, the UE may reuse existing orthogonal DMRS ports. Different antenna ports can be reused for different UEs. For example, the UE may associate the DMRS ports with different OCC sequence indexes for different UEs sequentially. When at least one condition is satisfied, the DMRS sequence corresponding to the OCC sequence index for the NPUSCH can be determined. For example, the OCC sequence index can be configured as {0,1, 2, 3} , the mapping rules between the OCC sequence index and DMRS port can be defined as: the 1st/2nd/3rd/4th configured OCC sequence index are mapped to “port index 0” , “port index 1” , “port index 2” , “port index 3” of DMRS ports, respectively, such as in Table 1.

In some embodiments, the DMRS sequences corresponding to different antenna ports can be orthogonal to each other, as shown in Table 2. The mechanism/DMRS sequence can be reused to enhance the DMRS capacity of an IoT system. Multiple orthogonal DMRSs can be distinguished by frequency domain, while a group of DMRSs within the same CDM group can be distinguished by code domain (e.g., OCC) .

Table 1. Mapping relationship between OCC sequence indexex and DMRS ports.

Table 2. Parameters for PUSCH DM-RS configuration type 1 in NR.

Case-2: The wireless communication device (e.g., UE) may determine the index of the OCC sequence to be a value mapped to the index of the cyclic shift or at least one value of a plurality of cyclic shifts. The wireless communication device may determine the DMRS transmission corresponding to the index of the cyclic shift or the at least one value of a plurality of cyclic shifts. In some embodiments, existing cyclic shifts can be reused to generate orthogonal DMRS sequence. Different cyclic shifts can be reused for different UEs, for example, associate the cyclic shift with different OCC sequence index for different UE sequentially. When at least one condition is satisfied, the DMRS sequence corresponding to the OCC sequence index for the NPUSCH can be determined. For example, the OCC sequence indexes can be configured as {0, 1, 2, 3} . The mapping rules between the OCC sequence index and cyclic shift value/index can be defined as: the 1st/2nd/3rd/4th configured OCC sequence index are mapped to “cyclic shift value/index 0” , “cyclic shift value/index 1” , “cyclic shift value/index 2” , “cyclic shift value/index 3” of cyclic shifts, respectively, such as in Table 3.

Table 3. Mapping relationship between OCC sequence indexes and cyclic shift values/indexes.

Table 1. Mapping of Cyclic Shift Field in uplink-related DCI format toand [w^(λ) (0) w ^(λ) (1) ] .

In some embodiments, such as in LTE, the DMRS sequences corresponding to cyclic shift can be orthogonal to each other, as shown in Table 4. The mechanism/DMRS sequences can be reused to enhance the DMRS capacity of an IoT system.

Case-3: The wireless communication device (e.g., UE) may determine the index of the OCC sequence to be a value mapped to the index of the cyclic shift or at least one value of a plurality of cyclic shifts. A number of cyclic shifts for performing the DMRS transmission of multi-tone repetition can be configured as a list of multiple values (e.g., {cyclicShift value1, cyclicShift value2, cyclicShift value3, cyclicShift value4} ) . For example, the number of existing cyclic shifts can be enhanced to generate orthogonal DMRS sequences. In IoT, for the multi-tone, the DMRS sequence corresponding to specific cyclic shift can be orthogonal to each other, but a 3-tone approach only supports 3 cyclic shift values {0, 2π/3, 4π/3} , and 12-tone may only support 2 cyclic shifts {0, π} for PUR NPUSCH. the number of cyclic shifts for 12-tone can be enhanced as {cyclicShift value1, cyclicShift value2, cyclicShift value3, cyclicShift value4} .

