In this article, 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.

中文翻译：

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延迟和可靠性之间的权衡与计算复杂性约束：OS解码器和通用化

在本文中，我们研究了在存在解码复杂性约束的情况下，超可靠的低延迟通信（URLLC）中的延迟和可靠性之间的权衡问题。我们考虑通过二进制输入AWGN通道传输并使用阶数统计（OS）解码器解码的线性块编码码字。我们首先研究OS解码器的性能作为解码复杂度的函数，并提出一种可以准确量化相应折衷的经验模型。接下来，提出了一种计算复杂度受限的接收机的总等待时间的一致方法，其中还包括了由于解码而引起的等待时间。结果表明，在严格的等待时间要求下，在复杂度受限制的接收器中不能忽略解码等待时间。接下来，基于提出的模型，几个优化问题，介绍并解决了与URLLC系统设计有关的问题。结果表明，在考虑解码复杂度的约束条件下，解码时间对URLLC系统的设计产生了巨大影响。最后，还说明了所提出的模型可以紧密描述URLLC的其他候选编码解决方案（例如尾比特卷积码，极性码和低密度奇偶校验码）的性能与复杂度之间的权衡。