WO2019192016A1

WO2019192016A1 - Harq design for large signal quality unbalance among polar encoded transmissions

Info

Publication number: WO2019192016A1
Application number: PCT/CN2018/082092
Authority: WO
Inventors: Changlong Xu; Liangming WU; Jian Li; Kai Chen; Hao Xu; Joseph Binamira Soriaga; Jing Jiang
Original assignee: Qualcomm Incorporated
Priority date: 2018-04-06
Filing date: 2018-04-06
Publication date: 2019-10-10

Abstract

Certain aspects of the present disclosure provide techniques for hybrid automatic repeat request (HARQ) design for large signal quality unbalance among polar encoded transmissions. A method for transmitting device generally includes sending a transmission of a packet with a first HARQ redundancy version (RV). The transmitting device sends a retransmission of the packet with the first HARQ RV or a second HARQ RV based on a signal quality difference between the transmission and the retransmission. A method for receiving device generally includes decoding a received transmission of a packet. The receiving device decodes a received retransmission of the packet independently or joint decodes the received retransmission of the packet and the received retransmission of the packet, based on a signal quality difference between the transmission and the retransmission.

Description

HARQ DESIGN FOR LARGE SIGNAL QUALITY UNBALANCE AMONG POLAR ENCODED TRANSMISSIONS

INTRODUCTION

Field of the Disclosure

Aspects of the present disclosure relate to wireless communications, and more particularly, to techniques for hybrid automatic repeat request (HARQ) design for large signal quality unbalance among polar encoded transmissions.

Description of Related Art

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, broadcasts, etc. These wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc. ) . Examples of such multiple-access systems include 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) systems, LTE Advanced (LTE-A) systems, 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, to name a few.

In some examples, a wireless multiple-access communication system may include a number of base stations (BSs) , which are each capable of simultaneously supporting communication for multiple communication devices, otherwise known as user equipments (UEs) . In an LTE or LTE-A network, a set of one or more base stations may define an eNodeB (eNB) . In other examples (e.g., in a next generation, a new radio (NR) , or 5G network) , a wireless multiple access communication system may include a number of distributed units (DUs) (e.g., edge units (EUs) , edge nodes (ENs) , radio heads (RHs) , smart radio heads (SRHs) , transmission reception points (TRPs) , etc. ) in communication with a number of central units (CUs) (e.g., central nodes (CNs) , access node controllers (ANCs) , etc. ) , where a set of one or more distributed units, in communication with a central unit, may define an access node (e.g., which may be referred to as a base station, 5G NB, next generation NodeB (gNB or gNodeB) , TRP, etc. ) . A base station or distributed unit may communicate with a set of UEs on downlink channels (e.g., for transmissions from a base station or to a UE) and uplink channels (e.g., for transmissions from a UE to a base station or distributed unit) .

These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. New Radio (NR) (e.g., 5G) is an example of an emerging telecommunication standard. NR is a set of enhancements to the LTE mobile standard promulgated by 3GPP. It is designed to better support mobile broadband Internet access by improving spectral efficiency, lowering costs, improving services, making use of new spectrum, and better integrating with other open standards using OFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink (UL) . To these ends, NR supports beamforming, multiple-input multiple-output (MIMO) antenna technology, and carrier aggregation.

However, as the demand for mobile broadband access continues to increase, there exists a need for further improvements in NR and LTE technology. Preferably, these improvements should be applicable to other multi-access technologies and the telecommunication standards that employ these technologies.

BRIEF SUMMARY

The systems, methods, and devices of the disclosure each have several aspects, no single one of which is solely responsible for its desirable attributes. Without limiting the scope of this disclosure as expressed by the claims which follow, some features will now be discussed briefly. After considering this discussion, and particularly after reading the section entitled “Detailed Description” one will understand how the features of this disclosure provide advantages that include improved communications between access points and stations in a wireless network.

Certain aspects provide a method for wireless communication by a transmitting device. The method generally includes sending a transmission of a packet with a first HARQ redundancy version (RV) . The method generally includes sending a retransmission of the packet with the first HARQ RV or a second HARQ RV based on a signal quality difference between the transmission and the retransmission.

Certain aspects provide a method for wireless communication by a receiving device. The method generally includes decoding a received transmission of a packet. The method generally includes decoding a received retransmission of the packet independently or joint decoding the received retransmission of the packet and the received retransmission of the packet, based on a signal quality difference between the transmission and the retransmission.

Certain aspects provide an apparatus for wireless communication by a transmitting device. The apparatus generally includes means for sending a transmission of a packet with a first HARQ RV. The apparatus generally includes means for sending a retransmission of the packet with the first HARQ RV or a second HARQ RV based on a signal quality difference between the transmission and the retransmission.

Certain aspects provide an apparatus for wireless communication by a receiving device. The apparatus generally includes means for decoding a received transmission of a packet. The apparatus generally includes means for decoding a received retransmission of the packet independently or joint decoding the received retransmission of the packet and the received retransmission of the packet, based on a signal quality difference between the transmission and the retransmission.

Certain aspects provide an apparatus for wireless communication by a transmitting device. The apparatus generally includes a transmitter configured to send a transmission of a packet with a first HARQ RV. The transmitter is generally also configured to send a retransmission of the packet with the first HARQ RV or a second HARQ RV based on a signal quality difference between the transmission and the retransmission.

Certain aspects provide an apparatus for wireless communication by a receiving device. The method generally includes at least one processor coupled with a memory and configured to decode a received transmission of a packet. The at least one processor is generally also configured to decode a received retransmission of the packet independently or joint decoding the received retransmission of the packet and the received retransmission of the packet, based on a signal quality difference between the transmission and the retransmission.

Certain aspects provide a computer readable medium having computer executable code stored thereon for wireless communication by a transmitting device. The computer executable code generally includes code for sending a transmission of a packet with a first HARQ RV. The computer executable code generally includes code for sending a retransmission of the packet with the first HARQ RV or a second HARQ RV based on a signal quality difference between the transmission and the retransmission.

Certain aspects provide a computer readable medium having computer executable code stored thereon for wireless communication by a receiving device. The computer executable code generally includes code for decoding a received transmission of a packet. The computer executable code generally includes code for decoding a received retransmission of the packet independently or joint decoding the received retransmission of the packet and the received retransmission of the packet, based on a signal quality difference between the transmission and the retransmission.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the appended drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the drawings. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.

FIG. 1 is a block diagram conceptually illustrating an example telecommunications system, in accordance with certain aspects of the present disclosure.

FIG. 2 is a block diagram illustrating an example logical architecture of a distributed radio access network (RAN) , in accordance with certain aspects of the present disclosure.

FIG. 3 is a diagram illustrating an example physical architecture of a distributed RAN, in accordance with certain aspects of the present disclosure.

FIG. 4 is a block diagram conceptually illustrating a design of an example base station (BS) and user equipment (UE) , in accordance with certain aspects of the present disclosure.

FIG. 5 is a diagram showing examples for implementing a communication protocol stack, in accordance with certain aspects of the present disclosure.

FIG. 6 illustrates an example of a frame format for a new radio (NR) system, in accordance with certain aspects of the present disclosure.

FIG. 7 is a simplified block diagram illustrating an encoder, in accordance with certain aspects of the present disclosure.

FIG. 8 is a simplified block diagram illustrating a decoder, in accordance with certain aspects of the present disclosure.

FIG. 9 is a flow diagram illustrating example operations for wireless communication by a transmitting device, in accordance with certain aspects of the present disclosure.

FIG. 10 is a block diagram illustrating an example decision tree for hybrid automatic repeat request (HARQ) operation by a transmitting device, in accordance with certain aspects of the present disclosure.

