Communication system using public and private codewords

Abstract

Methods, systems, and devices for wireless communication are described. A user equipment (UE) receives an initial transmission of a common codeword and a private codeword. The common codeword is common to the UE and at least one other UE. The private code word points to the UE. An acknowledgement indicating a decoding result of the common codeword and the private codeword is transmitted based on a result of whether the common codeword is successfully decoded and whether the private codeword is successfully decoded. At a network entity (NE), an initial transmission of the common codeword and the private codeword is transmitted and an acknowledgement indicating a decoding result is received. At least one of the public codeword or the private codeword can be retransmitted according to the acknowledgement.

Description

[0001] Cross-reference

[0002] This patent application claims priority to U.S. Patent Application No. 17 / 959,949, titled "COMMUNICATIONS SYSTEM USING COMMON AND PRIVATE CODEWORDS," filed on October 4, 2022, by Khoshnevisan et al., which is assigned to the assignee of the present application and is hereby incorporated by reference in its entirety. Field of Technology

[0003] The following relates to the field of wireless communications. In particular, example aspects of the present disclosure relate to wireless communications between a user entity (UE) and a network entity (NE), such as but not exclusively, by using common and private message parts.

[0004] Description of Related Technologies

[0005] Wireless communication systems are widely deployed to provide various telecommunication services, such as telephony, video, data, messaging, and broadcasting. A typical wireless communication system may employ a multiple access technology that can support communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). 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, Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems, and Long Term Evolution (LTE). LTE / Advanced LTE is an enhanced collection of the Universal Mobile Telecommunications System (UMTS) mobile standards promulgated by the Third Generation Partnership Project (3GPP).

[0006] A wireless network may include multiple base stations (BSs), where a BS is capable of supporting communication with multiple user equipments (UEs). A user equipment (UE) may communicate with a base station (BS) via a downlink and an uplink. The downlink (or forward link) refers to the communication link from the BS to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the BS. As will be described in more detail herein, a BS may be referred to as a Node B, gNB, access point (AP), radio head, transmit receive point (TRP), New Radio (NR) BS, 5G Node B, etc.

[0007] The above multiple access techniques have been adopted in various telecommunication standards to provide a common protocol that enables different user equipments to communicate over a city, a country, a region, or even a global scale. New Radio (NR) (which may also be referred to as 5G) is an enhanced set of the LTE mobile standard released by the 3rd Generation Partnership Project (3GPP). NR is designed to better integrate with other open standards by improving spectral efficiency, reducing cost, enhancing services, utilizing new spectrums, and using Orthogonal Frequency Division Multiplexing with Cyclic Prefix (CP-OFDM) on the Downlink (DL), and CP-OFDM and / or SC-FDM (e.g., also referred to as Discrete Fourier Transform Spread OFDM (DFT-s-OFDM)) on the Uplink (UL), as well as supporting beamforming, Multiple-Input Multiple-Output (MIMO) antenna technology, and carrier aggregation, so as to better support mobile broadband Internet access. SUMMARY OF THE INVENTION

[0008] There is a need for a new communication system that efficiently uses communication resources and is reliable. Rate splitting techniques that split messages into a common part and a private part offer promise in these regards, but in order to achieve both efficiency and reliability, consideration needs to be given to how acknowledgments are handled.

[0009] According to a first aspect of the present disclosure, there is provided a method for communicating at a user entity, the method comprising: receiving an initial transmission of a common codeword and a private codeword, wherein the common codeword is common to the UE and at least one other UE and is received in a first stream, and the private codeword for the UE is received in a different stream; and sending an acknowledgment indicating the decoding results of the common codeword and the private codeword based on the results of whether the common codeword is successfully decoded and whether the private codeword is successfully decoded. The first stream and the second stream preferably comprise different sets of one or more spatial layers.

[0010] Sending the acknowledgment preferably is at least partially based on the behavior or capabilities of the UE communicated between the UE and the network, e.g., based on UE capability signaling to a network entity related to support for rate splitting communication or based on one or more configuration parameters received from the network entity related to support for rate splitting communication.

[0011] The method may further comprise receiving a retransmission of at least one of the common codeword or the private codeword based on the sending of the acknowledgment. The initial transmission and the retransmission may be selectively combined to decode at least the undecoded one of the common codeword and the private codeword (i.e., based on which one of the common codeword and the private codeword is not successfully decoded). The selective combination depends on at least one factor from a set of predetermined and context factors.

[0012] In the case where the common codeword is not decoded, the decoding of the private codeword can be skipped.

[0013] The context factor relates to the context of the UE at a given time, such as signals or messages received (or not received) by the UE, such as at the time of determining whether to combine an initial transmission and a retransmission. The predetermined factor is a factor predetermined prior to a particular instance of selective combining, such as UE capabilities (whether fixed or signaled to the network) and / or network configuration (whether fixed or signaled to the UE).

[0014] The context factor may include the reception of the transmission of a common codeword including information for the UE and / or the context factor may include the reception of a retransmission of a common codeword not including information for the UE. The combining may include using the retransmitted common codeword for decoding the initially transmitted private codeword (with or without soft combining with the retransmission). When the common codeword does not include information directed to the UE, the UE does not have to decode it to obtain information bits, but for the purpose of increasing the chance of decoding the p-CW, joint demodulation or SIC may still be used.

[0015] The context factor may include not receiving a retransmission of a common codeword not including information to the UE.

[0016] An example of the combination of the predetermined and context factors would be the case where the UE does not have the ability to perform soft combining (predetermined factor) and the common codeword does not include information for the UE (context factor).

[0017] The UE may attempt to decode the private codeword regardless of whether the common codeword is decoded (e.g., even though the common codeword is not decoded).

[0018] When the initial transmission of the private codeword is not decoded, the retransmission of the private codeword can be combined with the initial transmission of the private codeword. Such combination of undecoded signals (e.g., in the log-likelihood ratio domain as described below) can be referred to as "soft combining".

[0019] When transmitting a negative acknowledgment regarding at least the common codeword, the network entity may transmit and the UE may receive an indication allowing the UE to refresh the soft combining buffer at the UE.

[0020] The predetermined factor includes whether the UE is equipped with the ability to store the in-phase and quadrature I and Q samples of the initial transmission.

[0021] The UE may have the ability to store the I and Q samples of the initial transmission, in which case the combination may be performed using the I and Q samples of the initial transmission and the I and Q samples of the retransmission.

[0022] The method may further include: providing at least three states in the acknowledgment, where the states correspond to: successful decoding of both the common codeword and the private codeword; acknowledgment of decoding of the common codeword and negative acknowledgment of the private codeword; and negative acknowledgment of both the common codeword and the private codeword.

[0023] Acknowledgment states for multiple channels may be combined to provide compression of the combined acknowledgment.

[0024] The UE may signal its capabilities to a network entity, in which case the predetermined factor includes the capabilities previously signaled by the UE to a serving entity.

[0025] The capabilities may include one or more of the following: (i) whether the UE stores in-phase and quadrature I and Q samples for the initial transmission; (ii) an indication of the buffer size for the UE; (iii) the number of retransmissions supported by the UE for soft combining.

[0026] There is also provided an apparatus at a user entity, the apparatus including: a memory; and a processor coupled to the memory, the processor being configured to: receive an initial transmission of a common codeword and a private codeword, where the common codeword is common to the UE and at least one other UE and is received in a first stream, and the private codeword for the UE is received in a different stream; and based on the result of whether the common codeword is successfully decoded and whether the private codeword is successfully decoded, send an acknowledgment indicating the decoding results of the common codeword and the private codeword.

[0027] The processor may be configured to provide a soft combining buffer for combining an initial transmission of at least one of the common codeword or the private codeword with a retransmission of the initial transmission. The soft combining buffer may be configured to store log-likelihood ratios (LLRs) for decoding of the initial transmission and combine these LLRs with the LLRs of the retransmission.

[0028] The UE may receive an indication that allows the UE to refresh the soft combining buffer.

[0029] The processor may be configured to store in-phase and quadrature I and Q samples of the initial transmission and channel estimates and may be arranged to signal to a network entity the UE's ability to store such samples (and estimates). The combining may be performed using the I and Q samples of the initial transmission and the I and Q samples of the retransmission.

[0030] There is also provided a method for communication at a network entity, the method comprising: transmitting an initial transmission of a common codeword and a private codeword, wherein the common codeword is common to a first user equipment (UE) and at least a second UE and is transmitted in a first stream, and the private codeword for the first UE is transmitted in a different stream; receiving an acknowledgement indicating a decoding result of the common codeword and the private codeword; and retransmitting at least one of the common codeword or the private codeword according to the received acknowledgement.

