US-12627420-B2 - Interpreting multiplexed HARQ feedback data

US12627420B2US 12627420 B2US12627420 B2US 12627420B2US-12627420-B2

Abstract

The present disclosure relates to a method of a radio base station of interpreting multiplexed Hybrid Automatic Repeat Request (HARQ) feedback data received from a wireless communication device in response to a downlink transmission to the wireless communication device, and a radio base station performing the method.

Inventors

Biruk Silase GELETU
Diana Yamalova
Ahmed NOUAH
Tariku Temesgen Mehari

Assignees

TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

Dates

Publication Date: 20260512
Application Date: 20210224

Claims (20)

1 . A method of a radio base station of interpreting multiplexed Hybrid Automatic Repeat Request, HARQ, feedback data received from a wireless communication device in response to a downlink transmission to the wireless communication device, comprising: receiving, in response to a downlink transmission, a multiplexed HARQ feedback data set from the wireless communication device; acquiring information indicating each possible combination of reception status of Downlink Control Information, DCI, and decoding status for associated Physical Downlink Shared Channel, PDSCH, data received at the wireless communication device for the number of DCIs being included with the downlink transmission, the information further indicating a multiplexed HARQ feedback data set transmitted by the wireless communication device for each of the combinations and whether or not there is ambiguity as to if one or more Negative Acknowledgements, NACKs, of a multiplexed HARQ feedback data set associated with each of the combinations is a result of failed decoding of PDSCH data or of non-reception of one or more DCIs utilized to schedule the PDSCH data at the wireless communication device; determining whether the received multiplexed HARQ feedback data set includes one or more NACKs indicated to be ambiguous, and in response to determining that the received multiplexed HARQ feedback data set includes one or more NACKs indicated to be ambiguous, computing, for each received NACK determined to indicate ambiguity, a weight indicating probability that the NACK is a result of failed decoding of PDSCH data, based on the acquired information.
2 . The method of claim 1 , the computing of the weight comprising: identifying, from the acquired information, all multiplexed HARQ feedback data sets indicated to comprise one or more ambiguous NACKs; grouping all identical multiplexed HARQ feedback data sets indicated to comprise one or more ambiguous NACKs in the same group; and computing the weight by determining, from the acquired information, a proportion of NACKs being the result of failed decoding at the wireless communication device for each ambiguous NACK in a grouped multiplexed HARQ feedback data set corresponding to the HARQ feedback data set received from the wireless communication device.
3 . The method of claim 2 , the computing of the weight by determining a proportion of NACKs being the result of failed decoding at the wireless communication device comprising: dividing, for each ambiguous NACK entry in the grouped multiplexed HARQ feedback data set, number of NACKs for the grouped multiplexed HARQ feedback data sets by total number of NACKs being result of failed decoding of the PDSCH data and of non-reception of the one or more DCIs utilized to schedule the PDSCH data at the wireless communication device for the grouped multiplexed HARQ feedback sets.
4 . The method of claim 2 , wherein separate groupings are performed depending on whether HARQ feedback data sets are transported via Physical Uplink Shared Channel, PUSCH, or via Physical Uplink Control Channel, PUCCH.
5 . The method of claim 2 , wherein possible HARQ feedback data sets further being a result of decoding errors at the radio base station are identified and grouped with said identical multiplexed HARQ feedback data sets.
6 . The method of claim 1 , the determining if the received multiplexed HARQ feedback data set includes one or more NACKs indicated to be ambiguous comprising: determining that the multiplexed HARQ feedback data set is received via PUCCH; determining PUCCH format used for the received HARQ feedback data set, and if the PUCCH format is either 0 or 1: determining that a number of DCIs utilized to schedule the PDSCH data being included in the downlink transmission is greater than one; determining that a last number of the DCIs utilized to schedule the PDSCH data comprised in the downlink transmission, the number equaling the number of DCIs utilized to schedule the PDSCH data being transmitted minus 2, is not received at the wireless communication device; determining that if only a single bit is received in the HARQ feedback data set, a first DCI utilized to schedule the PDSCH data in the downlink transmission is not ambiguous while the a second DCI utilized to schedule the PDSCH data is not received at the wireless communication device; and determining that if a NACK is received followed by an Acknowledgement, ACK, indicating successful decoding of a DCI utilized to schedule the PDSCH data, the NACK is ambiguous, while if an ACK is followed by a NACK, both are received at the wireless communication device and the NACK is not ambiguous.