FIG. 11 is a flow diagram illustrating example operations for wireless communication by a receiving device, in accordance with certain aspects of the present disclosure.

FIG. 12 is a block diagram illustrating an example decision tree for decoding HARQ transmissions by a receiving device, in accordance with certain aspects of the present disclosure.

FIG. 13 illustrates a communications device that may include various components configured to perform operations for the techniques disclosed herein in accordance with aspects of the present disclosure.

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements disclosed in one aspect may be beneficially utilized on other aspects without specific recitation.

DETAILED DESCRIPTION

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums hybrid automatic repeat request (HARQ) design for large signal quality unbalance among polar encoded transmissions.

Example HARQ techniques used in wireless communication include incremental redundancy (IR) HARQ (HARQ-IR) and Chase combining HARQ (HARQ-CC) . HARQ-IR typically has better performance than HARQ-CC. In some examples, however, such as polar encoded transmissions, HARQ-IR may have worse performance than HARQ-CC when there is a large signal quality unbalance among transmissions. In addition, joint decoding performance in the presence of a large signal quality unbalance may be worse than only decoding the single transmission with the higher signal quality.

Accordingly, aspects of the present disclosure provide techniques for a transmitting device to transmit using HARQ-IR or HARQ-CC based on the signal quality unbalance among transmissions. A receiving device can decode only a single transmission or can jointly decode multiple transmissions based on the amount signal quality unbalance amongst transmissions.

The following description provides examples, and is not limiting of the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of elements discussed without departing from the scope of the disclosure. Various examples may omit, substitute, or add various procedures or components as appropriate. For instance, the methods described may be performed in an order different from that described, and various steps may be added, omitted, or combined. Also, features described with respect to some examples may be combined in some other examples. For example, an apparatus may be implemented or a method may be practiced using any number of the aspects set forth herein. In addition, the scope of the disclosure is intended to cover such an apparatus or method which is practiced using other structure, functionality, or structure and functionality in addition to, or other than, the various aspects of the disclosure set forth herein. It should be understood that any aspect of the disclosure disclosed herein may be embodied by one or more elements of a claim. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration. ” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects.

The techniques described herein may be used for various wireless communication technologies, such as LTE, CDMA, TDMA, FDMA, OFDMA, SC-FDMA and other networks. The terms “network” and “system” are often used interchangeably. A CDMA network may implement a radio technology such as Universal Terrestrial Radio Access (UTRA) , cdma2000, etc. UTRA includes Wideband CDMA (WCDMA) and other variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMA network may implement a radio technology such as Global System for Mobile Communications (GSM) . An OFDMA network may implement a radio technology such as NR (e.g. 5G RA) , Evolved UTRA (E-UTRA) , Ultra Mobile Broadband (UMB) , IEEE 802.11 (Wi-Fi) , IEEE 802.16 (WiMAX) , IEEE 802.20, Flash-OFDMA, etc. UTRA and E-UTRA are part of Universal Mobile Telecommunication System (UMTS) .

New Radio (NR) is an emerging wireless communications technology under development in conjunction with the 5G Technology Forum (5GTF) . 3GPP Long Term Evolution (LTE) and LTE-Advanced (LTE-A) are releases of UMTS that use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-Aand GSM are described in documents from an organization named “3rd Generation Partnership Project” (3GPP) . cdma2000 and UMB are described in documents from an organization named “3rd Generation Partnership Project 2” (3GPP2) . The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, while aspects may be described herein using terminology commonly associated with 3G and/or 4G wireless technologies, aspects of the present disclosure can be applied in other generation-based communication systems, such as 5G and later, including NR technologies.

New radio (NR) access (e.g., 5G technology) may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g., 80 MHz or beyond) , millimeter wave (mmW) targeting high carrier frequency (e.g., 25 GHz or beyond) , massive machine type communications MTC (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC) . These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same subframe.

Example Wireless Communications System

FIG. 1 illustrates an example wireless communication network 100 in which aspects of the present disclosure may be performed. For example, the wireless communication network 100 may be a New Radio (NR) or 5G network. For example, a transmitting device, such as a BS 110 or a UE 120, is configured for HARQ operation. The BS 110 or UE 120 can determine the signal quality for a first transmission to a receiving device, such as the other one of the BS 110 or the UE 120, and sends the first transmission to the receiving device with a first HARQ redundancy version (RV) . If the first transmission does not succeed, the BS 110 or UE 120 determines the signal quality for a retransmission. The BS 110 or UE 120 compares the signal qualities of the first transmission and the retransmission. If there is a large signal quality unbalance, the BS 110 or UE 120 sends the retransmission with the same RV as the first retransmission, i.e., according to HARQ-CC operation, but if the signal quality unbalance is small, the BS 110 or UE 120 sends the retransmission with a different RV, i.e., according to HARQ-IR operation. The receiving device can compare the signal quality of the transmission and retransmission. If the signal quality of the retransmission is much better than the signal quality of the first transmission, the receiving device decodes the retransmission independently; otherwise, the receiving device joint decodes the retransmission and the first transmission.

As illustrated in FIG. 1, the wireless network 100 may include a number of base stations (BSs) 110 and other network entities. A BS may be a station that communicates with user equipments (UEs) . Each BS 110 may provide communication coverage for a particular geographic area. In 3GPP, the term “cell” can refer to a coverage area of a Node B (NB) and/or a Node B subsystem serving this coverage area, depending on the context in which the term is used. In NR systems, the term “cell” and next generation NodeB (gNB) , new radio base station (NR BS) , 5G NB, access point (AP) , or transmission reception point (TRP) may be interchangeable. In some examples, a cell may not necessarily be stationary, and the geographic area of the cell may move according to the location of a mobile BS. In some examples, the base stations may be interconnected to one another and/or to one or more other base stations or network nodes (not shown) in wireless communication network 100 through various types of backhaul interfaces, such as a direct physical connection, a wireless connection, a virtual network, or the like using any suitable transport network.

In general, any number of wireless networks may be deployed in a given geographic area. Each wireless network may support a particular radio access technology (RAT) and may operate on one or more frequencies. A RAT may also be referred to as a radio technology, an air interface, etc. A frequency may also be referred to as a carrier, a subcarrier, a frequency channel, a tone, a subband, etc. Each frequency may support a single RAT in a given geographic area in order to avoid interference between wireless networks of different RATs. In some cases, NR or 5G RAT networks may be deployed.

A base station (BS) may provide communication coverage for a macro cell, a pico cell, a femto cell, and/or other types of cells. A macro cell may cover a relatively large geographic area (e.g., several kilometers in radius) and may allow unrestricted access by UEs with service subscription. A pico cell may cover a relatively small geographic area and may allow unrestricted access by UEs with service subscription. A femto cell may cover a relatively small geographic area (e.g., a home) and may allow restricted access by UEs having an association with the femto cell (e.g., UEs in a Closed Subscriber Group (CSG) , UEs for users in the home, etc. ) . 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 the example shown in FIG. 1, the

BSs

110a, 110b and 110c may be macro BSs for the

macro cells

102a, 102b and 102c, respectively. The BS 110x may be a pico BS for a pico cell 102x. The BSs 110y and 110z may be femto BSs for the

femto cells

102y and 102z, respectively. A BS may support one or multiple (e.g., three) cells.

Wireless communication network 100 may also include relay stations. A relay station is a station that receives a transmission of data and/or other information from an upstream station (e.g., a BS or a UE) and sends a transmission of the data and/or other information to a downstream station (e.g., a UE or a BS) . A relay station may also be a UE that relays transmissions for other UEs. In the example shown in FIG. 1, a relay station 110r may communicate with the BS 110a and a UE 120r in order to facilitate communication between the BS 110a and the UE 120r. A relay station may also be referred to as a relay BS, a relay, etc.