[0031] The network entity may also receive an indication of the capabilities of the UE from the UE, and in response to the indication, determine whether to retransmit the common codeword in response to receiving a negative acknowledgement for the common codeword.

[0032] It may receive an indication of the number of retransmissions supported by the UE from the UE, and in response to the indication, determine whether to retransmit one of the common codeword and the private codeword.

[0033] The common codewords for different UEs may be concatenated together and transmitted in a set of one or more spatial layers, and the private codewords for different UEs are transmitted in other different sets of one or more spatial layers.

[0034] There is also provided an apparatus at a network entity, the apparatus comprising: a memory; and a processor coupled to the memory, the processor being configured to: transmit an initial transmission of a common codeword and a private codeword, wherein the common codeword is common to a first user equipment (UE) and at least a second UE and is transmitted in a first stream, and the private codeword is for the first UE and is transmitted in a different stream; receive an acknowledgement indicating a decoding result of the common codeword and the private codeword; and retransmit at least one of the common codeword or the private codeword according to the received acknowledgement. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is a diagram illustrating an example of a wireless network in accordance with various aspects of the present disclosure.

[0036] Figure 2 is a diagram illustrating an example of communication between a network entity and a UE in a wireless network in accordance with various aspects of the present disclosure.

[0037] Figure 3 is a process flow diagram of a process of transmitting a message at a network entity (NE).

[0038] Figure 4 is a process flow diagram of a process of receiving a message at a UE.

[0039] Figure 5 is a more detailed process flow diagram of steps in a process of receiving at a UE.

[0040] Figure 6 It is an illustration of a circular buffer implemented in hardware or software at the UE.

[0041] Figure 7 It is a process flow diagram of the receiving process at the UE with HARQ feedback.

[0042] Figure 8 and Figure 9 It is a state diagram showing possible states in the receiving process at the UE according to different behaviors.

[0043] Figure 10 It is a flowchart of the acknowledgment process at the UE.

[0044] Figure 11 It is a flowchart of the acknowledgment process at the NE.

[0045] Figure 12 and Figure 13 It shows a flowchart illustrating a method for supporting communication using common and private codewords according to one or more aspects of the present disclosure. Detailed Description

[0046] Aspects of the present disclosure are more fully described below with reference to the accompanying drawings. However, the present disclosure may be embodied in many different forms and should not be construed as limited to any specific structure or function presented throughout the present disclosure. Rather, these aspects are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. Based on the teachings herein, those skilled in the art should appreciate that the scope of the present disclosure is intended to cover any aspect of the present disclosure disclosed herein, whether implemented independently of or in combination with any other aspect of the present disclosure. For example, any number of the aspects described herein may be used to implement a device or practice a method. In addition, the scope of the present disclosure is intended to cover such devices or methods practiced using other structures, functionality, or a combination of structures and functionality in addition to or different from the aspects of the present disclosure described herein. It should be understood that any aspect of the present disclosure disclosed herein may be embodied by one or more elements of the present invention.

[0047] Several aspects of a telecommunications system will now be presented with reference to various devices and techniques. These devices and techniques will be described in the following detailed description and illustrated in the drawings by various boxes, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using hardware, software, or a combination thereof. Whether such elements are implemented as hardware or software depends on the particular application and design constraints imposed on the overall system.

[0048] Note that, while aspects of the present disclosure may be described herein using terms typically associated with 5G or NR radio access technology (RAT), aspects of the present disclosure may be applicable to other RATs such as 3G RAT, 4G RAT, and / or post-5G RAT (e.g., 6G).

[0049] Figure 1 FIG. is an illustration of an example of a wireless network 100 in accordance with various aspects of the present disclosure. The wireless network 100 may be a 5G (NR) network, an LTE network, etc., or may include elements of a 5G (NR) network, an LTE network, etc. The wireless network 100 may include a plurality of base stations 110 (shown as BS110a, BS110b, BS110c, and BS110d) and other network entities (NE). A base station (BS) is an entity that communicates with user equipment (UE) and may also be referred to as an NR BS, Node B, gNB, 5G Node B (NB), access point, transmit receive point (TRP), etc. Each BS may provide communication coverage for a particular geographic area. In 3GPP, depending on the context of the term usage, the term “cell” may refer to the coverage area of a BS and / or the BS subsystem serving that coverage area.

[0050] The BS may provide communication coverage for macro cells, pico cells, femto cells, and / or another type of cell. A macro cell may cover a relatively large geographic area (e.g., with a radius of several kilometers) and may allow unrestricted access by UEs having a service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs having a service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs associated with the femto cell (e.g., UEs in a closed subscriber group (CSG)). A BS for a macro cell may be referred to as a macro BS. A BS for a pico cell may be referred to as a pico BS. A BS for a femto cell may be referred to as a femto BS or a home BS. In Figure 1In the example shown, BS110a can be a macro BS for macro cell 102a, BS110b can be a pico BS for pico cell 102b, and BS110c can be a femto BS for femto cell 102c. The BS can support one or more (e.g., three) cells. In some examples, the NE can be implemented in a split architecture (e.g., split base station architecture, split RAN architecture), which can be configured to utilize a protocol stack that is physically or logically distributed between two or more NEs (such as an integrated access backhaul (IAB) network, an open RAN (O-RAN) (e.g., a network configuration sponsored by the O-RAN Alliance), or a virtualized RAN (vRAN) (e.g., a cloud RAN (C-RAN))). For example, the NE can include one or more of the following: a central unit (CU), a distributed unit (DU), a radio unit (RU), a RAN intelligent controller (RIC) (e.g., a near real-time RIC (near RT RIC), a non-real-time RIC (non RT RIC)), a service management and orchestration (SMO) system, or any combination thereof. One or more components of the NE in the split RAN architecture can be co-located, or one or more components of the NE can be located in distributed locations (e.g., separate physical locations). In some examples, one or more NEs of the split RAN architecture can be implemented as virtual units (e.g., virtual CU, virtual DU, virtual RU). The functional division between the CU, DU, and RU is flexible and can support different functions, depending on which functions are performed (e.g., network layer functions, protocol layer functions, baseband functions, RF functions, and any combination thereof). The terms "eNB", "base station", "NR BS", "gNB", "TRP", "AP", "node B", "5G NB", "RU", "NE", and "cell" can be used interchangeably herein.

[0051] In some aspects, the cell does not need to be stationary, and the geographical area of the cell can move according to the location of the mobile BS. In some aspects, the BSs can interconnect with each other and / or interconnect to one or more other BSs or network nodes (not shown) in the wireless network 100 using any suitable transport network via various types of backhaul interfaces (such as direct physical connections, virtual networks, etc.).

[0052] The wireless network 100 can also include relay stations. A relay station is an entity that can receive a transmission of data from an upstream station (e.g., a BS or a UE) and forward the transmission of the data to a downstream station (e.g., a UE or a BS). A relay station can also be a UE that can relay transmissions for other UEs. In Figure 1In the example shown, relay BS110d can communicate with macro BS110a and UE 120d to facilitate communication between BS 110a and UE 120d. The relay BS can also be referred to as a relay station, relay base station, relay, etc.

[0053] Wireless network 100 can be a heterogeneous network that includes different types of BSs (such as macro BSs, pico BSs, femto BSs, relay BSs, etc.). These different types of BSs can have different transmit power levels, different coverage areas, and different impacts on interference in wireless network 100. For example, a macro BS can have a high transmit power level (e.g., 5 watts to 40 watts), while pico BSs, femto BSs, and relay BSs can have lower transmit power levels (e.g., 0.1 watt to 2 watts).

[0054] Network controller 130 can be coupled to a set of BSs and can provide coordination and control for these BSs. Network controller 130 can communicate with the BSs via a backhaul. The BSs can also communicate with each other (e.g., directly or indirectly via a wireless or wired backhaul).

[0055] UEs 120 (e.g., 120a, 120b, 120c) can be dispersed throughout wireless network 100, and each UE can be stationary or mobile. A UE can also be referred to as an access terminal, terminal, mobile station, subscriber unit, station, etc. A UE can be a cellular phone (e.g., a smart phone), a personal digital assistant (PDA), a wireless modem, a wireless communication device, a handheld device, a laptop computer, a cordless phone, a wireless local loop (WLL) station, a tablet device, a camera, a gaming device, a netbook, a smartbook, a ultrabook, a medical device or equipment, a biosensor / device, a wearable device (smart watch, smart clothing, smart glasses, smart wristband, smart jewelry (e.g., smart ring, smart bracelet)), an entertainment device (e.g., a music or video device, or a satellite radio), a vehicle-mounted component or sensor, a smart meter / sensor, an industrial manufacturing equipment, a global positioning system device, or any other suitable device configured to communicate via a wireless medium or a wired medium.

