WO2022151165A1

WO2022151165A1 - Apparatus, method, and computer program

Info

Publication number: WO2022151165A1
Application number: PCT/CN2021/071786
Authority: WO
Inventors: Volker PAULI; David Bhatoolaul; Naizheng ZHENG; David Navratil; Athul Prasad; Ugur Baran ELMALI
Original assignee: Nokia Shanghai Bell Co., Ltd.; Nokia Solutions And Networks Oy; Nokia Technologies Oy
Priority date: 2021-01-14
Filing date: 2021-01-14
Publication date: 2022-07-21

Abstract

The disclosure relates to an apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: receive (800) a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission; and determine (802) whether to attempt to decode a part of the transmission comprising the transport block based on the transport block indicator.

Description

APPARATUS, METHOD, AND COMPUTER PROGRAM

Field of the disclosure

The present disclosure relates to an apparatus, a method, and a computer program for determining whether to attempt to decode a part of a transmission comprising a transport block based on a transport block indicator in a communication system.

Background

A communication system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, base stations/access points and/or other nodes by providing carriers between the various entities involved in the communications path. A communication system can be provided for example by means of a communication network and one or more compatible communication devices. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, electronic mail (email) , text message, multimedia and/or content data and so on. Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet. In a wireless communication system at least a part of a communication session between at least two stations occurs over a wireless link.

A user can access the communication system by means of an appropriate communication device or terminal. A communication device of a user is often referred to as user equipment (UE) or user device. A communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other users. The communication device may access a carrier provided by a station or access point and transmit and/or receive communications on the carrier.

The communication system and associated devices typically operate in accordance with a required standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and/or parameters which shall be used for the connection are also typically defined. One example of a communications system is UTRAN (3G radio) . Another example of an architecture that is known as the long-term evolution (LTE) or the Universal Mobile Telecommunications System (UMTS) radio-access technology. Another example of a communication system is so called 5G radio or new radio (NR) access technology. Another example of a communication system is a wireless local area network (WLAN) such as WiFi.

Summary

According to an aspect there is provided an apparatus comprising means for: receiving a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission; and determining whether to attempt to decode a part of the transmission comprising the transport block based on the transport block indicator.

A medium access control packet data unit may comprise the transport block of the transmission.

The apparatus may comprise means for: determining that the transport block indicator indicates a retransmission comprising the transport block; determining that a previous transmission comprising the transport block has been decoded; and abstaining from attempting to decode the transport block.

The apparatus may comprise means for: determining that the transport block indicator indicates a retransmission comprising the transport block; determining that a previous transmission comprising the transport block has not been decoded; and attempting to decode the transport block based on the retransmission comprising transport block.

The apparatus may comprise means for: attempting to decode the transport block based on the retransmission comprising the transport block and a previous transmission comprising the transport block.

The apparatus may comprise means for: determining that the transport block indicator indicates a first transmission comprising the transport block; and attempting to decode the transport block based on the first transmission comprising the transport block.

The apparatus may comprise means for: determining whether the decoding is successful or not successful; and provide a negative feedback if the decoding is not successful.

The transport block indicator may be received on resource elements of the semi-persistently scheduled resources, wherein the resource elements are dispersed in frequency.

The transport block indicator may be received on a first symbol of the semi-persistently scheduled resources.

The transport block indicator may comprise one or more bits.

The transport block indicator may further comprise a redundancy version or an index of retransmission.

The transport block may convey data for a unicast service, a multicast or a broadcast service.

The apparatus may be a terminal.

According to an aspect there is provided an apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: receive a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission; and determine whether to attempt to decode a part of the transmission comprising the transport block based on the transport block indicator.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus at least to: determine that the transport block indicator indicates a retransmission comprising the transport block; determine that a previous transmission comprising the transport block has been decoded; and abstain from attempting to decode the transport block.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus at least to: determine that the transport block indicator indicates a retransmission comprising the transport block; determine that a previous transmission comprising the transport block has not been decoded; and attempt to decode the transport block based on the retransmission comprising transport block.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus at least to: attempt to decode the transport block based on the retransmission comprising the transport block and a previous transmission comprising the transport block.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus at least to: determine that the transport block indicator indicates a first transmission comprising the transport block; and attempt to decode the transport block based on the first transmission comprising the transport block.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus at least to: determine whether the decoding is successful or not successful; and provide a negative feedback if the decoding is not successful.

The transport block indicator may comprise one or more bits.

The apparatus may be a terminal.

According to an aspect there is provided an apparatus comprising circuitry configured to: receive a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission; and determine whether to attempt to decode a part of the transmission comprising the transport block based on the transport block indicator.

The apparatus may comprise circuitry configured to: determine that the transport block indicator indicates a retransmission comprising the transport block; determine that a previous transmission comprising the transport block has been decoded; and abstain from attempting to decode the transport block.

The apparatus may comprise circuitry configured to: determine that the transport block indicator indicates a retransmission comprising the transport block; determine that a previous transmission comprising the transport block has not been decoded; and attempt to decode the transport block based on the retransmission comprising transport block.

The apparatus may comprise circuitry configured to: attempt to decode the transport block based on the retransmission comprising the transport block and a previous transmission comprising the transport block.

The apparatus may comprise circuitry configured to: determine that the transport block indicator indicates a first transmission comprising the transport block; and attempt to decode the transport block based on the first transmission comprising the transport block.

The apparatus may comprise circuitry configured to: determine whether the decoding is successful or not successful; and provide a negative feedback if the decoding is not successful.

The transport block indicator may comprise one or more bits.

The apparatus may be a terminal.

According to an aspect there is provided a method comprising: receiving a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission; and determining whether to attempt to decode a part of the transmission comprising the transport block based on the transport block indicator.

The method may comprise: determining that the transport block indicator indicates a retransmission comprising the transport block; determining that a previous transmission comprising the transport block has been decoded; and abstaining from attempting to decode the transport block.

The method may comprise: determining that the transport block indicator indicates a retransmission comprising the transport block; determining that a previous transmission comprising the transport block has not been decoded; and attempting to decode the transport block based on the retransmission comprising transport block.

The method may comprise: attempting to decode the transport block based on the retransmission comprising the transport block and a previous transmission comprising the transport block.

