PHY3: Emerging Coding Techniques for 5G

Wednesday, 17 June 2020, 12:15-14:30 CEST, Recommended re-viewing,

Wednesday, 17 June 2020, 12:15-16:00 CEST, Non-Live interaction (Chat),  link sent only to Registered people


Low Latency Decoder for Short Blocklength Polar Codes

Heshani Gamage, Vismika Ranasinghe, Nandana Rajatheva and Matti Latva-aho (University of Oulu, Finland)
Polar codes have been gaining a lot of interest due to it being the first coding scheme to provably achieve the symmetric capacity of a binary memoryless channel with an explicit construction. However, the main drawback of polar codes is the low throughput of its successive cancellation (SC) decoding. Simplified SC decoding algorithms of polar codes can be used to reduce the latency of the polar decoder by faster processing of specific sub-codes in the polar code. By combining simplified SC with a list decoding technique, such as SC list (SCL) decoding, polar codes can cater to the two conflicting requirements of high reliability and low latency in ultra-reliable low-latency (URLLC) communication systems. Simplified SC algorithm recognizes some special nodes in the SC decoding tree, corresponding to the specific subcodes in the polar code construction, and efficiently prunes the SC decoding tree, without traversing the sub-trees and computing log-likelihood ratios (LLRs) for each child node. However, this decoding process still suffers from the latency associated with the serial nature of SC decoding. We propose some new algorithms to process new types of node patterns that appear within multiple levels of pruned sub-trees and it enables to process certain nodes in parallel. In short blocklength polar codes, our proposed algorithm can achieve up to 13% latency reduction from fast-simplified SC [1] without any performance degradation. Furthermore, it can achieve up to 27% latency reduction if small
error-correcting performance degradation is allowed.


Finite Blocklength Analysis of Coded Modulation for Block Fading Channels with Linear Precoding

Maha Zohdy (Rensselaer Polytechnic Institute, USA); Eva Song (Futurewei Technologies, USA); Guosen Yue (FutureWei Technologies, Inc., USA)
In this paper, we consider the finite blocklength analysis for the single-user block fading channel with discrete input constellations. In particular, we derive novel achievability results on Block Error Rate (BLER) for a given code rate and blocklength.
We first consider the scalar block fading channel case for which we adopt linear precoding as a method to increase the spectral efficiency associated with full temporal diversity. Then, we extend our analysis to the multiple-input multiple-output block fading channels under space-time linear precoding.
Numerical evaluations demonstrate the impact of finite blocklength and diversity in block fading channels as well as the effectiveness of linear precoding in minimizing the achievable BLER under practical modulation schemes, such as QPSK.