[0056] Some UEs may be considered Machine-Type Communication (MTC) UEs, or evolved or enhanced Machine-Type Communication (eMTC) UEs. For example, MTC and eMTC UEs include robots, drones, remote devices, sensors, meters, monitors, location tags, etc. that can communicate with a base station, another device (e.g., a remote device), or some other entity. A wireless node may provide a connection to or for a network (e.g., a wide area network such as the Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet of Things (IoT) devices and / or may be implemented as NarrowBand IoT (NB-IoT) devices. Some UEs may be considered Customer Premises Equipment (CPE). UE 120 may be included within a housing that houses components of UE 120, such as a processor component, a memory component, etc. In some aspects, the processor component and the memory component may be coupled together. For example, the processor component (e.g., one or more processors) and the memory component (e.g., a memory) may be operatively coupled, communicatively coupled, electronically coupled, electrically coupled, etc.

[0057] Generally speaking, any number of wireless networks may be deployed in a given geographical area. Each wireless network may support a specific RAT and may operate on one or more frequencies. The RAT may also be referred to as a radio technology, an air interface, etc. The frequency may also be referred to as a carrier, a frequency channel, etc. Each frequency in a given geographical area may support a single RAT to avoid interference between wireless networks of different RATs. In some cases, an NR, 5G, or 6G RAT network may be deployed.

[0058] In some aspects, two or more UEs 120 (e.g., shown as UE 120a and UE 120e) may communicate directly using one or more sidelink channels (e.g., communicate with each other without using the base station 110 as an intermediate device). For example, UE 120 may communicate using peer-to-peer (P2P) communication, device-to-device (D2D) communication, vehicle-to-everything (V2X) protocols (e.g., which may include vehicle-to-vehicle (V2V) protocols, vehicle-to-infrastructure (V2I) protocols, etc.), mesh networks, and so on. In such cases, UE 120 may perform scheduling operations, resource selection operations, and / or other operations described elsewhere herein that are performed by the base station 110.

[0059] Devices of the wireless network 100 can communicate using the electromagnetic spectrum, which can be subdivided into various categories, frequency bands, channels, etc. based on frequency or wavelength. For example, devices of the wireless network 100 can communicate using an operating frequency band having a first frequency range (FR1) that can span from 410 MHz to 7.125 GHz, and / or can communicate using an operating frequency band having a second frequency range (FR2) that can span from 24.25 GHz to 52.6 GHz. The frequencies between FR1 and FR2 are sometimes referred to as mid-band frequencies. Although a portion of FR1 is greater than 6 GHz, FR1 is generally referred to as the "sub-6 GHz" band. Similarly, FR2 is generally referred to as the "millimeter wave" band, although it is different from the extremely high frequency (EHF) band (30 GHz - 300 GHz) identified by the International Telecommunication Union (ITU) as the "millimeter wave" band. Thus, unless otherwise specifically stated, it should be understood that the term "sub-6 GHz" etc. (if used herein) can broadly represent frequencies less than 6 GHz, frequencies within FR1, and / or mid-band frequencies (e.g., greater than 7.125 GHz). Similarly, unless otherwise specifically stated, it should be understood that the term "millimeter wave" etc. (if used herein) can broadly represent frequencies within the EHF band, frequencies within FR2, and / or mid-band frequencies (e.g., less than 24.25 GHz). It is expected that the frequencies included in FR1 and FR2 can be modified, and the techniques described herein can be applied to those modified frequency ranges.

[0060] As indicated above, Figure 1 is provided as an example. Other examples may be different from the examples Figure 1 described with respect to

[0061] Figure 2 is a diagram illustrating Example 200 of a base station 110 communicating with a UE 120 in a wireless network 100 in accordance with various aspects of the present disclosure. The base station 110 can be equipped with T antennas 234a through 234t, and the UE 120 can be equipped with R antennas 252a through 252r, where typically T > I and R > 1.

[0062] At base station 110, transmit processor 220 may receive data for one or more UEs from data source 212, select one or more modulation and coding schemes (MCSs) for each UE at least in part based on the channel quality indicator (CQI) received from each UE, process (e.g., encode and modulate) the data for each UE at least in part based on the MCS selected for each UE, and provide data symbols for all UEs. Transmit processor 220 may also process system information (e.g., for semi-static resource partitioning information (SRPI), etc.) and control information (e.g., CQI requests, grants, upper layer signaling, etc.), and provide overhead symbols and control symbols. Transmit processor 220 may also generate reference symbols for reference signals (e.g., cell-specific reference signal (CRS), demodulation reference signal (DMRS), etc.) and synchronization signals (e.g., primary synchronization signal (PSS) and secondary synchronization signal (SSS)). Transmit (TX) multiple-input multiple-output (MIMO) processor 230 may perform spatial processing (e.g., precoding) on the data symbols, control symbols, overhead symbols, and / or reference symbols where applicable, and may provide T output symbol streams to T modulators / demodulators (MOD / DEMOD) 232a through 232t. Each modulator / demodulator may process the corresponding output symbol stream (e.g., for OFDM, etc.) to obtain an output sample stream. Each of modulators / demodulators 232a through 232t may further process the output sample stream (e.g., convert the output sample stream to analog, amplify, filter, and up-convert) to obtain a downlink signal. The T downlink signals from modulators / demodulators 232a through 232t may be transmitted via T antennas 234a through 234t, respectively.

[0063] At the UE 120, antennas 252a through 252r may receive downlink signals from the base station 110 and / or other base stations, and may respectively provide the received signals to the demodulators (DEMOD) 254a through 254r. (In the opposite direction, the DEMOD 254 is also a modulator and will be referred to by either term.) Each demodulator 254 may condition (e.g., filter, amplify, down-convert, and digitize) the received signals to obtain input samples. Each demodulator 254 may further process these input samples (e.g., for OFDM, etc.) to obtain the received symbols. The MIMO detector 256 may obtain the received symbols from all R demodulators 254a through 254r, perform MIMO detection on the received symbols (if applicable), and provide the detected symbols. The receive processor 258 may process (e.g., demodulate and decode) the detected symbols, provide the decoded data for the UE 120 to the data sink 260, and provide the decoded control information and system information to the controller / processor 280. The term "controller / processor" may refer to one or more controllers, one or more processors, or a combination thereof. The channel processor may determine the reference signal received power (RSRP), received signal strength indicator (RSSI), reference signal received quality (RSRQ), channel quality indicator (CQI), etc. In some aspects, one or more components of the UE 120 may be included in the housing 284.

[0064] The network controller 130 may include a communication unit 294, a controller / processor 290, and a memory 292. For example, the network controller 130 may include one or more devices in the core network. The network controller 130 may communicate with the base station 110 via the communication unit 294.

[0065] On the uplink, at the UE 120, the transmit processor 264 may receive data from the data source 262, as well as control information (e.g., for reports including RSRP, RSSI, RSRQ, CQI, etc.) from the controller / processor 280, and process the data and control information. The transmit processor 264 may also generate reference symbols for one or more reference signals. The symbols from the transmit processor 264 may be pre-coded by the TX MIMO processor 266 when applicable, further processed by the modulators 254a to 254r (e.g., for DFT-s-OFDM, CP-OFDM, etc.), and transmitted to the base station 110. In some aspects, the UE 120 includes a transceiver. The transceiver may include any combination of the antenna 252, modulators and / or demodulators 254, MIMO detector 256, receive processor 258, transmit processor 264, and / or TX MIMO processor 266. The transceiver may be used by a processor (e.g., the controller / processor 280) and the memory 282 to perform aspects of any method described herein (e.g., as referenced Figures 3 to 10 as described).

[0066] At the base station 110, the uplink signals from the UE 120 and other UEs may be received by the antenna 234, processed by the modulators / demodulators 232a to 232t, detected by the MIMO detector 236 when applicable, and further processed by the receive processor 238 to obtain the decoded data and control information transmitted by the UE 120. The receive processor 238 may provide the decoded data to the data sink 239 and the decoded control information to the controller / processor 240. The base station 110 may include a communication unit 244 and communicate with the network controller 130 via the communication unit 244. The base station 110 may include a scheduler 246 to schedule the UE 120 for downlink communication and / or uplink communication. In some aspects, the base station 110 includes a transceiver. The transceiver may include any combination of the antenna 234, modulators and / or demodulators 232a to 232t, MIMO detector 236, receive processor 238, transmit processor 220, and / or TX MIMO processor 230. The transceiver may be used by a processor (e.g., the controller / processor 240) and the memory 242 to perform aspects of any method described herein (e.g., as referenced Figures 3 to 10 as described).