The method may comprise: determining that the transport block indicator indicates a first transmission comprising the transport block; and attempting to decode the transport block based on the first transmission comprising the transport block.

The method may comprise: determining whether the decoding is successful or not successful; and provide a negative feedback if the decoding is not successful.

The transport block indicator may comprise one or more bits.

The method may be performed by a terminal.

According to an aspect there is provided a computer program comprising computer executable code which when run on at least one processor is configured to: receive a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission; and determine whether to attempt to decode a part of the transmission comprising the transport block based on the transport block indicator.

The computer program may comprise computer executable code which when run on at least one processor is configured to: determine that the transport block indicator indicates a retransmission comprising the transport block; determine that a previous transmission comprising the transport block has been decoded; and abstain from attempting to decode the transport block.

The computer program may comprise computer executable code which when run on at least one processor is configured to: determine that the transport block indicator indicates a retransmission comprising the transport block; determine that a previous transmission comprising the transport block has not been decoded; and attempt to decode the transport block based on the retransmission comprising transport block.

The computer program may comprise computer executable code which when run on at least one processor is configured to: attempt to decode the transport block based on the retransmission comprising the transport block and a previous transmission comprising the transport block.

The computer program may comprise computer executable code which when run on at least one processor is configured to: determine that the transport block indicator indicates a first transmission comprising the transport block; and attempt to decode the transport block based on the first transmission comprising the transport block.

The computer program may comprise computer executable code which when run on at least one processor is configured to: determine whether the decoding is successful or not successful; and provide a negative feedback if the decoding is not successful.

The transport block indicator may comprise one or more bits.

The at least one processor may be part of a terminal.

According to an aspect there is provided an apparatus comprising means for: transmitting a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission.

A medium access control packet data unit comprises the transport block of the transmission.

The apparatus may comprise means for: receiving a negative feedback if the decoding is not successful.

The transport block indicator may be transmitted on resource elements of the semi-persistently scheduled resources, wherein the resource elements are dispersed in frequency.

The transport block indicator may be transmitted on a first symbol of the semi-persistently scheduled resources.

The transport block indicator may comprise one or more bits.

The apparatus may be a base station.

According to an aspect there is provided an apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to: transmit a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission.

The at least one memory and the computer code may be configured, with the at least one processor, to cause the apparatus at least to: receive a negative feedback if the decoding is not successful.

The transport block indicator may comprise one or more bits.

The apparatus may be a base station.

According to an aspect there is provided an apparatus comprising circuitry configured to:transmit a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission.

The apparatus may comprise circuitry configured to: receive a negative feedback if the decoding is not successful.

The transport block indicator may comprise one or more bits.

The apparatus may be a base station.

According to an aspect there is provided a method comprising: transmitting a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission.

The method may comprise: receiving a negative feedback if the decoding is not successful.

The transport block indicator may comprise one or more bits.

The method may be performed by a base station.

According to an aspect there is provided a computer program comprising computer executable code which when run on at least one processor is configured to: transmit a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission.

The computer program may comprise computer executable code which when run on at least one processor is configured to: receive a negative feedback if the decoding is not successful.

The transport block indicator may comprise one or more bits.

The at least one processor may be part of a base station.

According to an aspect, there is provided a computer readable medium comprising program instructions stored thereon for performing at least one of the above methods.

According to an aspect, there is provided a non-transitory computer readable medium comprising program instructions stored thereon for performing at least one of the above methods.

According to an aspect, there is provided a non-volatile tangible memory medium comprising program instructions stored thereon for performing at least one of the above methods.

In the above, many different aspects have been described. It should be appreciated that further aspects may be provided by the combination of any two or more of the aspects described above.

Various other aspects are also described in the following detailed description and in the attached claims.

List of abbreviations

ACK: Acknowledgement

AF: Application Function

AMC: Adaptive Modulation and Coding

AMF: Access Management Function

API: Application Protocol Interface

BLER: Block Error Rate

BS: Base Station

CDF: Cumulative Distributive Function

CSI: Channel State Information

CU: Centralized Unit

DCI: Downlink Control Information

DL: Downlink

DMRS: Demodulation Reference Signal

DU: Distributed Unit

gNB: gNodeB

GCS RNTI: Group-common Configured Scheduling Radio Network Temporary Identifier

G-RNTI: Group Radio Network Temporary Identifier

GSM: Global System for Mobile communication

HARQ: Hybrid Automated Repeat Request

HSS: Home Subscriber Server

IMT: International Mobile Telecommunications

IoT: Internet of Things

LTE: Long Term Evolution

MAC: Medium Access Control

MCS: Modulation and Coding Scheme

MS: Mobile Station

MTC: Machine Type Communication

NACK: Non-Acknowledgement

NDI: New Data indicator

NEF: Network Exposure Function

NF: Network Function

NR: New radio

NRF: Network function Repository Function

PDCCH: Physical Downlink Control Channel

PRB: Physical Resource Block

PDSCH: Physical Downlink Shared Channel

PDU: Packet Data Unit

PUCCH: Physical Uplink Control Channel

RAM: Random Access Memory

(R) AN: (Radio) Access Network

ROM: Read Only Memory

RRC: Radio Resource Control

SCI: Sidelink Control Information

SC-PTM: Single Cell Point to Multipoint

SDU: Service Data unit

SE: Spectrum Efficiency

SMF: Session Management Function

SPS: Semi-Persistent Scheduling

TB: Transport Block

TR: Technical Report

TS: Technical Specification

TTI: Transmission Time Interval

UE: User Equipment

UMTS: Universal Mobile Telecommunication System

WID: Work Item Description

WLAN: Wireless Local Area Network

3GPP: 3 ^rd Generation Partnership Project

5G: 5 ^th Generation

5GC: 5G Core network

5GS: 5G System

Brief Description of the Figures

Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which:

Figure 1 shows a schematic representation of a 5G system;

Figure 2 shows a schematic representation of a control apparatus;

Figure 3 shows a schematic representation of a terminal;

Figure 4 shows the spectral efficiency of NR single cell point to multipoint with different adaptive modulation and coding strategies;

Figure 5 shows a proposed scheme with split control signaling for retransmissions in semi-persistent scheduling;

Figure 6 shows a scheme with a conventional new data indicator;

Figure 7a shows the proposed scheme with a proposed new data indicator;

Figure 7b shows the proposed scheme with the proposed new data indicator when a new data indicator error occurs on a last retransmission of a transport block;

Figure 7c shows the proposed scheme with the proposed new data indicator when a new data indicator error occurs on a first transmission of a transport block;

Figure 8 shows a block diagram of a method for determining whether to attempt to decode a transport block based on a transport block indicator performed, for example, by a terminal;

Figure 9 shows a block diagram of a method for determining whether to attempt to decode a transport block based on a transport block indicator performed, for example, by a base station; and

Figure 10 shows a schematic representation of a non-volatile memory medium storing instructions which when executed by a processor allow a processor to perform one or more of the steps of the methods of Figures 8 and 9.

