Latency and Reliability Limits with Decoding Complexity Constraints
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One of the most important application scenarios in next-generation wireless networks is ultra-reliable low-latency communication (URLLC) where stringent constraints on both reliability and latency must be guaranteed. In most existing communication-theoretic studies, latency is defined as the time required for the transmission of a message over the communication channel. This implies that other operations necessary for the successful delivery of the information, e. g., the time required for the decoding of the transmitted message, are assumed to happen instantaneously. However, with strict latency requirements, the decoding time cannot be neglected. In contrast, a more refined modeling of the decoding complexity and the delay that this incurs must be considered. In this paper, we study the performance of state-of-the-art channel codes as a function of the decoding complexity and propose an empirical model that accurately quantifies the corresponding trade-off. 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 aggregate latency when decoding complexity constraints are considered.
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