Selective retransmission on non-orthogonal channels

Abstract

An apparatus for wireless communication is provided. The apparatus may be a network node. The apparatus receives, via a first resource of a non-orthogonal channel, a set of uplink transmissions from a set of user equipments (UEs), wherein the apparatus is unable to decode the set of uplink transmissions. The apparatus sends a retransmission request to a subset of the set of UEs. The apparatus receives a retransmission of a first uplink transmission in the set of uplink transmissions via a second resource of the non-orthogonal channel in response to the retransmission request. The apparatus decodes a second uplink transmission of the set of uplink transmissions based at least on the retransmission of the first uplink transmission.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of U.S. non-provisional application serial number 17 / 853,784, entitled “SELECTIVE RETRANSMISSIONS ON A NON-ORTHOGONALCHANNEL,” filed in the U.S. Patent and Trademark Office on June 29, 2022, the entire contents of which are incorporated herein as if fully set forth below and for all applicable purposes. Background Art Technical Field

[0003] The present disclosure relates generally to communication systems and, more particularly, to selective retransmission over non-orthogonal channels.

[0004] introduction

[0005] Wireless communication systems are widely deployed to provide a variety of telecommunication services, such as telephony, video, data, messaging, and broadcast. Typical wireless communication systems may employ multiple access technologies capable of supporting communication with multiple users by sharing available system resources. Examples of such multiple access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

[0006] These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate at city, national, regional, and even global levels. An example telecommunication standard is 5G New Radio (NR). 5G NR is part of the continued mobile broadband evolution promulgated by the Third Generation Partnership Project (3GPP) to meet new requirements associated with latency, reliability, security, scalability (e.g., with the Internet of Things (IoT)) and other requirements. 5G NR includes services associated with enhanced mobile broadband (eMBB), massive machine type communications (mMTC), and ultra-reliable low latency communications (URLLC). Certain aspects of 5G NR may be based on the 4G Long Term Evolution (LTE) standard. Further improvements to 5G NR technology are needed. In addition, these improvements may also be applicable to other multiple access technologies and telecommunication standards that employ these technologies. Summary of the invention

[0007] The following presents a simplified summary of one or more aspects in order to provide a basic understanding of these aspects. This summary is not an extensive overview of all contemplated aspects, and is neither intended to identify key or important elements of all aspects, nor to describe the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to a more detailed description presented later.

[0008] A grant-free non-orthogonal multiple access (NOMA) scheme can be used to support large-scale connectivity. In a grant-free NOMA scheme, multiple users (e.g., multiple user equipments (UEs)) can use the same resources (e.g., the same time-frequency resources) to send data without a grant (e.g., a permission to send using scheduled resources) from a network (e.g., a base station). The reliability of grant-free NOMA uplink transmissions may vary depending on how many users send packets simultaneously. A retransmission scheme (e.g., a hybrid automatic repeat request (HARQ) scheme) can be implemented to improve the reliability of grant-free NOMA uplink transmissions, however, the management of retransmissions and the overhead generated by retransmissions may affect the performance of the network. The various aspects described herein can improve the reliability of grant-free NOMA uplink transmissions while achieving a significant reduction in the number of retransmissions from users.

[0009] In one aspect of the present disclosure, a method, a computer-readable medium, and an apparatus are provided. The apparatus may be a network node (e.g., a base station). The apparatus receives an uplink transmission set from a set of user equipment (UE) via a first resource of a non-orthogonal channel, wherein the apparatus cannot decode the uplink transmission set. The apparatus sends a retransmission request to a subset of the UE set. The apparatus receives a retransmission of a first uplink transmission in the uplink transmission set via a second resource of a non-orthogonal channel in response to the retransmission request. The apparatus decodes a second uplink transmission in the uplink transmission set based at least on the retransmission of the first uplink transmission.

[0010] In one aspect of the present disclosure, a method, a computer readable medium, and an apparatus are provided. The apparatus may be a UE. The apparatus uses a first resource of a non-orthogonal channel to send an uplink transmission. The apparatus receives a retransmission request for the uplink transmission. The apparatus uses a second resource of the non-orthogonal channel to retransmit the uplink transmission or a portion of the uplink transmission in response to the retransmission request. The apparatus receives a wait signal in response to the retransmission of the uplink transmission or a portion of the uplink transmission.

[0011] To achieve the foregoing and related ends, one or more aspects include the features fully described below and particularly pointed out in the claims. The following description and the accompanying drawings set forth in detail some illustrative features of one or more aspects. However, these features are merely indicative of some of the various ways in which the principles of the various aspects may be employed, and this specification is intended to include all such aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a diagram illustrating an example of a wireless communication system and an access network.

[0013] Figure 2A , Figure 2B , Figure 2C and Figure 2D 2 are diagrams illustrating examples of a first 5G / NR frame, a DL channel within a 5G / NR subframe, a second 5G / NR frame, and a UL channel within a 5G / NR subframe, respectively.

[0014] Figure 3 is a diagram illustrating an example of a base station and a user equipment (UE) in an access network.

[0015] Figure 4 A diagram illustrating an example decomposed base station architecture is shown.

[0016] Figure 5 is a diagram illustrating a hybrid automatic repeat request (HARQ) procedure for non-orthogonal multiple access (NOMA) transmission.

[0017] Figure 6 is a diagram illustrating the HARQ procedure for NOMA transmission.

[0018] Figure 7 is a diagram illustrating the HARQ combination procedure for NOMA transmission.

[0019] Figure 8 is a diagram illustrating the HARQ procedure for NOMA transmission.

[0020] Fig. 9 is a diagram illustrating uplink transmissions on a NOMA channel from a set of UEs and selective retransmissions from a subset of the set of UEs according to various aspects of the present disclosure.

[0021] Fig.10 A signal flow diagram is illustrated according to various aspects of the present disclosure.

[0022] Fig.11 A signal flow diagram is illustrated according to various aspects of the present disclosure.

[0023] Fig.12Includes N UEs sending initial NOMA uplink transmission and NOMA uplink retransmission.

[0024] Fig.13 HARQ feedback messages according to various aspects of the present disclosure are illustrated.

[0025] Fig.14 A flow chart of a wireless communication method.

[0026] Fig.15 A flow chart of a wireless communication method.

[0027] Fig.16 is a conceptual data flow diagram illustrating the flow of data between different parts / components in an example device.

[0028] Fig.17 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

[0029] Fig.18 A flow chart of a wireless communication method.

[0030] Fig.19 A flow chart of a wireless communication method.

[0031] Fig. 20 is a conceptual data flow diagram illustrating the flow of data between different parts / components in an example device.

[0032] Fig.21 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system. DETAILED DESCRIPTION

[0033] The detailed description set forth below in conjunction with the accompanying drawings is intended as a description of various configurations and is not intended to represent the only configuration with which the concepts described herein can be practiced. In order to provide a thorough understanding of the various concepts, the specific embodiments include specific details. However, it is apparent to those skilled in the art that these concepts can be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form to avoid blurring these concepts.

[0034] Several aspects of telecommunication systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether these elements are implemented as hardware or software depends on the specific application and the design constraints imposed on the overall system.

[0035] As an example, an element, or any part of an element, or any combination of elements can be implemented as a "processing system", which includes one or more processors. The example of a processor includes a microprocessor, a microcontroller, a graphics processing unit (GPU), a central processing unit (CPU), an application processor, a digital signal processor (DSP), a reduced instruction set computing (RISC) processor, a system on a chip (SoC), a baseband processor, a field programmable gate array (FPGA), a programmable logic device (PLD), a state machine, a gate logic piece, a discrete hardware circuit and other suitable hardware configured to perform various functionalities described throughout the present disclosure. One or more processors in a processing system can execute software. Whether it is referred to as software, firmware, middleware, microcode, hardware description language or other names, software should be widely interpreted as meaning instructions, instruction sets, codes, code segments, program codes, programs, subroutines, software components, applications, software applications, software packages, routines, subroutines, objects, executable files, threads of execution, processes, functions, etc.

[0036] Therefore, in one or more example embodiments, the described functions can be implemented with hardware, software or any combination thereof. If implemented with software, the function can be stored or encoded on a computer-readable medium as one or more instructions or codes. Computer-readable media include computer storage media. Storage media can be any available medium that can be accessed by a computer. By way of example and not limitation, such computer-readable media can include a random access memory (RAM), a read-only memory (ROM), an electrically erasable programmable ROM (EEPROM), an optical disk storage device, a magnetic disk storage device, other magnetic storage devices, a combination of computer-readable media of the above type, or any other medium that can be used to store computer executable code in the form of instructions or data structures that can be accessed by a computer.

[0037] Figure 1 1 is a diagram illustrating an example of a wireless communication system and an access network 100. The wireless communication system (which is also referred to as a wireless wide area network (WWAN)) includes a base station 102, a UE 104, an evolved packet core (EPC) 160, and another core network 190 (e.g., a 5G core (5GC)). The base station 102 may include a macro cell (a high-power cellular base station) and / or a small cell (a low-power cellular base station). A macro cell includes a base station. A small cell includes a femto cell, a pico cell, and a micro cell.

[0038] Base stations 102 configured for 4G LTE (collectively referred to as Evolved Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access Network (E-UTRAN)) can interface with EPC 160 via a backhaul link 132 (e.g., S1 interface). Base stations 102 configured for 5G NR (collectively referred to as Next Generation RAN (NG-RAN)) can interface with core network 190 via a backhaul link 184. Among other functions, base stations 102 can perform one or more of the following functions: transmission of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution of non-access stratum (NAS) messages, NAS node selection, synchronization, radio access network (RAN) sharing, multimedia broadcast multicast service (MBMS), subscriber and equipment tracking, RAN information management (RIM), paging, positioning, and delivery of warning messages. Base stations 102 may communicate with each other directly or indirectly (eg, through EPC 160 or core network 190) via backhaul links 134 (eg, X2 interfaces). Backhaul links 134 may be wired or wireless.

[0039] Base station 102 can communicate wirelessly with UE 104. Each of base stations 102 can provide communication coverage for a corresponding geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, a small cell 102' can have a coverage area 110' that overlaps with the coverage area 110 of one or more macro base stations 102. A network including both small cells and macro cells can be referred to as a heterogeneous network. A heterogeneous network can also include a home evolved Node B (eNB) (HeNB), which can provide services to a restricted group called a closed subscriber group (CSG). The communication link 120 between base station 102 and UE 104 can include an uplink (UL) (also called a reverse link) transmission from UE 104 to base station 102 and / or a downlink (DL) (also called a forward link) transmission from base station 102 to UE 104. The communication link 120 can use multiple input multiple output (MIMO) antenna technology, including spatial multiplexing, beamforming and / or transmit diversity. The communication link can be through one or more carriers. For each carrier allocated in the carrier aggregation for a total of up to Yx MHz (x component carriers) for transmission in each direction, the base station 102 / UE 104 may use spectrum of up to Y MHz (e.g., 5 MHz, 10 MHz, 15 MHz, 20 MHz, 100 MHz, 400 MHz, etc.) bandwidth. The carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to DL and UL (e.g., more or fewer carriers may be allocated for DL ​​compared to UL). The component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell) and the secondary component carrier may be referred to as a secondary cell (SCell).

[0040] Some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 158. The D2D communication link 158 may use DL / UL WWAN spectrum. The D2D communication link 158 may use one or more sidelink channels, such as a physical sidelink broadcast channel (PSBCH), a physical sidelink discovery channel (PSDCH), a physical sidelink shared channel (PSSCH), and a physical sidelink control channel (PSCCH). The D2D communication may be through various wireless D2D communication systems, such as, for example, FlashLinQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based on IEEE 802.11 standards, LTE, or NR.

[0041] The wireless communication system may also include a Wi-Fi access point (AP) 150 that communicates with a Wi-Fi station (STA) 152 via a communication link 154 in the 5 GHz unlicensed spectrum. When communicating in the unlicensed spectrum, the STA 152 / AP 150 may perform a clear channel assessment (CCA) to determine whether the channel is available prior to communication.

[0042] The small cell 102' may operate in licensed and / or unlicensed spectrum. When operating in the unlicensed spectrum, the small cell 102' may employ NR and use the same 5 GHz unlicensed spectrum used by the Wi-Fi AP 150. The small cell 102' employing NR in the unlicensed spectrum may improve the coverage of the access network and / or increase the capacity of the access network.

[0043] The base station 102, whether a small cell 102' or a large cell (e.g., a macro base station), may include an eNB, a gNodeB (gNB), or another type of base station. Some base stations, such as gNB 180, may operate in conventional sub-6 GHz spectrum, millimeter wave (mmW) frequencies, and / or near mmW frequencies to communicate with UE 104. When the gNB 180 operates at mmW or near mmW frequencies, the gNB 180 may be referred to as a mmW base station. Extremely high frequency (EHF) is a portion of the RF in the electromagnetic spectrum. EHF has a range of 30 GHz to 300 GHz with a wavelength between 1 mm and 10 mm. The radio waves in this band may be referred to as millimeter waves. Near mmW may extend down to a frequency of 3 GHz with a wavelength of 100 mm. The super high frequency (SHF) band extends between 3 GHz and 30 GHz, which is also referred to as centimeter waves. Communications using mmW / near mmW radio frequency bands (e.g., 3 GHz-300 GHz) have extremely high path losses and shorter distances. The mmW base station 180 may use beamforming 182 with the UE 104 to compensate for the extremely high path loss and short range.

[0044] Base station 180 may send beamformed signals to UE 104 in one or more transmit directions 182'. UE 104 may receive beamformed signals from base station 180 in one or more receive directions 182". UE 104 may also send beamformed signals to base station 180 in one or more transmit directions. Base station 180 may receive beamformed signals from UE 104 in one or more receive directions. Base station 180 / UE 104 may perform beam training to determine the best receive direction and transmit direction for each of base station 180 / UE 104. The transmit direction and receive direction of base station 180 may be the same or different. The transmit direction and receive direction of UE 104 may be the same or different.

[0045] The EPC 160 may include a mobility management entity (MME) 162, other MMEs 164, a serving gateway 166, a multimedia broadcast multicast service (MBMS) gateway 168, a broadcast multicast service center (BM-SC) 170, and a packet data network (PDN) gateway 172. The MME 162 may communicate with a home subscriber server (HSS) 174. The MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. In general, the MME 162 provides bearer and connection management. All user Internet Protocol (IP) packets are passed through the serving gateway 166, which itself is connected to the PDN gateway 172. The PDN gateway 172 provides UE IP address allocation and other functions. The PDN gateway 172 and the BM-SC 170 are connected to IP services 176. The IP services 176 may include the Internet, an intranet, an IP multimedia subsystem (IMS), PS streaming services, and / or other IP services. The BM-SC 170 may provide functionality for MBMS user service configuration and delivery. The BM-SC 170 may serve as an entry point for content provider MBMS delivery, may be used to authorize and initiate MBMS bearer services in a public land mobile network (PLMN), and may be used to schedule MBMS delivery. The MBMS gateway 168 may be used to distribute MBMS services to base stations 102 belonging to a multicast broadcast single frequency network (MBSFN) area that broadcasts a specific service, and may be responsible for session management (start / stop) and for collecting eMBMS-related billing information.

[0046] The core network 190 may include an access and mobility management function (AMF) 192, other AMFs 193, a session management function (SMF) 194, and a user plane function (UPF) 195. The AMF 192 may communicate with a unified data management (UDM) 196. The AMF 192 is a control node that handles signaling between the UE 104 and the core network 190. Generally speaking, the AMF 192 provides QoS flow and session management. All user Internet Protocol (IP) packets are transmitted through the UPF 195. The UPF 195 provides UE IP address allocation and other functions. The UPF 195 is connected to an IP service 197. The IP service 197 may include the Internet, an intranet, an IP multimedia subsystem (IMS), a PS streaming service, and / or other IP services.

[0047] A base station may also be referred to as a gNB, a Node B, an evolved Node B (eNB), an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), a transmit receive point (TRP), or some other suitable term. Base station 102 provides an access point to EPC 160 or core network 190 for UE 104. Examples of UE 104 include a cellular phone, a smart phone, a Session Initiation Protocol (SIP) phone, a laptop, a personal digital assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., an MP3 player), a camera, a game console, a tablet, a smart device, a wearable device, a vehicle, an electric meter, a gas pump, a large or small kitchen appliance, a healthcare device, an implant, a sensor / actuator, a display, or any other similarly functional device. Some of UE 104 may be referred to as IoT devices (e.g., a parking meter, a gas pump, a toaster, a vehicle, a heart monitor, etc.). UE 104 may also be referred to as a station, a mobile station, a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communication device, a remote device, a mobile subscriber station, an access terminal, a mobile terminal, a wireless terminal, a remote terminal, a handset, a user agent, a mobile client, a client, or some other suitable terminology.

[0048] Reference again Figure 1 In some aspects, base station 180 may be configured to receive a set of uplink transmissions from a set of UEs via a first resource of a non-orthogonal channel, wherein the set of uplink transmissions cannot be decoded, and to send a retransmission request to a subset of the set of UEs (198). Although the following description may focus on 5G NR, the concepts described herein may be applicable to other similar areas, such as 6G, LTE, LTE-A, CDMA, GSM, and other wireless technologies.