Detailed Description of the Figures

In the following certain embodiments are explained with reference to mobile communication devices capable of communication via a wireless cellular system and mobile communication systems serving such mobile communication devices. Before explaining in detail the exemplifying embodiments, certain general principles of a wireless communication system, access systems thereof, and mobile communication devices are briefly explained with reference to Figures 1, 2 and 3 to assist in understanding the technology underlying the described examples.

Figure 1 shows a schematic representation of a 5G system (5GS) . The 5GS may comprises a terminal, a (radio) access network ( (R) AN) , a 5G core network (5GC) , one or more application functions (AF) and one or more data networks (DN) .

The 5G (R) AN may comprise one or more gNodeB (gNB) distributed unit functions connected to one or more gNodeB (gNB) centralized unit functions.

The 5GC may comprise an access management function (AMF) , a session management function (SMF) , an authentication server function (AUSF) , a user data management (UDM) , a user plane function (UPF) and/or a network exposure function (NEF) . Although not illustrated the 5GC may comprise other network functions (NF) .

Figure 2 illustrates an example of a control apparatus 200 for controlling a function of the (R) AN or the 5GC as illustrated on Figure 1. The control apparatus may comprise at least one random access memory (RAM) 211a, at least on read only memory (ROM) 211b, at least one

processor

212, 213 and an input/output interface 214. The at least one

processor

212, 213 may be coupled to the RAM 211a and the ROM 211b. The at least one

processor

212, 213 may be configured to execute an appropriate software code 215. The software code 215 may for example allow to perform one or more steps to perform one or more of the present aspects. The software code 215 may be stored in the ROM 211b. The control apparatus 200 may be interconnected with another control apparatus 200 controlling another function of the 5G (R) AN or the 5GC. In some embodiments, each function of the (R) AN or the 5GC comprises a control apparatus 200. In alternative embodiments, two or more functions of the (R) AN or the 5GC may share a control apparatus.

Figure 3 illustrates an example of a terminal 300, such as the terminal illustrated on Figure 1. The terminal 300 may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a user equipment, a mobile station (MS) or mobile device such as a mobile phone or what is known as a ’smart phone’ , a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle) , a personal data assistant (PDA) or a tablet provided with wireless communication capabilities, a machine-type communications (MTC) device, a Cellular Internet of things (CIoT) device or any combinations of these or the like. The terminal 300 may provide, for example, communication of data for carrying communications. The communications may be one or more of voice, electronic mail (email) , text message, multimedia, data, machine data and so on.

The terminal 300 may receive signals over an air or radio interface 307 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 3 transceiver apparatus is designated schematically by block 306. The transceiver apparatus 306 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

The terminal 300 may be provided with at least one processor 301, at least one memory ROM 302a, at least one RAM 302b and other possible components 303 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The at least one processor 301 is coupled to the RAM 302a and the ROM 211b. The at least one processor 301 may be configured to execute an appropriate software code 308. The software code 308 may for example allow to perform one or more of the present aspects. The software code 308 may be stored in the ROM 302b.

The processor, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 304. The device may optionally have a user interface such as keypad 305, touch sensitive screen or pad, combinations thereof or the like. Optionally one or more of a display, a speaker and a microphone may be provided depending on the type of the device.

As part of a work item description (WID) on 5G /NR multicast (RP-201038 [1] ) , 3GPP is currently defining mechanisms for enabling the delivery of multicast/broadcast traffic to a multitude of UEs. One of the key aims of the WID is to define group scheduling mechanisms that enable the multicast/broadcast traffic to be scheduled using common data channel resources while maintaining maximum commonalities with the currently defined unicast scheduling and operation mechanisms.

Among other things, the option of semi-persistent scheduling (SPS) is being considered as per agreement of RAN1 during the meeting #103-e:

“Agreements: Support SPS group-common PDSCH for MBS for RRC_CONNECTED UEs

● FFS (1) : use group-common PDCCH or UE-specific PDCCH for SPS group-common PDSCH activation/deactivation

● FFS (2) : whether to support more than one SPS group-common PDSCH configuration per UE

● FFS (3) : whether and how uplink feedback could be configured

● FFS (4) : retransmission of SPS group-common PDSCH”

With SPS not each transmission on the physical downlink shared channel (PDSCH) may be scheduled individually. A periodic pattern of resources may be allocated for repeated use until further notice.

SPS may be attractive for periodic traffic or more generally any traffic that can be transmitted using a fairly persistent allocation of radio resources. SPS may save control signaling overhead in the form of physical downlink control channel (PDCCH) .

Solutions have been provided to address basic SPS scheduling and configuration for NR point to multipoint (PTM) and focus on FFS (1) and FFS (2) in the above agreement.

On or more aspects of this disclosure may provide a solution for FFS (4) in the above agreement.

SPS has been defined for scheduling of periodic unicast traffic (e.g. VoIP in LTE) . Sticking to the example of VoIP traffic, where during active periods speech frames are sent every 20ms, the basic approach foresees an SPS allocation of sufficient physical resource bocks (PRBs) every 20ms to transmit the speech frames. In case of a decoding failure (i.e. in the downlink case the UE reporting a non-acknowledgement (NACK) ) , hybrid automatic repeat request (HARQ) retransmissions may be scheduled dynamically. That is, there may be no SPS allocation to cater for such retransmissions. Downlink control information (DCI) may be sent on PDCCH announcing a dynamic allocation for one particular HARQ retransmission. This may still result in considerable PDCCH overhead savings as the modulation and coding scheme (MCS) may typically be adjusted to have only in the order of 10%transmission failures on the first transmission.

