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EP-4742573-A2 - HYBRID AUTOMATIC REPEAT REQUEST ENHANCEMENTS

EP4742573A2EP 4742573 A2EP4742573 A2EP 4742573A2EP-4742573-A2

Abstract

A user equipment (UE) receives physical downlink (DL) shared channel (PDSCH) in a DL slot as scheduled using a DL control indicator (DCI). The UE identifies that the DL slot is part of a group of DL slots based on the DCI and/or another DCI corresponding to the group. The UE identifies one or more uplink (UL) slots at which to transmit hybrid automatic repeat request (HARQ) feedback corresponding to the slots in the group, and transmits the HARQ feedback information at one of these UL slots. In some cases, if HARQ feedback information is not received, a semi-static codebook may prevent HARQ payload size misalignment.

Inventors

  • HSIEH, CHIA-WEN
  • LEE, CHIEN-MIN

Assignees

  • Acer Incorporated

Dates

Publication Date
20260513
Application Date
20200401

Claims (13)

  1. A method of handling hybrid automatic repeat request, HARQ, configuration, performed by a base station, BS, in a long-term evolution, LTE, system, an LTE-advanced, LTE-A, or a fifth generation, 5G, system, the method comprising: transmitting a first downlink, DL, control information, DCI, to a user equipment, UE, wherein the first DCI schedules a first physical DL shared channel, PDSCH, in a first DL slot that is within a first slot group, wherein the first DCI includes a first slot group indicator, and the first slot group indicator identifies the first slot group and a first PDSCH-to-HARQ_feedback timing indicator, wherein the first PDSCH-to-HARQ_feedback timing indicator mapping to a number of the first DL slot, and the number of the first DL slot is an inapplicable value, wherein the inapplicable value is a null value, a blank value, a void value, or a non-numeric character; transmitting the first PDSCH to the UE, wherein the first PDSCH is transmitted during the first DL slot, and wherein the first PDSCH is transmitted as scheduled according to the first DCI; transmitting a second DCI to the UE, wherein the second DCI is transmitted after the first DCI, wherein the second DCI includes a second slot group indicator equal to the first slot group indicator, and wherein a second PDSCH-to-HARQ_feedback timing indicator included in the second DCI is an applicable value, wherein the first PDSCH-to-HARQ_feedback timing indicator enables the UE to determine that a first HARQ feedback information corresponding to the first PDSCH is to be transmitted in a first uplink, UL, slot in a first UL slot group, wherein a slot number of the first UL slot is related to the second PDSCH-to-HARQ_feedback timing indicator; and assigning a cell radio temporary network identifier, C-RNTI, to the UE, wherein the first UL slot for transmitting the first HARQ feedback information corresponding to the first PDSCH is selected using the C-RNTI by a formula i = mod(C-RNTI, m) + 1, wherein m is a quantity of slots in the first UL slot group, the first UL slot is the ith slot from the m slots, wherein C-RNTI is an identifier.
  2. A BS apparatus for hybrid automatic repeat request, HARQ, configuration to operate in a long-term evolution, LTE, system, an LTE-advanced, LTE-A, or a fifth generation, 5G, system, the apparatus comprising: one or more receivers; one or more transmitters; and memory storing thereon instructions that, as a result of being executed by a processor, cause the processor to: transmit a first downlink, DL, control information, DCI, to a user equipment, UE, wherein the first DCI schedules a first physical DL shared channel, PDSCH, in a first DL slot that is within a first slot group, wherein the first DCI includes a first slot group indicator, and the first slot group indicator identifies the first slot group and a first PDSCH-to-HARQ_feedback timing indicator, wherein the first PDSCH-to-HARQ_feedback timing indicator mapping to a number of the first DL slot, and the number of the first DL slot is an inapplicable value, wherein the inapplicable value is a null value, a blank value, a void value, or a non-numeric character; transmit the first PDSCH to the UE, wherein the first PDSCH is transmitted during the first DL slot, and wherein the first PDSCH is transmitted as scheduled according to the first DCI; transmit a second DCI to the UE, wherein the second DCI is transmitted after the first DCI, wherein the second DCI includes a second slot group indicator equal to the first slot group indicator, and wherein a second PDSCH-to-HARQ_feedback timing indicator included in the second DCI is an applicable value, wherein the first PDSCH-to-HARQ_feedback timing indicator enables the UE to determine that a first HARQ feedback information corresponding to the first PDSCH is to be transmitted in a first uplink, UL, slot in a first UL slot group, wherein a slot number of the first UL slot is related to the second PDSCH-to-HARQ_feedback timing indicator; and assign a cell radio temporary network identifier, C-RNTI, to the UE, wherein the first UL slot for transmitting the first HARQ feedback information corresponding to the first PDSCH is selected using the C-RNTI by a formula i = mod(C-RNTI, m) + 1, wherein m is a quantity of slots in the first UL slot group, the first UL slot is the i th slot from the m slots, wherein C-RNTI is an identifier
  3. The method of any of claim 1, the first slot group indicator is a 1-bit value.
  4. The method of any of claims 1 and 2, the first DL slot is within a first channel occupancy time, COT.
  5. The method of claim 4, the first UL slot is within the first COT, or is outside of the first COT.
  6. The method of any of claims 1 and 3-5, wherein transmitting a third DCI, the third DCI scheduling a third PDSCH in a third DL slot that is within a third slot group, wherein the third DCI includes a third slot group indicator and a third PDSCH-to-HARQ_feedback timing indicator; transmitting, during the third DL slot, the third PDSCH as scheduled according to the third DCI; wherein the third DCI enables the UE to determine that a third HARQ feedback information corresponding to transmitting the third HARQ feedback information corresponding to the third PDSCH in the second UL slot.
  7. The method of claim 6, the first UL slot and the second UL slot are within a first COT, or the first UL slot is within the first COT and the second UL slot is outside of the first COT.
  8. The method of claim 6, the first slot group indicator is equal to the third slot group indicator, and the first UL slot is the second UL slot.
  9. The method of claim 6, the first slot group indicator is different from the third slot group indicator, and the first UL slot and the second UL slot are different.
  10. The method of claim 6, HARQ feedback information corresponding to the first slot group is carried in a HARQ codebook.
  11. The method of claim 10, the HARQ codebook has a dynamic size, or has a pre-determined size.
  12. The method of claim 11, the HARQ codebook stores one or more padding bits following encoding the HARQ feedback information corresponding to the first slot group.
  13. The method of claim 11, the pre-determined size of the HARQ codebook is based on at least one of a maximum DL HARQ process number, a number of configured serving cells and a maximum code block grouping, called CBG hereinafter, number.