[0049] Figure 2A 200 is a diagram illustrating an example of a first subframe within a 5G / NR frame structure. Figure 2B FIG230 is a diagram illustrating an example of DL channels within a 5G / NR subframe. Figure 2C 250 is a diagram illustrating an example of a second subframe within a 5G / NR frame structure. Figure 2D FIG280 is a diagram illustrating an example of UL channels within a 5G / NR subframe. The 5G / NR frame structure may be FDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to either DL or UL, or may be TDD, where for a particular set of subcarriers (carrier system bandwidth), subframes within that subcarrier set are dedicated to both DL and UL. Figure 2A , Figure 2CIn the example provided, it is assumed that the 5G / NR frame structure is TDD, where subframe 4 is configured with slot format 28 (mainly DL), where D is DL, U is UL, and X is used flexibly between DL / UL, and subframe 3 is configured with slot format 34 (mostly UL). Although subframes 3 and 4 are shown as having slot formats 34 and 28, respectively, any particular subframe may be configured with any of the various available slot formats 0 to 61. Slot formats 0 and 1 are both DL and both UL, respectively. Other slot formats 2-61 include a mixture of DL, UL and flexible symbols. The slot format is configured for the UE by a received slot format indicator (SFI) (dynamically configured by DL control information (DCI) or semi-statically / statically configured by radio resource control (RRC) signaling). Note that the following description also applies to the 5G / NR frame structure for TDD.

[0050] Other wireless communication technologies may have different frame structures and / or different channels. A frame (10ms) may be divided into 10 subframes of equal size (1ms). Each subframe may include one or more time slots. A subframe may also include a microslot, which may include 7, 4 or 2 symbols. Each time slot may contain 7 or 14 symbols, depending on the time slot configuration. For time slot configuration 0, each time slot may include 14 symbols, and for time slot configuration 1, each time slot may include 7 symbols. The symbols on the DL may be cyclic prefix (CP) OFDM (CP-OFDM) symbols. The symbols on the UL may be CP-OFDM symbols (for high throughput scenarios) or discrete Fourier transform (DFT) spread OFDM (DFT-s-OFDM) symbols (also called single carrier frequency division multiple access (SC-FDMA) symbols) (for power-limited scenarios; limited to single stream transmission). The number of time slots in a subframe is based on the time slot configuration and parameter set. For slot configuration 0, different parameter sets μ0 to 5 allow 1, 2, 4, 8, 16, and 32 slots per subframe, respectively. For slot configuration 1, different parameter sets 0 to 2 allow 2, 4, and 8 slots per subframe, respectively. Thus, for slot configuration 0 and parameter set μ, there are 14 symbols per slot and 2 per subframe. μ time slots. The subcarrier spacing and symbol length / duration are functions of the parameter set. The subcarrier spacing can be equal to 2 μ *15kKz, where μ is parameter set 0 to 5. Therefore, the subcarrier spacing for parameter set μ=0 is 15kHz, and the subcarrier spacing for parameter set μ=5 is 480kHz. The symbol length / duration is inversely related to the subcarrier spacing. FIG. 2A to FIG. 2D An example is provided for slot configuration 0 with 14 symbols per slot and parameter set μ=0 with 1 slot per subframe. The subcarrier spacing is 15 kHz and the symbol duration is about 66.7 μs.

[0051] A resource grid may be used to represent a frame structure. Each slot includes a resource block (RB) (also referred to as a physical RB (PRB)) extending over 12 consecutive subcarriers. The resource grid is divided into a plurality of resource elements (REs). The number of bits carried by each RE depends on the modulation scheme.

[0052] like Figure 2A As illustrated, some of the REs carry reference (pilot) signals (RS) for the UE. The RS may include a demodulation RS (DM-RS) for channel estimation at the UE (indicated as R for a particular configuration). x , where 100x is the port number, but other DM-RS configurations are possible) and a channel state information reference signal (CSI-RS). RS may also include a beam measurement RS (BRS), a beam refinement RS (BRRS), and a phase tracking RS (PT-RS).

[0053] Figure 2B Examples of various DL channels within a subframe of a frame are illustrated. The physical downlink control channel (PDCCH) carries DCI within one or more control channel elements (CCEs), each CCE including nine RE groups (REGs), each REG including four consecutive REs in an OFDM symbol. The primary synchronization signal (PSS) may be within symbol 2 of a specific subframe of the frame. The PSS is used by UE 104 to determine the subframe / symbol timing and the physical layer identification. The secondary synchronization signal (SSS) may be within symbol 4 of a specific subframe of the frame. The SSS is used by the UE to determine the physical layer cell identification group number and the radio frame timing. Based on the physical layer identification and the physical layer cell identification group number, the UE can determine the physical cell identifier (PCI). Based on the PCI, the UE can determine the location of the aforementioned DM-RS. The physical broadcast channel (PBCH) carrying the master information block (MIB) can be logically grouped with the PSS and SSS to form a synchronization signal (SS) / PBCH block. The MIB provides the system frame number (SFN) and the number of RBs in the system bandwidth. The Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information such as System Information Blocks (SIBs) that are not sent through the PBCH, and paging messages.

[0054] like Figure 2CAs illustrated, some of the REs carry DM-RS (indicated as R for a particular configuration, but other DM-RS configurations are possible) for channel estimation at the base station. The UE may send DM-RS for a physical uplink control channel (PUCCH) and DM-RS for a physical uplink shared channel (PUSCH). The PUSCH DM-RS may be sent in the first or first two symbols of the PUSCH. The PUCCH DM-RS may be sent in different configurations depending on whether a short PUCCH or a long PUCCH is sent and depending on the specific PUCCH format used. Although not shown, the UE may send a sounding reference signal (SRS). The SRS may be used by the base station for channel quality estimation to enable frequency-dependent scheduling of the UL.

[0055] Figure 2D Examples of various UL channels within a subframe of a frame are illustrated. The PUCCH may be located at a position as indicated in one configuration. The PUCCH carries uplink control information (UCI), such as scheduling requests, channel quality indicator (CQI), precoding matrix indicator (PMI), rank indicator (RI), and HARQ ACK / NACK feedback. The PUSCH carries data and may additionally be used to carry a buffer status report (BSR), a power headroom report (PHR), and / or UCI.

[0056] Figure 33 is a block diagram of a base station 310 communicating with a UE 350 in an access network. In the DL, IP packets from the EPC 160 may be provided to the controller / processor 375. The controller / processor 375 implements layer 3 and layer 2 functionality. Layer 3 includes a radio resource control (RRC) layer, and layer 2 includes a service data adaptation protocol (SDAP) layer, a packet data convergence protocol (PDCP) layer, a radio link control (RLC) layer, and a medium access control (MAC) layer. The controller / processor 375 provides RRC layer functionality associated with broadcasting of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-radio access technology (RAT) mobility, and measurement configuration for UE measurement reporting; PDCP layer functionality associated with header compression / decompression, security (encryption, decryption, integrity protection, integrity verification), and handover support functions; RLC layer functionality associated with delivery of upper layer packet data units (PDUs), error correction through ARQ, concatenation, segmentation and reassembly of RLC service data units (SDUs), re-segmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto transport blocks (TBs), demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0057] The transmit (TX) processor 316 and receive (RX) processor 370 implement layer 1 functionality associated with various signal processing functions. Layer 1 (which includes the physical (PHY) layer) may include error detection on the transport channel, forward error correction (FEC) coding / decoding of the transport channel, interleaving, rate matching, mapping to the physical channel, modulation / demodulation of the physical channel, and MIMO antenna processing. The TX processor 316 handles the mapping to the signal constellation based on various modulation schemes (e.g., binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), M-order phase shift keying (M-PSK), M-order quadrature amplitude modulation (M-QAM)). The decoded and modulated symbols can then be divided into parallel streams. Subsequently, each stream can be mapped to an OFDM subcarrier, multiplexed with a reference signal (e.g., a pilot) in the time domain and / or frequency domain, and then combined using an inverse fast Fourier transform (IFFT) to produce a physical channel carrying a time domain OFDM symbol stream. The OFDM stream is spatially pre-coded to generate multiple spatial streams. Channel estimates from a channel estimator 374 may be used to determine the coding and modulation schemes, as well as for spatial processing. Channel estimates may be derived from reference signals and / or channel state feedback sent by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318TX. Each transmitter 318TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0058] At the UE 350, each receiver 354RX receives a signal through its corresponding antenna 352. Each receiver 354RX recovers the information modulated onto the RF carrier and provides the information to a receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functionality associated with various signal processing functions. The RX processor 356 can perform spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they can be merged into a single OFDM symbol stream by the RX processor 356. The RX processor 356 then converts the OFDM symbol stream from the time domain to the frequency domain using a fast Fourier transform (FFT). The frequency domain signal includes a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier and the reference signal are recovered and demodulated by determining the most likely signal constellation point sent by the base station 310. These soft decisions can be based on channel estimates calculated by the channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally sent on the physical channel by the base station 310. The data and control signals are then provided to the controller / processor 359, which implements layer 3 and layer 2 functionality.

[0059] The controller / processor 359 may be associated with a memory 360 that stores program codes and data. The memory 360 may be referred to as a computer readable medium. In the UL, the controller / processor 359 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, and control signal processing to recover IP packets from the EPC 160. The controller / processor 359 is also responsible for error detection using an ACK and / or NACK protocol to support HARQ operations.

[0060] Similar to the functions described in conjunction with DL transmissions performed by the base station 310, the controller / processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting; PDCP layer functionality associated with header compression / decompression and security (encryption, decryption, integrity protection, integrity verification); RLC layer functionality associated with delivery of upper layer PDUs, error correction through ARQ, concatenation, segmentation and reassembly of RLC SDUs, resegmentation of RLC data PDUs, and reordering of RLC data PDUs; and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction through HARQ, priority handling, and logical channel prioritization.

[0061] The TX processor 368 may use channel estimates derived by the channel estimator 358 from a reference signal or feedback sent by the base station 310 to select appropriate coding and modulation schemes and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via corresponding transmitters 354TX. Each transmitter 354TX may modulate an RF carrier with a corresponding spatial stream for transmission.

[0062] UL transmissions are processed at the base station 310 in a manner similar to that described in conjunction with the receiver functionality at the UE 350. Each receiver 318RX receives a signal through its respective antenna 320. Each receiver 318RX recovers information modulated onto an RF carrier and provides the information to a RX processor 370.

[0063] The controller / processor 375 may be associated with a memory 376 that stores program codes and data. The memory 376 may be referred to as a computer readable medium. In the UL, the controller / processor 375 provides demultiplexing between transport channels and logical channels, packet reassembly, decryption, header decompression, control signal processing to recover IP packets from the UE 350. The IP packets from the controller / processor 375 may be provided to the EPC 160. The controller / processor 375 is also responsible for error detection using ACK and / or NACK protocols to support HARQ operations.

[0064] At least one of the TX processor 316, the RX processor 370, and the controller / processor 375 may be configured to combine Figure 1 The 198 came to execute all aspects.

[0065] The deployment of a communication system (such as a 5G New Radio (NR) system) can be arranged with various components or constituent parts in a variety of ways. In a 5G NR system or network, a network node, a network entity, a mobility element of a network, a radio access network (RAN) node, a core network node, a network element or a network equipment (such as a base station (BS), or one or more units (or one or more components) that perform base station functionality can be implemented in an aggregated architecture or a decomposed architecture. For example, a BS (such as a Node B (NB), an evolved NB (eNB), an NR BS, a 5G NB, an access point (AP), a transmit receive point (TRP) or a cell, etc.) can be implemented as an aggregated base station (also referred to as an independent BS or a monolithic BS) or a decomposed base station.

[0066] A converged base station may be configured to utilize a radio protocol stack physically or logically integrated within a single RAN node. A decomposed base station may be configured to utilize a protocol stack physically or logically distributed between two or more units, such as one or more central or centralized units (CUs), one or more distributed units (DUs), or one or more radio units (RUs). In some aspects, a CU may be implemented within a RAN node, and one or more DUs may be co-located with the CU, or alternatively, may be geographically or virtually distributed in one or more other RAN nodes. A DU may be implemented to communicate with one or more RUs. Each of a CU, a DU, and a RU may also be implemented as a virtual unit, i.e., a virtual central unit (VCU), a virtual distributed unit (VDU), or a virtual radio unit (VRU).

[0067] Base station type operations or network designs may take into account the aggregated nature of base station functionality. For example, a disaggregated base station may be used in an integrated access backhaul (IAB) network, an open radio access network (O-RAN (network configurations such as those initiated by the O-RAN Alliance)), or a virtualized radio access network (vRAN, also known as a cloud radio access network (C-RAN)). Decomposition may include distributing functionality across two or more units at various physical locations, as well as virtually distributing functionality of at least one unit, which may enable flexibility in network design. Various units of a disaggregated base station or disaggregated RAN architecture may be configured for wired or wireless communication with at least one other unit.

[0068] Figure 4 A diagram illustrating an example decomposed base station 400 architecture is shown. The decomposed base station 400 architecture may include one or more central units (CUs) 410 that may communicate directly with a core network 420 via a backhaul link, or indirectly with the core network 420 through one or more decomposed base station units, such as a near real-time (near-RT) RAN intelligent controller (RIC) 425 via an E2 link, or a non-real-time (non-RT) RIC 415 associated with a service management and orchestration (SMO) framework 405, or both. The CU 410 may communicate with one or more distributed units (DUs) 430 via respective midhaul links, such as an F1 interface. The DU 430 may communicate with one or more radio units (RUs) 440 via respective fronthaul links. The RU 440 may communicate with respective UEs 120 via one or more radio frequency (RF) access links. In some implementations, a UE 120 may be served simultaneously by multiple RUs 440.

[0069] Each of the units (i.e., CU 410, DU 430, RU 440, and near-RT RIC 425, non-RT RIC 415, and SMO framework 405) may include or be coupled to one or more interfaces configured to receive or send signals, data, or information (collectively referred to as signals) via a wired or wireless transmission medium. Each of the units or an associated processor or controller that provides instructions to the communication interface of the unit may be configured to communicate with one or more of the other units via a transmission medium. For example, the units may include a wired interface configured to receive or send signals to one or more of the other units via a wired transmission medium. Additionally, the units may include a wireless interface that may include a receiver, a transmitter, or a transceiver (such as a radio frequency (RF) transceiver) configured to receive or send signals, or both, to one or more of the other units on a wireless transmission medium.

[0070] In some aspects, CU 410 may host one or more higher layer control functions. Such control functions may include radio resource control (RRC), packet data convergence protocol (PDCP), service data adaptation protocol (SDAP), etc. Each control function may be implemented using an interface that is configured to communicate signals with other control functions hosted by CU 410. CU 410 may be configured to handle user plane functionality (i.e., central unit-user plane (CU-UP)), control plane functionality (i.e., central unit-control plane (CU-CP)), or a combination thereof. In some specific implementations, CU 410 may be logically split into one or more CU-UP units and one or more CU-CP units. When implemented in an O-RAN configuration, the CU-UP unit may communicate bidirectionally with the CU-CP unit via an interface (such as an E1 interface). As needed, CU 410 may be implemented to communicate with DU 430 for network control and signaling.

[0071] DU 430 may correspond to a logical unit that includes one or more base station functions for controlling the operation of one or more RUs 440. In some aspects, DU 430 may host one or more of a radio link control (RLC) layer, a medium access control (MAC) layer, and one or more high physical (PHY) layers (such as modules for forward error correction (FEC) encoding and decoding, scrambling, modulation and demodulation, etc.) at least in part according to a functional split such as defined by the Third Generation Partnership Project (3GPP). In some aspects, DU 430 may also host one or more low PHY layers. Each layer (or module) may be implemented using an interface that is configured to communicate signals with other layers (and modules) hosted by DU 430 or with control functions hosted by CU 410.

[0072] The lower layer functionality may be implemented by one or more RUs 440. In some deployments, a RU 440 controlled by a DU 430 may correspond to a logical node that hosts RF processing functions or low PHY layer functions (such as performing Fast Fourier Transform (FFT), Inverse FFT (iFFT), digital beamforming, physical random access channel (PRACH) extraction and filtering, etc.), or both, based at least in part on a functional split (such as a lower layer functional split). In such an architecture, the RU 440 may be implemented to handle over-the-air (OTA) communications with one or more UEs 120. In some implementations, real-time and non-real-time aspects of control plane and user plane communications with the RU 440 may be controlled by the corresponding DU 430. In some scenarios, this configuration may enable the implementation of the DU 430 and the CU 410 in a cloud-based RAN architecture (such as a vRAN architecture).