7 . The method of claim 6 , wherein if the PUCCH format is determined to be either 2, 3 or 4: determining that if a number of bits included in the HARQ feedback data set equals the number of DCIs utilized to schedule the PDSCH data in the downlink transmission, the last DCI utilized to schedule the PDSCH data is not ambiguous but any NACK for the remaining DCIs utilized to schedule the PDSCH data is ambiguous; and determining that if the number of bits included in the HARQ feedback data set is less than the number DCIs utilized to schedule the PDSCH data in the downlink transmission: a last number of the DCIs utilized to schedule the PDSCH data comprised in the downlink transmissions, the number equaling the number of DCIs utilized to schedule the PDSCH data being transmitted minus the number of bits included in the HARQ feedback data set, is not received at the wireless communication device; the DCI utilized to schedule the PDSCH data at a position corresponding to the number bits included in the HARQ feedback data is not ambiguous; and all NACKS are ambiguous for the remaining DCIs utilized to schedule the PDSCH data.
8 . The method of claim 1 , the determining if the received multiplexed HARQ feedback data set includes one or more NACKs indicated to be ambiguous comprising: determining that the multiplexed HARQ feedback data set is received via the PUSCH; determining that if a number of DCIs utilized to schedule the PDSCH data being included in the downlink transmitted is less than five, all NACKs are ambiguous; determining that if a number of DCIs utilized to schedule the PDSCH data being included in the downlink transmitted is five or more and a cyclic redundant check on the PUSCH is successful, all but one NACK are ambiguous in case only NACKs are received while if both ACKs and NACKs are received, all NACKs are ambiguous.
9 . The method of claim 1 , wherein the reception status of a DCI indicates whether the DCI was received or not and the decoding status for the associated PDSCH data indicates whether the data was successfully decoded or not.
10 . The method of claim 1 , said information being acquired by the radio base station itself being configured to derive the information for a particular number of DCIs being included in a downlink transmission.
11 . The method of claim 1 , said information being acquired from an entity being configured to derive the information for a particular number of DCIs being included in a downlink transmission.
12 . A non-transitory computer readable medium comprising computer-executable instructions that, when executed on a processing unit included in a radio base station, cause the radio base station to: receive, in response to a downlink transmission, a multiplexed Hybrid Automatic Repeat Request, HARQ, feedback data set from the wireless communication device; acquire information indicating each possible combination of reception status of Downlink Control Information, DCI, and decoding status for associated Physical Downlink Shared Channel, PDSCH, data received at the wireless communication device for the number of DCIs being included with the downlink transmission, the information further indicating a multiplexed HARQ feedback data set transmitted by the wireless communication device for each of the combinations and whether or not there is ambiguity as to if one or more Negative Acknowledgements, NACKs, of a multiplexed HARQ feedback data set associated with each of the combinations is a result of failed decoding of PDSCH data or of non-reception of one or more DCIs utilized to schedule the PDSCH data at the wireless communication device; determine whether the received multiplexed HARQ feedback data set includes one or more NACKs indicated to be ambiguous, and in response to determining that the received multiplexed HARQ feedback data set includes one or more NACKs indicated to be ambiguous, compute, for each received NACK determined to indicate ambiguity, a weight indicating probability that the NACK is a result of failed decoding of PDSCH data, based on the acquired information.
13 . A radio base station configured to interpret multiplexed Hybrid Automatic Repeat Request, HARQ, feedback data received from a wireless communication device in response to a downlink transmission to the wireless communication device, the radio base station comprising a processing unit and a memory, said memory containing instructions executable by said processing unit, whereby the radio base station is operative to: receive, in response to a downlink transmission, a multiplexed HARQ feedback data set from the wireless communication device; acquire information indicating each possible combination of reception status of Downlink Control Information, DCI, and decoding status for associated Physical Downlink Shared Channel, PDSCH, data received at the wireless communication device for the number of DCIs being included with the downlink transmission, the information further indicating a multiplexed HARQ feedback data set transmitted by the wireless communication device for each of the combinations and whether or not there is ambiguity as to if one or more Negative Acknowledgements, NACKs, of a multiplexed HARQ feedback data set associated with each of the combinations is a result of failed decoding of PDSCH data or of non-reception of one or more DCIs utilized to schedule the PDSCH data at the wireless communication device; determine whether the received multiplexed HARQ feedback data set includes one or more NACKs indicated to be ambiguous, and to in response to determining that the received multiplexed HARQ feedback data set includes one or more NACKs indicated to be ambiguous, compute, for each received NACK determined to indicate ambiguity, a weight indicating probability that the NACK is a result of failed decoding of PDSCH data, based on the acquired information.