Wireless network 100 may be a heterogeneous network that includes BSs of different types, e.g., macro BS, pico BS, femto BS, relays, etc. These different types of BSs may have different transmit power levels, different coverage areas, and different impact on interference in the wireless network 100. For example, macro BS may have a high transmit power level (e.g., 20 Watts) whereas pico BS, femto BS, and relays may have a lower transmit power level (e.g., 1 Watt) .

Wireless communication network 100 may support synchronous or asynchronous operation. For synchronous operation, the BSs may have similar frame timing, and transmissions from different BSs may be approximately aligned in time. For asynchronous operation, the BSs may have different frame timing, and transmissions from different BSs may not be aligned in time. The techniques described herein may be used for both synchronous and asynchronous operation.

A network controller 130 may couple to a set of BSs and provide coordination and control for these BSs. The network controller 130 may communicate with the BSs 110 via a backhaul. The BSs 110 may also communicate with one another (e.g., directly or indirectly) via wireless or wireline backhaul.

The UEs 120 (e.g., 120x, 120y, etc. ) may be dispersed throughout the wireless network 100, and each UE may be stationary or mobile. A UE may also be referred to as a mobile station, a terminal, an access terminal, a subscriber unit, a station, a Customer Premises Equipment (CPE) , a cellular phone, 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 computer, a camera, a gaming device, a netbook, a smartbook, an ultrabook, an appliance, a medical device or medical equipment, a biometric sensor/device, a wearable device such as a smart watch, smart clothing, smart glasses, a smart wrist band, smart jewelry (e.g., a smart ring, a smart bracelet, etc. ) , an entertainment device (e.g., a music device, a video device, a satellite radio, etc. ) , a vehicular component or sensor, a smart meter/sensor, industrial manufacturing equipment, a global positioning system device, or any other suitable device that is configured to communicate via a wireless or wired medium. Some UEs may be considered machine-type communication (MTC) devices or evolved MTC (eMTC) devices. MTC and eMTC UEs include, for example, robots, drones, remote devices, sensors, meters, monitors, location tags, etc., that may communicate with a BS, another device (e.g., remote device) , or some other entity. A wireless node may provide, for example, connectivity for or to a network (e.g., a wide area network such as Internet or a cellular network) via a wired or wireless communication link. Some UEs may be considered Internet-of-Things (IoT) devices, which may be narrowband IoT (NB-IoT) devices.

Certain wireless networks (e.g., LTE) utilize orthogonal frequency division multiplexing (OFDM) on the downlink and single-carrier frequency division multiplexing (SC-FDM) on the uplink. OFDM and SC-FDM partition the system bandwidth into multiple (K) orthogonal subcarriers, which are also commonly referred to as tones, bins, etc. Each subcarrier may be modulated with data. In general, modulation symbols are sent in the frequency domain with OFDM and in the time domain with SC-FDM. The spacing between adjacent subcarriers may be fixed, and the total number of subcarriers (K) may be dependent on the system bandwidth. For example, the spacing of the subcarriers may be 15 kHz and the minimum resource allocation (called a “resource block” (RB) ) may be 12 subcarriers (or 180 kHz) . Consequently, the nominal Fast Fourier Transfer (FFT) size may be equal to 128, 256, 512, 1024 or 2048 for system bandwidth of 1.25, 2.5, 5, 10, or 20 megahertz (MHz) , respectively. The system bandwidth may also be partitioned into subbands. For example, a subband may cover 1.08 MHz (i.e., 6 resource blocks) , and there may be 1, 2, 4, 8, or 16 subbands for system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz, respectively.

While aspects of the examples described herein may be associated with LTE technologies, aspects of the present disclosure may be applicable with other wireless communications systems, such as NR. NR may utilize OFDM with a CP on the uplink and downlink and include support for half-duplex operation using TDD. Beamforming may be supported and beam direction may be dynamically configured. MIMO transmissions with precoding may also be supported. MIMO configurations in the DL may support up to 8 transmit antennas with multi-layer DL transmissions up to 8 streams and up to 2 streams per UE. Multi-layer transmissions with up to 2 streams per UE may be supported. Aggregation of multiple cells may be supported with up to 8 serving cells.

In some examples, access to the air interface may be scheduled, wherein a. A scheduling entity (e.g., a base station) allocates resources for communication among some or all devices and equipment within its service area or cell. The scheduling entity may be responsible for scheduling, assigning, reconfiguring, and releasing resources for one or more subordinate entities. That is, for scheduled communication, subordinate entities utilize resources allocated by the scheduling entity. Base stations are not the only entities that may function as a scheduling entity. In some examples, a UE may function as a scheduling entity and may schedule resources for one or more subordinate entities (e.g., one or more other UEs) , and the other UEs may utilize the resources scheduled by the UE for wireless communication. In some examples, a UE may function as a scheduling entity in a peer-to-peer (P2P) network, and/or in a mesh network. In a mesh network example, UEs may communicate directly with one another in addition to communicating with a scheduling entity.

In FIG. 1, a solid line with double arrows indicates desired transmissions between a UE and a serving BS, which is a BS designated to serve the UE on the downlink and/or uplink. A finely dashed line with double arrows indicates interfering transmissions between a UE and a BS.

FIG. 2 illustrates an example logical architecture of a distributed Radio Access Network (RAN) 200, which may be implemented in the wireless communication network 100 illustrated in FIG. 1. A 5G access node 206 may include an access node controller (ANC) 202. ANC 202 may be a central unit (CU) of the distributed RAN 200. The backhaul interface to the Next Generation Core Network (NG-CN) 204 may terminate at ANC 202. The backhaul interface to neighboring next generation access Nodes (NG-ANs) 210 may terminate at ANC 202. ANC 202 may include one or more transmission reception points (TRPs) 208 (e.g., cells, BSs, gNBs, etc. ) .

The TRPs 208 may be a distributed unit (DU) . TRPs 208 may be connected to a single ANC (e.g., ANC 202) or more than one ANC (not illustrated) . For example, for RAN sharing, radio as a service (RaaS) , and service specific AND deployments, TRPs 208 may be connected to more than one ANC. TRPs 208 may each include one or more antenna ports. TRPs 208 may be configured to individually (e.g., dynamic selection) or jointly (e.g., joint transmission) serve traffic to a UE.

The logical architecture of distributed RAN 200 may support fronthauling solutions across different deployment types. For example, the logical architecture may be based on transmit network capabilities (e.g., bandwidth, latency, and/or jitter) .

The logical architecture of distributed RAN 200 may share features and/or components with LTE. For example, next generation access node (NG-AN) 210 may support dual connectivity with NR and may share a common fronthaul for LTE and NR.

The logical architecture of distributed RAN 200 may enable cooperation between and among TRPs 208, for example, within a TRP and/or across TRPs via ANC 202. An inter-TRP interface may not be used.

Logical functions may be dynamically distributed in the logical architecture of distributed RAN 200. As will be described in more detail with reference to FIG. 5, the Radio Resource Control (RRC) layer, Packet Data Convergence Protocol (PDCP) layer, Radio Link Control (RLC) layer, Medium Access Control (MAC) layer, and a Physical (PHY) layers may be adaptably placed at the DU (e.g., TRP 208) or CU (e.g., ANC 202) .

FIG. 3 illustrates an example physical architecture of a distributed Radio Access Network (RAN) 300, according to aspects of the present disclosure. A centralized core network unit (C-CU) 302 may host core network functions. C-CU 302 may be centrally deployed. C-CU 302 functionality may be offloaded (e.g., to advanced wireless services (AWS) ) , in an effort to handle peak capacity.

