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EP-4082141-B1 - APPARATUS, SYSTEM AND METHOD OF WIRELESS COMMUNICATION ACCORDING TO A HYBRID AUTOMATIC REPEAT REQUEST (HARQ) SCHEME

EP4082141B1EP 4082141 B1EP4082141 B1EP 4082141B1EP-4082141-B1

Inventors

  • RUBIN, AMIR
  • RESHEF, EHUD

Dates

Publication Date
20260506
Application Date
20191225

Claims (15)

  1. An apparatus of wireless communication according to a Hybrid Automatic Repeat Request, HARQ, scheme, the apparatus comprising: a HARQ buffer (132) configured to buffer compressed Log Likelihood Ratio, LLR, values corresponding to an unsuccessfully-decoded transmission of a data block, a bit size of the HARQ buffer is equal to or less than 2.5 times a supported HARQ receive, Rx, size, which is to be reported to a transmitter of the data block, wherein a different LLR compression scheme is applied to LLR values corresponding to different bit indexes based on respective distribution of the LLR values; and a decoder (134) configured to decode a retransmission of the data block according to the HARQ scheme based on combined LLR values, which are based on the compressed LLR values and on LLR values corresponding the retransmission of the data block, wherein a HARQ gain of decoding the retransmission of the data block based on the combined LLR values is at least 2 Decibel, dB, for an Additive White Gaussian Noise, AWGN, channel.
  2. The apparatus of claim 1, wherein the HARQ gain comprises a gain of a first decoding error probability relative to a second decoding error probability, the first decoding error probability comprising a decoding error probability of decoding the retransmission of the data block based on the combined LLR values, the second decoding error probability comprising a decoding error probability of decoding the data block without retransmission.
  3. The apparatus of claim 1 or 2, wherein the HARQ gain of decoding the retransmission of the data block based on the combined LLR values is at least 2dB for the AWGN channel and for any supported Modulation and Coding Scheme, MCS, for the retransmission of the data block.
  4. The apparatus of any one of claims 1-3, wherein the supported HARQ Rx size comprises a count of LLR values supported for buffering by the HARQ buffer according to the HARQ scheme.
  5. The apparatus of any one of claims 1-4 comprising: an LLR compressor (136) to generate the compressed LLR values by compressing LLR values corresponding to the unsuccessfully-decoded transmission of a data block according to an LLR compression scheme; an LLR de-compressor (138) to decompress the compressed LLR values into de-compressed LLR values according to the LLR compression scheme; and an LLR combiner (142) to generate the combined LLR values by combining the de-compressed LLR values and the LLR values corresponding the retransmission of the data block.
  6. The apparatus of claim 5, wherein the LLR compressor (136) is configured to generate the compressed LLR values based on a modulation scheme of the unsuccessfully-decoded transmission of the data block.
  7. The apparatus of claim 5 or 6, wherein the LLR compressor (136) is configured to generate a compressed LLR value by compressing an LLR value corresponding to a soft bit of the unsuccessfully-decoded transmission of the data block, the LLR compressor is configured to generate the compressed LLR value based on a bit-index of the soft bit.
  8. The apparatus of claim 7, wherein the LLR compressor (136) is configured to generate the compressed LLR value based on a predefined LLR mapping corresponding to the bit-index, the LLR mapping to map a plurality of possible LLR values to one or more possible compressed LLR values.
  9. The apparatus of claim 8, wherein the LLR mapping is to map a plurality of possible LLR value ranges to a respective plurality of possible compressed LLR values.
  10. The apparatus of claim 8 or 9, wherein the LLR compressor (136) is configured to: for a first retransmission of the data block, generate a first compressed LLR value corresponding to the soft bit value based on the predefined LLR mapping corresponding to the bit-index, and for a subsequent retransmission of the data block, which is subsequent to the first retransmission, generate a subsequent compressed LLR value based on another LLR mapping, which is independent of the bit-index.
  11. The apparatus of any one of claims 5-10, wherein the LLR compressor (136) is configured to generate the compressed LLR values based on at least one of a Signal to Noise Ratio, SNR, corresponding to the unsuccessfully-decoded transmission of the data block, and/or a retransmission number of the unsuccessfully-decoded transmission of the data block.
  12. The apparatus of any one of claims 1-11, wherein a compressed LLR value of the compressed LLR values is to represent an LLR value corresponding to a soft bit of the unsuccessfully-decoded transmission of the data block, the LLR value having a bit size of at least 6 bits.
  13. A wireless communication device configured for communication according to a Hybrid Automatic Repeat Request, HARQ, scheme, the wireless communication device comprising: a memory to store operations of an operating system of the wireless communication device; a processor to execute the operations of the operating system of the wireless communication device; one or more antennas; a radio connected to the one or more antennas to communicate over a wireless communication medium; and the apparatus of any one of claims 1-12.
  14. A product comprising one or more tangible computer-readable non-transitory storage media comprising computer-executable instructions operable to, when executed by at least one processor, enable the at least one processor to cause a wireless communication device to: buffer in a Hybrid Automatic Repeat Request, HARQ, buffer compressed Log Likelihood Ratio, LLR, values corresponding to an unsuccessfully-decoded transmission of a data block, a bit size of the HARQ buffer is equal to or less than 2.5 times a supported HARQ receive, Rx, size, which is to be reported to a transmitter of the data block, wherein a different LLR compression scheme is applied to LLR values corresponding to different bit indexes based on respective distribution of the LLR values; and decode a retransmission of the data block according to a HARQ scheme based on combined LLR values, which are based on the compressed LLR values and on LLR values corresponding the retransmission of the data block, wherein a HARQ gain of decoding the retransmission of the data block based on the combined LLR values is at least 2 Decibel, dB, for an Additive White Gaussian Noise, AWGN, channel.
  15. The product of claim 14, wherein the instructions, when executed, cause the wireless communication device to: generate the compressed LLR values by compressing LLR values corresponding to the unsuccessfully-decoded transmission of a data block according to an LLR compression scheme; decompress the compressed LLR values into de-compressed LLR values according to the LLR compression scheme; and generate the combined LLR values by combining the de-compressed LLR values and the LLR values corresponding the retransmission of the data block.