However, studies have shown that single cell point to multipoint (SC-PTM) in NR may be much more spectrally efficient when operating with several HARQ transmissions per transport block.

Figure 4 provides some results on spectral efficiency (SE) in a dense urban (IMT-2020 evaluation) scenario with twenty UEs per cell and a maximum of eight HARQ transmissions per transport block. Specifically, Figure 4 shows the cumulative distribution function (CDF) of the SE achieved in the SC-PTM delivery, where samples for the distribution are taken per cell and per random dropping of the 20 UEs per cell.

Starting from the left, the first graph (dotted line) shows a reference case of running an adaptive modulation and coding (AMC) to meet a target block error rate (BLER) of 1%without any retransmissions (e.g. using SPS only and no dynamic scheduling of HARQ retransmissions at all) .

The second graph (dash-dotted line) shows the SE performance for an AMC scheme configured with conventional settings from unicast. Even here, it may be noted that the BLER of 30%may apply to the worst UE in the cell. However, in total (due to uncorrelated error events of different UEs) the overall rate of retransmissions in a cell may be considerably higher than 30%. Accordingly, while SE of the PTM transmission itself may be improved considerably, benefits of SPS for first transmissions may be quite limited.

The third graph (dashed line) shows the SE performance for an AMC scheme relying exclusively on blind transmissions of four different redundancy versions (i.e. four different blocks of code bits representing the same transport block) . It may be observed that a comparable SE performance may be obtained as for the conventional AMC configuration, while this scheme could be operated exclusively based on SPS. It may be noted that the simulated AMC scheme may not follow fast fading variations of UEs (e.g. based on frequent channel state information (CSI) reports) . The simulated AMC scheme may be adjusted at a quite slow pace based on BLER measurements, which is well aligned with SPS resource allocations for transmission of data traffic at a fairly steady rate.

The fourth graph (solid line) shows the SE performance for an AMC scheme relying heavily on HARQ retransmissions. Considerable improvements in SE performance may be achieved. Here, approximately 80%of all PDSCH transmissions are in fact HARQ retransmissions (i.e. for every transport block there are in addition to the initial transmission further on average four HARQ retransmissions) . It may be noted that this high rate of retransmissions when averaged over a time in the order of 100ms is in fact quite stable due to the fact that multiple UEs with uncorrelated error events may contribute to this.

SPS scheduling has been defined for unicast in LTE and NR. Retransmissions may be scheduled dynamically using dedicated full DCI structures sent on the PDCCH. Such allocations are either in transmission time intervals (TTIs) that are not covered by the SPS pattern or they overrule the SPS allocation in a particular TTI.

Solutions have been proposed to address SPS scheduling for PTM in NR. These solutions do not deal with scheduling of HARQ retransmissions.

The concept of “inband signaling” at physical layer (i.e. transmitting DCI structures on the PDSCH resources) may be used in EPDCCH for LTE or for machine type communication (MTC) .

NR vehicle to everything (V2X) in release 16 introduced a mode where sidelink control information (SCI) may be split in two parts. One of which may be transmitted on the PSCCH and the other may be transmitted along with the payload on the PSSCH. In release 15 the whole SCI may be transmitted on the PSCCH.

A binary new data indicator (NDI) that is signaled in the DCI as NDI=1 to indicate a first HARQ transmission and NDI=0 to indicate a HARQ retransmission may be used in LTE and NR.

One or more aspects of this disclosure may combine SPS based resource allocation with in-band signalling of HARQ retransmissions.

On the one hand SPS may be used to semi-persistently allocate radio resources for a data service (e.g. PTM data service) to be transmitted. In this way, the PDCCH may only be used sporadically to activate /deactivate /modify the SPS allocation. Herein, the DCIs sent on the PDCCH may be conventional DCIs indicating some of or all that is needed for the receiver to decode the PDSCH (e.g. PRB allocation, frequency domain resource allocation (FDRA) , MCS and/or SPS-specific configuration such as periodicity of the PDSCH allocation) .

On the other hand, in order to minimize the overhead of scheduling of retransmissions, a transport block indicator is defined that is signalled in-band (i.e. on the SPS-allocated PDSCH resources) to help the receiving UEs understand, whether the transmission in this TTI is another retransmission of a transport block (TB) or whether it is a first transmission of a TB. A TB may comprise the data payload passed between a MAC layer and a PHY layer. A TB may be transmitted as a MAC PDU. A TB may comprise one or more MAC SDUs. A transmission may comprise both the TB (e.g. MAC PDU) and the transport block indicator. The transport block indicator may be transmitted outside any MAC PDU. The transport block and the transport block indicator may be signalled in the PDSCH.

The transport block indicator may comprise a conventional NDI.

The transport block indicator may comprise a new NDI with a different definition than the conventional NDI.

The transport block indicator may comprise a redundancy version or an index of retransmission.

For each (re-) transmission related to a TB the transmitter may select a block of code bits that represent the TB. Each (distinct but not necessarily non-overlapping) selection of code bits may constitute a redundancy version. For example, in 5G NR, there may be 4 different redundancy versions.

The index of (re-) transmission may count the number of blocks of code bits the transmitter sends. In 5G NR, this may be limited to e.g. 8. However, there may be no one-to-one mapping between index of retransmission and redundancy version (i.e. the maximum number of transmissions per TB may be different to the number of different redundancy versions) .

The receiving UE may know whether to:

(i) combine the signal (i.e. control and/or data) received in this TTI for a TB with already collected signals for the same TB, in case the NDI indicates a retransmission of a TB and the UE has not successfully decoded the TB

(ii) ignore the data received in this TTI for a TB in case the NDI indicates a retransmission of a TB (e.g. requested by another UE but the UE has already successfully decoded the TB based on earlier transmissions related to the TB)

(iii) try to decode the signal (i.e. control and/or data) received in this TTI for a TB (and possibly flush any obsolete content related to an preceding TB from a corresponding soft buffer of the HARQ process) in case the NDI indicates a first transmission of a TB.

One or more aspects of this disclosure may deviate from the conventional NDI, where a value of 1 indicates a first HARQ transmission of a TB while a value of 0 indicates a HARQ retransmission of a TB.