[0067] The controller / processor 240 of the base station 110, the controller / processor 280 of the UE 120, and / or Figure 2 any other components of Figures 3 to 11Those of and / or operations of other processes as described herein. Memories 242 and 282 may store data and program code for base station 110 and UE 120, respectively. In some aspects, memories 242 and / or memory 282 may include: a non-transitory computer-readable medium storing one or more instructions for wireless communication (e.g., code, program code, etc.). For example, when the one or more instructions are executed (e.g., directly, or after compilation, conversion, interpretation, etc.) by one or more processors of base station 110 and / or UE 120, they may cause the one or more processors, UE 120, and / or base station 110 to perform or direct, for example Figure 10 and Figure 11 Those of and / or operations of other processes as described herein. In some aspects, executing the instructions may include running the instructions, converting the instructions, compiling the instructions, interpreting the instructions, etc.

[0068] Network entities (gNB, TRP, etc.) and UEs may implement multiple hybrid automatic repeat request (HARQ) processes associated with a configured scheduling process for forward error correction of downlink communication and / or uplink communication. The HARQ process may store in a buffer memory the received original communication and any received retransmissions associated with a particular process instance of the configured scheduling process (which may include semi-persistent scheduling transmissions in the case of downlink communication, or grant-free transmissions or uplink configured grant transmissions in the case of uplink communication). In this way, the original communication and the received retransmissions may be combined (which may be referred to as soft combining, as described below) to correct any errors that may have occurred in the original communication.

[0069] In some aspects, a UE (e.g., UE 120) may include components for receiving a communication from a network entity (NE); components for sending HARQ-ACK feedback to the NE based at least in part on the communication received from the NE. In some aspects, such components may include one or more components of UE 120 described in connection with Figure 2 such as controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD / DEMOD 254, antenna 252, MIMO detector 256, receive processor 258, etc.

[0070] In some aspects, a UE (e.g., UE 120) may include: components for sending data to an NE; components for receiving HARQ-ACK feedback from the NE based at least in part on the data sent to the NE. In some aspects, such components may include those described in connection with Figure 2One or more components of the described UE 120, such as controller / processor 280, transmit processor 264, TX MIMO processor 266, MOD 254, antenna 252, DEMOD 254, MIMO detector 256, receive processor 258, etc.

[0071] Although Figure 2 the boxes in are illustrated as different components, the functions described above for these boxes can be implemented in a single hardware, software, or combined component, or in various combinations of components. For example, the functions described with respect to transmit processor 264, receive processor 258, and / or TX MIMO processor 266 can be performed by controller / processor 280, or under the control of controller / processor 280.

[0072] As indicated above, Figure 2 is provided as an example. Other examples may be different from the example described with respect to Figure 2 the example described.

[0073] The rate splitting (RS) scheme is described as follows. A message directed to the UE is split into a common part W c and a private part W p , where W c consists of the common parts of multiple individual messages, and W p is directed to a specific UE. W c is encoded into a stream using a common (or public) codebook and is thus decoded or demodulated by all users, while each W p is encoded into a private stream using a private or individual codebook. The stream is linearly precoded using precoders P c , P 1 , P 2 (where P c is a common precoder) to provide the stream X = P c X c +P 1 X 1 +P 2 X 2 . After transmission through the antenna ports represented by the matrix H 1 , the resulting transmitted signal can be expressed as: Y 1 = H 1 P c X c +H 1 P 1 X 1 +H 1 P 2 X 2 +N 1 .

[0074] This scheme differs from the simple superposition of MU beamforming and multicast beamforming in that the transmission of the common message has a fundamentally different purpose. In particular, multicast transmission conveys information requested by multiple users in the system and directed to those multiple users. On the other hand, the common message in rate splitting encapsulates a part of the private messages of the rate splitting users, which is decoded by all users in the system for interference mitigation and performance enhancement purposes.

[0075] Reference will be made to Figure 3 and Figure 4 for a further description of the rate splitting technique. Two messages 310 and message 312 from message flows W 1 and W 2 are shown being transmitted from BS110a to two UEs, such as UE 120a and UE 120b. The messages for the respective UEs are split into common and private parts. Message 310 is split into a private part W 1,p and a common part W 1,c and message W 2 is split into a common part W 2,c and a private part W 2,p . Part W 1,p is encoded in encoder 314. Part W 2,p is encoded in encoder 316. The common parts of the respective messages are concatenated into a common message W c that is encoded in encoder 315. Encoders 314 to 316 are shown as blocks and can be implemented in hardware or as software functions in a digital signal processor.

[0076] The principles described apply to more than two messages. Each message is split into two parts. The common parts for two or more UEs are concatenated into one part and encoded.

[0077] The encoder also performs modulation and mapping to one or more layers. A "layer" can refer to a spatial layer in a MIMO arrangement or some other multiplexing layer separated by frequency, code, or other layering arrangements.

[0078] The private parts of the respective messages (W 1,p and W 2,p ) are separately encoded and modulated into private streams (X 1 and X 2 ) for the respective UEs.

[0079] The common part is modulated onto X c , which is referred to as the "common stream", and can have one or more layers. This common stream is denoted by P cPrecoding. A common stream is transmitted from the Tx antenna array of a BS110a (or TRP, gNB, etc.), or in a coordinated multi-point (CoMP) scenario, from multiple TRPs.

[0080] In the precoder 320, the private streams are precoded separately by P 1 and P 2 and these streams are transmitted by the Tx antennas (from one TRP / gNB or multiple TRPs in a CoMP scenario) to the target UEs 120a and 120b (and any other UEs).

[0081] As Figure 4 shown, at the receiver of the UE (e.g., UE 120a), channel estimation for the common stream is performed at 410, and channel estimation for the private streams is performed at 412. Since each stream is in a different layer, separate channel estimation is performed for each stream. Using the channel estimation (CE) for the common stream, this stream is decoded at 414. If all goes well, this will result in the decoding of the common message W c which includes the common part W 1 of the message stream W 1,c indicating data destined for the UE.

[0082] In some implementations, when the UE performs successive interference cancellation (SIC), the common message W c (where W are the information bits before encoding) is further used for SIC to decode the private message. This is achieved by estimating the effective channel corresponding to the common stream (H 1 P c ), decoding the common message W c as described, re-encoding the common message into the common stream X c at 416, multiplying the common stream X c by the estimated effective channel and subtracting it from the received signal at 418.

[0083] Under the assumption of ideal channel estimation and successful decoding:

[0084] Y 1,p = Y 1 - H 1 P c X c = H 1 P 1 X 1 + H 1 P 2 X 2 + N 1 ,

[0085] Where X (modulation signal) is a function of W (original information bits), and Y is the signal received at the UE after the encoded W bits are modulated, mapped to layers, pre-coded, and transmitted through the wireless channel.

[0086] Thus, at 420, UE1 uses Y 1,p to decode the private message to provide the private codeword W 1,p .

[0087] In addition to decoding, Figure 4 steps 414 and 420 in

[0088] also include demodulation and demapping.

[0089] Instead of performing SIC, the UE may perform joint demodulation or joint decoding. Joint decoding is more complex because it involves decoding two messages in a joint manner. Joint demodulation involves generating log-likelihood ratios (LLRs) for the decoded bits of the common and private messages by considering inter-layer interference, which is also known as maximum likelihood (or reduced-complexity maximum likelihood) demodulation.

[0090] This splitting into common and private streams enables increased capacity and / or other benefits.

[0091] After receiving the message of the reconstructed stream Wc, UE 120a is able to transmit an acknowledgement (ACK) of the reception and / or a negative acknowledgement (NACK) indicating an incomplete reception (or reception failure).

[0092] In the case of transmitting a NACK from the UE to BS110a, BS110a may schedule a retransmission. The exact timing of the retransmission may depend on the preferred hybrid automatic repeat request (HARQ) scheme. There are multiple options for how the UE may transmit the NACK, and multiple options for how BS110a transmits the retransmission in response. When receiving the repeated transmission, there are various ways in which the UE may combine the original transmission with the repeated transmission to decode a particular message or message part. These combination methods are generally referred to as "soft combining".

[0093] Soft combining may occur in the domain of the I and Q samples of the received signal or in the domain of the log-likelihood ratios (LLRs). Refer to Figure 5 for an explanation of this.

[0094] There can be a maximum number of HARQ retransmissions configured for each UE. This can be configured as a constant (e.g., 4) by the Radio Resource Control (RRC) layer. What happens when this number is reached depends on the operating mode. For example, the Radio Link Control (RLC) process can start to retransmit data, so for each RLC single retransmission, the HARQ process will start over and repeat until its maximum number of retransmissions. If the RLC maximum retransmission occurs again when starting over, the RLC can declare a Radio Link Failure (RLF) and follow the RLF process. Alternatively, once the HARQ maximum retransmission is reached, the transport block (TB) can be discarded and the transmission process can move to the next TB.