[0073] The SMO framework 405 may be configured to support RAN deployment and provisioning of non-virtualized network elements and virtualized network elements. For non-virtualized network elements, the SMO framework 405 may be configured to support the deployment of dedicated physical resources for RAN coverage requirements, which may be managed via an operation and maintenance interface (such as an O1 interface). For virtualized network elements, the SMO framework 405 may be configured to interact with a cloud computing platform (such as an open cloud (O-Cloud) 490) to perform network element lifecycle management (such as instantiating virtualized network elements) via a cloud computing platform interface (such as an O2 interface). Such virtualized network elements may include, but are not limited to, CU 410, DU 430, RU 440, and near-RT RIC 425. In some specific implementations, the SMO framework 405 may communicate with hardware aspects of the 4G RAN (such as an open eNB (O-eNB) 411) via the O1 interface. Additionally, in some specific implementations, the SMO framework 405 may communicate directly with one or more RUs 440 via the O1 interface. The SMO framework 405 may also include a non-RT RIC 415 configured to support the functionality of the SMO framework 405 .

[0074] The non-RT RIC 415 may be configured to include logic functions that enable non-real-time control and optimization of RAN elements and resources, artificial intelligence / machine learning (AI / ML) workflows including model training and updating, or policy-based guidance of applications / features in the near-RT RIC 425. The non-RT RIC 415 may be coupled to or in communication with the near-RT RIC 425 (such as via an A1 interface). The near-RT RIC 425 may be configured to include logic functions that enable near-real-time control and optimization of RAN elements and resources via data collection and actions through an interface (such as via an E2 interface) that connects one or more CUs 410, one or more DUs 430, or both, and the O-eNB with the near-RT RIC 425.

[0075] In some implementations, in order to generate an AI / ML model to be deployed in the near-RT RIC 425, the non-RT RIC 415 may receive parameters or external enrichment information from an external server. Such information may be utilized by the near-RT RIC 425 and may be received from a non-network data source or from a network function at the SMO framework 405 or the non-RT RIC 415. In some examples, the non-RT RIC 415 or the near-RT RIC 425 may be configured to tune RAN behavior or performance. For example, the non-RT RIC 415 may monitor long-term trends and patterns of performance and employ AI / ML models to perform corrective actions through the SMO framework 405 (such as via reconfiguration of O1) or via the creation of RAN management policies (such as A1 policies).

[0076] Massive connectivity can provide network access to anywhere from hundreds to billions of wireless communication devices. In some examples, the wireless communication device can be a user equipment (UE). As previously mentioned, the UE can be an IoT device such as an industrial sensor device, a utility meter, a home network, a wearable device, an asset tracker, a health monitor, a video surveillance unit, etc.

[0077] When implementing large-scale connectivity in a network (e.g., a 5G NR network), the performance of a wireless communication device and / or network may degrade as the connection density in a given area increases. Therefore, large-scale connectivity deployment should consider the connection density in a given area. For example, in a 5G NR network, it may be necessary to support a connection density of one million devices per square kilometer. Looking forward to 6G networks, it may be necessary to support a connection density of ten million devices per square kilometer.

[0078] A grant-free non-orthogonal multiple access (NOMA) scheme can be used to support large-scale connectivity. In a grant-free NOMA scheme, multiple users can use the same resources to send data without a grant (e.g., a permission to send using scheduled resources) from the network (e.g., a base station). Therefore, if a UE has data to send, it can use the resources of a non-orthogonal multiple access channel (also called a NOMA channel) to autonomously send the data. The resources of the NOMA channel can be pre-configured by a network node (e.g., a base station) and used by the UE opportunistically to send data based on data services.

[0079] For example, large-scale connectivity may require support for large connection density, small packet size, and bursty traffic with large inter-arrival time. The grant-free NOMA scheme can support these needs by improving multiplexing gain and uplink cell capacity, by providing grant-free operation to reduce control overhead, and / or by providing efficient resource utilization.

[0080] A hybrid automatic repeat request (HARQ) mechanism may be used for grant-free NOMA transmissions. For example, if the initial transmission from a UE is a grant-free NOMA transmission, the reliability may vary depending on the number of other UEs that simultaneously transmit packets. Therefore, a HARQ mechanism may be implemented to achieve sufficient reliability. Various aspects described herein may control retransmissions for an initial grant-free NOMA transmission from a UE.

[0081] In some examples, to support grant-free NOMA transmissions from UEs, network nodes may be equipped with advanced receivers capable of interference cancellation. Such advanced receivers may also benefit HARQ retransmissions.

[0082] In some examples, a UE may use a unique multiple access (MA) signature for grant-free NOMA transmissions. For example, if multiple UEs use the same time-frequency resources associated with a NOMA channel to transmit data, the network node may distinguish transmissions from the UEs based on the unique MA signature of each UE. For example, the MA signature may include a UE scrambling sequence, a UE spreading sequence, or other suitable types of signatures.

[0083] Figure 5 500 is a diagram illustrating a HARQ procedure for NOMA transmission. Figure 5 A network node 502 and N UEs including UE_1 504, UE_M 506, UE_M+1 508, and UE_N 510. For example, N and M may represent positive integers, where N>M. Each of the N UEs may send an initial uplink transmission (e.g., data transmission) using the same time-frequency resources of the NOMA channel 511. For example, UE_1 504, UE_M 506, UE_M+1 508, and UE_N 510 may send respective initial uplink transmissions 512, 514, 516_1, and 518_1 without a grant from the network node 502. In some examples, the network node 502 may be a base station.

[0084] The network node 502 may receive N initial uplink transmissions from N UEs at the NOMA receiver 520. Figure 5In an example, the NOMA receiver 520 may successfully decode M initial transmissions from M UEs and may fail to decode NM initial transmissions from NM UEs. For example, at 522, the NOMA receiver 520 may successfully decode M initial transmissions including initial uplink transmissions 512, 514. In one example, if N=10 and M=7, the NOMA receiver 520 may successfully decode seven initial transmissions from seven of the N UEs at 522 and may fail to decode three initial transmissions from the remaining three UEs (e.g., NM=10-7=3).

[0085] The network node 502 may use DCI to send an UL grant to each of the NM UEs for retransmission on the orthogonal multiple access channel 519. Each UL grant may indicate a different time-frequency resource of the orthogonal multiple access channel 519 for each of the NM UEs. Figure 5 In the example of , the NM UEs may include UE_M+1 508 and UE_N 510. Each of the NM UEs may retransmit its uplink transmission using the time-frequency resources of its assigned orthogonal multiple access channel 519. Figure 5 In the example, uplink transmission 516_2 represents a retransmission of initial uplink transmission 516_1, and uplink transmission 518_2 represents a retransmission of initial uplink transmission 518_1.

[0086] The network node 502 may receive NM retransmissions from the NM UEs at the orthogonal multiple access receiver 530. Figure 5 In the example of , the orthogonal multiple access receiver 530 can successfully decode NM retransmissions from NM UEs. For example, at 532, the orthogonal multiple access receiver 530 can successfully decode NM retransmissions including retransmissions 516_2, 518_2. In one example, if N=10 and M=7, the orthogonal multiple access receiver 530 can successfully decode three retransmissions (e.g., NM=10-7=3) from three UEs in the N UEs.

[0087] Figure 6 600 is a diagram illustrating the HARQ procedure for NOMA transmission. Figure 6A network node 602 and N UEs including UE_1 604, UE_M 606, UE_M+1 608, and UE_N 610. For example, N and M may represent positive integers, where N>M. Each of the N UEs may send an initial uplink transmission (e.g., data transmission) using the same time-frequency resources of the NOMA channel 611. For example, UE_1 604, UE_M 606, UE_M+1 608, and UE_N 610 may send respective initial uplink transmissions 612, 614, 616_1, and 618_1 without a grant from the network node 602.

[0088] The network node 602 may receive N initial uplink transmissions from N UEs at the NOMA receiver 620. Figure 6 In an example, the NOMA receiver 620 may successfully decode M initial transmissions from M UEs and may fail to decode NM initial transmissions from NM UEs. For example, at 622, the NOMA receiver 620 may successfully decode M initial transmissions including initial uplink transmissions 612, 614. In one example, if N=10 and M=7, the NOMA receiver 620 may successfully decode seven initial transmissions from seven of the N UEs at 622 and may fail to decode three initial transmissions from the remaining three UEs (e.g., NM=10-7=3).

[0089] The network node 602 may send a negative acknowledgement (NACK) to the NM UEs. Figure 6 In the example of , the NM UEs may include UE_M+1 608 and UE_N 610. Each of the NM UEs may retransmit its respective initial uplink transmission without a grant from the network node 602 in response to the NACK. Figure 6 , uplink transmission 616_2 represents a retransmission of initial uplink transmission 616_1, and uplink transmission 618_2 represents a retransmission of initial uplink transmission 618_1. In some examples, the retransmission of initial uplink transmission 616_1 and uplink transmission 618_2 may be based on synchronized HARQ operation.

[0090] The network node 602 may receive NM retransmissions from NM UEs at the NOMA receiver 620. Figure 6In an example, the NOMA receiver 620 may successfully decode NM retransmissions from NM UEs. For example, at 624, the NOMA receiver 620 may successfully decode NM retransmissions including retransmissions 616_2, 618_2. In an example, if N=10 and M=7, the NOMA receiver 620 may successfully decode three retransmissions from three of the N UEs (e.g., NM=10-7=3).

[0091] Figure 7 700 is a diagram illustrating a HARQ combination procedure for NOMA transmission. Figure 7 A network node 702 and N UEs including UE_1 704, UE_M 706, UE_M+1 708, and UE_N 710. For example, N and M may represent positive integers, where N>M. Each of the N UEs may send an initial uplink transmission (e.g., data transmission) using the same time-frequency resources of the NOMA channel 711. For example, UE_1 704, UE_M 706, UE_M+1 708, and UE_N 710 may send respective initial uplink transmissions 712, 714, 716_1, and 718_1 without a grant from the network node 702.

[0092] The network node 702 may receive N initial uplink transmissions from N UEs at a NOMA receiver 720. In some examples, the NOMA receiver 720 may perform advanced interference cancellation operations (e.g., minimum mean square error successive interference cancellation (MMSE-SIC) or other suitable types of successive interference cancellation) on the N initial uplink transmissions and may attempt to decode the N initial uplink transmissions. The network node 702 may successfully decode the M initial transmissions from the M UEs and may fail to decode the NM initial transmissions from the NM UEs.

[0093] For example, at 722, the NOMA receiver 720 may successfully decode M initial transmissions including the initial uplink transmissions 712, 714. In one example, if N=10 and M=7, the NOMA receiver 720 may successfully decode seven initial transmissions from seven of the N UEs at 722, and may fail to decode three initial transmissions from the remaining three UEs (e.g., NM=10-7=3).

[0094] The network node 702 may send NACKs to the NM UEs. Figure 7In the example of , the NM UEs may include UE_M+1 708 and UE_N 710. Each of the NM UEs may retransmit its respective initial uplink transmission without a grant from the network node 702 in response to the NACK. Figure 7 , uplink transmission 716_2 represents a retransmission of initial uplink transmission 716_1, and uplink transmission 718_2 represents a retransmission of initial uplink transmission 718_1. In some examples, the retransmission of initial uplink transmission 716_1 and uplink transmission 718_2 may be based on synchronized HARQ operation.

[0095] The NOMA receiver 720 may generate and store a log-likelihood ratio (LLR) for each of the NM retransmissions. For example, the NOMA receiver 720 may generate an LLR value 726 for the initial uplink transmission 716_1 and an LLR value 728 for the initial uplink transmission 718_1. The NOMA receiver 720 may provide each LLR value of the NM retransmissions to a corresponding LLR combiner device of the HARQ reception mechanism 724, such as the LLR combiner devices 730, 732. Figure 7 It should be noted that the NOMA receiver 720 stores LLR values ​​for NM UEs (e.g., UEs to which NACK is sent) and may not store LLR values ​​for M UEs, which reduces memory consumption at the network node 702.

[0096] The network node 702 may provide each of the NM retransmissions from the NM UEs to a corresponding LLR combiner device to successfully decode the transmissions from the NM UEs. For example, the network node 702 may provide the uplink transmission 716_2 to the LLR combiner device 730 and may provide the uplink transmission 718_2 to the LLR combiner device 732. However, referring to Figure 7 The performance of the HARQ combining method described may be inferior to the reference Figure 8 The reception scheme based on interference cancellation.

[0097] Figure 8 800 is a diagram illustrating the HARQ procedure for NOMA transmission. Figure 8A network node 802 and N UEs including UE_1 804, UE_M 806, UE_M+1 808, and UE_N 810. For example, N and M may represent positive integers, where N>M. Each of the N UEs may send an initial uplink transmission (e.g., data transmission) using the same time-frequency resources of the NOMA channel 811. For example, UE_1 804, UE_M 806, UE_M+1 808, and UE_N 810 may send respective initial uplink transmissions 812, 814, 816_1, and 818_1 without a grant from the network node 802.

[0098] The network node 802 may receive N initial uplink transmissions from N UEs at a NOMA receiver 820. In some examples, the NOMA receiver 820 may perform advanced interference cancellation operations (e.g., MMSE-SIC or other suitable types of successive interference cancellation at 821) on the N initial uplink transmissions and may attempt to decode the N initial uplink transmissions. The NOMA receiver 820 may successfully decode the M initial transmissions from the M UEs and may fail to decode the NM initial transmissions from the NM UEs.

[0099] For example, at 822, the NOMA receiver 820 may successfully decode M initial transmissions including the initial uplink transmissions 812, 814. In one example, if N=10 and M=8, the NOMA receiver 820 may successfully decode seven initial transmissions from seven of the N UEs at 822, and may fail to decode three initial transmissions from the remaining three UEs (e.g., NM=10-7=3).

[0100] The network node 802 may send NACKs to the NM UEs. Figure 8 In the example of , the NM UEs may include UE_M+1 808 and UE_N 810. Each of the NM UEs may retransmit its respective initial uplink transmission without a grant from the network node 802 in response to the NACK. Figure 8 , uplink transmission 816_2 represents a retransmission of initial uplink transmission 816_1, and uplink transmission 818_2 represents a retransmission of initial uplink transmission 818_1. In some examples, the retransmission of initial uplink transmission 816_1 and uplink transmission 818_2 may be based on synchronized HARQ operation.

[0101] The NOMA receiver 820 may store the NM initial transmissions (e.g., initial uplink transmissions 816_1, 818_1) and may perform MMSE-SIC (or other suitable type of successive interference cancellation) at 826 on the NM initial transmissions and NM retransmissions (e.g., uplink transmissions 816_2, 818_2) from the NM UEs. The MMSE-SIC at 826 may be part of the HARQ reception mechanism 824. The NOMA receiver 820 may use a large amount of memory space to store the NM initial transmissions (e.g., channel coefficients for the NM initial transmissions of the NM UEs).

[0102] Fig. 9 900 is a diagram illustrating uplink transmissions on a NOMA channel from a set of UEs and selective retransmissions from a subset of the set of UEs in accordance with various aspects of the present disclosure. Fig. 9 The system includes a network node 902, a first UE (UE_1) 904, a second UE (UE_2) 906, a NOMA receiver 908, and a retransmission request controller 910. The NOMA receiver 908 may include an IC-based decoder 912.

[0103] The first UE 904 may send an initial uplink transmission 914 and the second UE 906 may send an initial uplink transmission 916. The first UE 904 and the second UE 906 may send the initial uplink transmission (e.g., data transmission) using the same time-frequency resources of the NOMA channel 918. For example, the first UE 904 and the second UE 906 may send the initial uplink transmissions 914, 916 without a grant from the network node 902.

[0104] The network node 902 may receive the initial uplink transmissions 914, 916 at the NOMA receiver 908. Fig. 9 In the example of , the NOMA receiver 908 may fail to decode the initial uplink transmissions 914, 916. The NOMA receiver 908 may store uplink transmission information associated with the initial uplink transmissions 914, 916. The NOMA receiver 908 may send a first message 920 indicating that the NOMA receiver 908 failed to decode the initial uplink transmission 914 and a second message 922 indicating that the NOMA receiver 908 failed to decode the initial uplink transmission 916.

[0105] The retransmission request controller 910 may receive the first message 920 and the second message 922 and may request a retransmission from the first UE 904 or the second UE 906. In one example, the retransmission request controller 910 may select the second UE 906 to retransmit the initial transmission 916. For example, the retransmission request controller 910 may send a retransmission request 924 to the second UE 906. In some examples, the retransmission request 924 may be a NACK.

[0106] It should be noted that the retransmission request controller 910 may not request a retransmission of the initial uplink transmission 914 from the first UE 904. In some aspects, the retransmission request controller 910 may send a wait signal 926 to the first UE 904. The wait signal 926 serves as an indication to the first UE 904 to temporarily store the most recent transmission (e.g., in a buffer) in case a retransmission is needed from the first UE 904. For example, the first UE 904 may store the initial uplink transmission 914 for a certain period of time in response to the wait signal 926.

[0107] The second UE 906 may retransmit the initial uplink transmission 916 in response to the retransmission request 924 without a grant from the network node 902. Fig. 9 , uplink transmission 928 represents a retransmission of initial uplink transmission 916. In some examples, the retransmission of initial uplink transmission 916 may be based on synchronized HARQ operation.

[0108] IC-based decoder 912 may perform successive interference cancellation (eg, MMSE-SIC) to successfully decode initial uplink transmission 916 based on initial uplink transmission 916 and uplink transmission 928. At 930, IC-based decoder 912 may output the successfully decoded initial uplink transmission 916.