One or more aspects of this disclosure may introduce a new NDI that is toggled between 0 and 1 from HARQ (re-) transmissions that belong to one TB to HARQ (re-) transmissions that belong to another TB. That is, the new NDI is constant for a TB regardless the TB is transmitted for the first time or retransmitted. The new NDI toggles every time another TB is transmitted for the first time. The NDI toggling may be performed on a per-HARQ-process basis (i.e. each HARQ process may have its own NDI) .

The NDI may be error-protected separately from the data. In this way, a UE may decode the NDI and the data independently and may subsequently properly process the data. Hereby, a conventional error protection scheme for very small amounts of control information can be applied. For the sake of diversity, the resource elements used for the NDI may be dispersed in frequency across the SPS allocated resources. Examples of conventional error protection scheme may comprise Polar codes, other block or spreading codes, as already applied for control signalling on PDCCH or PUCCH. The NDI may be sent in the first symbol of the SPS allocated resources. In this way, if the NDI indicates a retransmission of a TB, all UEs that have already successfully decoded the TB may not process the data thereby conserving battery power.

Apart from the new NDI definition, other elements may be borrowed from what has been defined for SCI transmission in release 16. Redundancy versions may be transmitted in a sequence defined by the increasing order of redundancy version value (i.e. redundancy version 0 may be followed by redundancy version 1 and so on) . The sequence may be reset when the NDI indicates new transmission. If other sequences should be supported then these could be signaled by radio resource control (RRC) as part of SPS configuration. However, any of the options above may not allow the network to select the redundancy version dynamically based on the HARQ feedback. A dynamic selection of redundancy version may require that the redundancy version is signaled inband along with the NDI. In any case, signalling the redundancy version may improve the resilience against transport block decoding errors in consequence to errors on the NDI.

An advantage of the proposed scheme is that HARQ retransmissions may be scheduled within the SPS allocated resources without creating any load on the PDCCH and with only minimal overhead on the PDSCH.

Another advantage of the proposed scheme is that the NDI may be transmitted along with the other PDSCH data such that better channel estimation/equalization performance may to be expected due to the collocation to larger PDSCH allocations and with that demodulation reference signals (DMRS) in the time and/or frequency domain.

Figure 5 illustrates an example of the proposed scheme with the new NDI. A gNB may signal an SPS grant to a UE via PDCCH. The SPS grant may indicate periodically SPS allocated resources on PDSCH. The gNB may signal data and an NDI for a TB to the UE in the SPS allocated resources on PDSCH. The UE may fail to decode successfully the TB. The UE may signal a NACK to the gNB via PUCCH.

The gNB may signal data and an NDI for the same TB to the UE in the SPS allocated resources on PDSCH. The NDI is constant (i.e. not toggled) to indicate a retransmission of the same TB. The UE may decode successfully the TB. The UE may signal an ACK to the gNB via PUCCH.

The gNB may signal data and the NDI for another TB to the UE in the SPS allocated resources on PDSCH. The NDI is changed (i.e. toggled) to indicate a first transmission of a new TB.

In contrast with existing schemes, the proposed scheme support HARQ retransmissions in SPS mode without requiring PDCCH resources to announce the individual HARQ retransmissions.

For simplicity Figure 5 shows operation of only one HARQ process while it is to be understood that if multiple HARQ processes are available/configured for an SPS process, these can operate in an interleaved manner.

The PUCCH signalling shown in the lower part of Figure 5 is to be understood as being illustrative. In general, the one or more UEs may send such HARQ feedback (in the form of an ACK/NACK on a dedicated PUCCH resource or NACK-only on a group-common PUCCH resource) . Typically, a retransmission would be sent in response to a NACK from any of the one or more UEs.

Figure 6 illustrates an example of a scheme with the conventional NDI. A gNB may signal an SPS grant to UE1, UE2 and UE3 via PDCCH (not shown) . The SPS grant may indicate SPS allocated resources on PDSCH.

The gNB may transmit MAC PDU 1 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI is set to ‘1’ to indicate a first transmission of MAC PDU 1 (1 ^st TX of MAC PDU 1) . UE1 and UE2 may fail to decode successfully the MAC PDU 1. UE1 and UE2 may signal a NACK to the gNB via PUCCH. UE3 may decode successfully the MAC PDU 1. UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit the MAC PDU 1to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI is set to ‘0’ to indicate a retransmission of MAC PDU 1 (2 ^nd TX of MAC PDU 1) . UE1 may fail to decode successfully the MAC PDU 1. UE1 may signal a NACK to the gNB via PUCCH. UE2 may decode successfully the MAC PDU 1. UE2 may signal an ACK to the gNB via PUCCH. After observing the NDI UE3 may abstain from decoding the MAC PDU 1. UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit the MAC PDU 1 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI is set to ‘0’ to indicate a retransmission of MAC PDU 1 (3 ^rd TX of MAC PDU 1) . UE1 may fail to decode successfully the MAC PDU 1. UE1 may signal a NACK to the gNB via PUCCH. After observing the NDI UE2 and UE3 may abstain from decoding the MAC PDU 1. UE2 and UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit MAC PDU 1 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI is set to ‘0’ to indicate a retransmission of MAC PDU 1 (4 ^th TX of MAC PDU 1) . UE1 may decode successfully the MAC PDU 1. UE1, UE2 and UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit MAC PDU 2 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI is set to ‘1’ to indicate a first transmission of the MAC PDU 2 (1 ^st TX of MAC PDU 1) . UE1 and UE2 may fail to decode successfully the MAC PDU 2. UE1 and UE2 may signal a NACK to the gNB via PUCCH. UE3 may decode successfully the TB. UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit the MAC PDU 2 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI is set to ‘0’ to indicate a retransmission of the MAC PDU 2 (2 ^nd TX of MAC PDU 2) . UE2 may fail to decode successfully the MAC PDU 2. UE2 may signal a NACK to the gNB via PUCCH. UE1 may decode successfully the MAC PDU 2. UE1 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH. After observing the NDI UE3 may abstain from decoding the TB. UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit the MAC PDU 2 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI is set to ‘0’ to indicate a retransmission of the MAC PDU 2 (3 ^rd TX of MAC PDU 2) . UE1 may decode successfully the TB. UE1, UE2 and UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit MAC PDU 3 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI is set to ‘1’ to indicate a first transmission of the MAC PDU 3 (1 ^st TX of MAC PDU 3) and so on.

