Latency and Reliability Trade-off with Computational Complexity Constraints: OS Decoders and Generalizations

TL;DR

This paper analyzes the trade-off between latency, reliability, and decoding complexity in URLLC systems, proposing an empirical model for OS decoders and demonstrating its applicability to various coding schemes.

Contribution

It introduces a comprehensive empirical model for decoding complexity and latency trade-offs, including optimization frameworks for URLLC system design.

Findings

Decoding latency significantly impacts URLLC system performance under complexity constraints.

The proposed model accurately predicts performance for OS decoders and other coding schemes.

Design optimization considering decoding time improves URLLC reliability and latency balance.

Abstract

In this paper, we study the problem of latency and reliability trade-off in ultra-reliable low-latency communication (URLLC) in the presence of decoding complexity constraints. We consider linear block encoded codewords transmitted over a binary-input AWGN channel and decoded with order-statistic (OS) decoder. We first investigate the performance of OS decoders as a function of decoding complexity and propose an empirical model that accurately quantifies the corresponding trade-off. Next, a consistent way to compute the aggregate latency for complexity constrained receivers is presented, where the latency due to decoding is also included. It is shown that, with strict latency requirements, decoding latency cannot be neglected in complexity constrained receivers. Next, based on the proposed model, several optimization problems, relevant to the design of URLLC systems, are introduced and solved. It is shown that the decoding time has a drastic effect on the design of URLLC systems when constraints on decoding complexity are considered. Finally, it is also illustrated that the proposed model can closely describe the performance versus complexity trade-off for other candidate coding solutions for URLLC such as tail-biting convolutional codes, polar codes, and low-density parity-check codes.