A centralized RAN unit (C-RU) 304 may host one or more ANC functions. Optionally, the C-RU 304 may host core network functions locally. The C-RU 304 may have distributed deployment. The C-RU 304 may be close to the network edge.

A DU 306 may host one or more TRPs (Edge Node (EN) , an Edge Unit (EU) , a Radio Head (RH) , a Smart Radio Head (SRH) , or the like) . The DU may be located at edges of the network with radio frequency (RF) functionality.

FIG. 4 illustrates example components of BS 110 and UE 120 (as depicted in FIG. 1) , which may be used to implement aspects of the present disclosure. For example, antennas 452,

processors

466, 458, 464, and/or controller/processor 480 of the UE 120 and/or antennas 434,

processors

420, 460, 438, and/or controller/processor 440 of the BS 110 may be used to perform the various techniques and methods described herein for HARQ design for large signal unbalance of polar encoded transmissions.

At the BS 110, a transmit processor 420 may receive data from a data source 412 and control information from a controller/processor 440. The control information may be for the physical broadcast channel (PBCH) , physical control format indicator channel (PCFICH) , physical hybrid ARQ indicator channel (PHICH) , physical downlink control channel (PDCCH) , group common PDCCH (GC PDCCH) , etc. The data may be for the physical downlink shared channel (PDSCH) , etc. The processor 420 may process (e.g., encode and symbol map) the data and control information to obtain data symbols and control symbols, respectively. The processor 420 may also generate reference symbols, e.g., for the primary synchronization signal (PSS) , secondary synchronization signal (SSS) , and cell-specific reference signal (CRS) . A transmit (TX) multiple-input multiple-output (MIMO) processor 430 may perform spatial processing (e.g., precoding) on the data symbols, the control symbols, and/or the reference symbols, if applicable, and may provide output symbol streams to the modulators (MODs) 432a through 432t. Each modulator 432 may process a respective output symbol stream (e.g., for OFDM, etc. ) to obtain an output sample stream. Each modulator may further process (e.g., convert to analog, amplify, filter, and upconvert) the output sample stream to obtain a downlink signal. Downlink signals from modulators 432a through 432t may be transmitted via the antennas 434a through 434t, respectively.

At the UE 120, the antennas 452a through 452r may receive the downlink signals from the base station 110 and may provide received signals to the demodulators (DEMODs) in transceivers 454a through 454r, respectively. Each demodulator 454 may condition (e.g., filter, amplify, downconvert, and digitize) a respective received signal to obtain input samples. Each demodulator may further process the input samples (e.g., for OFDM, etc. ) to obtain received symbols. A MIMO detector 456 may obtain received symbols from all the demodulators 454a through 454r, perform MIMO detection on the received symbols if applicable, and provide detected symbols. A receive processor 458 may process (e.g., demodulate, deinterleave, and decode) the detected symbols, provide decoded data for the UE 120 to a data sink 460, and provide decoded control information to a controller/processor 480.

On the uplink, at UE 120, a transmit processor 464 may receive and process data (e.g., for the physical uplink shared channel (PUSCH) ) from a data source 462 and control information (e.g., for the physical uplink control channel (PUCCH) from the controller/processor 480. The transmit processor 464 may also generate reference symbols for a reference signal (e.g., for the sounding reference signal (SRS)) . The symbols from the transmit processor 464 may be precoded by a TX MIMO processor 466 if applicable, further processed by the demodulators in transceivers 454a through 454r (e.g., for SC-FDM, etc. ) , and transmitted to the base station 110. At the BS 110, the uplink signals from the UE 120 may be received by the antennas 434, processed by the modulators 432, detected by a MIMO detector 436 if applicable, and further processed by a receive processor 438 to obtain decoded data and control information sent by the UE 120. The receive processor 438 may provide the decoded data to a data sink 439 and the decoded control information to the controller/processor 440.

The controllers/

processors

440 and 480 may direct the operation at the base station 110 and the UE 120, respectively. The processor 440 and/or other processors and modules at the BS 110 may perform or direct the execution of processes for the techniques described herein. The

memories

442 and 482 may store data and program codes for BS 110 and UE 120, respectively. A scheduler 444 may schedule UEs for data transmission on the downlink and/or uplink.

FIG. 5 illustrates a diagram 500 showing examples for implementing a communications protocol stack, according to aspects of the present disclosure. The illustrated communications protocol stacks may be implemented by devices operating in a wireless communication system, such as a 5G system (e.g., a system that supports uplink-based mobility) . Diagram 500 illustrates a communications protocol stack including a Radio Resource Control (RRC) layer 510, a Packet Data Convergence Protocol (PDCP) layer 515, a Radio Link Control (RLC) layer 520, a Medium Access Control (MAC) layer 525, and a Physical (PHY) layer 530. In various examples, the layers of a protocol stack may be implemented as separate modules of software, portions of a processor or ASIC, portions of non-collocated devices connected by a communications link, or various combinations thereof. Collocated and non-collocated implementations may be used, for example, in a protocol stack for a network access device (e.g., ANs, CUs, and/or DUs) or a UE.

A first option 505-ashows a split implementation of a protocol stack, in which implementation of the protocol stack is split between a centralized network access device (e.g., an ANC 202 in FIG. 2) and distributed network access device (e.g., DU 208 in FIG. 2) . In the first option 505-a, an RRC layer 510 and a PDCP layer 515 may be implemented by the central unit, and an RLC layer 520, a MAC layer 525, and a PHY layer 530 may be implemented by the DU. In various examples the CU and the DU may be collocated or non-collocated. The first option 505-amay be useful in a macro cell, micro cell, or pico cell deployment.

A second option 505-b shows a unified implementation of a protocol stack, in which the protocol stack is implemented in a single network access device. In the second option, RRC layer 510, PDCP layer 515, RLC layer 520, MAC layer 525, and PHY layer 530 may each be implemented by the AN. The second option 505-b may be useful in, for example, a femto cell deployment.

Regardless of whether a network access device implements part or all of a protocol stack, a UE may implement an entire protocol stack as shown in 505-c (e.g., the RRC layer 510, the PDCP layer 515, the RLC layer 520, the MAC layer 525, and the PHY layer 530) .

In LTE, the basic transmission time interval (TTI) or packet duration is the 1 ms subframe. In NR, a subframe is still 1 ms, but the basic TTI is referred to as a slot. A subframe contains a variable number of slots (e.g., 1, 2, 4, 8, 16, …slots) depending on the subcarrier spacing. The NR RB is 12 consecutive frequency subcarriers. NR may support a base subcarrier spacing of 15 KHz and other subcarrier spacing may be defined with respect to the base subcarrier spacing, for example, 30 kHz, 60 kHz, 120 kHz, 240 kHz, etc. The symbol and slot lengths scale with the subcarrier spacing. The CP length also depends on the subcarrier spacing.

FIG. 6 is a diagram showing an example of a frame format 600 for NR. The transmission timeline for each of the downlink and uplink may be partitioned into units of radio frames. Each radio frame may have a predetermined duration (e.g., 10 ms) and may be partitioned into 10 subframes, each of 1 ms, with indices of 0 through 9. Each subframe may include a variable number of slots depending on the subcarrier spacing. Each slot may include a variable number of symbol periods (e.g., 7 or 14 symbols) depending on the subcarrier spacing. The symbol periods in each slot may be assigned indices. A mini-slot is a subslot structure (e.g., 2, 3, or 4 symbols) .

Each symbol in a slot may indicate a link direction (e.g., DL, UL, or flexible) for data transmission and the link direction for each subframe may be dynamically switched. The link directions may be based on the slot format. Each slot may include DL/UL data as well as DL/UL control information.