[0095] Figure 5 Illustrates some processes that can occur, for example, in the receiving processor 258 of a UE. It shows a cyclic prefix removal stage 501, a fast Fourier transform stage 502, a demodulator / demapper stage 503, and a decoder stage 504.

[0096] In operation, the cyclic prefix removal stage 501 removes any cyclic prefix from the received samples and, through a fast Fourier transform, derives symbols with in-phase and quadrature (I / Q) components. As will be described, these can optionally be stored for later use. The I / Q samples undergo demodulation and demapping to derive log-likelihood ratios (LLRs). These represent the confidence level of a given symbol being demodulated to a given result. These LLRs can be stored for later use.

[0097] The LLRs are preferably stored in a cyclic buffer, as Figure 6 shown. As shown, multiple redundant versions of a transport block (TB) can be stored, which are represented by RV = 0 to RV = 3. RV = 0 represents the initial transmission. The first retransmission is represented by a value selected by the network (which can again use RV = 1 or RV = 2 or RV = 0). The number of resources does not necessarily occupy the entire buffer. In the case where a retransmission includes some of the decoded bits that have already been transmitted, due to the characteristics of the cyclic buffer, those repeated decoded bits do not require additional buffer space. Many retransmissions can be received and stored, and the buffer can recycle. It can recycle multiple times. The starting point for storing each retransmission is configured according to the RV indicated for the corresponding retransmission, because later redundant versions can have different lengths, for example, can have more parity bits.

[0098] The cyclic buffer is not required. The redundant versions can be saved and accumulated in other ways in the LLR domain. However, the cyclic buffer is an effective mechanism for maintaining a sliding set of redundant LLR values.

[0099] Thus, for soft combining in the LLR domain, the UE stores the LLRs corresponding to the TBs that were not decoded (in the initial transmission) and soft combines them with the retransmitted LLRs. The size of the cyclic buffer determines the buffer size at the UE (for each HARQ process ID), regardless of the number of retransmissions or the size of each allocation.

[0100] Limited buffer rate matching (LBRM) and cyclic buffer size determination ensure that excessive memory for soft combining is avoided. N cb = min(N, N rfe ) Otherwise, where where TBS is the transport block size, and R LBRM and TBS LBRM are defined in subclause 5.4.2.1 of TS38.212.

[0101] For a given initial transmission of common CW (c-CW) and private codewords (p-CW) on different spatial layers, different ACK / NACK responses are possible depending on the decoding results. Four possible responses can be provided as (A,A), (A,N), (N,A), and (N,N) as follows.

[0102] (A,A) indicates successful reception of both the c-CW and the p-CW. No retransmission is required. The network may retransmit the c-CW at the request of another UE, but the UE that made the acknowledgement may ignore such retransmissions.

[0103] (A,N) indicates an ACK for the c-CW and a NACK for the p-CW. In this case, the network may only schedule the p-CW for retransmission. The UE already has the LLRs of the p-CW from the initial transmission and can perform soft combining in the LLR domain. The rules of LBRM and cyclic buffer size determination apply. Optionally, the network may schedule a new c-CW, for example, in the case where another UE has issued a NACK for the c-CW.

[0104] (N,A) indicates a NACK for the c-CW and an ACK for the p-CW. This is a low-probability event because if the c-CW is not decoded, the p-CW may also not be decoded (since at least when the UE performs SIC, the decoding of the p-CW generally requires subtracting the reconstructed c-CW). In this case, the network may only schedule the c-CW. The UE already has the LLRs of the c-CW from the initial transmission and can soft combine them with the retransmitted c-CW in the LLR domain. This may be referred to as "behavior 1" in this document. The rules of LBRM and cyclic buffer size determination apply.

[0105] Alternatively, the network may additionally schedule a new p-CW. This would be advantageous in cases where the UE is programmed to skip decoding the p-CW if the c-CW is not decoded (e.g., in the case of a UE that performs SIC before decoding the p-CW).

[0106] (N,N) indicates NAKs for both the c-CW and the p-CW. In this case, the network will schedule both the c-CW and the p-CW for retransmission. For the c-CW, the UE already has the LLRs, and the rules of LBRM and the cyclic buffer size determination apply. For the p-CW, a new framework may be needed because in the case where the c-CW is not decoded in the initial transmission (e.g., in the case where the UE performs SIC first), the UE may not have attempted to decode or calculate the LLRs for the p-CW. Even if the UE still attempts to decode the p-CW without SIC, soft combining in the LLR domain may not be appropriate because the LLRs may be too noisy.

[0107] For the UE to be able to soft combine the initially transmitted and retransmitted p-CW, the UE needs to store not only the received I / Q samples (the signal received before demodulation in the frequency or time domain), but also the estimated channel for the common stream. These requirements impose certain buffer size requirements.

[0108] When there is a new transmission of data in a HARQ process, the new data indicator (NDI) may be toggled (e.g., from "0" to "1") by the transmitting entity to indicate new data. Preferably, there is an NDI for the c-CW and another NDI for the p-CW. The NDI for the c-CW is toggled when all ACKs are received from all expected UEs or at least for a specific UE that receives the downlink control information (DCI) that schedules a new transmission for the c-CW of at least the same HARQ ID. The NDI for the p-CW is toggled when an ACK is received from an expected UE. The NDI bit is toggled for a specific HARQ ID, and the transmission along with the toggled NDI represents new data.

[0109] Note that in the case of Behavior 1, there are only three HARQ-ACK feedback possibilities for (c-CW, p-CW). These possibilities are: (N,N), (A,N), and (A,A). That is, (N,A) is not possible (because the UE skips decoding the p-CW if the c-CW is not decoded).

[0110] This observation can be used to compress the HARQ-ACK codebook because the codebook for the PDSCH can be formed using only three states instead of four states. For example, for each of the 3 PDSCHs with c-CW and p-CW, at most log2(3*3*3) bits (i.e., 5 bits) can be used to form the HARQ-ACK codebook instead of 6 bits that may be required without such compression. Thus, the method can include combining the acknowledgement states for multiple downlink channels at the UE to provide compressed combined acknowledgements. The multiple channels can be multiple spatial channels or time / frequency and / or code division channels.

[0111] According to Behavior 1, there are many sub-possibilities.

[0112] First, consider the case where a portion of the c-CW contains information directed to the UE 120a. This can be a dynamic indication in the DCI that schedules the PDSCH or can be a semi-static configuration indicated by RRC or MAC-CE. This will be referred to as "Case A".

[0113] Within Case A, the first option is that (where the UE sends a NACK for a previously transmitted c-CW) the UE does not perform soft combining for the previously transmitted p-CW and the current retransmission. This would be the case where the UE does not store the I / Q samples received for the first transmission. In this case, soft combining for the p-CW is not possible. This will be referred to as "Behavior 1A-1".

[0114] Within Case A, the second option is that the UE stores the received I / Q samples of the initial transmission and can thus soft combine these (in the I / Q domain) with the retransmitted c-CW to decode the c-CW. Then, the UE performs SIC on the initial transmission from which the c-CW has been decoded by the retransmission. This will be referred to as "Behavior 1A-2". In this case, soft combining for the p-CW is still possible when the c-CW was not initially decoded. This behavior requires additional I / Q buffering at the UE.

[0115] Now consider the case where no portion of the c-CW contains information directed to the UE 120a and it contains information only for other UEs 120b and / or 120c, etc. This will be referred to as "Case B". In this case, the c-CW is only useful for the UE 120a for SIC purposes. Retransmission of the c-CW may be useful for the UE 120a, but only if it has a specific behavior.

[0116] In the case where the UE does not store the received I / Q samples, when the c-CW is not decoded, soft combining for the p-CW is not possible. In this case, soft combining for the c-CW may also not be useful because the only reason to decode the c-CW is for SIC, but when the c-CW is not decoded, SIC is not performed on the initial transmission. This will be referred to as "Behavior 1B-1".

[0117] Therefore, in this scenario where the c-CW does not contain information of interest to a given UE, in the case where the only UE transmitting a NACK for the c-CW is a UE to which the c-CW is not specifically addressed (specifically but not exclusively, where the network knows that the UE operates according to Behavior 1), the network may prohibit retransmission of the c-CW.

[0118] However, note that in the case where another UE 120b - 120e has also not decoded the c-CW in the initial transmission, the gNB may still need to retransmit the c-CW. In this case, soft combining for the c-CW at UE 120a is still useful such that it can decode the p-CW from the retransmission (but does not perform soft combining for the p-CW). Under this assumption, this behavior is the same as Behavior 1A-1.