Description

TECHNICAL FIELD Embodiments described herein generally relate to wireless communication according to a Hybrid Automatic Repeat Request (HARQ) scheme. BACKGROUND A Hybrid Automatic Repeat Request (HARQ) operation may tie retransmissions to Physical layer (PHY) Forward Error Correction (FEC) blocks, where a receiver stores FEC decoder inputs for failed FEC blocks, and may combine the FEC decoder inputs for the failed FEC blocks with related retransmission inputs. Anton Laktyushkin et al., "An adaptive Log-likelihood Ratio compression algorithm for Downlink Shared Channel processing in LTE receiver", 2013 International SOC Design Conference (ISOCC), IEEE, 17 November 2013 relates to an adaptive LLR compression algorithm for downlink shared channel processing in an LTE receiver. Anton Laktyushkin et al. discloses that in a HARQ process, significant LLR values at the demodulator output should be stored at a receiver, but due to memory size limitation, a problem of efficient LLR compression is needed. Anton Laktyushkin et al. discloses algorithm for LLR compression. US 2010/272033 discloses a method for HARQ buffer management. US 2010/272033 discloses that the HARQ buffer management allows the mobile station to control the size of its own buffer. US 2010/272033 discloses that the HARQ buffer management reports buffer overflow, buffer occupancy status, and buffer size to the base station to facilitate efficient communication between the base station and the mobile station. Yongbin Wei, "Performance Gain Evaluation of HARQ Operation", 3GPP2 Draft; C30-20030414-075R2-QCOM HARQ GAINS, 3rd Generation Partnership Project 2, 3GPP2, 2500 WILSON BOULEVARD, SUITE 300, ARLINGTON, VIRGINIA 22201, USA, vol. TSGC 5 May 2003 relates to performance gain evaluation of HARQ operation. Yongbin Wei discloses simulation results with different channel models, different payload sizes, and different maximum allowed numbers of retransmissions. Rosati S. et al., "LLR Compression for BICM Systems Using Large Constellations", IEEE Transactions on Communications, IEEE Service Center, PISCATAWAY, NJ. USA, vol. 61, no. 7, 1 July 2013 relates to LLR compression for BICM systems using large constellations. Rosati S. et al. discloses that by quantizing log-likelihood ratios with bit-specific quantizers and compressing the quantized output, the memory size can be significantly reduced with a negligible increase in computational complexity. Rosati S. et al. discloses that not only the quantization levels are adapted, but also the number of bits used for the representation of the LLR of each bit of the constellation is optimized. Rosati S. et al. discloses that the quantized LLR levels are not uniformly distributed, therefore compression can reduce the memory needed to store the LLRs. US 2015/109996 discloses a device for changing the compression level of a log likelihood ratio (LLR) signal. US 2015/109996 discloses that a compression level decision unit calculates a first compression level based on quality of a received signal, calculates a second compression level based on an available memory size, and decides a final compression level and a compressor compresses the LLR signal according to the final compression level. BRIEF DESCRIPTION OF THE DRAWINGS For simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity of presentation. Furthermore, reference numerals may be repeated among the figures to indicate corresponding or analogous elements. The figures are listed below. Fig. 1 is a schematic block diagram illustration of a system, in accordance with some exemplary embodiments.Fig. 2 is a schematic block diagram illustration of a modulation scheme, which may be implemented in accordance with some exemplary embodiments.Fig. 3 is a schematic illustration of a graph depicting distributions of Log Likelihood Ratio (LLR) values per bit index of a soft bit, in accordance with some exemplary embodiments.Fig. 4 is a schematic illustration of a Hybrid Automatic Repeat Request (HARQ) scheme, in accordance with some exemplary embodiments.Fig. 5 is a schematic illustration of a graph depicting simulation results of HARQ performance of a HARQ scheme utilizing a HARQ compression scheme, in accordance with some exemplary embodiments.Fig. 6 is a schematic flow-chart illustration of a method of wireless communication according to a HARQ scheme, in accordance with some exemplary embodiments.Fig. 7 is a schematic illustration of a product of manufacture, in accordance with some exemplary embodiments. DETAILED DESCRIPTION In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of some embodiments. However, it will be understood by persons of ordinary skill in the art that some embodiments may be practiced without these specific details. I