In NR, a synchronization signal (SS) block is transmitted. The SS block includes a PSS, a SSS, and a two symbol PBCH. The SS block can be transmitted in a fixed slot location, such as the symbols 0-3 as shown in FIG. 6. The PSS and SSS may be used by UEs for cell search and acquisition. The PSS may provide half-frame timing, the SS may provide the CP length and frame timing. The PSS and SSS may provide the cell identity. The PBCH carries some basic system information, such as downlink system bandwidth, timing information within radio frame, SS burst set periodicity, system frame number, etc. The SS blocks may be organized into SS bursts to support beam sweeping. Further system information such as, remaining minimum system information (RMSI) , system information blocks (SIBs) , other system information (OSI) can be transmitted on a physical downlink shared channel (PDSCH) in certain subframes.

In some circumstances, two or more subordinate entities (e.g., UEs) may communicate with each other using sidelink signals. Real-world applications of such sidelink communications may include public safety, proximity services, UE-to-network relaying, vehicle-to-vehicle (V2V) communications, Internet of Everything (IoE) communications, IoT communications, mission-critical mesh, and/or various other suitable applications. Generally, a sidelink signal may refer to a signal communicated from one subordinate entity (e.g., UE1) to another subordinate entity (e.g., UE2) without relaying that communication through the scheduling entity (e.g., UE or BS) , even though the scheduling entity may be utilized for scheduling and/or control purposes. In some examples, the sidelink signals may be communicated using a licensed spectrum (unlike wireless local area networks, which typically use an unlicensed spectrum) .

A UE may operate in various radio resource configurations, including a configuration associated with transmitting pilots using a dedicated set of resources (e.g., a radio resource control (RRC) dedicated state, etc. ) or a configuration associated with transmitting pilots using a common set of resources (e.g., an RRC common state, etc. ) . When operating in the RRC dedicated state, the UE may select a dedicated set of resources for transmitting a pilot signal to a network. When operating in the RRC common state, the UE may select a common set of resources for transmitting a pilot signal to the network. In either case, a pilot signal transmitted by the UE may be received by one or more network access devices, such as an AN, or a DU, or portions thereof. Each receiving network access device may be configured to receive and measure pilot signals transmitted on the common set of resources, and also receive and measure pilot signals transmitted on dedicated sets of resources allocated to the UEs for which the network access device is a member of a monitoring set of network access devices for the UE. One or more of the receiving network access devices, or a CU to which receiving network access device (s) transmit the measurements of the pilot signals, may use the measurements to identify serving cells for the UEs, or to initiate a change of serving cell for one or more of the UEs.

Example Polar Codes

Polar codes may be used to encode a stream of bits for transmission. Polar codes are a capacity-achieving coding scheme with almost linear (in block length) encoding and decoding complexity. Polar codes have many desirable properties such as deterministic construction (e.g., based on a fast Hadamard transform) , very low and predictable error floors, and simple successive-cancellation (SC) based decoding.

Polar codes are linear block codes of length N=2 ⁿ where their generator matrix is constructed using the n ^th Kronecker power of the matrix

denoted by G ⁿ. For example, Equation (1) shows the resulting generator matrix for n=3.

A codeword may be generated by using the generator matrix to encode a number of input bits (e.g., information bits) . For example, given a number of input bits u=(u ₀, u _1, ..., u _N-1) , a resulting codeword vector x= (x ₀ , x ₁, ..., x _N-1) may be generated by encoding the input bits using the generator matrix G. This resulting codeword may then be rate matched and transmitted.

When the received vectors are decoded) using a Successive Cancellation (SC) decoder (e.g., decoder 816) , every estimated bit,

has a predetermined error probability given that bits u ₀ ^i-1 were correctly decoded, that tends towards either 0 or 0.5. Moreover, the proportion of estimated bits with a low error probability tends towards the capacity of the underlying channel. Polar codes exploit a phenomenon called channel polarization by using the most reliable K bits to transmit information, while setting, or freezing, the remaining (N-K) bits to a predetermined value, such as 0, for example as explained below.

For very large N, polar codes transform the channel into N parallel “virtual” channels for the N information bits. If C is the capacity of the channel, then there are almost N*C channels which are completely noise free and there are N (1 –C) channels which are completely noisy. The basic polar coding scheme then involves freezing (i.e., not transmitting) the information bits to be sent along the completely noisy channel and sending information only along the perfect channels. For short-to-medium N, this polarization may not be complete in the sense there could be several channels which are neither completely useless nor completely noise free (i.e., channels that are in transition) . Depending on the rate of transmission, these channels in the transition are either frozen or they are used for transmission.

In NR as described above, Polar codes may be used to encode information. For example, Polar codes may be used as forward error correction (FEC) for control channels (e.g., 5G control channels) . Generally, cyclic redundancy check (CRC) bits can be added in the Polar codes (e.g., CRC-aided polar coding (CA-polar) ) to improve the error rate performance and error detection. Generally, other types of “assistant bits” can also be used.

Because Polar codes are linear block codes with a recursively constructed generator matrix, a polar code of length N is built from the concatenation of two constituent polar codes of length N _v = N/2. This recursive construction is carried out in a way that polarizes the probability of correctly estimating bits: some bit estimates become more reliable and others becomes less reliable. As the blocklength increases, some bit estimates become more reliable and the rest become less reliable.

Each polar code bit-channel (e.g., channel index) is assigned a reliability value, used to determine which bits transmit information and which parity. Relative reliabilities may be known (e.g., stored and/or computed) by both encoders and decoders. The relative order of reliabilities can be dependent on the code length and on the signal-to-noise ratio (SNR) for which the code has been constructed. The reliabilities associated with the bit-channels can be determined, for example, by using the Bhattacharyya parameter, through the direct use of probability functions, or other reliability computation.

In Polar encoding, the most reliable channels (e.g., most reliable bit locations/positions) are typically selected to carry information (e.g., information bits) , and the rest of the bits are set as a fixed value (e.g., 0) . These fixed bits may be referred to as frozen bits. However if some of the frozen bits are selected having values that depend on the information bits, the performance can be improved.

FIG. 7 is a simplified block diagram illustrating an encoder, in accordance with certain aspects of the present disclosure. FIG. 7 illustrates a portion of a radio frequency (RF) modem 704 that may be configured to provide an encoded message for wireless transmission (e.g., using Polar codes) . In one example, an encoder 706 in a BS (e.g., BS 110) or a UE (e.g., UE 120) on the reverse path receives a message 702 for transmission. The message 702 may contain data and/or encoded voice or other content directed to the receiving device. In aspects, the message 702 is first input into a sequencer 700 that receives the message 702 and output the message 702 as a sequence of bits in a channel index order. In aspects, the sequencer 700 determines the channel index order for the sequence of bits. The encoder 706 encodes the message using a suitable modulation and coding scheme (MCS) , typically selected based on a configuration defined by the BS 110 or another network entity. In some cases, the encoder 706 may select, from a set of rate codes, a rate code to be used to encode the message. The encoded bitstream 708 may then be stored in circular buffer and rate-matching may be performed on the stored encoded bitstream, for example, according to aspects presented below. After the encoded bitstream 708 is rate-matched, the encoded bitstream 708 may then be provided to a mapper 710 that generates a sequence of Tx symbols 712 that are modulated, amplified and otherwise processed by Tx chain 714 to produce an RF signal 716 for transmission through antenna 718.