[0109] At 932, the IC-based decoder 912 may perform successive interference cancellation (e.g., MMSE-SIC) using the successfully decoded initial uplink transmission 916 provided at 930 to retrospectively cancel interference from the initial uplink transmission 914. This may enable the IC-based decoder 912 to successfully decode the initial uplink transmission 914 at 934 and output the successfully decoded initial uplink transmission 914.

[0110] Fig.10 A signal flow diagram 1000 is illustrated in accordance with various aspects of the present disclosure. The signal flow diagram 1000 includes a network node 1002, a first UE (UE_1) 1004, and a second UE (UE_2) 1006.

[0111] The network node 1002 may send configuration information 1008, 1010 to the first UE 1004 and the second UE 1006. In some examples, the configuration information 1008, 1010 may include at least one of the following: a first resource of a NOMA channel (e.g., a first time-frequency resource of the NOMA channel 918), a second resource of a NOMA channel (e.g., a second time-frequency resource of the NOMA channel 918), a time period to be used as a duration for a timer associated with a wait signal, mapping information, or a combination thereof.

[0112] In some examples, the network node 1002 may use higher layer signaling (e.g., RRC signaling, MAC signaling, etc.) to send the configuration information 1008, 1010. In some examples, the configuration information 1008, 1010 may be sent using a single message broadcast to a group of UEs.

[0113] The mapping information may include at least one of a first set of demodulation reference signal ports or a first set of unique multiple access signatures associated with the first resource and at least one of a second set of demodulation reference signal ports or a second set of unique multiple access signatures associated with the second resource.

[0114] The first UE 1004 may use the first resource of the NOMA channel to send a first NOMA uplink transmission 1012, and the second UE 1006 may use the first resource of the NOMA channel to send a second NOMA uplink transmission 1014. In some examples, the first UE 1004 and the second UE 1006 may concurrently send the first NOMA uplink transmission 1012 and the second NOMA uplink transmission 1014. In other examples, at least a portion of the first NOMA uplink transmission 1012 may overlap with at least a portion of the second NOMA uplink transmission 1014 in the time domain.

[0115] At 1016 , the network node 1002 may fail to decode the first NOMA uplink transmission 1012 and the second NOMA uplink transmission 1014 .

[0116] At 1018, the network node 1002 may store NOMA uplink transmission information. For example, the network node 1002 may store uplink transmission information associated with the first NOMA uplink transmission 1012 and the second NOMA uplink transmission 1014 in a storage device (e.g., a memory). For example, the uplink transmission information may include symbols (e.g., QAM symbols) of a modulation scheme associated with the uplink transmission.

[0117] The network node 1002 may selectively send a retransmission request to the first UE 1004 or the second UE 1006. For example, the network node 1002 may send a retransmission request 1020 to the second UE 1006. In some examples, the retransmission request 1020 may be a NACK.

[0118] At 1030, the second UE 1006 may retransmit the second NOMA uplink transmission 1014 in response to the retransmission request 1020. For example, the second UE 1006 may use a second resource of the NOMA channel (e.g., a second time-frequency resource of the NOMA channel 918) for the retransmission of the second NOMA uplink transmission 1014 (e.g., at 1030). The second resource may be predefined and indicated to the second UE 1006 via the configuration information 1010.

[0119] The network node 1002 may send a wait signal 1022 to the first UE 1004. The wait signal 1022 serves as an indication to the first UE 1004 to temporarily store the latest transmission (e.g., in a buffer) in case a retransmission is required from the first UE 1004. For example, the wait signal 1022 may serve as an indication to the first UE 1004 to store the second NOMA uplink transmission 1012 for a certain period of time. As previously described, the time period may be indicated in the configuration information 1008.

[0120] At 1024, the first UE 1004 may start a timer in response to the wait signal 1022. In one example, the timer duration 1026 may be a time period indicated in the configuration information 1008. After expiration of the timer duration 1026, at 1028, the first UE 1004 may discard one or more packets associated with the first NOMA uplink transmission from the buffer 1012.

[0121] At 1032, the network node 1002 may successfully decode the retransmission of the second NOMA uplink transmission 1014 (eg, at 1030).

[0122] The network node 1002 may send a wait signal 1034 to the second UE 1006. The wait signal 1034 serves as an indication to the second UE 1006 to temporarily store the latest transmission (e.g., in a buffer) in case a retransmission is required from the second UE 1006. For example, the wait signal 1034 may serve as an indication to the second UE 1006 to store the second NOMA uplink transmission 1012 for a certain period of time. As previously described, the time period may be indicated in the configuration information 1010.

[0123] At 1038, the second UE 1006 may start a timer in response to the wait signal 1034. In one example, the timer duration 1040 may be the time period indicated in the configuration information 1010. After expiration of the timer duration 1040, at 1042, the second UE 1006 may discard one or more packets associated with the second NOMA uplink transmission from the buffer 1014.

[0124] At 1036, the network node 1002 may successfully decode the first NOMA uplink transmission 1012 based on the NOMA uplink transmission information stored at 1018 and the successfully decoded retransmission of the second NOMA uplink transmission 1014. In some aspects, the network node 1002 may decode the first NOMA uplink transmission 1012 by performing a retrospective interference cancellation operation. For example, the network node 1002 may implement an interference cancellation (IC) based decoder (e.g., IC based decoder 912), which may use the successfully decoded retransmission of the second NOMA uplink transmission 1014 to retrospectively cancel interference from the first NOMA uplink transmission 1012. This may enable the IC based decoder to successfully decode the first NOMA uplink transmission 1012.

[0125] Fig.11 A signal flow diagram 1100 is illustrated in accordance with various aspects of the present disclosure. The signal flow diagram 1100 includes a network node 1102, a first UE (UE_1) 1104, and a second UE (UE_2) 1106.

[0126] The network node 1102 may send configuration information 1108, 1110 to the first UE 1104 and the second UE 1106. In some examples, the configuration information 1108, 1110 may include at least one of the following: a first resource of a NOMA channel (e.g., a first time-frequency resource of the NOMA channel 918), a second resource of a NOMA channel (e.g., a second time-frequency resource of the NOMA channel 918), a time period to be used as a duration for a timer associated with a wait signal, mapping information, or a combination thereof.

[0127] In some examples, the network node 1102 may use higher layer signaling (e.g., RRC signaling, MAC signaling, etc.) to send the configuration information 1108, 1110. In some examples, the configuration information 1108, 1110 may be sent using a single message broadcast to a group of UEs.

[0128] The mapping information may include at least one of a first set of demodulation reference signal ports or a first set of unique multiple access signatures associated with the first resource and at least one of a second set of demodulation reference signal ports or a second set of unique multiple access signatures associated with the second resource.

[0129] The first UE 1104 may use the first resource (e.g., the first time-frequency resource) of the NOMA channel to send a first NOMA uplink transmission 1112, and the second UE 1106 may use the first resource of the NOMA channel to send a second NOMA uplink transmission 1114. In some examples, the first UE 1104 and the second UE 1106 may concurrently send the first NOMA uplink transmission 1112 and the second NOMA uplink transmission 1114. In other examples, at least a portion of the first NOMA uplink transmission 1112 may overlap with at least a portion of the second NOMA uplink transmission 1114 in the time domain.

[0130] At 1116 , the network node 1102 may fail to decode the first NOMA uplink transmission 1112 and the second NOMA uplink transmission 1114 .

[0131] At 1118, the network node 1102 may store the NOMA uplink transmission information. For example, the network node 1102 may store the uplink transmission information associated with the first NOMA uplink transmission 1112 and the second NOMA uplink transmission 1114 in a storage device (e.g., a memory). For example, the uplink transmission information may include symbols (e.g., QAM symbols) of a modulation scheme associated with the uplink transmission.

[0132] The network node 1102 may selectively send a retransmission request to the first UE 1104 or the second UE 1106. For example, the network node 1102 may send a retransmission request 1120 to the second UE 1106. In some examples, the retransmission request 1120 may be a NACK.

[0133] The network node 1102 may send a wait signal 1122 to the first UE 1104. The wait signal 1122 serves as an indication to the first UE 1104 to temporarily store the latest transmission (e.g., in a buffer) in case a retransmission is required from the first UE 1104. For example, the wait signal 1122 may serve as an indication to the first UE 1104 to store the first NOMA uplink transmission 1112 for a certain period of time. As previously described, the time period may be indicated in the configuration information 1108.

[0134] At 1124, the first UE 1104 can start a timer in response to the wait signal 1122. In one example, the timer duration 1126 can be the time period indicated in the configuration information 1108.

[0135] At 1128, the second UE 1106 may retransmit the second NOMA uplink transmission 1114 in response to the retransmission request 1120. For example, the second UE 1106 may use a second resource (e.g., a second time-frequency resource) of the NOMA channel for the retransmission of the second NOMA uplink transmission 1114 (e.g., at 1128). The second resource may be predefined and indicated to the second UE 1106 via the configuration information 1110.

[0136] At 1130 , the network node 1102 may fail to decode the retransmission of the second NOMA uplink transmission 1114 .

[0137] At 1132, the network node 1102 may store uplink transmission information associated with the retransmission of the second NOMA uplink transmission 1114. For example, the network node 1102 may store the uplink transmission information associated with the retransmission (e.g., 1128) of the second NOMA uplink transmission 1114 in a storage device (e.g., a memory). For example, the uplink transmission information may include symbols (e.g., QAM symbols) of a modulation scheme associated with the uplink transmission.

[0138] The network node 1102 may send a wait signal 1134 to the second UE 1106. The wait signal 1134 serves as an indication to the second UE 1106 to temporarily store the latest transmission (e.g., in a buffer) in case a retransmission is required from the second UE 1106. For example, the wait signal 1134 may serve as an indication to the second UE 1106 to store the second NOMA uplink transmission 1114 for a certain period of time. As previously described, the time period may be indicated in the configuration information 1110.

[0139] At 1136, the second UE 1106 may start a timer in response to the wait signal 1134. In one example, the timer duration 1138 may be the time period indicated in the configuration information 1110. At 1140, the second UE 1106 may discard one or more packets associated with the second NOMA uplink transmission 1114 from a buffer at the second UE 1106 upon expiration of the timer (e.g., at the end of the timer duration 1138).

[0140] The network node 1102 may send a retransmission request 1142 to the first UE 1104. In some examples, the retransmission request 1142 may be a NACK. It should be noted that the network node 1102 may send the retransmission request 1142 before the timer expires (e.g., before the timer duration 1126 ends).

[0141] At 1144, the first UE 1104 may retransmit the first NOMA uplink transmission 1112 in response to the retransmission request 1142. For example, the first UE 1104 may use a third resource (e.g., a third time-frequency resource) of the NOMA channel for retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144). The third resource may be predefined and indicated to the first UE 1104 via the configuration information 1108.

[0142] At 1146 , the network node 1102 may successfully decode the retransmission of the first NOMA uplink transmission 1112 .

[0143] At 1148 , the network node 1102 may successfully decode the second NOMA uplink transmission 1114 based on the stored NOMA uplink transmission information (eg, at 1118 , 1132 ) and the successfully decoded retransmission of the first NOMA uplink transmission 1146 .

[0144] At 1148, the network node 1102 may successfully decode the second NOMA uplink transmission 1114 based on the NOMA uplink transmission information stored at 1118, 1132 and the successfully decoded retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144). In some aspects, the network node 1102 may decode the second NOMA uplink transmission 1114 by performing a retrospective interference cancellation operation. For example, the network node 1102 may implement an IC-based decoder (e.g., IC-based decoder 912), which may use the successfully decoded retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144) to retrospectively cancel interference from the second NOMA uplink transmission 1114. This may enable the IC-based decoder to successfully decode the second NOMA uplink transmission 1114.

[0145] In some aspects of the present disclosure, a UE (e.g., UE 904, 1004, 1104) may use a first DM-RS port and / or a first unique multi-access signature for an initial NOMA uplink transmission on a NOMA channel, and may use a second DM-RS port and / or a second unique multi-access signature for a retransmission of the initial NOMA uplink transmission on the NOMA channel. In some examples, based on a preconfigured mapping, the second DM-RS port is associated with the first DM-RS port and the second unique multi-access signature is associated with the first unique multi-access signature. In some aspects, a network node (e.g., network node 902, 1002, 1102) may provide the preconfigured mapping to a UE (e.g., UE 904, 1004, 1104) via configuration information (e.g., configuration information 1008, 1010, 1108, 1110). Reference will now be made to Fig.12 Describes an example of a preconfigured mapping.

[0146] Fig.12 Including N UEs sending an initial NOMA uplink transmission 1200 and a NOMA UL retransmission 1201. The N UEs include a first UE (UE_1) 1202, a second UE (UE_2) 1202, and an Nth UE (UE_N) 1206. Each of the N UEs may use a first resource 1214 for an initial NOMA uplink transmission to send an initial NOMA uplink transmission. For example, the first UE 1202, the second UE 1204, and the Nth UE 1206 may use the first resource 1214 to send corresponding initial NOMA uplink transmissions 1208, 1210, 1212. In some examples, the first resource 1214 may be a first time-frequency resource of a NOMA channel.

[0147] Each of the N UEs may retransmit the initial NOMA uplink transmission using the second resource 1224 for NOMA uplink retransmission. For example, the first UE 1202, the second UE 1204, and the Nth UE 1206 may retransmit the respective initial NOMA uplink transmissions 1208, 1210, 1212 using the second resource 1224. In some examples, the second resource 1224 may be a second time-frequency resource of the NOMA channel.

[0148] exist Fig.12, each of NOMA uplink retransmissions 1218, 1220, 1222 may be a HARQ retransmission of an initial NOMA uplink transmission. For example, NOMA uplink retransmission 1218 may be a HARQ retransmission of initial NOMA uplink transmission 1208, NOMA uplink retransmission 1220 may be a HARQ retransmission of initial NOMA uplink transmission 1210, and NOMA uplink retransmission 1222 may be a HARQ retransmission of initial NOMA uplink transmission 1212.

[0149] Each of the N UEs may receive or may be preconfigured with resource mapping information. In some examples, the resource mapping information may include a first set of DM-RS ports associated with the first resource 1214 and a first set of unique multi-access signatures, and may include a second set of DM-RS ports associated with the second resource 1224 and a second set of unique multi-access signatures.

[0150] Each DM-RS port in the first set of DM-RS ports may be mapped to a corresponding DM-RS port in the second set of DM-RS ports, and each unique multi-access signature in the first set of unique multi-access signatures may be mapped to a corresponding unique multi-access signature in the second set of unique multi-access signatures. Table 1 illustrates an example of resource mapping information.

[0151] Table 1

[0152]

[0153] In one example, referring to Table 1 and Fig.12 , the first UE 1202 may use a first DM-RS port (e.g., DM-RS#1-1) and / or a first multiple access signature (e.g., MAS#1-1) from the first set of DM-RS ports and the first set of unique multiple access signatures for initial NOMA uplink transmission 1208. The first UE 1202 may use a corresponding first DM-RS port (e.g., DM-RS#2-1) and / or a first multiple access signature (e.g., MAS#2-1) from the second set of DM-RS ports and the second set of unique multiple access signatures for NOMA uplink retransmission 1218.

[0154] In another example, the Nth UE 1206 may use the Nth DM-RS port (e.g., DM-RS #1-N) and / or the Nth multiple access signature (e.g., MAS #1-N) from the first set of DM-RS ports and the first set of unique multiple access signatures for initial NOMA uplink transmission 1212. The Nth UE 1206 may use the corresponding first DM-RS port (e.g., DM-RS #2-N) and / or the first multiple access signature (e.g., MAS #2-N) from the second set of DM-RS ports and the second set of unique multiple access signatures for NOMA uplink retransmission 1222.

[0155] It should be understood that Fig.12 The retransmissions 1218, 1220, and 1222 of the N UEs in Table 1 are shown to facilitate understanding of the resource mapping information in Table 1. For example, according to the described aspects, Fig.12 A subset (e.g., some) of the N UEs may be allowed to retransmit their initial NOMA uplink transmissions.

[0156] In some aspects, the UE may select a DM-RS port from a first set of DM-RS ports and / or a unique multiple access signature from a first set of unique multiple access signatures. In some aspects, the UE may randomly select a DM-RS port and / or a unique multiple access signature. In other aspects, the UE may select a DM-RS port and / or a unique multiple access signature based on pre-configured information at the UE.

[0157] Since there is a predefined relationship between the DM-RS ports that the UE can use for the initial NOMA uplink transmission and the different DM-RS ports that the UE can use for the retransmissions of the initial NOMA uplink transmission, the network node that knows the predefined relationship can determine that a specific retransmission is associated with a specific initial NOMA uplink transmission based on the DM-RS ports used at the UE. This can allow the network node to combine the initial NOMA uplink transmission from the UE with the retransmission from the same UE.

[0158] In another example, because there is a predefined relationship between a unique multi-access signature that a UE may use for an initial NOMA uplink transmission and a different unique multi-access signature that the UE may use for a retransmission of the initial NOMA uplink transmission, a network node that is aware of the predefined relationship may determine that a particular retransmission is associated with a particular initial NOMA uplink transmission based on the unique multi-access signature used at the UE. This may allow the network node to combine an initial NOMA uplink transmission from a UE with a retransmission from the same UE.