[0119] In the case where other UEs 120b - 120e have decoded the c-CW (or if the gNB transmits the c-CW to other UEs separately (i.e., not through rate splitting in the retransmission)), the behavior is as follows: (i) UE 120a does not perform soft combining for the c-CW; (ii) the NDI for the c-CW is not required (not signaled in the scheduling DCI) or is ignored in the case where the c-CW does not include information for the UE, instead, UE 120a assumes that the NDI for the c-CW is toggled (indicating that soft combining is not required); and (iii) in the case where the UE transmits a NACK for a previously transmitted c-CW, UE 120a does not perform soft combining for the previously transmitted and currently retransmitted p-CW. This is similar to Behavior 1A-1.

[0120] Next (in Behavior 1, Case B), the case where the UE has the ability to store the received I / Q samples can be considered. This can be referred to as Behavior 1B-2 and it is the same as Behavior 1A-2. In this case, soft combining for the c-CW is still useful for the purpose of SIC.

[0121] In summary, in the case where a part of the c-CW contains information pointing to UE 120a (Case A), the retransmission of the c-CW is still useful, enabling UE 120a to soft combine with the initial transmission. This is independent of whether the UE operates according to Behavior 1A or Behavior 1B. However, in the case where the c-CW does not include information for UE 120a (Case B), the network retransmission of the c-CW is useful only when another UE transmits a NAK for the c-CW (in which case the c-CW needs to be sent anyway for the purposes of other UEs and can thus also be used for UE 120a) or when UE 120a (as the UE that sent the NACK, but the c-CW does not include information for this UE) has the ability to soft combine with the initial transmission (e.g., in the I / Q domain).

[0122] An alternative behavior to Behavior 1 will now be described and referred to as Behavior 2. In this behavior, if the c-CW is not decoded, the UE still attempts to decode the p-CW. In this case, there are 4 possibilities for the HARQ-ACK feedback from the UE to the gNB, i.e., 2 bits are required (i.e., 1 bit per CW).

[0123] If the c-CW is not decoded, but the p-CW is decoded, the UE transmits the response (N,A). (This does not happen in Behavior 1). Whether the UE performs soft combining for the c-CW depends on the above Case A and Case B, i.e., whether a part of the c-CW contains information pointing to the UE (Case A) or does not contain information pointing to the UE (Case B). The UE assumes that when the c-CW does not include information for the UE (Case B) and when the NDI for the p-CW is toggled (because the previously transmitted p-CW has been decoded), the NDI for the c-CW is toggled (i.e., no soft combining).

[0124] If the c-CW is not decoded and the p-CW is also not decoded, i.e., (N,N), three possible behaviors need to be considered.

[0125] The first case is when the UE soft combines the LLR generated as part of decoding the p-CW in the initial transmission with the LLR of the retransmitted p-CW. This can be referred to as Behavior 2A and is different from Behavior 1A-1, Behavior 1A-2, Behavior 1B-1, and Behavior 1B2.

[0126] The second of the three behaviors is similar to Behavior 1A-1 and Behavior 1B-1 (depending on Case A and Case B), and involves not soft combining p-CW. It is similar to Behavior 1A-1 and Behavior 1B-1 not because the UE cannot perform soft combining (in the LLR domain), but because it chooses not to. This will be referred to as "Behavior 2B". Given that the UE has not yet performed SIC for the initial transmission because the c-CW from the initial transmission was not decoded, and the LLR of the p-CW from the initial transmission may be too noisy to be worth attempting, the fact that the UE can better not perform soft combining justifies this behavior. This behavior can be indicated to the UE by the network (either via RRC configuration or in the DCI scheduling the retransmission), such that when the c-CW is not decoded in the initial transmission, the UE flushes its buffer for the p-CW.

[0127] Accordingly, a characteristic of the network entity can be that when the NE receives a NACK for the c-CW and when the network knows, based on the channel condition or other circumstances, that it is not worth the UE attempting soft combining, the network entity transmits an indication identifier to the UE to indicate that the UE should flush its soft combining buffer.

[0128] The third of the three behaviors is similar to Behavior 1A-2 (which is the same as 1B-2) and is as follows. Instead of using the LLR generated as part of decoding the p-CW in the initial transmission, the UE stores the received I / Q samples and can thus perform (and does perform) SIC for the initial transmission once it decodes the c-CW from the retransmission. It then combines (if necessary) with the retransmitted p-CW. This can be referred to as "Behavior 2C".

[0129] Thus, it has been described how the UE receives a PDSCH including the initial transmission of c-CW and p-CW on different sets of spatial layers of the PDSCH and attempts to decode the c-CW and p-CW, and the UE transmits a HARQ-ACK message indicating the decoding results for the c-CW and p-CW. At least three possibilities of the HARQ-ACK message have been described.

[0130] It has been described that in the case where at least one of the c-CW or p-CW is not successfully decoded, the UE receives a retransmission of the PDSCH including the c-CW and / or p-CW, and the UE combines the initial transmission of the c-CW and / or p-CW with the retransmission of the c-CW and / or p-CW to decode the c-CW and / or p-CW. The retransmission received by the UE is at least based on whether the c-CW was decoded but the p-CW was not decoded, or the p-CW was decoded but the c-CW was not decoded, or neither the c-CW nor the p-CW was decoded since the initial transmission.

[0131] The UE may (optionally) signal its capabilities to the network, and the network may use the signaled capabilities to determine which of the c-CW and p-CW to retransmit in certain situations. In this context, "capabilities" may be understood to include "behavior".

[0132] A first example of a capability is whether the UE skips decoding of the c-CW when the c-CW in the same PDSCH (e.g., initially transmitted) is not decoded. The skipping of the decoding of the c-CW is referred to as "behavior 1", and decoding the p-CW despite the failure to decode the c-CW is referred to as "behavior 2". The UE may indicate (e.g., by previously signaling) which of these behaviors it adopts. This is useful for the network. For example, in the case of a double NACK (N,N), depending on the behavior of the UE, there may be different retransmissions or other signals from the network.

[0133] A second example of a capability is whether the UE performs SIC by first attempting to decode the c-CW and subtracting the contribution of the c-CW from the received signal and then attempting to decode the p-CW. This determines whether the UE operates according to behavior 1A2, behavior 1B-2, and behavior 2C.

[0134] A third example of a capability is whether the UE stores the received I / Q samples (soft signals before or after FFT and before demodulation) of the data tones for the initially transmitted and estimated channels. The ability to store the received I / Q samples affects the buffer size required at the UE. This is an alternative way of determining whether the UE operates according to behavior 1A2, behavior 1B-2, and behavior 2C.

[0135] Thus, for example, the UE may indicate its buffer size, and thereby the network may infer that it has the ability to store I / Q samples and perform soft combining of such samples, and thus it has the ability to operate according to behavior 1A-2, behavior 1B-2, or behavior 2C and it does operate according to one of those behaviors (or, depending on the situation, all behaviors).

[0136] Alternatively, the UE may signal its "type" or "version", and the network may infer its capabilities based on its "type" or "version". Alternatively, the UE may specifically signal that it operates according to one behavior or another. Alternatively, one of these behaviors may be the default behavior, and the UE may signal that it operates according to another behavior only if it does not adopt the default behavior.

[0137] One or more of the described behaviors may be indicated by UE capabilities and / or indicated by the network dynamically (in DCI or MAC-CE) or semi-statically (in RRC), or the behavior may be a function of the above conditions.

[0138] A fourth example of a capability / behavior is whether the UE flushes its buffer or performs soft combining for c-CW and / or p-CW. This may be conditional, such as conditional on whether the UE performs soft combining for p-CW based on whether the initially transmitted c-CW is decoded. This indicates behavior 2B.

[0139] Figure 7 Illustrated is a process of performing HARQ operations at UE 120a according to behavior 1A-2, behavior 1B2, and / or behavior 2C. Time is represented from left to right. Process steps are illustrated from top to bottom.

[0140] At process 700, common stream 701 and private stream 702 each have a respective one or more codewords, and corresponding channel estimates (CE) are computed. At process 704, the UE attempts to decode the received c-CW. In this example, the case where this fails is considered. However, the UE may (if it adopts behavior 2) attempt to decode the p-CW received at 710. If so, the case where this also fails (behavior / scenario 2C) will also be considered.

[0141] Accordingly, the UE sends negative acknowledgments for two parts equivalent to (N,N). This is indicated by process 720.