FIG. 8 is a simplified block diagram illustrating a decoder, in accordance with certain aspects of the present disclosure. FIG. 8 illustrates a portion of a RF modem 810 that may be configured to receive and decode a wirelessly transmitted signal including an encoded message (e.g., a message encoded using a Polar code) . In various examples, the modem 810 receiving the signal may reside at the UE, at the BS, or at any other suitable apparatus or means for carrying out the described functions. An antenna 802 provides an RF signal 716 (i.e., the RF signal produced in FIG. 4) to a UE (e.g., UE 120) . An Rx chain 806 processes and demodulates the RF signal 716 and may provide a sequence of demodulated symbols 808 to a demapper 812, which produces a bitstream 814 representative of the encoded message.

A decoder 816 may then be used to decode m-bit information strings from a bitstream that has been encoded using a coding scheme (e.g., a Polar code) . The decoder 816 may comprise a Viterbi decoder, an algebraic decoder, a butterfly decoder, or another suitable decoder. In one example, a Viterbi decoder employs the well-known Viterbi algorithm to find the most likely sequence of signaling states (the Viterbi path) that corresponds to a received bitstream 814. The bitstream 814 may be decoded based on a statistical analysis of LLRs calculated for the bitstream 814. In one example, a Viterbi decoder may compare and select the correct Viterbi path that defines a sequence of signaling states using a likelihood ratio test to generate LLRs from the bitstream 814. Likelihood ratios can be used to statistically compare the fit of a plurality of candidate Viterbi paths using a likelihood ratio test that compares the logarithm of a likelihood ratio for each candidate Viterbi path (i.e. the LLR) to determine which path is more likely to account for the sequence of symbols that produced the bitstream 814. The decoder 816 may then decode the bitstream 814 based on the LLRs to determine the message 818 containing data and/or encoded voice or other content transmitted from the base station (e.g., BS 110) .

Example HARQ Design For Large Signal Quality Unbalance Among Polar Encoded Transmissions

Aspects of the present disclosure provide apparatus, methods, processing systems, and computer readable mediums for NR (new radio access technology or 5G technology) . NR may support various wireless communication services, such as enhanced mobile broadband (eMBB) targeting wide bandwidth (e.g. 80 MHz or beyond) , millimeter wave (mmW) targeting high carrier frequency (e.g. 25 GHz or beyond) , massive machine type communications (mMTC) targeting non-backward compatible MTC techniques, and/or mission critical targeting ultra-reliable low-latency communications (URLLC) . These services may include latency and reliability requirements. These services may also have different transmission time intervals (TTI) to meet respective quality of service (QoS) requirements. In addition, these services may co-exist in the same subframe.

In NR, hybrid automatic repeat request (HARQ) can be used for error control. Example HARQ techniques include incremental redundancy (IR) HARQ (HARQ-IR) and Chase combining HARQ (HARQ-CC) . HARQ-IR may be higher complexity than HARQ-CC. In HARQ-IR, each retransmission contains different information than the previous transmission. Multiple sets of coded bits are generated, each representing the same set of information bits. For example, each retransmission can use a different set of coded bits than the previous transmission. Different redundancy versions can be generated by puncturing the encoder output. Thus, with each retransmission, the receiver gains extra information. In HARQ-CC, each retransmission contains the same information (i.e., same data and parity bits) . The receiver combines the received with the same bits from previous transmissions. Thus, with each retransmission, the energy per bit to noise power spectral density ratio (E _b/N ₀) is increased.

In NR, polar codes are used as the correction coding for some transmissions. In some examples, polar codes are used for the uplink and downlink control channels for eMBB service. In some examples, polar codes could also be used for a data channel. In some examples, polar codes could be used for URLLC service. Typically, HARQ-IR has better performance than HARQ-CC. In some cases, however, such as for polar encoded transmissions, HARQ-IR may have worse performance than HARQ-CC when there is a large signal quality unbalance among transmissions. In addition, joint decoding performance in the presence of a large signal quality unbalance may be worse than only decoding the single transmission with the higher signal quality.

Therefore, HARQ design for polar encoded transmissions with large signal quality unbalance is needed.

FIG. 9 is a flow diagram illustrating example operations 900 for wireless communication, in accordance with certain aspects of the present disclosure. The operations 900 can be performed, for example, by a transmitting device such as a base station (e.g., a BS 110 as illustrated in FIG. 1) or a user equipment (e.g., a UE 120 as illustrated in FIG. 1) .

The operations 900 begin, at 902, by sending a transmission (or retransmission) of a packet with a first HARQ RV.

At 904, the transmitting device sends (e.g., if the transmission at 902 fails, such as after receiving a NACK or if an ACK is not received after a predetermined duration) a retransmission (e.g., the next transmission following the transmission at 902) of the packet with the first HARQ RV or a second HARQ RV based on a signal quality difference between the transmission and the retransmission. According to certain aspects, the transmitting device uses HARQ-IR if the signal quality unbalance is low and the transmitting device use HARQ-CC if the signal quality unbalance is high. In some examples, the transmitting device sends the retransmission of the packet with the first HARQ RV if the difference exceeds a threshold value (e.g., a signal-to-noise ratio (SNR) difference of 6 dB) or sends the retransmission of the packet with the second HARQ RV if the difference is equal to or below the threshold value.

According to certain aspects, the transmitting device determines a first signal quality value for the transmission of the packet and a second signal quality value for the retransmission of the packet. The transmitting device may determine an absolute value of the difference between the first and second signal quality values. In some examples, the transmitting device determines the signal quality values by performing one or more channel measurements and/or the transmitting device receives information from the receiving device (e.g., a measurement report or other indication) indicating the signal quality value. In some examples, the signal quality values may be signal-to-noise ratio (SNR) values, signal-to-interference plus noise ratio (SINR) values, channel quality indicator (CQI) values, channel state information (CSI) values, or other values representing the signal quality.

According to certain aspects, the transmitting device encodes the transmission and retransmission using polar codes. In some examples, the transmissions are polar encoded control channel transmissions.

According to certain aspects, the transmitting device continues to monitor the signal quality unbalance for further retransmissions. If the signal quality unbalance is low, the transmitting device can continue using HARQ-IR, or if the signal quality unbalance later goes higher, the transmitting device can switch to HARQ-CC. If the signal quality unbalance is high and the transmitting device switches to HARQ-CC, the transmitting device can continue using HARQ-CC is the signal quality unbalance remains high or if the signal quality balance lowers later, the transmitting device can switch back to HARQ-IR. According to certain aspects, the transmitting device determines a signal quality for another retransmission of the packet and sends the other retransmission of the packet with the first HARQ RV, the second HARQ RV, or a third HARQ RV, based on the determined signal quality and the RV used for the previous retransmission at step 904.

FIG. 10 is a block diagram illustrating an example decision tree 1000 for HARQ operation by a transmitting device, in accordance with certain aspects of the present disclosure. As shown in FIG. 10, at block 1002, the transmitting device gets (e.g., determines, computes, receives, measures, etc. ) the SNR_1 (e.g., or another signal quality value) for a first transmission. At block 1004, the transmitting device generates and transmits the RV for the first transmission. At block 1006, the transmitting device gets (e.g., determines, computes, receives, measures, etc. ) the SNR_2 (e.g., or another signal quality value) for a second transmission (i.e., a retransmission after the first transmission fails) . At block 1008, the transmitting device determines if the absolute value of the difference between the first and second transmission is greater than a threshold L: Abs (SNR_2 –SNR_1) > L dB. If YES, then at block 1010 the transmitting device generates the same RV used for the first transmission according to HARQ-CC. If NO, then at block 1012 the transmitting device generates a new RV according to HARQ-IR. At block 1014, the transmitting device transmitting the RV for the second transmission generated at block 1010 or block 1012.

FIG. 11 is a flow diagram illustrating example operations 1100 for wireless communication, in accordance with certain aspects of the present disclosure. The operations 1100 can be performed, for example, by a receiving device such as a BS (e.g., a BS 110 as illustrated in FIG. 1) or a UE (e.g., a UE 120 as illustrated in FIG. 1) .

