Distributed Space-Time Coding for Two-Way Wireless Relay Networks

• Published in: IEEE transactions on signal processing Vol. 57; no. 2; pp. 658 - 671
• Main Authors: Tao Cui, Feifei Gao, Ho, T., Nallanathan, A.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-02-2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Access control; Applied sciences; Coding; Coding, codes; Decoding; Digital relays; Diversity methods; Exact sciences and technology; Galois fields; Information, signal and communications theory; Media Access Protocol; Miscellaneous; Network coding; Networks; Portable document format; Protocol (computers); Rayleigh-fading channels; Relay; Relay networks; Signal and communications theory; Signal processing; space-time coding; Telecommunication traffic; Telecommunications and information theory; Terminals; two-way channel; Wireless networks; wireless relay networks; Wireless sensor networks; Fading channels; Access control; Finite field; Relaying; Space-time codes; Unitary matrix; Relay; Random matrix; Two channel system; Wireless telecommunication; space-time coding; Rayleigh channels; Diversity; Transmission protocol; Teletraffic; two-way channel; Random coding; Rayleigh-fading channels; Linear code; Linear coding; Signal processing; Wireless network; Routing protocols; wireless relay networks
• ISSN: 1053-587X; 1941-0476
• DOI: 10.1109/TSP.2008.2009025

In this paper, we consider distributed space-time coding for two-way wireless relay networks, where communication between two terminals is assisted by relay nodes. Relaying protocols using two, three, and four time slots are proposed. The protocols using four time slots are the traditional amplify-and-forward (AF) and decode-and-forward (DF) protocols, which do not consider the property of the two-way traffic. A new class of relaying protocols, termed as partial decode-and-forward (PDF), is developed for the two time slots transmission, where each relay first removes part of the noise before sending the signal to the two terminals. Protocols using three time slots are proposed to compensate the fact that the two time slots protocols cannot make use of direct transmission between the two terminals. For all protocols, after processing their received signals, the relays encode the resulting signals using a distributed linear dispersion (LD) code. The proposed AF protocols are shown to achieve the diversity order of min{N,K}(1- (log log P/log P)), where N is the number of relays, P is the total power of the network, and K is the number of symbols transmitted during each time slot. When random unitary matrix is used for LD code, the proposed PDF protocols resemble random linear network coding, where the former operates on the unitary group and the latter works on the finite field. Moreover, PDF achieves the diversity order of min{N,K} but the conventional DF can only achieve the diversity order of 1. Finally, we find that two time slots protocols also have advantages over four-time-slot protocols in media access control (MAC) layer.