Finite Blocklength Analysis of Multiple Access Channels With/Without Cooperation

• Published in: IEEE transactions on communications Vol. 68; no. 10; pp. 6317 - 6330
• Main Authors: Kourtellaris, Christos K., Psomas, Constantinos, Krikidis, Ioannis
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.10.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Bursty traffic; Channel capacity; cognitive cooperation; Cooperation; Finite blocklength analysis; Information theory; MAC; Metadata; network stability; Numerical stability; Packets (communication); Protocol (computers); Protocols; Queuing theory; Relaying; Relays; Signal to noise ratio; Stability analysis; Stochastic processes; Strategy; TDMA; Throughput; Time Division Multiple Access
• ISSN: 0090-6778; 1558-0857
• DOI: 10.1109/TCOMM.2020.3009260

Motivated by the demand of reliable and finite blocklength communications, we employ tools from information theory, stochastic processes and queueing theory, in order to provide a comprehensive framework regarding the analysis of a Time Division Multiple Access (TDMA) network with bursty traffic, in the finite blocklength regime. Specifically, we re-examine the stability conditions of a non-cooperative TDMA multiple access channel, evaluate the optimal throughput, and identify the optimal data packet size, <inline-formula> <tex-math notation="LaTeX">k </tex-math></inline-formula>, for fixed codeword of blocklength, <inline-formula> <tex-math notation="LaTeX">n </tex-math></inline-formula>. The evaluation is performed both numerically and via the proposed approximations, which result in closed form expressions and provide insight on how the optimal data size, <inline-formula> <tex-math notation="LaTeX">k^{*} </tex-math></inline-formula>, relates to the information metrics of channel capacity and channel dispersion in the finite blocklength regime. Then, we examine the stability conditions and the performance of the Multiple Access Relay Channel with TDMA scheduling, subject to finite blocklength constraints, by applying a cognitive cooperation protocol that assumes relaying is enabled when sources are idle. Finally, we propose the novel Batch-And-Forward (BAF) strategy, a mechanism that allows terminals to send batches of data packets instead on individual data packets, and evaluate the stability conditions and the optimal throughput. Numerical evaluation of the proposed strategy indicates that the performance of the cooperative network in the finite blocklength regime, in terms of throughput, can be significantly enhanced. Moreover, it reduces the requirement in control signals (metadata) <xref ref-type="bibr" rid="ref3">[3] , since, it avoids the unnecessary repetition of metadata (e.g. address of the source terminal and the destination). The BAF strategy is quite versatile, thus, it can be embedded in existing cooperative protocols, without imposing additional complexity on the overall scheme.