The operations 1100 begin, at 1102, by decoding (e.g., attempting to decode) a received transmission of a packet.

At 1104, the receiving device decodes a received retransmission (e.g., the next transmission following the transmission received at 1102) of the packet independently or joint decodes (e.g., or attempts to decode) the received retransmission of the packet and the received retransmission of the packet, based on a signal quality difference between the transmission and the retransmission. According to certain aspects, the receiving device uses joint decoding (of the retransmission and the transmission) if the signal quality unbalance is low and the receiving device use independent decoding of only the retransmission if the signal quality unbalance is high. In some examples, the receiving device decodes only (e.g., independently, not jointly) the retransmission of the packet if the difference exceeds a threshold value (e.g., 8 dB SNR difference) or joint decodes the retransmission of the packet with the first transmission if the difference is equal to or below the threshold value.

According to certain aspects, the receiving device determines a first signal quality value for the transmission of the packet and a second signal quality value for the retransmission of the packet. The transmitting device may determine a value of the difference between the second signal quality value and the first signal quality value. In some examples, the receiving device determines the signal quality values by performing one or more channel measurements and/or the receiving device receives information from the transmitting device indicating the signal quality value. In some examples, the signal quality values may be SNR values, SINR values, CQI values, CSI values, or other values representing the signal quality.

According to certain aspects, the receiving device decodes the transmission and retransmission using polar codes. In some examples, the transmissions are polar encoded control channel transmissions.

FIG. 12 is a block diagram illustrating an example decision tree 1200 for decoding HARQ transmissions by a receiving device, in accordance with certain aspects of the present disclosure. As shown in FIG. 12, at block 1202, the receiving device evaluates (e.g., determines, computes, receives, measures, etc. ) the SNR_1 (e.g., or another signal quality value) for a first transmission. At block 1204, the receiving device decodes (e.g., attempts to decode) the receive signal for the first transmission. At block 1206, the receiving device evaluates (e.g., determines, computes, receives, measures, etc. ) the SNR_2 (e.g., or another signal quality value) for a second transmission (i.e., a retransmission after the first transmission fails) . At block 1208, the receiving device determines if the value of the difference between the second transmission and the first transmission is greater than a threshold M: (SNR_2 –SNR_1) > M dB. If YES, then at block 1210 the receiving decides to decode only the second transmission independently without joint decoding. If NO, then at block 1212 the receiving device decides to joint decode the first and second transmission. At block 1214, the receiving device decodes the received signal for the second transmission based on the determination at block 1210 or block 1212.

FIG. 13 illustrates a communications device 1000 that may include various components (e.g., corresponding to means-plus-function components) configured to perform operations for the techniques disclosed herein, such as the operations illustrated in FIGs. 9-12. The communications device 1300 includes a processing system 1302 coupled to a transceiver 1308. The transceiver 1308 is configured to transmit and receive signals for the communications device 1300 via an antenna (s) 1310, such as the various signal described herein. The processing system 1302 may be configured to perform processing functions for the communications device 1300, including processing signals received and/or to be transmitted by the communications device 1300.

The processing system 1302 includes a processor 1304 coupled to a computer-readable medium/memory 1312 via a bus 1306. In certain aspects, the computer-readable medium/memory 1312 is configured to store instructions (e.g., code) that when executed by processor 1304, cause the processor 1304 to perform the operations illustrated in FIGs. 9-12, or other operations for performing the various techniques discussed herein. In some examples, the computer-readable medium/memory 1312 includes signal quality evaluation code 1314. The signal quality evaluation code 1314, when executed by the processor 1304 may cause the processor 1304 to determine at least the first and second signal quality values for first and second transmissions, determine a difference between the first and second signal quality values, and compare the difference to a threshold value. In some examples, the computer-readable medium/memory 1312 further includes HARQ type determination code 1316. The HARQ type determination code 1316, when executed by the processor 1304 may cause the processor 1304 to determine whether to use HARQ-IR or HARQ-CC for sending different transmissions based on the signal quality unbalance. In some examples, the computer-readable medium/memory 1312 further includes decoding type determination code 1318. The decoding type determination code 1318, when executed by the processor 1304 may cause the processor 1304 to determine whether to use single transmission decoding or joint decoding for a transmission based on the signal quality unbalance.

The methods disclosed herein comprise one or more steps or actions for achieving the methods. The method steps and/or actions may be interchanged with one another without departing from the scope of the claims. In other words, unless a specific order of steps or actions is specified, the order and/or use of specific steps and/or actions may be modified without departing from the scope of the claims.

As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiples of the same element (e.g., a-a, a-a-a, a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or any other ordering of a, b, and c) .

As used herein, the term “determining” encompasses a wide variety of actions. For example, “determining” may include calculating, computing, processing, deriving, investigating, looking up (e.g., looking up in a table, a database or another data structure) , ascertaining and the like. Also, “determining” may include receiving (e.g., receiving information) , accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

The previous 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 readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more. ” Unless specifically stated otherwise, the term “some” refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112 (f) unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for. ”

The various operations of methods described above may be performed by any suitable means capable of performing the corresponding functions. The means may include various hardware and/or software component (s) and/or module (s) , including, but not limited to a circuit, an application specific integrated circuit (ASIC) , or processor. Generally, where there are operations illustrated in figures, those operations may have corresponding counterpart means-plus-function components with similar numbering.

The various illustrative logical blocks, modules and circuits described in connection with the present disclosure may be implemented or performed with a general purpose processor, a digital signal processor (DSP) , an application specific integrated circuit (ASIC) , a field programmable gate array (FPGA) or other programmable logic device (PLD) , discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any commercially available processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

If implemented in hardware, an example hardware configuration may comprise a processing system in a wireless node. The processing system may be implemented with a bus architecture. The bus may include any number of interconnecting buses and bridges depending on the specific application of the processing system and the overall design constraints. The bus may link together various circuits including a processor, machine-readable media, and a bus interface. The bus interface may be used to connect a network adapter, among other things, to the processing system via the bus. The network adapter may be used to implement the signal processing functions of the PHY layer. In the case of a user terminal 120 (see FIG. 1) , a user interface (e.g., keypad, display, mouse, joystick, etc. ) may also be connected to the bus. The bus may also link various other circuits such as timing sources, peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further. The processor may be implemented with one or more general-purpose and/or special-purpose processors. Examples include microprocessors, microcontrollers, DSP processors, and other circuitry that can execute software. Those skilled in the art will recognize how best to implement the described functionality for the processing system depending on the particular application and the overall design constraints imposed on the overall system.

If implemented in software, the functions may be stored or transmitted over as one or more instructions or code on a computer readable medium. Software shall be construed broadly to mean instructions, data, or any combination thereof, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. Computer-readable media include both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. The processor may be responsible for managing the bus and general processing, including the execution of software modules stored on the machine-readable storage media. A computer-readable storage medium may be coupled to a processor such that the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. By way of example, the machine-readable media may include a transmission line, a carrier wave modulated by data, and/or a computer readable storage medium with instructions stored thereon separate from the wireless node, all of which may be accessed by the processor through the bus interface. Alternatively, or in addition, the machine-readable media, or any portion thereof, may be integrated into the processor, such as the case may be with cache and/or general register files. Examples of machine-readable storage media may include, by way of example, RAM (Random Access Memory) , flash memory, ROM (Read Only Memory) , PROM (Programmable Read-Only Memory) , EPROM (Erasable Programmable Read-Only Memory) , EEPROM (Electrically Erasable Programmable Read-Only Memory) , registers, magnetic disks, optical disks, hard drives, or any other suitable storage medium, or any combination thereof. The machine-readable media may be embodied in a computer-program product.

