Delay constrained throughput optimization in multi-hop AF relay networks, using limited quantized CSI

• Published in: EURASIP journal on wireless communications and networking 2019-04, Vol.2019 (1), p.1-12, Article 102
• Main Authors: Taki, Mehrdad, Svensson, Tommy, Nezafati, Mohammad Bagher
• Format: Article
• Language: English
• Subjects: Adaptive modulation and coding; Algorithms; Amplify and forward relaying; Communications Engineering; Delay; Delay-QoS constraint; Discrete link adaptation; Engineering; Information Systems Applications (incl.Internet); Multi-hop relay; Networks; Nonlinear programming; Optimization; Probability density functions; Random access memory; Relay networks; Signal,Image and Speech Processing
• ISSN: 1687-1499; 1687-1472; 1687-1499
• DOI: 10.1186/s13638-019-1423-3

In this paper, we analyze the throughput of multi-hop amplify and forward (AF) relay networks in delay-constrained scenario. Using quantized channel state information (CSI), the transmission rates and powers are discretely adapted with individual average power constraint on each node. A sub-gradient projection-based algorithm is utilized, by which there is no need for probability density functions (PDFs) to solve the optimization problem. Our numerical evaluations show that the sub-gradient projection-based algorithm results in a comparable performance with an analytical approach using PDFs. As shown, a considerably better performance obtained by the designed scheme compared to previous schemes with constant power transmission. More than 70% throughput improvement is achieved by our scheme compared to constant power transmission with just two more feedback bits and a short training time required at the beginning of the transmission.