Linear Network Coding Strategies for the Multiple Access Relay Channel with Packet Erasures

• Published in: IEEE transactions on wireless communications Vol. 12; no. 1; pp. 218 - 227
• Main Authors: Dai, Mingjun, Kwan, Ho Yuet, Sung, Chi Wan
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.01.2013; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Applied sciences; Channels; Coding; Coding, codes; Encoding; Equipments and installations; Exact sciences and technology; Information, signal and communications theory; Mobile radiocommunication systems; Multiple access; Multiple access relay channel; Network coding; Networks; Numerical control; Packet transmission; Radiocommunications; Relay; Relays; Signal and communications theory; Signal to noise ratio; Strategy; Studies; Switching and signalling; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Vectors; wireless relay network; Performance evaluation; Fading; Mobile radiocommunication; Multiple access; Lower bound; Packet switching; Relay; Relay network; Wireless telecommunication; Loss rate; Data transmission; Cell network; Multiple access relay channel; Hybrid system; Linear coding; Relay channel; wireless relay network; Network coding; Wireless network; Optimal planning; Transmission loss; Multiple channel; Signal to noise ratio
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2012.120412.112266

The multiple access relay channel (MARC) where multiple users send independent information to a single destination aided by a single relay under large-scale path loss and slow fading is investigated. At the beginning, the users take turns to transmit their packets. The relay is not aware of the erasure status of each packet at the destination but has the knowledge of the average signal-to-noise-ratio (SNR) of every communication link. With this knowledge, the relay applies network coded retransmission on the overheard packets so as to maximize the expected total number of recovered packets or minimize the average packet loss rate at the destination. Several network coding (NC) strategies at the relay are designed. In particular, for the case where the relay is given only one time slot for retransmission, an optimal NC construction is derived. For the multiple-slot case, three sub-optimal schemes are investigated, namely network coding with maximum distance separable (MDS) code (NC-MDS), the worst-user-first (WUF) scheme and a hybrid of NC-MDS and WUF. We prove that NC-MDS and WUF are asymptotically optimal in the high and low SNR regimes, respectively. A lower bound on the average packet loss rate has been derived. Numerical studies show that, in a cellular system, the hybrid scheme offers significant performance gain over a number of existing schemes in a wide range of SNR. We also observe that performance curves of both WUF and the hybrid scheme touch the derived lower bound in the low SNR regime.