14 . The radio base station of claim 13 , further being operative to, when computing the weight: identify, from the acquired information, all multiplexed HARQ feedback data sets indicated to comprise one or more ambiguous NACKs; group all identical multiplexed HARQ feedback data sets indicated to comprise one or more ambiguous NACKs in the same group; and compute the weight by determining, from the acquired information, a proportion of NACKs being the result of failed decoding at the wireless communication device for each ambiguous NACK in a grouped multiplexed HARQ feedback data set corresponding to the HARQ feedback data set received from the wireless communication device.
15 . The radio base station of claim 14 , further being operative to, when computing the weight by determining a proportion of NACKs being the result of failed decoding at the wireless communication device: divide, for each ambiguous NACK entry in the grouped multiplexed HARQ feedback data set, number of NACKs for the grouped multiplexed HARQ feedback data sets by total number of NACKs being result of failed decoding of the PDSCH data and of non-reception of the one or more DCIs utilized to schedule the PDSCH data at the wireless communication device for the grouped multiplexed HARQ feedback sets.
16 . The radio base station of claim 14 , further being operative to perform separate groupings depending on whether HARQ feedback data sets are transported via Physical Uplink Shared Channel, PUSCH, or via Physical Uplink Control Channel, PUCCH.
17 . The radio base station of claim 14 , further being operative to identify possible HARQ feedback data sets further being a result of decoding errors at the radio base station and group these with said identical multiplexed HARQ feedback data sets.
18 . The radio base station of claim 13 , further being operative to, when determining if the received multiplexed HARQ feedback data set includes one or more NACKs indicated to be ambiguous: determine that the multiplexed HARQ feedback data set is received via PUCCH; determine PUCCH format being used for the received HARQ feedback data set, and if the PUCCH format is either 0 or 1: determine that a number of DCIs utilized to schedule the PDSCH data being included in the downlink transmission is greater than one; determine that a last number of the DCIs utilized to schedule the PDSCH data comprised in the downlink transmission, the number equaling the number of DCIs utilized to schedule the PDSCH data being transmitted minus 2, is not received at the wireless communication device; determine that if only a single bit is received in the HARQ feedback data set, a first DCI utilized to schedule the PDSCH data in the downlink transmission is not ambiguous while the a second DCI utilized to schedule the PDSCH data is not received at the wireless communication device; and to determine that if a NACK is received followed by an Acknowledgement, ACK, indicating successful decoding of a DCI utilized to schedule the PDSCH data, the NACK is ambiguous, while if an ACK is followed by a NACK, both are received at the wireless communication device and the NACK is not ambiguous.
19 . The radio base station of claim 18 , further being operative to, if the PUCCH format is determined to be either 2, 3 or 4: determine that if a number of bits included in the HARQ feedback data set equals the number of DCIs utilized to schedule the PDSCH data in the downlink transmission, the last DCI utilized to schedule the PDSCH data is not ambiguous but any NACK for the remaining DCIs utilized to schedule the PDSCH data is ambiguous; and determine that if the number of bits included in the HARQ feedback data set is less than the number DCIs utilized to schedule the PDSCH data in the downlink transmission: a last number of the DCIs utilized to schedule the PDSCH data comprised in the downlink transmissions, the number equaling the number of DCIs utilized to schedule the PDSCH data being transmitted minus the number of bits included in the HARQ feedback data set, is not received at the wireless communication device; the DCI utilized to schedule the PDSCH data at a position corresponding to the number bits included in the HARQ feedback data is not ambiguous; and all NACKS are ambiguous for the remaining DCIs utilized to schedule the PDSCH data.
20 . The radio base station of claim 13 , further being operative to, when determining if the received multiplexed HARQ feedback data set includes one or more NACKs indicated to be ambiguous: determine that the multiplexed HARQ feedback data set is received via the PUSCH; determine that if a number of DCIs utilized to schedule the PDSCH data being included in the downlink transmitted is less than five, all NACKs are ambiguous; determine that if a number of DCIs utilized to schedule the PDSCH data being included in the downlink transmitted is five or more and a cyclic redundant check on the PUSCH is successful, all but one NACK are ambiguous in case only NACKs are received while if both ACKs and NACKs are received, all NACKs are ambiguous.