In some embodiments, the cyclic shifts may be associated with different OCC sequence indexes for different UEs sequentially. When at least one condition is satisfied, the DMRS sequence corresponding to the OCC sequence index for the NPUSCH can be determined. For example, the OCC sequence indexes can be configured as {0, 1, 2, 3} . The mapping rules between the OCC sequence indexes and cyclic shift values/indexes can be defined as: the 1st/2nd/3rd/4th configured OCC sequence indexes are mapped to “cyclic shift value/index 0” , “cyclic shift value/index 1” , “cyclic shift value/index 2” , “cyclic shift value/index 3” of cyclic shifts for 12-tone, respectively, such as in Table 3. For 3-tone and 6-tone approaches, the mapping rule between the OCC sequence index and cyclic shift value can be reused as: the 1st/2nd/3rd/4th configured OCC sequence indexes are mapped to “cyclic shift value/index 0” , “cyclic shift value/index 1” , “cyclic shift value/index 2” , “cyclic shift value/index 3 (if exist) ” of cyclic shifts for 3-tone and 6-tone approaches, respectively. In some embodiment, the mapping relationship can be as shown in Table 5.

Table 5. Mapping relationship between OCC sequence index and cyclic shift.

In some embodiments, OCC sequence index can be configured through a signaling (e.g., high layer signaling or DCI signaling) or equal to the sequence index for data part (e.g., no additional signaling for DMRS) . In some examples, the DMRS for specific UE can be determined by the OCC sequence index for data part, through methods defined above.

Implementation Example 3: Whether/when to use enhanced DMRS sequence

In some embodiments, the wireless communication device (e.g., UE) may determine to perform an enhanced DMRS transmission when a condition is satisfied. The condition may include at least one of: the wireless communication device is capable of supporting capacity enhancement; an orthogonal cover code (OCC) sequence index is configured for the wireless communication device; a threshold is configured, and a measured reference signal received power (RSRP) is higher than the threshold; a modulation coding scheme (MCS) index is lower than a specific MCS configuration; or a channel condition is higher than a specific threshold configuration. In some embodiments, performing the DMRS transmission can be used both for a legacy DMRS transmission and an enhanced DMRS transmission. The above condition may be for the enhanced DMRS transmission.

Due to the possibility of some UE (s) supporting capacity enhancement and other UE (s) not supporting capacity enhancement within the same cell, the use of enhanced DMRS (e.g., the DMRS defined in implementation example -1 and 2) may need to satisfy certain conditions, which can be at least one of the following conditions: when the UE is capable of supporting capacity enhancement; when a OCC sequence index is configured for the specific UE; when a threshold is configured and the measured RSRP is higher than the configured threshold; when a MCS index is lower than a specific MCS configuration (which can be configured through high layer signaling) ; or when a channel condition (e.g., signal-to-interference-plus-noise ratio (SINR) ) is higher than a specific threshold configuration (which can be configured through high layer signaling) .

In some embodiments, whether to use the enhanced DMRS can be configured through a high layer signaling or a DCI signaling. For example, assuming that 1 bit is used, if the value of the bit is 0, this indicates not to use the enhanced DMRS; if the value is 1, this indicate to use the enhanced DMRS. In some embodiments, when the parameters related to OCC (e.g., length of OCC sequence) is/are configured/exist, the enhanced DMRS may be used; otherwise, the enhanced DMRS may not be used. In some embodiments, the OCC sequences can be configured as one or more sequences for one UE. Assuming that 2 OCC indexes are configured via a high layer signaling or a DCI signaling, the UE can use the 2 OCC sequences corresponding to the 2 sequence indexes.

It should be understood that one or more features from the above/following implementation examples are not exclusive to the specific implementation examples, but can be combined in any manner (e.g., in any priority and/or order, concurrently or otherwise) .

FIG. 10 illustrates a flow diagram of a method 1000 for demodulation reference signal (DMRS) capacity enhancement. The method 1000 may be implemented using any one or more of the components and devices detailed herein in conjunction with FIGs. 1–9. In overview, the method 1000 may be performed by a UE, in some embodiments. Additional, fewer, or different operations may be performed in the method 1000 depending on the embodiment. At least one aspect of the operations is directed to a system, method, apparatus, or a computer-readable medium.