[0142] After a configured time, which is configured according to the HARQ protocol, the network sends and the UE receives (730) common and private codewords, and computes the corresponding CE for the common stream (731) and private stream (732). The initial and retransmitted c-CWs are soft combined in process 734. Assuming this is successful, the common codeword Wc is available at 706 to reconstruct the original c-CW, and this can be subtracted from the original received signal to attempt to decode the original p-CW at 710. (If not successful, another NACK may be transmitted and the process may be repeated.)

[0143] Meanwhile, the soft combined c-CW is also available to reconstruct the retransmitted c-CW in process 736. Subtracting the reconstructed CE for the common stream from the received common part W 1,c results in Y 1,p (t 2 ), which can be used to decode the private message (as previously described) to produce the decoded private part W 1,p (after demodulation and demapping). Accordingly, the entire codeword W 1 with its common and private parts is decoded.

[0144] Figure 8 summarizes the above behavior at the UE. Figure 8 It can be considered as a process flow chart or state diagram for the UE, except that a given UE adopts the selected process according to its predefined behavior.

[0145] Starting from the failure to decode the c-CW at state 801, the case where the UE adopts Behavior 1 (state 802) will be considered first. The UE skips the decoding of the c-CW and sends a NACK equivalent to (N,N).

[0146] If the c-CW contains information for this UE, this is state 804, and if the UE does not store I and Q samples and does not soft combine the p-CW, it proceeds to state 806 (Behavior 1A1). Alternatively, if it stores I and Q samples and is able to perform SIC (or joint decoding) on the p-CW when it receives a retransmission, it enters state 808. This is Behavior 1A2.

[0147] Now consider the case where the c-CW does not have information directed to this UE. The UE proceeds from state 802 to state 810. This is Behavior 1B.

[0148] The UE can proceed from state 810 to state 814, where the UE chooses not to attempt to decode the p-PW because the channel is considered too noisy. This saves processing and thus saves power and battery consumption. This is Behavior 1B1.

[0149] Alternatively, it can receive a retransmission from the network (state 812) and continue to state 808. This is Behavior 1B2.

[0150] Now turn to the alternative behavior when decoding the c-CW fails (state 801). The UE can proceed to state 820 and attempt to decode the p-CW. This is Behavior 2. If unsuccessful, it transmits a double NACK (N,N) (state 822) and there are then three possibilities.

[0151] The UE can use the stored LLR to soft combine the p-CW (state 824). This is Behavior 2A. Alternatively, it can receive a signal from the network in response to the NACK to refresh its p-CW buffer (optional process 830) and / or proceed to state 832, where it skips the soft combination of the p-CW (regardless of whether the c-CW is for this UE). This is Behavior 2B. The third option is for the UE to proceed to 834, where it stores the I and Q samples for the p-CW in order to perform soft combination in the I / Q domain of one or both samples when a retransmission is received. This is Behavior 2C.

[0152] To complete Figure 8Regarding the description, if the UE successfully decodes the p-CW at 820, the UE may transmit an acknowledgement (N,A) at process 840. As described above, there are several options for NDI from this acknowledgement (842).

[0153] Figure 9 Illustrates the state / steps / processes at the UE in the case of successful decoding of the c-CW at the UE (state 900). The UE attempts to decode the p-CW using SIC or joint decoding (902). If not successful, an acknowledgement (A,N) is transmitted at 904, and a retransmission of at least the p-CW is received at 908. Note that the c-CW may be retransmitted by the network anyway at 910, e.g., in response to a NACK from another UE.

[0154] If the p-CW is successfully decoded from 902, the process proceeds to 906, and a full acknowledgement (A,A) is transmitted. The process ends at 920, all buffers may be flushed and the network may switch the NDI to restart the whole process (801 or 900) for the next transmission. (If there are other NACKs of the c-CW from other UEs, the NE may retransmit the c-CW, but may otherwise preferentially retransmit the necessary unreceived information to those UEs).

[0155] Note that in Figure 9 an acknowledgement of successful decoding of the transmitted c-CW is transmitted, regardless of whether the c-CW contains information for the UE.

[0156] N.B. Figure 8 and Figure 9 The states in can be redrawn at different levels. For example, the first separation can be between "IQ / No IQ storage capabilities" or between the states "Is it the CCW for the UE?".

[0157] Figure 10 Illustrates the process performed at the UE. At 1000, the UE performs decoding of the common codeword c-CW (attempt to decode). At 1002, a determination is made as to whether the decoding was successful. This can include checking parity bits or performing a cyclic redundancy check or other error checking. If successful, the process proceeds to 1010, and the received private codeword (p-CW) is decoded using the c-CW. At 1012, a check is made to determine whether this was successful. This can be similar to the process performed at 1002. If successful, the UE transmits an acknowledgement for both parts (step 1014). If not successful, it transmits only an acknowledgement of the c-CW or only a negative acknowledgement of the p-CW, but preferably both (1016).

[0158] If the c-CW is not successfully received at 1002, the UE transmits a NACK for the c-CW at 1020. Optionally, it may also transmit a NACK for the p-CW. This may depend on the pre-adopted behavior of the UE. Thereafter (1022), the UE may attempt to decode the p-CW according to its pre-adopted behavior and transmit an ACK or NACK for the p-CW according to the decoding result.

[0159] Figure 11 A process executed at a network entity (NE) is shown. There is an initial 1100 where the NE receives an indication of its capabilities / behaviors from a given UE. This is received from multiple UEs. At 1102, the NE transmits the c-CW and the p-CW, and at 1104, the NE receives an acknowledgement. For this explanation, the scenario where the c-CW is decoded will be ignored. This scenario follows the process already illustrated in Figure 9 is illustrated.

[0160] If the response received at 1104 is equivalent to (N,N), the process goes to 1108. In the case where the c-CW is addressed to this UE (or if another UE that requires the c-CW transmits a NACK for the c-CW), the NE will retransmit the c-CW and the p-CW (1110).

[0161] In the case where the c-CW is not for this UE and no other UE requires the c-CW and the UE operates according to behavior 1B1, there is no point in retransmitting the c-CW. The NE retransmits the p-CW with another c-CW (1112). The new c-CW may have data for this UE and / or for other UEs. In this way, unnecessary retransmissions are avoided.

[0162] At 1104, in the case where the response is a full acknowledgement, equivalent to (A,A), the NE retransmits the c-CW only if another UE that requires the c-CW has transmitted a NACK (but in the case where there is only a single UE that requires the c-CW, the NE has the option of transmitting this information to this UE in the p-CW or a private message, thereby allowing the process to continue). Otherwise, the NE proceeds to the next message (1120) and triggers NDI.

[0163] At 1104, the response can be equivalent to (N,A). This can only occur in a UE operating according to Behavior 2. In the case where there is no information in the c-CW directed to this UE, if another UE needs this c-CW or a sufficient number of other UEs need this c-CW, the NE will only retransmit this c-CW. This is Process 1130. In the case where there is information in the c-CW for this UE, but no other UE needs this information, the NE can re-encode this information in a new c-CW or p-CW or a combination thereof and retransmit this information. (In the same way, in the case where only one other UE needs the information in the c-CW, the NE can transmit this information to this UE in a new c-CW or p-CW or a combination thereof.) In the case where there is no information in the c-CW directed to this UE and no other UE needs this information, the NE will proceed to the next message and switch the NDI.

[0164] Figure 12 FIG. 1200 is a flowchart illustrating a method 1200 for supporting communication using common and private codewords in accordance with one or more aspects of the present disclosure. The operations of method 1200 may be implemented by a UE or components thereof as described herein. For example, the operations of method 1200 may be performed by a UE 120 as referred to in Figure 1 , Figure 2 and Figures 4 to 10 . In some examples, the UE may execute an instruction set to control functional elements of the UE to perform the described functions. Additionally or alternatively, the UE may use dedicated hardware to perform aspects of the described functions.

[0165] At 1205, the method may include receiving an initial transmission of a common codeword and a private codeword, where the common codeword is common to the UE and at least one other UE and is received in a first stream, and the private codeword for the UE is received in a different stream.

[0166] At 1210, the method may include sending an acknowledgment indicating the decoding results of the common codeword and the private codeword based on the results of whether the common codeword was successfully decoded and whether the private codeword was successfully decoded.

[0167] Figure 13 FIG. 1300 is a flowchart illustrating a method 1300 for supporting communication using common and private codewords in accordance with one or more aspects of the present disclosure. The operations of method 1300 may be implemented by an NE or components thereof as described herein. For example, the operations of method 1300 may be performed by a BS110 or other NE as referred to in Figures 1 to 3 and Figure 11 . In some examples, the NE may execute an instruction set to control functional elements of the NE to perform the described functions. Additionally or alternatively, the NE may use dedicated hardware to perform aspects of the described functions.