Figure 7a illustrates an example of the proposed scheme with the new NDI. A gNB may signal an SPS grant to UE1, UE2 and UE3 via PDCCH (not shown) . The SPS grant may indicate SPS allocated resources on PDSCH.

The gNB may transmit MAC PDU 1 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI is set to ‘1’ to indicate a first transmission of the MAC PDU 1 (1 ^st TX of MAC PDU 1) . UE1 and UE2 may fail to decode successfully the MAC PDU 1. UE1 and UE2 may signal a NACK to the gNB via PUCCH. UE3 may decode successfully the MAC PDU 1. UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit the MAC PDU 1 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI remains set to ‘1’ (i.e. not toggled) to indicate a retransmission of the MAC PDU 1 (2 ^nd TX of MAC PDU 1) . UE1 may fail to decode successfully the MAC PDU 1. UE1 may signal a NACK to the gNB via PUCCH. UE2 may decode successfully the TB. UE2 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH. After observing the NDI UE3 may abstain from decoding the MAC PDU 1. UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit the MAC PDU 1 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI remains set to ‘1’ (i.e. not toggled) to indicate a retransmission of the MAC PDU 1 (3 ^rd TX of MAC PDU 1) . UE1 may fail to decode successfully the MAC PDU 1. UE1 may signal a NACK to the gNB via PUCCH. After observing the NDI UE2 and UE3 may abstain from decoding the MAC PDU 1. UE2 and UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit the MAC PDU 1 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI remains set to ‘1’ to indicate a retransmission of the MAC PDU 1 (4 ^th TX of MAC PDU 1) . UE1 may decode successfully the MAC PDU 1. UE1, UE2 and UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit a MAC PDU 2 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI is set to ‘0’ (i.e. toggled) to indicate a first transmission of the MAC PDU 2 (1 ^st TX of MAC PDU 2) . UE1 and UE2 may fail to decode successfully the MAC PDU 2. UE1 and UE2 may signal a NACK to the gNB via PUCCH. UE3 may decode successfully the MAC PDU 2. UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit the MAC PDU 2 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI remains set to ‘0’ (i.e. not toggled) to indicate a retransmission of the MAC PDU 2 (2 ^nd TX of MAC PDU 2) . UE2 may fail to decode successfully the MAC PDU 2. UE2 may signal a NACK to the gNB via PUCCH. UE1 may decode successfully the TB. UE1 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH. After observing the NDI UE3 may abstain from decoding the MAC PDU 2. UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit the MAC PDU 2 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI remains set to ‘0’ (i.e. not toggled) to indicate a retransmission of the MAC PDU 2 (3 ^rd TX of MAC PDU) . UE1 may decode successfully the MAC PDU 2. UE1, UE2 and UE3 may signal an ACK to the gNB via PUCCH or may abstain from sending an ACK to the gNB via PUCCH.

The gNB may transmit a MAC PDU 3 to the UE1, UE2 and UE3 in the SPS allocated resources on PDSCH. The NDI is set to ‘1’ to indicate a first transmission of the MAC PDU 3 and so on.

It will be understood that the schemes of Figure 6 and 7 (i.e. scheme with conventional NDI and proposed scheme with new NDI) are both feasible. However, the scheme of Figure 7a (i.e. proposed scheme with new NDI) may be advantageous over the scheme of Figure 6 (i.e. scheme with conventional NDI) when errors occurs on the NDI (i.e. when an NDI set to ‘1’ is decoded as ‘0’ or vice versa.

With the scheme of Figure 7a (i.e. proposed scheme with new NDI) if the error occurs on the NDI within a first transmission of a TB, a UE may not decode the TB when first transmitted but the UE may decode the TB when retransmitted. The error might not cause any further harm, in particular not to the previous TB. The UE might not have decoded a previous TB anyway as the gNB apparently has no intention to send any more retransmission for the previous TB.

By contrast, with the scheme of Figure 6 (i.e. scheme with conventional NDI) if the error occurs on the NDI within a first transmission of a TB, a UE may not decode the TB when first transmitted but the UE may not decode the TB when retransmitted either because the UE missed the indication indicating the first transmission of the TB. For example, when not decoding NDI=1 for first transmission of MAC PDU 2, a UE may erroneously consider that all the transmissions of the new TB (MAC PDU 2) are retransmissions of the previous TB (MAC PDU 1) . Thus, if the UE has successfully decoded MAC PDU 1, then a UE may neglect all MAC PDU 2 transmissions.

With the scheme of Figure 7a (i.e. proposed scheme with new NDI) if the error occurs on the NDI outside a first transmission of a TB and a last retransmission of the TB (e.g. a first retransmission) , a UE may still decode the TB when subsequently retransmitted (e.g. a second retransmission) .

In this case, the first transmission of the TB and the first retransmission of the TB may be wasted. The number of transmission/retransmissions based on which the UE can attempt to decode the TB may be reduced by two. In case a UE succeeds in decoding the TB based on a transmission/retransmission where the NDI was in error, then duplicates may occur and may be filtered at higher layers.

By contrast, with the scheme of Figure 6 (i.e. scheme with conventional NDI) if the error occurs on the NDI outside a first transmission of a TB and a last retransmission of the TB (e.g. a first retransmission) , when subsequently retransmitted (e.g. a second retransmission) a UE may not decode the TB because the UE missed the indication indicating the first transmission of the TB.

With the scheme of Figure 7a (i.e. proposed scheme with new NDI) if the error occurs in the last retransmission of the TB, there may be a problem with decoding the subsequent TB because the UE may include erroneous soft bits from a transmission of a previous TB in the decoding.

Accordingly, the UE may keep sending NACKs and hence receiving more retransmissions from the gNB until the maximum number N _HARQ, max of allowed transmissions is reached.

If the UE knows N _HARQ, max, the UE may realize eventually that it has received too many retransmission of a TB with the same NDI value and may then attempt decoding using only the buffered soft bits of the last valid N _HARQ, max retransmission. Most likely, decoding would not be impacted by the NDI error. The only harm may be that this NDI error might have triggered a number of HARQ retransmissions that would not have been needed if there had not been that NDI error on the last retransmission of the previous TB.

Figure 7b shows the scheme of Figure 7a (i.e. proposed scheme with new NDI) when an NDI error occurs on a last retransmission of a transport block.