[0159] In some aspects of the present disclosure, a resend request (e.g., reference Fig. 9 , Fig.10 , Fig.11The retransmission requests 920, 1020, 1042 described above may be included in a control information message. Each bit position in the set of bit positions in the control information message may be associated with a different UE. For example, the control information message may be a HARQ feedback message common to a group of UEs. For example, each bit in the HARQ feedback message may be associated with a different DM-RS port and / or unique multiple access signature used by a specific UE for initial NOMA uplink transmission. The network node may indicate a subset of UEs that will use the resources of the NOMA channel to perform retransmissions by setting the bit positions associated with different DM-RS ports and / or unique multiple access signatures to a specific value (e.g., '0'). Reference Fig.13 Describe this.

[0160] Fig.13 A HARQ feedback message 1300 is illustrated in accordance with various aspects of the present disclosure. In some examples, the HARQ feedback message 1300 may be based on a group common DCI format. The length of the HARQ feedback message 1300 may depend on the number of DM-RS ports and / or unique multiple access signatures configured for NOMA resources.

[0161] exist Fig.13 In the example of , the length of HARQ feedback message 1300 can be N bits. The first bit 1312 can carry a first feedback value (Feedback_1), the second bit 1314 can carry a second feedback value (Feedback_2), the third bit 1316 can carry a third feedback value (Feedback_3), and the Nth bit 1318 can carry an Nth feedback value (Feedback_N).

[0162] Each of the N bits in the HARQ feedback message 1300 may be mapped to one of the N DM-RS ports 1302. Each of the N DM-RS ports 1302 may be used by a different UE for initial NOMA uplink transmission. For example, the first bit 1312 may be mapped to the first DM-RS port 1304, the second bit 1314 may be mapped to the second DM-RS port 1306, the third bit 1316 may be mapped to the third DM-RS port 1308, and the Nth bit 1318 may be mapped to the Nth DM-RS port 1310.

[0163] In some examples, each feedback value in the HARQ feedback message 1300 may be a first value (e.g., '0') or a second value (e.g., '1'). For example, the first value may indicate a request for a retransmission (e.g., NACK) of an initial uplink NOMA transmission, while the second value may indicate a waiting signal.

[0164] If the network node determines that the initial NOMA uplink transmission set from the set of UEs cannot be decoded, the network node may use the HARQ feedback message 1300 to selectively request retransmissions from a subset of the set of UEs. In an example scenario, the network node may determine that a first initial NOMA uplink transmission from a first UE using a first DM-RS port 1304 cannot be decoded and a second initial NOMA uplink transmission from a second UE using a second DM-RS port 1306 cannot be decoded. In this scenario, the network node may selectively request retransmissions from the first UE or the second UE. For example, if the network node selects retransmissions from a first UE using a first DM-RS port 1304, the network node may set the first bit 1312 to a first value (e.g., '0') and the second bit 1314 to a second value (e.g., '1'). If the network node selects retransmissions from a second UE using a second DM-RS port 1306, the network node may set the second bit 1314 to a first value (e.g., '0') and the first bit 1312 to a second value (e.g., '1').

[0165] A UE receiving the HARQ feedback message 1300 may monitor the bits in the HARQ feedback message 1300 that are mapped to the DM-RS ports used by the UE for the initial NOMA uplink transmission. For example, a first UE using the first DM-RS port 1304 may monitor the first bit 1312 in the HARQ feedback message 1300, and a second UE using the second DM-RS port 1306 may monitor the second bit 1314 in the HARQ feedback message 1300. Thus, if the first UE determines that the first bit 1312 is set to a first value (e.g., '0'), the first UE may retransmit the first initial NOMA uplink transmission. If the second UE determines that the second bit 1314 is set to a second value (e.g., '0'), the second UE may retransmit the second initial NOMA uplink transmission.

[0166] Fig.14 1400 is a flow chart of a method of wireless communication. The method may be performed by a network node (e.g., base station 102; network nodes 902, 1002, 1102, device 1602 / 1602'; processing system 1714, which may include memory 376 and may be an entire network node or a component of a network node, such as TX processor 316, RX processor 370 and / or controller / processor 375).

[0167] At 1402, a network node receives a set of uplink transmissions from a set of UEs via a first resource of a non-orthogonal channel, wherein the network node is unable to decode the set of uplink transmissions. Fig. 9, the network node 902 may receive an initial uplink transmission 914 from the first UE 904 and an initial uplink transmission 916 from the second UE 906 on the same time-frequency resources of the NOMA channel 918. Fig. 9 In the example of , the NOMA receiver 908 may fail to decode the initial uplink transmissions 914 , 916 .

[0168] For example, refer to Fig.10 , the network node 1002 may receive a first NOMA uplink transmission 1012 from the first UE 1004 and may receive a second NOMA uplink transmission 1014 from the second UE 1006 via a first resource of the NOMA channel. At 1016, the network node 1002 may fail to decode the first NOMA uplink transmission 1012 and the second NOMA uplink transmission 1014.

[0169] For example, refer to Fig.11 , the network node 1102 may receive a first NOMA uplink transmission 1112 from the first UE 1104 and may receive a second NOMA uplink transmission 1114 from the second UE 1106 via a first resource of the NOMA channel. At 1116, the network node 1102 may fail to decode the first NOMA uplink transmission 1112 and the second NOMA uplink transmission 1114.

[0170] In some examples, the first resource of the non-orthogonal channel includes at least one of a first time resource or a first frequency resource. The second resource of the non-orthogonal channel includes at least one of a second time resource or a second frequency resource.

[0171] At 1404, the network node sends a retransmission request to a subset of the set of UEs. Fig. 9 , a retransmission request controller 910 of the network node 902 may receive a first message 920 and a second message 922 indicating that the NOMA receiver 908 of the network node 902 failed to decode the initial uplink transmission 914, 916, and may request a retransmission from the first UE 904 or the second UE 906. In one example, the retransmission request controller 910 may select the second UE 906 to retransmit the initial transmission 916. For example, the retransmission request controller 910 may send a retransmission request 924 to the second UE 906. In some examples, the retransmission request 924 may be a NACK.

[0172] For example, refer to Fig.10, the network node 1002 may selectively send a retransmission request to the first UE 1004 or the second UE 1006. For example, the network node 1002 may send a retransmission request 1020 to the second UE 1006. In some examples, the retransmission request 1020 may be a NACK.

[0173] For example, refer to Fig.11 , the network node 1102 may selectively send a retransmission request to the first UE 1104 or the second UE 1106. For example, the network entity 1102 may send a retransmission request 1142 to the first UE 1104. In some examples, the retransmission request 1142 may be a NACK.

[0174] In some examples, the retransmission request is sent in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with a different UE in a set of UEs. In some examples, the retransmission request is sent in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with at least one of a unique multi-access signature or a different demodulation reference signal port for a non-orthogonal channel. For example, the control information message may be a HARQ feedback message common to a group of UEs. For example, each bit in the HARQ feedback message may be associated with a different DM-RS port and / or a unique multi-access signature used by a particular UE for an initial NOMA uplink transmission. The network node may be as described herein with reference to Fig.13 As described, a subset of UEs that will perform retransmissions using resources of the NOMA channel is indicated by setting bit positions associated with different DM-RS ports and / or unique multiple access signatures to specific values ​​(eg, '0').

[0175] In some examples, a first uplink transmission in the uplink transmission set (e.g., initial uplink transmission 914, first NOMA uplink transmission 1012, first NOMA uplink transmission 1112) is associated with at least one of a first demodulation reference signal port or a first unique multi-access signature, and a retransmission of the first uplink transmission (e.g., uplink transmission 928, a retransmission of a second NOMA uplink transmission 1014 (e.g., at 1030), a retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144)) is associated with at least one of a second demodulation reference signal port or a second unique multi-access signature. In some examples, based on a preconfigured mapping, the second demodulation reference signal port is associated with the first demodulation reference signal port and the second unique multi-access signature is associated with the first unique multi-access signature.

[0176] At 1406, the network node receives a retransmission of a first uplink transmission in the set of uplink transmissions via a second resource of the non-orthogonal channel in response to the retransmission request.

[0177] For example, refer to Fig. 9 , the network node 902 may receive a retransmission (e.g., uplink transmission 928) of the initial uplink transmission 916 from the second UE 906 in response to the retransmission request 924 without a grant from the network node 902. In some examples, the retransmission of the initial uplink transmission 916 may be based on synchronized HARQ operation.

[0178] For example, refer to Fig.10 , the network node 1002 may receive a retransmission of the second NOMA uplink transmission 1014 from the second UE 1006 in response to the retransmission request 1020 (e.g., at 1030). For example, the second UE 1006 may use a second resource of the NOMA channel (e.g., a second time-frequency resource of the NOMA channel 918) for the retransmission of the second NOMA uplink transmission 1014 (e.g., at 1030). The second resource may be predefined and indicated to the second UE 1006 via the configuration information 1010.

[0179] For example, refer to Fig.11 , the network node 1102 may receive a retransmission of the first NOMA uplink transmission 1112 from the first UE 1104 in response to the retransmission request 1142 (e.g., at 1144). For example, the first UE 1104 may use a third resource (e.g., a third time-frequency resource) of the NOMA channel for the retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144). The third resource may be predefined and indicated to the first UE 1104 via the configuration information 1108.

[0180] At 1408, the network node decodes a second uplink transmission in the set of uplink transmissions based at least on the retransmission of the first uplink transmission. Fig. 9 , the IC-based decoder 912 of the network node 902 may successfully decode the initial uplink transmission 916 based on the initial uplink transmission 916 and the uplink transmission 928 (e.g., a retransmission of the initial uplink transmission 916), and may output a successfully decoded uplink transmission 930. At 932, the IC-based decoder 912 uses the successfully decoded uplink transmission 930 to retrospectively cancel interference from the initial uplink transmission 914. This may enable the IC-based decoder 912 to successfully decode the initial uplink transmission 914 and output a successfully decoded uplink transmission 934.

[0181] For example, refer to Fig.10, at 1032 the network node 1002 may successfully decode the retransmission of the second NOMA uplink transmission 1014 (e.g., at 1030). At 1036 the network node 1002 may successfully decode the first NOMA uplink transmission 1012 based on the NOMA uplink transmission information stored at 1018 and the successfully decoded retransmission of the second NOMA uplink transmission 1014. In some aspects, the network node 1002 may decode the first NOMA uplink transmission 1012 by performing a retrospective interference cancellation operation. For example, the network node 1002 may implement an interference cancellation (IC) based decoder (e.g., IC based decoder 912) that may use the successfully decoded retransmission of the second NOMA uplink transmission 1014 to retrospectively cancel interference from the first NOMA uplink transmission 1012. This may enable the IC based decoder to successfully decode the first NOMA uplink transmission 1012.

[0182] For example, refer to Fig.11 , at 1146 the network node 1102 may successfully decode the retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144). At 1148, the network node 1102 may successfully decode the second NOMA uplink transmission 1114 based on the stored NOMA uplink transmission information (e.g., at 1118, 1132) and the successfully decoded retransmission of the first NOMA uplink transmission 1146.

[0183] At 1148, the network node 1102 may successfully decode the second NOMA uplink transmission 1114 based on the NOMA uplink transmission information stored at 1118, 1132 and the successfully decoded retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144). In some aspects, the network node 1102 may decode the second NOMA uplink transmission 1114 by performing a retrospective interference cancellation operation. For example, the network node 1102 may implement an interference cancellation (IC) based decoder (e.g., IC based decoder 912), which may use the successfully decoded retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144) to retrospectively cancel interference from the second NOMA uplink transmission 1114. This may enable the IC based decoder to successfully decode the second NOMA uplink transmission 1114.

[0184] Fig.151500 is a flow chart of a method of wireless communication. The method may be performed by a network node (e.g., base station 102; network node 902, 1002, 1102, device 1602 / 1602'; processing system 1714, which may include memory 376 and may be an entire network node or a component of a network node, such as TX processor 316, RX processor 370 and / or controller / processor 375).

[0185] At 1502, the network node sends configuration information. Fig.10 , the network node 1002 may send configuration information 1008, 1010 to the first UE 1004 and the second UE 1006. For example, referring to Fig.11 , the network node 1102 may send configuration information 1108 , 1110 to the first UE 1104 and the second UE 1106 .

[0186] In some examples, the configuration information (e.g., configuration information 1008, 1010, 1108, 1110) may include at least one of: a first resource of a NOMA channel (e.g., a first time-frequency resource of NOMA channel 918), a second resource of a NOMA channel (e.g., a second time-frequency resource of NOMA channel 918), a time period to be used as the duration of a timer associated with a wait signal, mapping information, or a combination thereof.

[0187] At 1504, the network node receives a set of uplink transmissions from a set of UEs via a first resource of a non-orthogonal channel, wherein the network node is unable to decode the set of uplink transmissions. Fig. 9 , the network node 902 may receive an initial uplink transmission 914 from the first UE 904 and an initial uplink transmission 916 from the second UE 906 on the same time-frequency resources of the NOMA channel 918. Fig. 9 In the example of , the NOMA receiver 908 may fail to decode the initial uplink transmissions 914 , 916 .

[0188] For example, refer to Fig.10 , the network node 1002 may receive a first NOMA uplink transmission 1012 from the first UE 1004 and may receive a second NOMA uplink transmission 1014 from the second UE 1006 via a first resource of the NOMA channel. At 1016, the network node 1002 may fail to decode the first NOMA uplink transmission 1012 and the second NOMA uplink transmission 1014.

[0189] For example, refer to Fig.11, the network node 1102 may receive a first NOMA uplink transmission 1112 from the first UE 1104 and may receive a second NOMA uplink transmission 1114 from the second UE 1106 via a first resource of the NOMA channel. At 1116, the network node 1102 may fail to decode the first NOMA uplink transmission 1112 and the second NOMA uplink transmission 1114.

[0190] In some examples, the first resource of the non-orthogonal channel includes at least one of a first time resource or a first frequency resource. The second resource of the non-orthogonal channel includes at least one of a second time resource or a second frequency resource.

[0191] At 1506, the network node stores uplink transmission information associated with the uplink transmission set. Fig. 9 , the NOMA receiver 908 of the network node 902 may store uplink transmission information associated with the initial uplink transmissions 914, 916. For example, referring to Fig.10 At 1018, the network node 1002 may store NOMA uplink transmission information. For example, the network node 1002 may store uplink transmission information associated with the first NOMA uplink transmission 1012 and the second NOMA uplink transmission 1014 in a storage device (e.g., a memory). For example, the uplink transmission information may include symbols of a modulation scheme associated with the uplink transmission (e.g., QAM symbols).

[0192] For example, refer to Fig.11 At 1118, the network node 1102 may store the NOMA uplink transmission information. For example, the network node 1102 may store the uplink transmission information associated with the first NOMA uplink transmission 1112 and the second NOMA uplink transmission 1114 in a storage device (e.g., a memory). For example, the uplink transmission information may include symbols of a modulation scheme associated with the uplink transmission (e.g., QAM symbols).

[0193] At 1508, the network node sends a retransmission request to a subset of the set of UEs. Fig. 9, a retransmission request controller 910 of the network node 902 may receive a first message 920 and a second message 922 indicating that the NOMA receiver 908 of the network node 902 failed to decode the initial uplink transmission 914, 916, and may request a retransmission from the first UE 904 or the second UE 906. In one example, the retransmission request controller 910 may select the second UE 906 to retransmit the initial transmission 916. For example, the retransmission request controller 910 may send a retransmission request 924 to the second UE 906. In some examples, the retransmission request 924 may be a NACK.

[0194] For example, refer to Fig.10 , the network node 1002 may selectively send a retransmission request to the first UE 1004 or the second UE 1006. For example, the network node 1002 may send a retransmission request 1020 to the second UE 1006. In some examples, the retransmission request 1020 may be a NACK.

[0195] For example, refer to Fig.11 , the network node 1102 may selectively send a retransmission request to the first UE 1104 or the second UE 1106. For example, the network entity 1102 may send a retransmission request 1142 to the first UE 1104. In some examples, the retransmission request 1142 may be a NACK.

[0196] In some examples, the retransmission request is sent in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with a different UE in a set of UEs. In some examples, the retransmission request is sent in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with at least one of a unique multi-access signature or a different demodulation reference signal port for a non-orthogonal channel. For example, the control information message may be a HARQ feedback message common to a group of UEs. For example, each bit in the HARQ feedback message may be associated with a different DM-RS port and / or a unique multi-access signature used by a particular UE for an initial NOMA uplink transmission. The network node may be as described herein with reference to Fig.13 As described, a subset of UEs that will perform retransmissions using resources of the NOMA channel is indicated by setting bit positions associated with different DM-RS ports and / or unique multiple access signatures to specific values ​​(eg, '0').

[0197] In some examples, a first uplink transmission in the uplink transmission set (e.g., initial uplink transmission 914, first NOMA uplink transmission 1012, first NOMA uplink transmission 1112) is associated with at least one of a first demodulation reference signal port or a first unique multi-access signature, and a retransmission of the first uplink transmission (e.g., uplink transmission 928, a retransmission of a second NOMA uplink transmission 1014 (e.g., at 1030), a retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144)) is associated with at least one of a second demodulation reference signal port or a second unique multi-access signature. In some examples, based on a preconfigured mapping, the second demodulation reference signal port is associated with the first demodulation reference signal port and the second unique multi-access signature is associated with the first unique multi-access signature.