Description

Field of the Invention The present disclosure generally relates to systems, methods, and related communication devices used in wireless communication systems, and more particularly, to techniques of enhancing hybrid automatic repeat request (HARQ) procedures in the context of new radio (NR) based technology in unlicensed spectrum (NR-U). Background of the Invention A long-term evolution (LTE) system supporting the 3rd Generation Partnership Project (3GPP) Rel-8 standard and/or the 3GPP Rel-9 standard were developed by the 3GPP as a successor to the universal mobile telecommunication system (UMTS).The LTE system was developed for further enhancing performance of the UMTS to satisfy increasing needs of users. The LTE system includes a new radio interface and a new radio network architecture that provides high data rate, low latency, packet optimization, and improved system capacity and coverage. In the LTE system, a radio access network known as an evolved universal terrestrial radio access network (E-UTRAN) includes multiple evolved Node-Bs (eNBs) for communicating with multiple user equipments (UEs), and for communicating with a core network including a mobility management entity (MME), a serving gateway, etc., for Non-Access Stratum (NAS) control. An LTE-advanced (LTE-A) system, as its name implies, is an evolution of the LTE system. The LTE-A system targets faster switching between power states, improves performance at the coverage edge of an eNB, and includes advanced techniques, such as carrier aggregation (CA), coordinated multipoint (COMP) transmissions/reception, uplink (UL) multiple-input multiple-output (UL-MIMO), etc. For a UE and an eNB to communicate with each other in the LTE-A system, the UE and the eNB must support standards developed for the LTE-A system, such as the 3GPP Rel-10 standard or later versions. A fifth generation (5G) system (5GS) (e.g., 5G new radio access network (5G-NR)) is an evolution of a continuous mobile broadband process to meet the requirements of 5G as introduced by International Mobile Telecommunications (IMT)-2020. The 5GS may include a radio access network (RAN) and a core network (CN). The RAN may include at least one base station (BS). The at least one BS may include an evolved Node-B (eNB) or a 5G Node-B (gNB), for communicating with at least one UE and for communicating with the CN. The CN may include a MME, a signaling gateway (SGW), an access and mobility management function (AMF), a user plane function (UPF), and/or other architecture components for a NAS control. In a LTE, LTE-A, or 5G system, time is divided into frames, with each frame lasting ten milliseconds (ms). Each frame includes ten subframes that each last one millisecond. Each subframe is divided into multiple slots. In LTE and LTE-A systems, each subframe is divided into two slots, with each slot being half a millisecond in length. In 5G new radio (NR) systems, the number of slots in a subframe may vary depending on SCS. In 5G NR, SCS of 15 kilohertz (kHz), 30 kHz, 60 kHz, 120 kHz, and 240 kHz are supported. For a SCS of 15 kHz, each subframe includes only one slot that, like the subframe, lasts one millisecond. For a SCS of 30 kHz, each subframe includes two slots, with each of the two slots lasting 0.5 ms. For a SCS of 60 kHz, each subframe includes four slots, with each slot lasting 0.25 ms. For a SCS of 120 kHz, each subframe includes eight slots, with each slot lasting 0.125 ms. For a SCS of 240 kHz, each subframe includes sixteen slots, with each slot lasting 0.0625 ms. Hybrid automatic repeat request (HARQ) is a combination of high-rate forward error-correcting coding and ARQ error-control. In a LTE, LTE-A, or 5G system, when a UE receives the DL data (e.g. downlink transport block) over a physical downlink shared channel (PDSCH) (during a DL slot or symbol), the UE typically transmits a downlink HARQ feedback information (during a UL slot or symbol) afterward. If the UE has correctly decoded a downlink transport block for a particular DL transmission, the HARQ feedback information transmitted corresponding to the downlink transport block may be an acknowledgment (ACK); otherwise, the HARQ feedback information transmitted may be a negative acknowledgment (NACK). The relative timing between receipt by the UE of the DL data over PDSCH and transmission by the UE of the corresponding HARQ feedback information is based on a PDSCH-to-HARQ_feedback timing indicator field in a downlink control information (DCI). However, the PDSCH-to-HARQ_feedback timing indicator field, and the way it is used, limits the number of timing values that can be used to represent the relative timing between receipt by the UE of the DL data over PDSCH and transmission by the UE of the corresponding HARQ feedback information so that some values cannot be represented. Especially for higher SCS values that result in higher number of slots per subframe, this inapplicability to represent certain timing values can result in f