In a scenario, when the NDI error occurs on a last retransmission of a TB (MAC PDU 1) , the UE 2 may decode the TB twice. The UE 2 may detect the duplicated PDU 1 and may realize that an NDI error must have occurred on the last retransmission of the TB.

In another scenario, when the NDI error occurs on a last retransmission of a TB (MAC PDU 2) , the UE 2 may successfully decode the TB. However, the UE 2 may ignore the first transmission of the subsequent TB (MAC PDU 3) . The UE 2 may also ignore the retransmissions of the subsequent TB. That is, the UE may abstain from decoding the subsequent TB. This scenario appears to be far less likely than the previous one, but it may arise in conjunction with beam sweeping. Then a non-binary NDI (e.g. 2-bit sequence number) or the redundancy version or index of the retransmission mentioned above could resolve the problem.

In this scenario: when there is no error on the NDI and index of the retransmission for the transmissions of MAC PDU 3, in particular on the first transmission of MAC PDU 3, the UE 2 may know that there must have been something wrong. Even if at this point, the UE 2 may not know, whether the error was on the last transmission of PDU 2 or the first transmission of the MAC PDU 3, the UE 2 may know that something is wrong. Having already allegedly decoded the MAC PDU 3 from the last transmission of the MAC PDU 2 the UE 2 could just go ahead and decode the first actual transmission of PDU 3 independently as the index of retransmission tells the UE that this is a first transmission.

It will be understood that if the index of retransmission is used then the NDI may not be needed at all. Whenever the UE 2 finds the index of retransmission being equal to 1 the UE 2 may assume that this is a first transmission.

If there was an error of detecting an NDI equal to 1 when the index of retransmission was actually larger than 1 then this may lead to duplicates or ignoring previous HARQ transmissions in subsequent decoding attempts. A smart UE 2 could also consider the sequence of received indexes of transmission and make guesses which indexes of transmission were most likely to be wrong (e.g. decoding a sequence of indexes of

transmission

5, 6, 1, 1, 2, 3, 4 could very well mean that 5, 6, 7, 1, 2, 3, 4 is what was actually sent, at least if this UE 2 had requested a 7th transmission on the first of the two TBs. The UE could then (also) try decoding the two TBs based on this assumed

sequence

5, 6, 7, 1, 2, 3, 4) .

The redundancy version or index of the retransmission may be used as an additional means to detect decoding errors on the NDI or might even be used instead of the NDI. An advantage would be improved resilience to errors on this control signalling. However, more resources may be required to protect this control signalling equally well as the NDI.

Figure 7c shows the scheme of Figure 7a (i.e. proposed scheme with new NDI) when an NDI error occurs on a first retransmission of a transport block.

In a scenario, when the NDI error occurs on a first transmission of a TB (MAC PDU 2) , a UE may not attempt to decode MAC PDU 2 based on first transmission because UE 1 and UE 2 may assume that it is a retransmission of a MAC PDU 1.

UE 1 and UE 2 may still attempt to decode MAC PDU 2 based on retransmissions of MAC PDU 2.

Here too, the index of retransmission may help such that the UE1 and UE 2 may in retrospect understand that there was an NDI error on the first transmission of the TB (MAC PDU 2) and the first transmission of the TB (MAC PDU 2) may also be included in subsequent decoding attempts. That is, the UE1 and UE 2 may observe for example indexes of

retransmission

1, 2, 3, 4, x, 2, 3, 1, where x may represent some index of retransmission different from the true value 1. So, the UE1 and UE 2 may know that either x should actually be equal to 1 or the subsequent 2 and 3 were both wrong, where the former (x actually being equal to 1) is the more likely scenario) .

It will be understood that additional dynamic resource allocation using further PDCCH resources in other TTIs may be used in situations where temporarily more resources are required to transmit the data. This may also include that a mixture of the proposed scheme described above and dynamic scheduling of HARQ retransmissions is applied. For example, the SPS allocation may be dimensioned to cater for a certain number N of HARQ (re-) transmissions that are very likely to be requested by some UE while further HARQ retransmissions that are only requested sporadically, are scheduled dynamically in addition to /outside of the SPS allocation as in SPS as used for unicast in LTE.

The NDI may be the only information element that needs to be transmitted besides the data on the PDSCH. However, it might be expedient-if possible-to not precluded that other information elements from conventional DCIs besides the NDI are included in the control signalling on the PDSCH, such as the redundancy version or index of the retransmission.

As explained above, the primary use case for the proposed scheme is broadcast/multicast service (e.g. PTM in NR) where significant improvements in spectral efficiency can be achieved if a very aggressive initial MCS is selected and a high rate of HARQ retransmissions is tolerated. This may be the case when using group radio network temporary identifier (G-RNTI) and possibly group-common configured scheduling GCS-RNTI) based group scheduling. However, in principle, the proposed scheme could also be applied to unicast service if the traffic pattern renders the application reasonable.

Figure 8 shows a block diagram of a method for determining whether to attempt to decode a TB based on an NDI performed, for example, by a terminal (e.g. UE) .

In step 800, the terminal may receive a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources. The transport block indicator may indicate a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission.

The transport block indicator may be received on resource elements of the semi-persistently scheduled resources. The resource elements may be dispersed in frequency.

The transport block indicator comprises one or more bits.

The transport block indicator further comprises a redundancy version or an index of retransmission.

The transport block may conveys data for a unicast service, a multicast or a broadcast service.

In step 802, the terminal may determine whether to attempt to decode a part of the transmission comprising the transport block based on the transport block indicator.

In a scenario, the terminal may determine that the transport block indicator indicates a retransmission comprising the transport block. The terminal may determine that a previous transmission comprising the transport block has been decoded. The terminal may abstain from attempting to decode the transport block.

In another scenario, the terminal may determine that the transport block indicator indicates a retransmission comprising the transport block. The terminal may determine that a previous transmission comprising the transport block has not been decoded. The terminal may attempt to decode the transport block based on the retransmission comprising transport block. The terminal may attempt to decode the transport block based on the retransmission comprising the transport block and a previous transmission comprising the transport block.

In another scenario, the terminal may determine that the transport block indicator indicates a first transmission comprising the transport block. The terminal may attempt to decode the transport block based on the first transmission comprising the transport block.