A wireless communication device (e.g., a user equipment (UE) ) may determine/receive a configuration message related to a demodulation reference signal (DMRS) transmission. The configuration message may indicate at least one of: one or more parameters for the DMRS transmission, one or more parameters for a physical uplink shared channel (PUSCH) transmission, or a sequence configuration for the DMRS transmission or the PUSCH transmission. The wireless communication device may perform the DMRS transmission according to the configuration message. In some embodiments, the wireless communication device may receive the configuration message from a wireless communication node (e.g., a base station (BS) ) .

In some embodiments, the wireless communication device may determine a sequence set of an orthogonal cover code (OCC) sequence corresponding to a length of the OCC sequence. The wireless communication device may determine a sequence of the OCC sequence according to an index of the OCC sequence and the sequence set. The wireless communication device may apply the sequence of the OCC sequence to the DMRS transmission.

In some embodiments, if the OCC sequence is applied across the plurality of slots for performing single-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence is repeated a number of times in a number of slots equal to a length of the OCC sequence.

In some embodiments, if the OCC sequence is applied across the plurality of slots for performing single-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of slots equal to a repetition number. In some embodiments, if the OCC sequence is applied across the plurality of slots for performing multi-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of slots equal to a length of the OCC sequence.

In some embodiments, if the OCC sequence is applied across the plurality of slots for performing multi-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of slots equal to a repetition number. In some embodiments, if the OCC sequence is applied across the plurality of sets of slots for performing multi-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of sets of slots equal to a length of the OCC sequence. In some embodiments, a sequence of the DMRS transmission to apply the OCC sequence can be repeated a number of times in a number of sets of slots equal to the number of repetitions of identical slots for PUSCH. The number of identical slots can be smaller than a length of the OCC sequence.

In some embodiments, the wireless communication device may determine the index of the OCC sequence to be a value mapped to the index of the cyclic shift or at least one value of a plurality of cyclic shifts. A number of cyclic shifts for performing the DMRS transmission of multi-tone repetition can be configured as a list of multiple values (e.g., {cyclicShift value1, cyclicShift value2, cyclicShift value3, cyclicShift value4} ) .

While various embodiments of the present solution have been described above, it should be understood that they have been presented by way of example only, and not by way of limitation. Likewise, the various diagrams may depict an example architectural or configuration, which are provided to enable persons of ordinary skill in the art to understand example features and functions of the present solution. Such persons would understand, however, that the solution is not restricted to the illustrated example architectures or configurations, but can be implemented using a variety of alternative architectures and configurations. Additionally, as would be understood by persons of ordinary skill in the art, one or more features of one embodiment can be combined with one or more features of another embodiment described herein. Thus, the breadth and scope of the present disclosure should not be limited by any of the above-described illustrative embodiments.

It is also understood that any reference to an element herein using a designation such as "first, " "second, " and so forth does not generally limit the quantity or order of those elements. Rather, these designations can be used herein as a convenient means of distinguishing between two or more elements or instances of an element. Thus, a reference to first and second elements does not mean that only two elements can be employed, or that the first element must precede the second element in some manner.

Additionally, a person having ordinary skill in the art would understand that information and signals can be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits and symbols, for example, which may be referenced in the above description can be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

A person of ordinary skill in the art would further appreciate that any of the various illustrative logical blocks, modules, processors, means, circuits, methods and functions described in connection with the aspects disclosed herein can be implemented by electronic hardware (e.g., a digital implementation, an analog implementation, or a combination of the two) , firmware, various forms of program or design code incorporating instructions (which can be referred to herein, for convenience, as "software" or a "software module) , or any combination of these techniques. To clearly illustrate this interchangeability of hardware, firmware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware, firmware or software, or a combination of these techniques, depends upon the particular application and design constraints imposed on the overall system. Skilled artisans can implement the described functionality in various ways for each particular application, but such implementation decisions do not cause a departure from the scope of the present disclosure.