A software module may comprise a single instruction, or many instructions, and may be distributed over several different code segments, among different programs, and across multiple storage media. The computer-readable media may comprise a number of software modules. The software modules include instructions that, when executed by an apparatus such as a processor, cause the processing system to perform various functions. The software modules may include a transmission module and a receiving module. Each software module may reside in a single storage device or be distributed across multiple storage devices. By way of example, a software module may be loaded into RAM from a hard drive when a triggering event occurs. During execution of the software module, the processor may load some of the instructions into cache to increase access speed. One or more cache lines may then be loaded into a general register file for execution by the processor. When referring to the functionality of a software module below, it will be understood that such functionality is implemented by the processor when executing instructions from that software module.

Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, digital subscriber line (DSL) , or wireless technologies such as infrared (IR) , radio, and microwave, then the coaxial cable, fiber optic cable, twisted pair, DSL, or wireless technologies such as infrared, radio, and microwave are included in the definition of medium. Disk and disc, as used herein, include compact disc (CD) , laser disc, optical disc, digital versatile disc (DVD) , floppy disk, and

disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Thus, in some aspects computer-readable media may comprise non-transitory computer-readable media (e.g., tangible media) . In addition, for other aspects computer-readable media may comprise transitory computer-readable media (e.g., a signal) . Combinations of the above should also be included within the scope of computer-readable media.

Thus, certain aspects may comprise a computer program product for performing the operations presented herein. For example, such a computer program product may comprise a computer-readable medium having instructions stored (and/or encoded) thereon, the instructions being executable by one or more processors to perform the operations described herein. For example, instructions for performing the operations described herein and illustrated in FIGs. 9-12.

Further, it should be appreciated that modules and/or other appropriate means for performing the methods and techniques described herein can be downloaded and/or otherwise obtained by a user terminal and/or base station as applicable. For example, such a device can be coupled to a server to facilitate the transfer of means for performing the methods described herein. Alternatively, various methods described herein can be provided via storage means (e.g., RAM, ROM, a physical storage medium such as a compact disc (CD) or floppy disk, etc. ) , such that a user terminal and/or base station can obtain the various methods upon coupling or providing the storage means to the device. Moreover, any other suitable technique for providing the methods and techniques described herein to a device can be utilized.

It is to be understood that the claims are not limited to the precise configuration and components illustrated above. Various modifications, changes and variations may be made in the arrangement, operation and details of the methods and apparatus described above without departing from the scope of the claims.

Claims

A method for wireless communications, comprising:

sending a transmission of a packet with a first hybrid automatic repeat request (HARQ) redundancy version (RV) ; and

sending a retransmission of the packet with the first HARQ RV or a second HARQ RV based on a signal quality difference between the transmission and the retransmission.
The method of claim 1, further comprising:

determining a first signal quality value for the transmission of the packet;

determining a second signal quality value for the retransmission of the packet; and

determining an absolute value of the difference between the first and second signal quality values.
The method of claim 2, wherein the first and second signal quality values comprise at least one of: a signal-to-noise ratio (SNR) value, a signal-to-interference plus noise ratio (SINR) value, a channel quality indicator (CQI) value, or a channel state information (CSI) value.
The method of claim 2, wherein determining the first and second signal quality values comprises at least one of:

performing one or more channel measurements; or

receiving information from a receiving device indicating at least one of the first signal quality value or the second signal quality value.
The method of claim 1, wherein sending the retransmission of the packet with the first HARQ RV or the second HARQ RV based on the difference comprises:

sending the retransmission of the packet with the first HARQ RV if the difference exceeds a threshold value; and

sending the retransmission of the packet with the second HARQ RV if the difference is equal to or below the threshold value.
The method of claim 5, wherein the threshold value comprises a signal-to-noise ratio (SNR) value of 6 dB.
The method of claim 1, wherein the retransmission comprises a first retransmission of the packet.
The method of claim 1, further comprising encoding the packet for the transmission and retransmission using at least one polar code.
The method of claim 1, further comprising:

determining a signal quality for another retransmission of the packet; and

sending the other retransmission of the packet with the first HARQ RV, the second HARQ RV, or a third HARQ RV, based on the determined signal quality and the RV used for the previous retransmission.
A method for wireless communications, comprising:

decoding a received transmission of a packet; and

decoding a received retransmission of the packet independently or joint decoding the received retransmission of the packet and the received retransmission of the packet, based on a signal quality difference between the transmission and the retransmission.
The method of claim 10, further comprising:

determining a first signal quality value for the transmission of the packet;

determining a second signal quality value for the transmission of the packet; and

determining a value of the difference between the second and first signal quality values.
The method of claim 11, wherein the first and second signal quality values comprise at least one of: a signal-to-noise ratio (SNR) value, a signal-to-interference plus noise ratio (SINR) value, a channel quality indicator (CQI) value, or a channel state information (CSI) value.
The method of claim 11, wherein determining the first and second signal quality values comprises at least one of:

performing one or more channel measurements; or

receiving information from a transmitting device indicating at least one of the first signal quality value or the second signal quality value.
The method of claim 10, wherein decoding or joint decoding the received retransmission of the packet based on the difference comprises:

decoding the retransmission of the packet independently if the difference exceeds a threshold value; and

joint decoding the retransmission of the packet and the transmission of the packet if the difference is equal to or below the threshold value.
The method of claim 14, wherein the threshold value comprises a signal-to-noise ratio (SNR) value of 8 dB.
The method of claim 10, wherein the retransmission comprises a first retransmission of the packet.
The method of claim 10, wherein decoding the packet for the transmission and retransmission comprises decoding the packet using at least one polar code.
The method of claim 10, wherein:

the transmission of the packet comprises a first hybrid automatic repeat request (HARQ) redundancy version (RV) ; and

the retransmission of the packet comprises the first HARQ RV or a second HARQ RV.
An apparatus for wireless communications, comprising:

means for sending a transmission of a packet with a first hybrid automatic repeat request (HARQ) redundancy version (RV) ; and

means for sending a retransmission of the packet with the first HARQ RV or a second HARQ RV based on a signal quality difference between the transmission and the retransmission.
An apparatus for wireless communications, comprising:

means for decoding a received transmission of a packet; and

means for decoding a received retransmission of the packet independently or joint decoding the received retransmission of the packet and the received retransmission of the packet, based on a signal quality difference between the transmission and the retransmission.
An apparatus for wireless communications, comprising:

a transmitter configured to:

send a transmission of a packet with a first hybrid automatic repeat request (HARQ) redundancy version (RV) ; and

send a retransmission of the packet with the first HARQ RV or a second HARQ RV based on a signal quality difference between the transmission and the retransmission.
An apparatus for wireless communications, comprising:

at least one processor coupled with a memory and configured to:

decode a received transmission of a packet; and

decode a received retransmission of the packet independently or joint decoding the received retransmission of the packet and the received retransmission of the packet, based on a signal quality difference between the transmission and the retransmission.
A computer readable medium having computer executable code stored thereon for wireless communications, comprising:

code for sending a transmission of a packet with a first hybrid automatic repeat request (HARQ) redundancy version (RV) ; and

code for sending a retransmission of the packet with the first HARQ RV or a second HARQ RV based on a signal quality difference between the transmission and the retransmission.
A computer readable medium having computer executable code stored thereon for wireless communications, comprising:

code for decoding a received transmission of a packet; and

code for decoding a received retransmission of the packet independently or joint decoding the received retransmission of the packet and the received retransmission of the packet, based on a signal quality difference between the transmission and the retransmission.