[0198] At 1510, the network node sends a wait signal to a UE in the set of UEs that is associated with the second uplink transmission, wherein the wait signal serves as an indication to the UE to store the second uplink transmission for a certain period of time.

[0199] For example, refer to Fig. 9 , the retransmission request controller 910 of the network node 902 may send a waiting signal 926 to the first UE 904. For example, referring to Fig.10 , the network node 1002 may send a wait signal 1022 to the first UE 1004. The wait signal 1022 serves as an indication to the first UE 1004 that the second NOMA uplink transmission 1012 is to be stored for a certain period of time. Fig.11 , the network node 1102 may send a wait signal 1122 to the first UE 1104. The wait signal 1122 serves as an indication to the first UE 1104 that the first NOMA uplink transmission 1112 is to be stored for a certain period of time.

[0200] At 1512, the network node receives a retransmission of a first uplink transmission in the set of uplink transmissions via a second resource of a non-orthogonal channel in response to the retransmission request. Fig. 9 , the network node 902 may receive a retransmission (e.g., uplink transmission 928) of the initial uplink transmission 916 from the second UE 906 in response to the retransmission request 924 without a grant from the network node 902. In some examples, the retransmission of the initial uplink transmission 916 may be based on synchronized HARQ operation.

[0201] For example, refer to Fig.10, the network node 1002 may receive a retransmission of the second NOMA uplink transmission 1014 from the second UE 1006 in response to the retransmission request 1020 (e.g., at 1030). For example, the second UE 1006 may use a second resource of the NOMA channel (e.g., a second time-frequency resource of the NOMA channel 918) for the retransmission of the second NOMA uplink transmission 1014 (e.g., at 1030). The second resource may be predefined and indicated to the second UE 1006 via the configuration information 1010.

[0202] For example, refer to Fig.11 , the network node 1102 may receive a retransmission of the first NOMA uplink transmission 1112 from the first UE 1104 in response to the retransmission request 1142 (e.g., at 1144). For example, the first UE 1104 may use a third resource (e.g., a third time-frequency resource) of the NOMA channel for the retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144). The third resource may be predefined and indicated to the first UE 1104 via the configuration information 1108.

[0203] At 1514, the network node determines that the retransmission of the first uplink transmission is associated with the first uplink transmission in the set of uplink transmissions based on at least one of the second demodulation reference signal port or the second unique multiple access signature value and the preconfigured mapping.

[0204] For example, as shown in Table 1, the resource mapping information and Fig.12 As described, there may be a predefined relationship between the DM-RS ports that the UE may use for an initial NOMA uplink transmission and different DM-RS ports that the UE may use for retransmissions of the initial NOMA uplink transmission. The network node may be aware of the predefined relationship and may determine that a particular retransmission is associated with a particular initial NOMA uplink transmission based on the DM-RS ports used at the UE.

[0205] In another example, as shown in Table 1, the resource mapping information and Fig.12 As described, there may be a predefined relationship between a unique multi-access signature that a UE may use for an initial NOMA uplink transmission and a different unique multi-access signature that the UE may use for a retransmission of the initial NOMA uplink transmission. The network node may be aware of the predefined relationship and may determine that a particular retransmission is associated with a particular initial NOMA uplink transmission based on the unique multi-access signature used at the UE.

[0206] At 1516, the network node decodes a second uplink transmission in the set of uplink transmissions based at least on the retransmission of the first uplink transmission. Fig. 9, the IC-based decoder 912 of the network node 902 may perform successive interference cancellation (e.g., MMSE-SIC) to successfully decode the initial uplink transmission 916 based on the initial uplink transmission 916 and the uplink transmission 928 (e.g., a retransmission of the initial uplink transmission 916). At 930, the IC-based decoder 912 may output the successfully decoded initial uplink transmission 916. At 932, the IC-based decoder 912 may perform successive interference cancellation (e.g., MMSE-SIC) using the successfully decoded initial uplink transmission 916 provided at 930 to retrospectively cancel interference from the initial uplink transmission 914. This may enable the IC-based decoder 912 to successfully decode the initial uplink transmission 914 at 934 and output the successfully decoded initial uplink transmission 914.

[0207] Fig.16 is a conceptual data flow diagram 1600 illustrating the flow of data between different parts / components in an example apparatus 1602. The apparatus may be a network node.

[0208] The apparatus 1602 includes a receiving component 1604 that receives uplink transmissions from a set of UEs including a first UE (UE_1) 1680 and a second UE (UE_2) 1690.

[0209] The device 1602 also includes a configuration information sending component 1606 that sends configuration information 1629, 1631.

[0210] The apparatus 1602 also includes a NOMA uplink transmit receive component 1608 that receives an uplink transmission set from a set of UEs (e.g., a first UE 1680 and a second UE 1690) via a first resource of a non-orthogonal channel. For example, the NOMA uplink transmit receive component 1608 receives (e.g., via the receiving component 1604) a first uplink transmission (Tx_1) 1622 from the first UE 1680 and a second uplink transmission (Tx_2) 1624 from the second UE 1690 via a first resource of a non-orthogonal channel.

[0211] The apparatus 1602 also includes a storage component 1610 that stores uplink transmit information associated with the uplink transmit set. The storage component 1610 can receive the uplink transmit information from the NOMA uplink transmit receiving component 1608 via the data path 1626.

[0212] The apparatus 1602 also includes a decoder component 1612 that decodes a second uplink transmission (e.g., second uplink transmission 1624) in the set of uplink transmissions based at least on a retransmission of the first uplink transmission (e.g., retransmission 1638 of the first uplink transmission 1622). For example, the decoder component 1612 can be an IC-based decoder, such as the IC-based decoder 912 described herein.

[0213] In some aspects, the decoder component 1612 provides an output 1642 comprising the decoded first uplink transmission 1622. For example, the decoder component 1612 may provide the output 1642 based on successive interference cancellation (e.g., MMSE-SIC) performed using uplink transmission information for the first uplink transmission 1622 and retransmissions 1638 of the first uplink transmission 1622 received from the storage component 1610 via the data path 1628.

[0214] In some aspects, the decoder component 1612 decodes a second uplink transmission (e.g., a second uplink transmission 1624) based on uplink transmission information (e.g., uplink transmission information received from the storage component 1610 via the data path 1628) and a retransmission 1638 of the first uplink transmission 1622. For example, the decoder component 1612 can decode the second uplink transmission by performing successive interference cancellation (e.g., MMSE-SIC) using the uplink transmission information for the second uplink transmission 1624 received from the storage component 1610 via the data path 1628 and the decoded first uplink transmission 1622 received at 1643. In some aspects, the decoder component 1612 provides an output 1644 including the decoded second uplink transmission 1624.

[0215] In some aspects, the decoder component 1612 determines that a retransmission of a first uplink transmission (e.g., a retransmission 1638 of the first uplink transmission 1622) is associated with a first uplink transmission in a set of uplink transmissions based on at least one of a second demodulation reference signal port or a second unique multiple access signature and a preconfigured mapping.

[0216] The apparatus 1602 also includes a retransmission request component 1614 that sends a retransmission request 1632 to a subset of the set of UEs. In some aspects, the retransmission request component 1614 sends the retransmission request 1632 in response to a message 1630 from the decoder component 1612 indicating a failure to decode the first uplink transmission 1622 and the second uplink transmission 1624.

[0217] The apparatus 1602 also includes a wait signal sending component 1616 that sends a wait signal 1636 to a UE in the set of UEs associated with the second uplink transmission (e.g., a second UE 1690 associated with the second uplink transmission 1624), wherein the wait signal 1636 serves as an indication to the UE that the second uplink transmission is to be stored for a certain period of time. In some aspects, the wait signal sending component 1616 sends the wait signal 1636 in response to a message 1634 from the retransmission request component 1614 indicating that the retransmission request 1632 has been sent to a subset of the set of UEs.

[0218] The device 1602 also includes a NOMA uplink retransmission receiving component 1618, which receives a retransmission (Re_Tx_1) 1638 of a first uplink transmission 1622 in the uplink transmission set via a second resource of a non-orthogonal channel.

[0219] The apparatus 1602 also includes a transmitting component 1620 that transmits a downlink signal to one or more UEs in a set of UEs including a first UE (UE_1) 1680 and a second UE (UE_2) 1690.

[0220] The device may include executing the aforementioned Fig.14 and Fig.15 Each box in the flowchart of the algorithm is an additional component. Therefore, Fig.14 and Fig.15 Each block in the aforementioned flow chart of can be performed by a component, and the apparatus may include one or more of these components. These components may be one or more hardware components, which are specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium so as to be implemented by a processor, or some combination thereof.

[0221] Fig.171700 is a diagram illustrating an example of a hardware implementation for an apparatus 1602' employing a processing system 1714. The processing system 1714 may be implemented with a bus architecture, generally represented by a bus 1724. The bus 1724 may include any number of interconnecting buses and bridges, depending on the specific application of the processing system 1714 and the overall design constraints. The bus 1724 links together various circuits, including one or more processors and / or hardware components (represented by the processor 1704, components 1604, 1606, 1608, 1610, 1612, 1614, 1616, 1618, 1620, and computer readable medium / memory 1706). The bus 1724 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further.

[0222] The processing system 1714 may be coupled to the transceiver 1710. The transceiver 1710 is coupled to one or more antennas 1720. The transceiver 1710 provides components for communicating with various other devices through a transmission medium. The transceiver 1710 receives signals from the one or more antennas 1720, extracts information from the received signals, and provides the extracted information to the processing system 1714 (specifically, the receiving component 1604). In addition, the transceiver 1710 receives information from the processing system 1714 (specifically, the transmitting component 1620), and based on the received information, generates a signal to be applied to the one or more antennas 1720. The processing system 1714 includes a processor 1704, which is coupled to a computer-readable medium / memory 1706. The processor 1704 is responsible for general processing, including executing software stored on the computer-readable medium / memory 1706. The software, when executed by the processor 1704, causes the processing system 1714 to perform the various functions described above for any particular device. The computer-readable medium / memory 1706 may also be used to store data manipulated by the processor 1704 when executing software. The processing system 1714 also includes at least one of the components 1604, 1606, 1608, 1610, 1612, 1614, 1616, 1618. These components may be software components running in the processor 1704, resident / stored in the computer-readable medium / memory 1706, one or more hardware components coupled to the processor 1704, or some combination thereof. The processing system 1714 may be a component of a network node (e.g., a base station 310), and may include a memory 376, and / or at least one of a TX processor 316, an RX processor 370, and a controller / processor 375. Alternatively, the processing system 1714 may be an entire network node (e.g., see Figure 3 310).

[0223] In one configuration, an apparatus 1602 / 1602' for wireless communication includes: a component for receiving an uplink transmission set from a set of UEs via a first resource of a non-orthogonal channel, wherein the apparatus is incapable of decoding the uplink transmission set; a component for sending a retransmission request to a subset of the set of UEs; a component for receiving a retransmission of a first uplink transmission in the set of uplink transmissions via a second resource of the non-orthogonal channel in response to the retransmission request; a component for decoding a second uplink transmission in the set of uplink transmissions based at least on the retransmission of the first uplink transmission; a component for sending a wait signal to a UE in the set of UEs associated with the second uplink transmission, wherein the wait signal serves as an indication to the UE that the second uplink transmission is to be stored for a certain period of time; and a component for A component for sending configuration information including at least the time period; a component for storing uplink transmission information associated with an uplink transmission set, wherein a second uplink transmission is decoded based on the uplink transmission information and a retransmission of the first uplink transmission; a component for determining that the retransmission of the first uplink transmission is associated with the first uplink transmission in the uplink transmission set based on at least one of a second demodulation reference signal port or a second unique multiple access signature and a preconfigured mapping; a component for sending configuration information including at least mapping information, the mapping information including at least one of a first plurality of demodulation reference signal ports or a first plurality of unique multiple access signatures associated with a first resource and at least one of a second plurality of demodulation reference signal ports or a second plurality of unique multiple access signatures associated with a second resource.

[0224] The aforementioned means may be one or more of the aforementioned components of the processing system 1714 of the device 1602 and / or device 1602' configured to perform the functions recited by the aforementioned means. As described above, the processing system 1714 may include the TX processor 316, the RX processor 370, and the controller / processor 375. Therefore, in one configuration, the aforementioned means may be the TX processor 316, the RX processor 370, and the controller / processor 375 configured to perform the functions recited by the aforementioned means.

[0225] Fig.18 1800 is a flow chart of a method of wireless communication. The method may be performed by a UE (e.g., UE 1004, 1006, 1104, 1106; apparatus 2002 / 2002'; processing system 2114, which may include memory 360 and may be the entire UE 1004, 1006, 1104, 1106, or a component of UE 1004, 1006, 1104, 1106, such as TX processor 368, RX processor 356 and / or controller / processor 359).

[0226] At 1802, the UE transmits an uplink transmission using a first resource of a non-orthogonal channel. Fig. 9 , the second UE 906 can use the time-frequency resources of the NOMA channel 918 to send the initial uplink transmission 916.

[0227] For example, refer to Fig.10 , the second UE 1006 may use the first resource of the NOMA channel to send a second NOMA uplink transmission 1014. For example, referring to Fig.11 , the first UE 1104 may use the first resources (e.g., the first time-frequency resources) of the NOMA channel to send the first NOMA uplink transmission 1112.

[0228] In some examples, the first resource of the non-orthogonal channel includes at least one of a first time resource or a first frequency resource. The second resource of the non-orthogonal channel includes at least one of a second time resource or a second frequency resource.

[0229] At 1804, the UE receives a retransmission request for an uplink transmission. Fig. 9 , the second UE 906 may receive a retransmission request 924. In some examples, the retransmission request 924 may be a NACK. Fig.10 , the second UE 1006 may receive a retransmission request 1020. In some examples, the retransmission request 1020 may be a NACK. Fig.11 , the network node 1102 may selectively send a retransmission request to the first UE 1104 or the second UE 1106. For example, the first UE 1104 may receive the retransmission request 1142. In some examples, the retransmission request 1142 may be a NACK.

[0230] In some examples, a retransmission request is received in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with a different UE in a set of UEs. In some examples, a retransmission request is received in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with at least one of a unique multi-access signature or a different demodulation reference signal port for a non-orthogonal channel. For example, the control information message may be a HARQ feedback message common to a group of UEs. For example, each bit in the HARQ feedback message may be associated with a different DM-RS port and / or a unique multi-access signature used by a particular UE for an initial NOMA uplink transmission. The UE may be as described herein with reference to Fig.13 As described, it is determined that retransmission is requested when a bit position associated with its DM-RS port and / or unique multiple access signature (eg, in a HARQ feedback message) is set to a specific value (eg, '0').

[0231] In some examples, a first uplink transmission in the uplink transmission set (e.g., initial uplink transmission 914, first NOMA uplink transmission 1012, first NOMA uplink transmission 1112) is associated with at least one of a first demodulation reference signal port or a first unique multi-access signature, and a retransmission of the first uplink transmission (e.g., uplink transmission 928, a retransmission of a second NOMA uplink transmission 1014 (e.g., at 1030), a retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144)) is associated with at least one of a second demodulation reference signal port or a second unique multi-access signature. In some examples, based on a preconfigured mapping, the second demodulation reference signal port is associated with the first demodulation reference signal port and the second unique multi-access signature is associated with the first unique multi-access signature.

[0232] At 1806, the UE retransmits the uplink transmission or a portion of the uplink transmission using a second resource of the non-orthogonal channel in response to the retransmission request. Fig. 9 , the second UE 906 may send a retransmission of the initial uplink transmission 916 (e.g., uplink transmission 928) in response to the retransmission request 924 without a grant from the network node 902. In some examples, the retransmission of the initial uplink transmission 916 may be based on synchronized HARQ operation.

[0233] For example, refer to Fig.10 , the second UE 1006 may send a retransmission of the second NOMA uplink transmission 1014 in response to the retransmission request 1020 (e.g., at 1030). For example, the second UE 1006 may use a second resource of the NOMA channel (e.g., a second time-frequency resource of the NOMA channel 918) for the retransmission of the second NOMA uplink transmission 1014 (e.g., at 1030). The second resource may be predefined and indicated to the second UE 1006 via the configuration information 1010.

[0234] For example, refer to Fig.11 , the first UE 1104 may send a retransmission of the first NOMA uplink transmission 1112 in response to the retransmission request 1142 (e.g., at 1144). For example, the first UE 1104 may use a third resource (e.g., a third time-frequency resource) of the NOMA channel for the retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144). The third resource may be predefined and indicated to the first UE 1104 via the configuration information 1108.

[0235] At 1808, the UE receives a waiting signal in response to an uplink transmission or a retransmission of a portion of an uplink transmission. Fig. 9, the first UE 904 may receive the wait signal 926. For example, referring to Fig.10 , the first UE 1004 may receive the wait signal 1022. For example, referring to Fig.11 , the second UE 1106 may receive the wait signal 1134. As described herein, the wait signals 926, 1022, 1134 serve as an indication to the UE to temporarily store the latest transmission (eg, in a buffer) in the event that a retransmission is required from the UE.