Furthermore, a person of ordinary skill in the art would understand that various illustrative logical blocks, modules, devices, components and circuits described herein can be implemented within or performed by an integrated circuit (IC) that can include a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic device, or any combination thereof. The logical blocks, modules, and circuits can further include antennas and/or transceivers to communicate with various components within the network or within the device. A general purpose processor can be a microprocessor, but in the alternative, the processor can be any conventional processor, controller, or state machine. A processor can also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other suitable configuration to perform the functions described herein.

If implemented in software, the functions can be stored as one or more instructions or code on a computer-readable medium. Thus, the steps of a method or algorithm disclosed herein can be implemented as software stored on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that can be enabled to transfer a computer program or code from one place to another. A storage media can be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can include RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer.

In this document, the term "module" as used herein, refers to software, firmware, hardware, and any combination of these elements for performing the associated functions described herein. Additionally, for purpose of discussion, the various modules are described as discrete modules; however, as would be apparent to one of ordinary skill in the art, two or more modules may be combined to form a single module that performs the associated functions according embodiments of the present solution.

Additionally, memory or other storage, as well as communication components, may be employed in embodiments of the present solution. It will be appreciated that, for clarity purposes, the above description has described embodiments of the present solution with reference to different functional units and processors. However, it will be apparent that any suitable distribution of functionality between different functional units, processing logic elements or domains may be used without detracting from the present solution. For example, functionality illustrated to be performed by separate processing logic elements, or controllers, may be performed by the same processing logic element, or controller. Hence, references to specific functional units are only references to a suitable means for providing the described functionality, rather than indicative of a strict logical or physical structure or organization.

Various modifications to the embodiments described in this disclosure will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other embodiments without departing from the scope of this disclosure. Thus, the disclosure is not intended to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the novel features and principles disclosed herein, as recited in the claims below.

Claims

A method comprising:

determining, by a wireless communication device, a configuration message related to a demodulation reference signal (DMRS) transmission, wherein the configuration message indicates at least one of:

one or more parameters for the DMRS transmission,

one or more parameters for a physical uplink shared channel (PUSCH) transmission, or

a sequence configuration for the DMRS transmission or the PUSCH transmission; and

performing, by the wireless communication device, the DMRS transmission according to the configuration message.
The method of claim 1, comprising:

receiving, by the wireless communication device from a wireless communication node, the configuration message.
The method of claim 1, wherein at least one of the one or more parameters or the sequence configuration indicate at least one of: an index of an orthogonal cover code (OCC) sequence, a length of the OCC sequence, an index of a cyclic shift, a repetition number, the number of repetitions of identical slots for PUSCH, or an index of an antenna port.
The method of claim 1, comprising:

determining, by the wireless communication device, a sequence set of an orthogonal cover code (OCC) sequence corresponding to a length of the OCC sequence;

determining, by the wireless communication device, a sequence of the OCC sequence according to an index of the OCC sequence and the sequence set; or

applying, by the wireless communication device, the sequence of the OCC sequence to the DMRS transmission.
The method of claim 1 or 4, comprising:

applying, by the wireless communication device, the OCC sequence to the DMRS transmission, wherein a unit of applying OCC sequence is across at least one of:

a plurality of repetitions;

a plurality of slots;

a plurality of sets of slots; or

a plurality of resource units (RUs) .
The method of claim 5, wherein if the OCC sequence is applied across at least one of the plurality of repetitions or slots or sets of slots or RUs, a sequence of the DMRS transmission to apply the OCC sequence is same across the plurality of repetitions or slots or sets of slots or RUs.
The method of claim 1 or 4, comprising:

applying, by the wireless communication device, a first OCC sequence to the DMRS transmission that is determined by an application of a second OCC sequence for the PUSCH transmission, wherein the DMRS corresponds to the PUSCH transmission.
The method of claim 7, wherein the determining indicates at least one of:

application of the first OCC sequence to the DMRS transmission is via a slot-level OCC when the application of the second OCC sequence to the PUSCH transmission is via a slot-level OCC;

the application of the first OCC sequence to the DMRS transmission is via the slot-level OCC when the application of the second OCC sequence to the PUSCH transmission is via a symbol-level OCC;

the application of the first OCC sequence to the DMRS transmission is via the slot-level OCC when the application of the second OCC sequence to the PUSCH transmission is via a resource unit (RU) -level OCC;

the application of the first OCC sequence to the DMRS transmission is via the RU-level OCC when the application of the second OCC sequence to the PUSCH transmission is via the RU-level OCC;

the application of the first OCC sequence to the DMRS transmission is via a repetition-level OCC when the application of the second OCC sequence to the PUSCH transmission is via the repetition-level OCC; or

the application of the first OCC sequence to the DMRS transmission is via the slot-level OCC when the application of the second OCC sequence to the PUSCH transmission is via the repetition-level OCC.
The method of claim 5, wherein if the OCC sequence is applied across the plurality of slots for performing single-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence is repeated a number of times in a number of slots equal to a length of the OCC sequence.
The method of claim 5, wherein if the OCC sequence is applied across the plurality of slots for performing single-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence is repeated a number of times in a number of slots equal to a repetition number.
The method of claim 5, wherein if the OCC sequence is applied across the plurality of slots for performing multi-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence is repeated a number of times in a number of slots equal to a length of the OCC sequence.
The method of claim 5, wherein if the OCC sequence is applied across the plurality of slots for performing multi-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence is repeated a number of times in a number of slots equal to a repetition number.
The method of claim 5, wherein if the OCC sequence is applied across the plurality of sets of slots for performing multi-tone repetition, a sequence of the DMRS transmission to apply the OCC sequence is repeated a number of times in a number of sets of slots equal to a length of the OCC sequence.
The method of claim 5, wherein a sequence of the DMRS transmission to apply the OCC sequence is repeated a number of times in a number of sets of slots equal to the number of repetitions of identical slots for PUSCH, wherein the number of identical slots is smaller than a length of the OCC sequence.
The method of claim 2, comprising:

determining, by the wireless communication device, the index of the OCC sequence to be a value mapped to the index of the antenna port; and

performing, by the wireless communication device, the DMRS transmission corresponding to the index of the antenna port.
The method of claim 2, comprising:

determining, by the wireless communication device, the index of the OCC sequence to be a value mapped to the index of the cyclic shift or at least one value of a plurality of cyclic shifts; and

performing, by the wireless communication device, the DMRS transmission corresponding to the index of the cyclic shift or the at least one value of a plurality of cyclic shifts.
The method of claim 2, comprising:

determining, by the wireless communication device, the index of the OCC sequence to be a value mapped to the index of the cyclic shift or at least one value of a plurality of cyclic shifts,

wherein a number of cyclic shifts for performing the DMRS transmission of multi-tone repetition is configured as a list of multiple values.
The method of claim 1, comprising:

determining, by the wireless communication device, to perform an enhanced DMRS transmission when a condition is satisfied, wherein the condition includes at least one of:

the wireless communication device is capable of supporting capacity enhancement;

an orthogonal cover code (OCC) sequence index is configured for the wireless communication device;

a threshold is configured, and a measured reference signal received power (RSRP) is higher than the threshold;

a modulation coding scheme (MCS) index is lower than a specific MCS configuration; or

a channel condition is higher than a specific threshold configuration.
A method comprising:

sending, by a wireless communication node to a wireless communication device , a configuration message,

wherein the wireless communication device determines the configuration message related to a demodulation reference signal (DMRS) transmission.
A non-transitory computer readable medium storing instructions, which when executed by at least one processor, cause the at least one processor to perform the method of any one of claims 1-19.
An apparatus comprising:

at least one processor configured to perform the method of any one of claims 1-19.