[0168] At 1305, the method may include transmitting an initial transmission of a common codeword and a private codeword, where the common codeword is common to a first user equipment (UE) and at least a second UE and is transmitted in a first stream, and the private codeword for the first UE is transmitted in a different stream.

[0169] At 1310, the method may include receiving an acknowledgement indicating the decoding results of the common codeword and the private codeword.

[0170] At 1320, the method may include retransmitting at least one of the common codeword or the private codeword based on the received acknowledgement.

[0171] Thus, a method of communicating at a user entity has been described, including: receiving an initial transmission of a common codeword and a private codeword (preferably on a PDSCH and preferably on different sets of spatial layers of the PDSCH); attempting to decode the common codeword and the private codeword; transmitting an acknowledgement indicating the decoding results of the common codeword and the private codeword (which may be an affirmative or negative acknowledgement or a combination of affirmative and negative acknowledgements for respective codeword portions); receiving a retransmission of at least one of the common codeword or the private codeword (depending on the acknowledgement); and combining the initial transmission and the retransmission to decode the common codeword and / or the private codeword based on which of the common codeword and the private codeword was not successfully decoded.

[0172] In the case where the common codeword is not decoded, decoding of the private codeword may be skipped.

[0173] At least three HARQ-ACK states may be provided, corresponding to: acknowledgement decoding of both the common codeword and the private codeword; acknowledgement of decoding of the common codeword and negative acknowledgement of the private codeword; and negative acknowledgements of both the common codeword and the private codeword.

[0174] HARQ-ACK states for multiple channels may be combined to provide compression of the combined HARK-ACK.

[0175] A further method of communicating at a user entity is also provided, including: receiving an initial transmission of a common codeword and a private codeword (e.g., on different sets of spatial layers); attempting to decode the common codeword, and when the initial transmission is successfully decoded, using the decoded common codeword to decode the private codeword by successive interference cancellation (SIC), but when the initial transmission is not successfully decoded, storing the decoded common codeword in a buffer, receiving a retransmission of at least the private codeword, and soft combining the initial transmission and the retransmission of the private codeword to decode (or attempt to decode) the private codeword.

[0176] Received signal samples may be stored together with a channel estimate for decoding of the retransmission of the private codeword.

[0177] When the initial transmission of the common codeword is successfully decoded, such an indication may be included in the HARQ acknowledgement. This may include an indication of whether the private codeword has been successfully transmitted (or not successfully transmitted).

[0178] A method of communicating at a network entity is also described, comprising: transmitting an initial transmission of a common codeword and a private codeword (preferably on the PDSCH and preferably on different sets of spatial layers); receiving an acknowledgement indicating the decoding result of the common codeword and the private codeword; and based on the acknowledgement, transmitting a retransmission of at least one of the common codeword or the private codeword.

Claims

1. A method for communication at a User Equipment (UE), the method comprises: Receiving an initial transmission of a common codeword and a private codeword, wherein the common codeword is common to the UE and at least one other UE and is received in a first stream, and the private codeword for the UE is received in a different stream; And Based on the result of whether the common codeword is successfully decoded and whether the private codeword is successfully decoded, sending an acknowledgement indicating the decoding results of the common codeword and the private codeword.

2. The method according to claim 1, wherein sending the acknowledgement is at least partially based on the UE sending capability signaling related to the support for rate-split communication or based on one or more configuration parameters related to rate-split communication received from a network entity.

3. The method according to claim 1, the method further comprises receiving a retransmission of at least one of the common codeword or the private codeword based on the sending of the acknowledgement.

4. The method according to claim 3, the method further comprises: Combining the initial transmission and the retransmission based on a pre-determined factor or a context factor or both to decode at least the undecoded one of the common codeword or the private codeword.

5. The method according to claim 4, wherein in the case where the common codeword is not decoded, decoding of the private codeword is skipped.

6. The method according to claim 4, wherein the context factor comprises: The common codeword already includes information for the UE, and the retransmission is a retransmission of the common codeword.

7. The method according to claim 4, wherein, The context factor comprises: The initial transmission does not include information for the UE, and the combining comprises using the retransmission for decoding the private codeword.

8. The method according to claim 4, wherein the context factor comprises: When the common codeword does not include information for the UE, a retransmission of the common codeword is not received.

9. The method according to claim 4, the method comprises attempting to decode the private codeword regardless of whether the common codeword is decoded.

10. The method according to claim 4, the method comprises when the initial transmission of the private codeword is not decoded, soft combining the retransmission of the private codeword with the initial transmission of the private codeword.

11. The method according to claim 4, wherein, When transmitting a negative acknowledgement regarding at least the common codeword, the UE receives an indication allowing the UE to refresh the soft combination buffer at the UE.

12. The method according to claim 4, wherein the pre-determined factor comprises whether the UE is equipped with the ability to store in-phase and quadrature I and Q samples of the initial transmission.

13. The method according to claim 4, wherein the UE has the ability to store I and Q samples of the initial transmission, and the combining is performed using the I and Q samples of the initial transmission and the I and Q samples of the retransmission.

14. The method according to claim 13, wherein the combination is performed on the common codeword.

15. The method according to claim 13, wherein the combination is performed on the private codeword.

16. The method according to claim 1, wherein the confirmation includes one of three states corresponding to: confirming the decoding of both the common codeword and the private codeword; confirming the decoding of the common codeword and a negative confirmation of the private codeword; and a negative confirmation of both the common codeword and the private codeword.

17. The method according to claim 16, the method further comprising combining the confirmation states for a plurality of channels to provide compression of the confirmation.

18. The method according to claim 16, the method further comprising signaling the capabilities of the UE to a network entity prior to receiving the initial transmission.

19. The method according to claim 18, wherein the capabilities include one or more of the following: whether the UE stores in-phase and quadrature I and Q samples for the initial transmission; an indication of the buffer size for the UE; and the number of retransmissions supported by the UE for soft combination.

20. An apparatus at a user equipment (UE), the apparatus comprising: a memory; and a processor coupled to the memory, the processor configured to: receive an initial transmission of a common codeword and a private codeword, wherein the common codeword is common to the UE and at least one other UE and is received in a first stream, and the private codeword for the UE is received in a different stream; and send a confirmation indicating the decoding results of the common codeword and the private codeword based on the results of whether the common codeword is successfully decoded and whether the private codeword is successfully decoded.

21. The apparatus according to claim 20, wherein the processor is configured to provide a soft combination buffer for combining the initial transmission of at least one of the common codeword or the private codeword with a retransmission of the initial transmission.

22. The apparatus according to claim 21, wherein the soft combination buffer is configured to store log-likelihood ratios LLRs for decoding the initial transmission and combine the LLRs with the LLRs of the retransmission.

23. The apparatus according to claim 22, wherein the processor is further configured to receive an indication allowing the UE to refresh the soft combination buffer.

24. The apparatus according to claim 21, wherein the processor is configured to store in-phase and quadrature I and Q samples of the initial transmission and is arranged to signal to a network entity the processor's ability to store such samples.

25. The apparatus according to claim 22, wherein the processor is configured to store in-phase and quadrature I and Q samples of the initial transmission, and the combination is performed using the I and Q samples of the initial transmission and the I and Q samples of the retransmission.

26. A method of communicating at a network entity, the method comprising: Transmit an initial transmission of a common codeword and a private codeword, where the common codeword is common to a first user equipment (UE) and at least a second UE and is transmitted in a first stream, and the private codeword for the first UE is transmitted in a different stream; Receive an acknowledgement indicating the decoding results of the common codeword and the private codeword; And According to the received acknowledgement, retransmit at least one of the common codeword or the private codeword.

27. The method according to claim 26, the method further comprising receiving an indication of the capabilities of the UE from the first UE, and in response to the indication, determining whether to retransmit the common codeword in response to receiving a negative acknowledgement for the common codeword.

28. The method according to claim 26, the method further comprising receiving an indication of the number of retransmissions supported by the first UE from the first UE, and in response to the indication, determining whether to retransmit one of the common codeword or the private codeword.

29. The method according to claim 26, wherein the common codewords for the first UE and the second UE are concatenated together and transmitted in a set of spatial layers, and the private codewords for the first UE and the second UE are transmitted in other different sets of spatial layers.

30. An apparatus at a network entity, the apparatus Comprises: A memory; And A processor, the processor being coupled to the memory, the processor being configured to: Transmit an initial transmission of a common codeword and a private codeword, where the common codeword is common to a first user equipment (UE) and at least a second UE and is transmitted in a first stream, and the private codeword is for the first UE and is transmitted in a different stream; Receive an acknowledgement indicating the decoding results of the common codeword and the private codeword; And According to the received acknowledgement, retransmit at least one of the common codeword or the private codeword.

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