[0236] Fig.19 1900 is a flow chart of a method of wireless communication. The method may be performed by a UE (e.g., UE 1004, 1006, 1104, 1106; apparatus 2002 / 2002'; processing system 2114, which may include memory 360 and may be the entire UE 1004, 1006, 1104, 1106, or a component of UE 1004, 1006, 1104, 1106, such as TX processor 368, RX processor 356 and / or controller / processor 359). It should be understood that Fig.19 A box indicated by a dotted line in the figure represents an optional box.

[0237] At 1902, the UE receives configuration information. Fig.10 , the second UE 1006 may receive the configuration information 1010. For example, referring to Fig.11 , the first UE 1104 can receive configuration information 1108.

[0238] In some examples, the configuration information (e.g., configuration information 1010, 1108) may include at least one of: a first resource of a NOMA channel (e.g., a first time-frequency resource of NOMA channel 918), a second resource of a NOMA channel (e.g., a second time-frequency resource of NOMA channel 918), a time period to be used as the duration of a timer associated with a wait signal, mapping information, or a combination thereof.

[0239] At 1904, the UE selects at least one of a first plurality of demodulation reference signal ports or a first plurality of unique signatures based on random selection or an indication in the configuration information. For example, the UE may select from a first set of DM-RS ports and / or a first set of unique multiple access signatures as described in reference Table 1.

[0240] At 1906, the UE transmits an uplink transmission using a first resource of a non-orthogonal channel. Fig. 9 , the second UE 906 may send an initial uplink transmission 916 on the time-frequency resources of the NOMA channel 918. For example, referring to Fig.10, the second UE 1006 may send a second NOMA uplink transmission 1014 on the first resource of the NOMA channel. For example, referring to Fig.11 , the first UE 1104 can use the first resource of the NOMA channel to send the first NOMA uplink transmission.

[0241] At 1908, the UE receives a retransmission request for the uplink transmission. Fig. 9 , the second UE 906 may receive a retransmission request 924. In some examples, the retransmission request 924 may be a NACK. Fig.10 , the second UE 1006 may receive a retransmission request 1020. In some examples, the retransmission request 1020 may be a NACK. Fig.11 , the network node 1102 may selectively send a retransmission request to the first UE 1104 or the second UE 1106. For example, the first UE 1104 may receive the retransmission request 1142. In some examples, the retransmission request 1142 may be a NACK.

[0242] In some examples, a retransmission request is received in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with a different UE in a set of UEs. In some examples, a retransmission request is received in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with at least one of a unique multi-access signature or a different demodulation reference signal port for a non-orthogonal channel. For example, the control information message may be a HARQ feedback message common to a group of UEs. For example, each bit in the HARQ feedback message may be associated with a different DM-RS port and / or a unique multi-access signature used by a particular UE for an initial NOMA uplink transmission. The UE may be as described herein with reference to Fig.13 As described, it is determined that retransmission is requested when a bit position associated with its DM-RS port and / or unique multiple access signature (eg, in a HARQ feedback message) is set to a specific value (eg, '0').

[0243] In some examples, a first uplink transmission in the uplink transmission set (e.g., initial uplink transmission 914, first NOMA uplink transmission 1012, first NOMA uplink transmission 1112) is associated with at least one of a first demodulation reference signal port or a first unique multi-access signature, and a retransmission of the first uplink transmission (e.g., uplink transmission 928, a retransmission of a second NOMA uplink transmission 1014 (e.g., at 1030), a retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144)) is associated with at least one of a second demodulation reference signal port or a second unique multi-access signature. In some examples, based on a preconfigured mapping, the second demodulation reference signal port is associated with the first demodulation reference signal port and the second unique multi-access signature is associated with the first unique multi-access signature.

[0244] At 1910, the UE retransmits an uplink transmission or a portion of an uplink transmission using a second resource of a non-orthogonal channel in response to a retransmission request. Fig. 9 , the second UE 906 may send a retransmission of the initial uplink transmission 916 (e.g., uplink transmission 928) in response to the retransmission request 924 without a grant from the network node 902. In some examples, the retransmission of the initial uplink transmission 916 may be based on synchronized HARQ operation.

[0245] For example, refer to Fig.10 , the second UE 1006 may send a retransmission of the second NOMA uplink transmission 1014 in response to the retransmission request 1020 (e.g., at 1030). For example, the second UE 1006 may use a second resource of the NOMA channel (e.g., a second time-frequency resource of the NOMA channel 918) for the retransmission of the second NOMA uplink transmission 1014 (e.g., at 1030). The second resource may be predefined and indicated to the second UE 1006 via the configuration information 1010.

[0246] For example, refer to Fig.11 , the first UE 1104 may send a retransmission of the first NOMA uplink transmission 1112 in response to the retransmission request 1142 (e.g., at 1144). For example, the first UE 1104 may use a third resource (e.g., a third time-frequency resource) of the NOMA channel for the retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144). The third resource may be predefined and indicated to the first UE 1104 via the configuration information 1108.

[0247] At 1912, the UE receives a waiting signal in response to an uplink transmission or a retransmission of a portion of an uplink transmission. Fig. 9, the first UE 904 may receive the wait signal 926. For example, referring to Fig.10 , the first UE 1004 may receive the wait signal 1022. For example, referring to Fig.11 , the second UE 1106 may receive the wait signal 1134. As described herein, the wait signals 926, 1022, 1134 serve as an indication to the UE to temporarily store the latest transmission (eg, in a buffer) in the event that a retransmission is required from the UE.

[0248] At 1914, the UE starts a timer in response to the wait signal. Fig.10 , the timer duration 1026 may be the time period indicated in the configuration information 1008. In one example, reference Fig.11 , the timer duration 1126 can be the time period indicated in the configuration information 1108.

[0249] At 1915, the UE determines whether a second retransmission request is received for retransmission of the uplink transmission or a portion of the uplink transmission before expiration of the timer.

[0250] At 1916, if no second retransmission request is received for retransmission of the uplink transmission or part of the uplink transmission before the timer expires, the UE clears the buffer including the uplink transmission. Fig.10 , at 1028 the first UE 1004 may discard one or more packets associated with the first NOMA uplink transmission from the buffer of the first UE 1004. For example, referring to Fig.11 , at 1140 the second UE 1106 may discard one or more packets associated with the second NOMA uplink transmission from the buffer of the second UE 1106.

[0251] At 1918, in the event that a second retransmission request is received for the uplink transmission before the timer expires, the UE retransmits the uplink transmission or a portion of the uplink transmission using a third resource of the non-orthogonal channel. Fig.11 , the first UE 1104 may receive a retransmission request 1142 before the timer expires (e.g., before the timer duration 1126 ends). At 1144, the first UE 1104 may retransmit the first NOMA uplink transmission 1112 in response to the retransmission request 1142. For example, the first UE 1104 may use a third resource (e.g., a third time-frequency resource) of the NOMA channel for retransmission of the first NOMA uplink transmission 1112 (e.g., at 1144). The third resource may be predefined and indicated to the first UE 1104 via the configuration information 1108.

[0252] Fig. 20 is a conceptual data flow diagram 2000 illustrating the data flow between different parts / components in an example apparatus 2002. The apparatus may be a UE. The apparatus 2002 includes a receiving component 2004 that receives one or more downlink transmissions (eg, from a network node 2050).

[0253] The apparatus 2002 also includes a configuration information receiving component 2006 that receives a configuration message 2022 (e.g., via the receiving component 2004). In some aspects, the configuration message 2022 includes at least mapping information including at least one of a first plurality of demodulation reference signal ports or a first plurality of unique multi-access signatures associated with the first resource and at least one of a second plurality of demodulation reference signal ports or a second plurality of unique multi-access signatures associated with the second resource. In some aspects, the configuration message 2022 includes at least a time period, wherein the time period is to be used as a duration for a timer associated with the wait signal.

[0254] Apparatus 2002 also includes a selection component 2008 that selects at least one of the first plurality of demodulation reference signal ports or the first plurality of unique multiple access signatures based on random selection or configuration information. Selection component 2008 can receive configuration information from configuration information receiving component 2006 via message 2024 .

[0255] The apparatus 2002 also includes a NOMA uplink transmit component 2010 that transmits an uplink transmission 2032 using a first resource of the non-orthogonal channel (e.g., via the transmit component 2020). The NOMA uplink transmit component 2010 can obtain one or more packets (e.g., data packets) to be included in the uplink transmission 2032 from a buffer 2028 via a data path 2030. The NOMA uplink transmit component 2010 can receive a message 2026 from the selection component indicating at least the first resource of the non-orthogonal channel.

[0256] The apparatus 2002 also includes a retransmission request receiving component 2012 that receives a retransmission request 2034 for an uplink transmission (eg, uplink transmission 2032).

[0257] The apparatus 2002 also includes a retransmission component 2014 that retransmits an uplink transmission (e.g., uplink transmission 2032) or a portion of the uplink transmission using a second resource of the non-orthogonal channel in response to the retransmission request 2034. For example, the retransmission component 2014 transmits an uplink transmission 2036 that is identical to the uplink transmission 2032. For example, the retransmission component 2014 can obtain one or more packets (e.g., data packets) included in the uplink transmission 2032 from the buffer 2028 via the data path 2044.

[0258] The apparatus 2002 also includes a wait signal receiving component 2016 that receives a wait signal 2038 in response to an uplink transmission or a retransmission of a portion of an uplink transmission (eg, uplink transmission 2036).

[0259] The apparatus 2002 also includes a timer component 2018 that starts a timer in response to the wait signal 2038. The timer component 2018 can receive a message 2040 including a time period to be used as a duration for the timer associated with the wait signal 2038 from the configuration information receiving component.

[0260] In some aspects, if a second retransmission request is not received for a retransmission of an uplink transmission or a portion of an uplink transmission before the timer expires, the timer component 2018 clears the buffer 2028 including the uplink transmission (e.g., one or more packets in the uplink transmission 2032). For example, the timer component 2018 may send a clear buffer signal 2042 to clear the buffer 2028. The buffer 2028 may discard one or more packets sent in the uplink transmission 2032 in response to the clear buffer signal 2042.

[0261] In some aspects, in the event that a second retransmission request is received for the uplink transmission before the timer expires, the timer component 2018 can send a retransmission command 2045 that causes the retransmission component 2014 to retransmit the uplink transmission (e.g., uplink transmission 2032) or a portion of the uplink transmission using a third resource of the non-orthogonal channel. For example, the retransmission component 2014 can send an uplink transmission 2046 that is identical to the uplink transmission 2032. For example, the retransmission component 2014 can obtain one or more packets (e.g., data packets) included in the uplink transmission 2032 from the buffer 2028 via the data path 2044.

[0262] Apparatus 2002 also includes a transmitting component 2020 that transmits one or more uplink transmissions (eg, to network node 2050).

[0263] The device may include executing the aforementioned Fig.18 and Fig.19 Each box in the flowchart of the algorithm is an additional component. Therefore, Fig.18 and Fig.19 Each block in the aforementioned flow chart of can be performed by a component, and the apparatus may include one or more of these components. These components may be one or more hardware components, which are specifically configured to perform the process / algorithm, implemented by a processor configured to perform the process / algorithm, stored in a computer-readable medium so as to be implemented by a processor, or some combination thereof.

[0264] Fig.21 21 is a diagram 2100 illustrating an example of a hardware implementation for an apparatus 2002' employing a processing system 2114. The processing system 2114 may be implemented with a bus architecture, generally represented by a bus 2124. The bus 2124 may include any number of interconnecting buses and bridges, depending on the specific application of the processing system 2114 and the overall design constraints. The bus 2124 links various circuits together, including one or more processors and / or hardware components (represented by the processor 2104, components 2004, 2006, 2008, 2010, 2012, 2014, 2016, 2018, 2020, and computer readable medium / memory 2106). The bus 2124 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art and therefore will not be described further.

[0265] The processing system 2114 may be coupled to the transceiver 2110. The transceiver 2110 is coupled to one or more antennas 2120. The transceiver 2110 provides components for communicating with various other devices through a transmission medium. The transceiver 2110 receives signals from the one or more antennas 2120, extracts information from the received signals, and provides the extracted information to the processing system 2114 (specifically, the receiving component 2004). In addition, the transceiver 2110 receives information from the processing system 2114 (specifically, the transmitting component 2020), and based on the received information, generates a signal to be applied to the one or more antennas 2120. The processing system 2114 includes a processor 2104, which is coupled to a computer-readable medium / memory 2106. The processor 2104 is responsible for general processing, including executing software stored on the computer-readable medium / memory 2106. The software, when executed by the processor 2104, causes the processing system 2114 to perform the various functions described above for any particular device. The computer-readable medium / memory 2106 may also be used to store data manipulated by the processor 2104 when executing software. The processing system 2114 also includes at least one of the components 2004, 2006, 2008, 2010, 2012, 2014, 2016, 2018, 2020. These components may be software components running in the processor 2104, resident / stored in the computer-readable medium / memory 2106, one or more hardware components coupled to the processor 2104, or some combination thereof. The processing system 2114 may be a component of the UE 350 and may include the memory 360 and / or at least one of the TX processor 368, the RX processor 356, and the controller / processor 359. Alternatively, the processing system 2114 may be the entire UE (e.g., see Figure 3 of 350).

[0266] In one configuration, an apparatus 2002 / 2002' for wireless communication includes: means for transmitting an uplink transmission using a first resource of a non-orthogonal channel; means for receiving a retransmission request for the uplink transmission; means for retransmitting the uplink transmission or a portion of the uplink transmission using a second resource of the non-orthogonal channel in response to the retransmission request; means for receiving a wait signal in response to the retransmission of the uplink transmission or a portion of the uplink transmission; means for starting a timer in response to the wait signal; means for: clearing a buffer including the uplink transmission if a second retransmission request is not received for the retransmission of the uplink transmission or a portion of the uplink transmission before the timer expires; and means for Components for: retransmitting an uplink transmission or a portion of an uplink transmission using a third resource of a non-orthogonal channel in the event that a second retransmission request is received for the uplink transmission before a timer expires; components for receiving a configuration message including at least one of a first plurality of demodulation reference signal ports or a first plurality of unique multi-access signatures associated with a first resource and at least one of a second plurality of demodulation reference signal ports or a second plurality of unique multi-access signatures associated with a second resource; components for selecting at least one of the first plurality of demodulation reference signal ports or the first plurality of unique multi-access signatures based on random selection or configuration information; and components for receiving a configuration message including at least a time period.

[0267] The aforementioned means may be one or more of the aforementioned components of the processing system 2114 of the apparatus 2002 and / or the apparatus 2002' configured to perform the functions recited by the aforementioned means. As described above, the processing system 2114 may include the TX processor 368, the RX processor 356, and the controller / processor 359. Therefore, in one configuration, the aforementioned means may be the TX processor 368, the RX processor 356, and the controller / processor 359 configured to perform the functions recited by the aforementioned means.

[0268] Various aspects described herein may improve the reliability of UE uplink retransmissions on a NOMA channel. For example, a UE may use a first resource (e.g., a first time-frequency resource) of a NOMA channel to send an initial NOMA uplink transmission and use a second resource (e.g., a second time-frequency resource) of the NOMA channel for retransmissions of the initial NOMA uplink transmission. The second resource may be predefined and indicated to the UE via configuration information. In some examples, the second resource of the NOMA channel may provide a higher channel quality than the first resource of the NOMA channel, thereby improving the reliability of retransmissions.

[0269] In addition, aspects described herein can reduce signaling overhead by allowing retransmissions from some, but not all, of the UEs for which initial NOMA uplink transmissions could not be decoded at the network entity. In these aspects, the network entity can perform retrospective interference cancellation operations to decode failed initial NOMA uplink transmissions from one UE without retransmissions from the UE. For example, the network entity can perform retrospective interference cancellation operations to decode failed initial NOMA uplink transmissions from one UE by using successfully decoded retransmissions of initial NOMA uplink transmissions from different UEs.

[0270] The following provides an overview of various aspects of the disclosure:

[0271] Aspect 1: A device for wireless communication, the device comprising: a memory; and at least one processor, the at least one processor being coupled to the memory and configured to: receive an uplink transmission set from a set of user equipment (UE) via a first resource of a non-orthogonal channel, wherein the device cannot decode the uplink transmission set; send a retransmission request to a subset of the UE set; receive a retransmission of a first uplink transmission in the uplink transmission set via a second resource of the non-orthogonal channel in response to the retransmission request; and decode a second uplink transmission in the uplink transmission set based at least on the retransmission of the first uplink transmission.

[0272] Aspect 2: An apparatus according to Aspect 1, wherein the at least one processor is further configured to: send a waiting signal to a UE in the UE set that is associated with the second uplink transmission, wherein the waiting signal serves as an indication to the UE that the second uplink transmission is to be stored for a certain period of time.

[0273] Aspect 3: The apparatus according to aspect 1 or 2, wherein the at least one processor is further configured to: send configuration information including at least the time period.