Description

This application is a 35 U.S.C. § 371 national phase filing of International Application No. PCT/SE2021/050155, filed Feb. 24, 2021, the disclosure of which is incorporated herein by reference in its entirety. TECHNICAL FIELD The present disclosure relates to a method of a radio base station of interpreting multiplexed Hybrid Automatic Repeat Request (HARQ) feedback data received from a wireless communication device in response to a downlink transmission to the wireless communication device, and a radio base station performing the method. BACKGROUND In cellular wireless systems, such as New Radio (NR) and Long Term Evolution (LTE) standards defined by 3rd Generation Partnership Project (3GPP), a mechanism referred to as Hybrid Automatic Repeat Request (HARQ) is used by wireless communication devices such as mobile phones to feedback decoding status of received transport blocks to a sender of the blocks being for instance a radio base station. The HARQ enables fast retransmission of data by the radio base station if the decoding of the transport blocks at the wireless communication device is not successful. In NR, no explicit HARQ feedback is provided for uplink (UL) transmissions. For downlink (DL) transmissions the wireless communication device feeds back the decoding result for each received DL transport block as ACK (positive acknowledgment) or NACK (negative acknowledgement) to the base station, thereby signalling either success or failure of the downlink transport block decoding at the wireless communication device. In the absence of HARQ feedback for a transport block transmitted by the base station, i.e. if the base station receives neither an ACK nor a NACK for a transmitted transport block, the base station concludes that the wireless communication device did not receive the downlink transmission. This is referred to as HARQ discontinuous transmission (DTX). The predominant duplex scheme in NR is time division duplex (TDD). In most of TDD configurations in NR, a single UL time slot can carry the DL HARQ feedback for transmission in a plurality of DL time slots and the wireless communication device multiplexes the HARQ feedback of the plurality of DL time slots in the single UL time slot. A drawback with the multiplexed HARQ feedback in the UL time slot is that if a transport block of one slot is not received (DTX) while a transport block of a subsequent slot indeed is received but not successfully decoded (NACK), the multiplexed UL HARQ feedback for the two DL slots will be a NACK. This creates ambiguity at the radio base station since the radio base station cannot conclude whether or not the reported NACK correctly pertains to a NACK or rather indicates DTX. SUMMARY One objective is to solve, or at least mitigate, this problem in the art and thus to provide an improved method of interpreting multiplexed HARQ feedback data. This objective is attained in a first aspect by a method of a radio base station of interpreting multiplexed HARQ feedback data received from a wireless communication device in response to a downlink transmission to the wireless communication device. The method comprises receiving, in response to a downlink transmission, a multiplexed HARQ feedback data set from the wireless communication device and acquiring information indicating each possible combination of reception status of Downlink Control Information (DCI) and decoding status for associated Physical Downlink Shared Channel (PDSCH) data received at the wireless communication device for the number of DCIs being included with the downlink transmission, the information further indicating a multiplexed HARQ feedback data set transmitted by the wireless communication device for each of the combinations and whether or not there is ambiguity as to if one or more NACKs of a multiplexed HARQ feedback data set associated with each of the combinations is a result of failed decoding of PDSCH data or of non-reception of one or more DCIs utilized to schedule the PDSCH data at the wireless communication device. The method further comprises determining if the received multiplexed HARQ feedback data set includes one or more NACKs indicated to be ambiguous, and if so computing, for each received NACK determined to indicate ambiguity, a weight indicating probability that the NACK is a result of failed decoding of PDSCH data, based on the acquired information. This objective is attained in a second aspect by a radio base station configured to interpret multiplexed HARQ feedback data received from a wireless communication device in response to a downlink transmission to the wireless communication device. The radio base station comprises a processing unit and a memory, said memory containing instructions executable by said processing unit, whereby the radio base station is operative to receive, in response to a downlink transmission, a multiplexed HARQ feedback data set from the wireless communication device and to acquire information indicati