The terminal my determine whether the decoding is successful or not successful. The terminal may provide a negative feedback if the decoding is not successful.

Figure 9 shows a block diagram of a method for determining whether to attempt to decode a TB based on an NDI performed, for example, by a BS (e.g. gNB) .

In step 900 the BS may transmit a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources. The transport block indicator may indicate a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission.

The BS may receive a negative feedback if the decoding is not successful.

The transport block indicator may be transmitted on resource elements of the semi-persistently scheduled resources. The resource elements may be dispersed in frequency.

The transport block indicator may comprise one or more bits.

Figure 10 shows a schematic representation of non-volatile memory media 1000a (e.g. computer disc (CD) or digital versatile disc (DVD) ) and 1000b (e.g. universal serial bus (USB) memory stick) storing instructions and/or parameters 1002 which when executed by a processor allow the processor to perform one or more of the steps of the methods of Figures 8 and 9.

It is noted that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

It will be understood that although the above concepts have been discussed in the context of a 5GS, one or more of these concepts may be applied to other cellular systems.

The embodiments may thus vary within the scope of the attached claims. In general, some embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although embodiments are not limited thereto. While various embodiments may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The embodiments may be implemented by computer software stored in a memory and executable by at least one data processor of the involved entities or by hardware, or by a combination of software and hardware. Further in this regard it should be noted that any procedures, e.g., as in Figures 8 and 9, may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD.

The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) , application specific integrated circuits (ASIC) , gate level circuits and processors based on multi-core processor architecture, as non-limiting examples.

Alternatively or additionally some embodiments may be implemented using circuitry. The circuitry may be configured to perform one or more of the functions and/or method steps previously described. That circuitry may be provided in the base station and/or in the communications device.

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

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

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

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

(ii) any portions of hardware processor (s) with software (including digital signal processor (s) ) , software, and memory (ies) that work together to cause an apparatus, such as the communications device or base station to perform the various functions previously described; and

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

This definition of circuitry applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term circuitry also covers an implementation of merely a hardware circuit or processor (or multiple processors) or portion of a hardware circuit or processor and its (or their) accompanying software and/or firmware. The term circuitry also covers, for example integrated device.

The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of some embodiments However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings will still fall within the scope as defined in the appended claims.

Claims

An apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to:

receive a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission; and

determine whether to attempt to decode a part of the transmission comprising the transport block based on the transport block indicator.
The apparatus of claim 1, wherein a medium access control packet data unit comprises the transport block of the transmission.
The apparatus of claim 1 or claim 2, where the at least one memory and the computer code are configured, with the at least one processor, to cause the apparatus at least to:

determine that the transport block indicator indicates a retransmission comprising the transport block;

determine that a previous transmission comprising the transport block has been decoded; and

abstain from attempting to decode the transport block.
The apparatus of claim 1 or claim 2, wherein the at least one memory and the computer code are configured, with the at least one processor, to cause the apparatus at least to:

determine that the transport block indicator indicates a retransmission comprising the transport block;

determine that a previous transmission comprising the transport block has not been decoded; and

attempt to decode the transport block based on the retransmission comprising transport block.
The apparatus of claim 4, wherein the at least one memory and the computer code are configured, with the at least one processor, to cause the apparatus at least to:

attempt to decode the transport block based on the retransmission comprising the transport block and a previous transmission comprising the transport block.
The apparatus of claim 1 or claim 2, wherein the at least one memory and the computer code are configured, with the at least one processor, to cause the apparatus at least to:

determine that the transport block indicator indicates a first transmission comprising the transport block; and

attempt to decode the transport block based on the first transmission comprising the transport block.
The apparatus of any of claims 4 to 6, wherein the at least one memory and the computer code are configured, with the at least one processor, to cause the apparatus at least to:

determine whether the decoding is successful or not successful; and

provide a negative feedback if the decoding is not successful.
The apparatus of any of claims 1 to 7, wherein the transport block indicator is received on resource elements of the semi-persistently scheduled resources, wherein the resource elements are dispersed in frequency.
The apparatus of any of claims 1 to 8, wherein the transport block indicator is received on a first symbol of the semi-persistently scheduled resources.
The apparatus of any of claims 1 to 9, wherein the transport block indicator comprises one or more bits.
The apparatus of any of claims 1 to 10, wherein the transport block indicator further comprises a redundancy version or an index of retransmission.
The apparatus of any of claims 1 to 11, wherein the transport block conveys data for a unicast service, a multicast or a broadcast service.
The apparatus of any of claims 1 to 12, wherein the apparatus is a terminal.
An apparatus comprising at least one processor and at least one memory including computer code for one or more programs, the at least one memory and the computer code configured, with the at least one processor, to cause the apparatus at least to:

transmit a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission.
The apparatus of claim 14, wherein a medium access control packet data unit comprises the transport block of the transmission.
The apparatus of claim 14 or claim 15, wherein the at least one memory and the computer code are configured, with the at least one processor, to cause the apparatus at least to:

receive a negative feedback if the decoding is not successful.
The apparatus of any of claims 14 to 16, wherein the transport block indicator is transmitted on resource elements of the semi-persistently scheduled resources, wherein the resource elements are dispersed in frequency.
The apparatus of any of claims 14 to 17, wherein the transport block indicator is transmitted on a first symbol of the semi-persistently scheduled resources.
The apparatus of any of claims 14 to 18, wherein the transport block conveys data for a unicast service, a multicast or a broadcast service.
The apparatus of any of claims 14 to 19, wherein the transport block indicator comprises one or more bits.
The apparatus of any of claims 14 to 20, wherein the transport block indicator further comprises a redundancy version or an index of retransmission.
The apparatus of any of claims 14 to 21, wherein the apparatus is a base station.
A method comprising:

receiving a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission; and

determining whether to attempt to decode a part of the transmission comprising the transport block based on the transport block indicator.
A method comprising:

transmitting a transmission comprising a transport block and a transport block indicator on semi-persistently scheduled resources, wherein the transport block indicator indicates a first transmission comprising the transport block when the transport block indicator has a different value than a previous transport block indicator comprised in a previous transmission or a retransmission comprising the transport block when the transport block indicator has a same value as the previous transport block indicator comprised in the previous transmission.
A computer program comprising computer executable instructions which when run on one or more processors perform the steps of the method of claim 23 or claim 24.