[0274] Aspect 4: An apparatus according to any one of Aspects 1 to 3, wherein the at least one processor is further configured to: store uplink transmission information associated with the uplink transmission set, wherein the second uplink transmission is decoded based on the uplink transmission information and the retransmission of the first uplink transmission.

[0275] Aspect 5: An apparatus according to any one of aspects 1 to 4, wherein the retransmission request is sent in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with a different UE in the set of UEs.

[0276] Aspect 6: An apparatus according to any one of Aspects 1 to 5, wherein the retransmission request is sent in a control information message, wherein each bit position in the set of bit positions in the control information message is associated with at least one of a unique multiple access signature or a different demodulation reference signal port for the non-orthogonal channel.

[0277] Aspect 7: An apparatus according to any one of Aspects 1 to 6, wherein the first resource of the non-orthogonal channel includes at least one of a first time resource or a first frequency resource, and wherein the second resource of the non-orthogonal channel includes at least one of a second time resource or a second frequency resource.

[0278] Aspect 8: An apparatus according to any one of Aspects 1 to 7, wherein the first uplink transmission in the uplink transmission set is associated with a first demodulation reference signal port or at least one of a first unique multiple access signature, and wherein the retransmission of the first uplink transmission is associated with a second demodulation reference signal port or at least one of a second unique multiple access signature.

[0279] Aspect 9: An apparatus according to any one of aspects 1 to 8, wherein based on a preconfigured mapping, the second demodulation reference signal port is associated with the first demodulation reference signal port and the second unique multiple access signature is associated with the first unique multiple access signature.

[0280] Aspect 10: An apparatus according to any one of Aspects 1 to 9, wherein the at least one processor is further configured to: determine, based on at least one of the second demodulation reference signal port or the second unique multiple access signature and the preconfigured mapping, that the retransmission of the first uplink transmission is associated with the first uplink transmission in the uplink transmission set.

[0281] Aspect 11: An apparatus according to any one of Aspects 1 to 10, wherein the at least one processor is further configured to: send configuration information including at least mapping information, the mapping information including at least one of a first plurality of demodulation reference signal ports or a first plurality of unique multi-access signatures associated with the first resource and at least one of a second plurality of demodulation reference signal ports or a second plurality of unique multi-access signatures associated with the second resource.

[0282] Aspect 12: A method for wireless communication, the method comprising: receiving an uplink transmission set from a set of user equipment (UE) via a first resource of a non-orthogonal channel, wherein the device is unable to decode the uplink transmission set; sending a retransmission request to a subset of the UE set; receiving a retransmission of a first uplink transmission in the uplink transmission set via a second resource of the non-orthogonal channel in response to the retransmission request; and decoding a second uplink transmission in the uplink transmission set based at least on the retransmission of the first uplink transmission.

[0283] Aspect 13: According to the method of Aspect 12, the method also includes: sending a waiting signal to the UE in the UE set that is associated with the second uplink transmission, wherein the waiting signal serves as an indication to the UE to store the second uplink transmission for a certain period of time.

[0284] Aspect 14: The method according to Aspect 12 or 13, further comprising: sending configuration information including at least the time period.

[0285] Aspect 15: According to the method described in any one of Aspects 12 to 14, the method further includes: storing uplink transmission information associated with the uplink transmission set, wherein the second uplink transmission is decoded based on the uplink transmission information and the retransmission of the first uplink transmission.

[0286] Aspect 16: A method according to any one of Aspects 12 to 15, wherein the retransmission request is sent in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with a different UE in the set of UEs.

[0287] Aspect 17: A method according to any one of Aspects 12 to 16, wherein the retransmission request is sent in a control information message, wherein each bit position in the set of bit positions in the control information message is associated with at least one of a unique multiple access signature or a different demodulation reference signal port for the non-orthogonal channel.

[0288] Aspect 18: A method according to any one of Aspects 12 to 17, wherein the first resource of the non-orthogonal channel includes at least one of a first time resource or a first frequency resource, and wherein the second resource of the non-orthogonal channel includes at least one of a second time resource or a second frequency resource.

[0289] Aspect 19: A method according to any one of Aspects 12 to 18, wherein the first uplink transmission in the uplink transmission set is associated with a first demodulation reference signal port or at least one of a first unique multiple access signature, and wherein the retransmission of the first uplink transmission is associated with a second demodulation reference signal port or at least one of a second unique multiple access signature.

[0290] Aspect 20: A method according to any one of aspects 12 to 19, wherein the second demodulation reference signal port is associated with the first demodulation reference signal port and the second unique multiple access signature is associated with the first unique multiple access signature based on a preconfigured mapping.

[0291] Aspect 21: According to the method described in any one of Aspects 12 to 20, the method further includes: determining that the retransmission of the first uplink transmission is associated with the first uplink transmission in the uplink transmission set based on at least one of the second demodulation reference signal port or the second unique multiple access signature and the preconfigured mapping.

[0292] Aspect 22: According to the method described in any one of Aspects 12 to 21, the method further includes: sending configuration information including at least mapping information, the mapping information including at least one of a first plurality of demodulation reference signal ports or a first plurality of unique multi-access signatures associated with the first resource and at least one of a second plurality of demodulation reference signal ports or a second plurality of unique multi-access signatures associated with the second resource.

[0293] Aspect 23: A device for wireless communication, the device comprising: a memory; and at least one processor, the at least one processor coupled to the memory and configured to: send an uplink transmission using a first resource of a non-orthogonal channel; receive a retransmission request for the uplink transmission; retransmit the uplink transmission or a portion of the uplink transmission using a second resource of the non-orthogonal channel in response to the retransmission request; and receive a wait signal in response to the retransmission of the uplink transmission or the portion of the uplink transmission.

[0294] Aspect 24: An apparatus according to Aspect 23, wherein the at least one processor is further configured to: start a timer in response to the wait signal; and clear a buffer including the uplink transmission if no second retransmission request is received for the uplink transmission or the retransmission of the part of the uplink transmission before the timer expires.

[0295] Aspect 25: An apparatus according to Aspect 23 or 24, wherein the at least one processor is further configured to: start a timer in response to the wait signal; and in a case where a second retransmission request is received for the uplink transmission before the timer expires, use a third resource of the non-orthogonal channel to retransmit the uplink transmission or the part of the uplink transmission.

[0296] Aspect 26: An apparatus according to any one of Aspects 23 to 25, wherein the at least one processor is further configured to: receive a configuration message comprising at least mapping information, the mapping information comprising at least one of a first plurality of demodulation reference signal ports or a first plurality of unique multi-access signatures associated with the first resource and at least one of a second plurality of demodulation reference signal ports or a second plurality of unique multi-access signatures associated with the second resource.

[0297] Aspect 27: An apparatus according to any one of Aspects 23 to 26, wherein the at least one processor is further configured to: select at least one of the first plurality of demodulation reference signal ports or the first plurality of unique multiple access signatures based on random selection or configuration information.

[0298] Aspect 28: An apparatus according to any one of Aspects 23 to 27, wherein the at least one processor is further configured to: receive a configuration message including at least a time period, wherein the time period is to be used as a duration for a timer associated with the wait signal.

[0299] Aspect 29: A method of wireless communication, the method comprising: sending an uplink transmission using a first resource of a non-orthogonal channel; receiving a retransmission request for the uplink transmission; retransmitting the uplink transmission or part of the uplink transmission using a second resource of the non-orthogonal channel in response to the retransmission request; and receiving a wait signal in response to the retransmission of the uplink transmission or the part of the uplink transmission.

[0300] Aspect 30: According to the method described in Aspect 29, the method also includes: receiving a configuration message including at least mapping information, the mapping information including at least one of a first plurality of demodulation reference signal ports or a first plurality of unique multi-access signatures associated with the first resource and at least one of a second plurality of demodulation reference signal ports or a second plurality of unique multi-access signatures associated with the second resource.

[0301] It should be understood that the specific order or hierarchy of the blocks in the disclosed process / flowchart is merely an illustration of the exemplary method. It should be understood that the specific order or hierarchy of the blocks in the process / flowchart can be rearranged based on design preferences. In addition, some blocks can be combined or omitted. The attached method claims provide the elements of each block in a sample order, but are not meant to be limited to the specific order or hierarchy provided.

[0302] The preceding description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects. Therefore, the claims are not intended to be limited to the aspects shown herein, but to conform to the full scope consistent with the language claims, wherein the elements mentioned in the singular are not intended to mean "one and only one", unless specifically so stated, but "one or more". The word "exemplary" is used herein to mean "used as an example, instance, or illustration". Any aspect described as "exemplary" herein is not necessarily interpreted as being preferred or having an advantage over other aspects. Unless otherwise specified, the term "some" refers to one or more. Combinations such as "at least one of A, B, or C", "one or more of A, B, or C", "at least one of A, B, and C", "one or more of A, B, and C", and "A, B, C, or any combination thereof" include any combination of A, B, and / or C, and may include multiple A, multiple B, or multiple C. Specifically, combinations such as "at least one of A, B, or C," "one or more of A, B, or C," "at least one of A, B and C," "one or more of A, B, and C," and "A, B, C, or any combination thereof" may be only A, only B, only C, A and B, A and C, B and C, or A and B and C, wherein any such combination may include one or more members of A, B, or C. All structural and functional equivalents of the elements of the various aspects described throughout the present disclosure that are or will later become known to a person of ordinary skill in the art are expressly incorporated herein by reference and are intended to be covered by the claims. In addition, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is expressly recited in the claims. Words such as "module," "mechanism," "element," "device," etc. cannot replace the word "component." Therefore, no claim element will be understood to be a part plus function unless the element is expressly stated using the phrase "component for..."

Claims

1. A device for wireless communication, comprising: Memory; and at least one processor coupled to the memory and configured to: receiving a set of uplink transmissions from a set of user equipment (UEs) via a first resource of a non-orthogonal channel, wherein the apparatus is incapable of decoding the set of uplink transmissions; sending a retransmission request to a subset of the set of UEs; receiving, in response to the retransmission request, via a second resource of the non-orthogonal channel, a retransmission of a first uplink transmission in the set of uplink transmissions; as well as A second uplink transmission in the set of uplink transmissions is decoded based at least on the retransmission of the first uplink transmission.

2. The apparatus of claim 1 , wherein the at least one processor is further configured to: A wait signal is sent to a UE in the set of UEs that is associated with the second uplink transmission, wherein the wait signal serves as an indication to the UE to store the second uplink transmission for a period of time.

3. The apparatus of claim 1 , wherein the at least one processor is further configured to: Sending configuration information including at least the time period.

4. The apparatus of claim 1 , wherein the at least one processor is further configured to: Uplink transmission information associated with the uplink transmission set is stored, wherein the second uplink transmission is decoded based on the uplink transmission information and the retransmission of the first uplink transmission.

5. The apparatus of claim 1, wherein the retransmission request is sent in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with a different UE in the set of UEs.

6. The apparatus of claim 1 , wherein the retransmission request is sent in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with at least one of a unique multiple access signature or a different demodulation reference signal port for the non-orthogonal channel.

7. The apparatus of claim 1, wherein the first resource of the non-orthogonal channel comprises at least one of a first time resource or a first frequency resource, and wherein the second resource of the non-orthogonal channel comprises at least one of a second time resource or a second frequency resource.

8. The apparatus of claim 1 , wherein the first uplink transmission in the set of uplink transmissions is associated with at least one of a first demodulation reference signal port or a first unique multiple access signature, and wherein the retransmission of the first uplink transmission is associated with at least one of a second demodulation reference signal port or a second unique multiple access signature.

9. The apparatus of claim 8, wherein the second demodulation reference signal port is associated with the first demodulation reference signal port and the second unique multiple access signature is associated with the first unique multiple access signature based on a preconfigured mapping.

10. The apparatus of claim 9, wherein the at least one processor is further configured to: The retransmission of the first uplink transmission is determined to be associated with the first uplink transmission in the set of uplink transmissions based on at least one of the second demodulation reference signal port or the second unique multiple access signature and the preconfigured mapping.

11. The apparatus of claim 1 , wherein the at least one processor is further configured to: Configuration information including at least mapping information is sent, the mapping information including at least one of a first plurality of demodulation reference signal ports or a first plurality of unique multiple access signatures associated with the first resource and at least one of a second plurality of demodulation reference signal ports or a second plurality of unique multiple access signatures associated with the second resource.

12. A method of wireless communication, the method comprising: receiving a set of uplink transmissions from a set of user equipment (UEs) via a first resource of a non-orthogonal channel, wherein the apparatus is incapable of decoding the set of uplink transmissions; sending a retransmission request to a subset of the set of UEs; receiving, in response to the retransmission request, via a second resource of the non-orthogonal channel, a retransmission of a first uplink transmission in the set of uplink transmissions; as well as A second uplink transmission in the set of uplink transmissions is decoded based at least on the retransmission of the first uplink transmission.

13. The method according to claim 12, further comprising: A wait signal is sent to a UE in the set of UEs that is associated with the second uplink transmission, wherein the wait signal serves as an indication to the UE to store the second uplink transmission for a period of time.

14. The method according to claim 12, further comprising: Sending configuration information including at least the time period.

15. The method according to claim 12, further comprising: Uplink transmission information associated with the uplink transmission set is stored, wherein the second uplink transmission is decoded based on the uplink transmission information and the retransmission of the first uplink transmission.

16. The method of claim 12, wherein the retransmission request is sent in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with a different UE in the set of UEs.

17. The method of claim 12, wherein the retransmission request is sent in a control information message, wherein each bit position in a set of bit positions in the control information message is associated with at least one of a unique multiple access signature or a different demodulation reference signal port for the non-orthogonal channel.

18. The method of claim 12, wherein the first resource of the non-orthogonal channel comprises at least one of a first time resource or a first frequency resource, and wherein the second resource of the non-orthogonal channel comprises at least one of a second time resource or a second frequency resource.

19. The method of claim 12, wherein the first uplink transmission in the uplink transmission set is associated with at least one of a first demodulation reference signal port or a first unique multiple access signature, and wherein the retransmission of the first uplink transmission is associated with at least one of a second demodulation reference signal port or a second unique multiple access signature.

20. The method of claim 19, wherein the second demodulation reference signal port is associated with the first demodulation reference signal port and the second unique multiple access signature is associated with the first unique multiple access signature based on a preconfigured mapping.

21. The method according to claim 20, further comprising: The retransmission of the first uplink transmission is determined to be associated with the first uplink transmission in the set of uplink transmissions based on at least one of the second demodulation reference signal port or the second unique multiple access signature and the preconfigured mapping.

22. The method according to claim 12, further comprising: Configuration information including at least mapping information is sent, the mapping information including at least one of a first plurality of demodulation reference signal ports or a first plurality of unique multiple access signatures associated with the first resource and at least one of a second plurality of demodulation reference signal ports or a second plurality of unique multiple access signatures associated with the second resource.

23. An apparatus for wireless communication, comprising: Memory; and at least one processor coupled to the memory and configured to: sending an uplink transmission using a first resource of a non-orthogonal channel; receiving a retransmission request for the uplink transmission; retransmitting the uplink transmission or a portion of the uplink transmission using a second resource of the non-orthogonal channel in response to the retransmission request; as well as A wait signal is received in response to the uplink transmission or the retransmission of the portion of the uplink transmission.

24. The apparatus of claim 23, wherein the at least one processor is further configured to: starting a timer in response to the wait signal; and In case no second retransmission request is received for the retransmission of the uplink transmission or the part of the uplink transmission before expiration of the timer, a buffer including the uplink transmission is cleared.

25. The apparatus of claim 23, wherein the at least one processor is further configured to: starting a timer in response to the wait signal; and In case a second retransmission request is received for the uplink transmission before the timer expires, the uplink transmission or the portion of the uplink transmission is retransmitted using a third resource of the non-orthogonal channel.

26. The apparatus of claim 23, wherein the at least one processor is further configured to: A configuration message including at least mapping information is received, the mapping information including at least one of a first plurality of demodulation reference signal ports or a first plurality of unique multiple access signatures associated with the first resource and at least one of a second plurality of demodulation reference signal ports or a second plurality of unique multiple access signatures associated with the second resource.

27. The apparatus of claim 26, wherein the at least one processor is further configured to: At least one of the first plurality of demodulation reference signal ports or the first plurality of unique multiple access signatures is selected based on random selection or configuration information.

28. The apparatus of claim 23, wherein the at least one processor is further configured to: A configuration message is received that includes at least a time period to be used as a duration for a timer associated with the wait signal.

29. A method of wireless communication, the method comprising: sending an uplink transmission using a first resource of a non-orthogonal channel; receiving a retransmission request for the uplink transmission; retransmitting the uplink transmission or a portion of the uplink transmission using a second resource of the non-orthogonal channel in response to the retransmission request; as well as A wait signal is received in response to the uplink transmission or the retransmission of the portion of the uplink transmission.

30. The method according to claim 29, further comprising: A configuration message including at least mapping information is received, the mapping information including at least one of a first plurality of demodulation reference signal ports or a first plurality of unique multiple access signatures associated with the first resource and at least one of a second plurality of demodulation reference signal ports or a second plurality of unique multiple access signatures associated with the second resource.

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