Energy-Efficient Channel-Dependent Cooperative Relaying for the Multiuser SC-FDMA Uplink

• Published in: IEEE transactions on vehicular technology Vol. 60; no. 3; pp. 992 - 1004
• Main Authors: Zhang, Jiayi, Yang, Lie-Liang, Hanzo, Lajos
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.03.2011; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Access methods and protocols, osi model; Amplification; Applied sciences; Channels; Connection and protection apparatus; Cooperative communications; Detection, estimation, filtering, equalization, prediction; diversity combining; Diversity reception; Electrical engineering. Electrical power engineering; Energy efficiency; Exact sciences and technology; Fading; frequency-domain equalization (FDE); Gain; Information, signal and communications theory; Mean square errors; Noise; Noise levels; opportunistic relaying (OR); power allocation; Power control; Receivers; Relay; relay selection; Relaying; Relays; Shadow mapping; Signal and communications theory; Signal, noise; single-carrier frequency-division multiple-access (SC-FDMA); Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Teleprocessing networks. Isdn; Transmission and modulation (techniques and equipments); Relaying; Relay; Frequency division multiple access; Energetic efficiency; energy efficiency; Electric power consumption; opportunistic relaying (OR); Minimum energy; Routing protocols; Uplink; Fading; Multiple access; Dispersive channel; Transmission protocol; Cooperative systems; Frequency domain method; power allocation; Power electronics; Single carrier; Amalgams; Equalization; Cooperative communications; Diversity combining; Carrier frequency; frequency-domain equalization (FDE); relay selection; Large scale; Low-power electronics; single-carrier frequency-division multiple-access (SC-FDMA); Gain
• ISSN: 0018-9545; 1939-9359
• DOI: 10.1109/TVT.2011.2104985

In this paper, we exploit the benefits of combining the diversity gains that arise from cooperation, multiple propagation paths, and opportunistic relaying (OR) of multiple users. Our goal is to improve the energy efficiency of the amplify-andforward (AF) single-relay-assisted single-carrier frequency-division multiple-access (SC-FDMA) uplink, where the single relay considered may support a single user or may be shared by multiple users who communicate over dispersive channels subject to large-scale fading. Based on the proposed amalgam of single-tap frequency-domain equalization (FDE) and a diversity-combining-aided receiver that relies on the minimum mean-square error (MMSE) criterion, three different relay selection schemes designed for either single-user or multiuser relaying scenarios are investigated, when combined with source/relay power sharing, which employ imperfect power control. Our results demonstrate that, at a bit error ratio (BER) of 10^{-4} , the proposed receiver can save 2 dB power by achieving a higher cooperative diversity gain than the conventional receiver. Moreover, a beneficial energy efficiency improvement may be achieved when the cooperative regime operates at E_{b}/N_{0} < 0 . Most importantly, when the shadowing variance is increased from 4 dB to 8 dB, the energy consumption gain gleaned from our multiuser and multiaccess relay selection schemes may increase to 4 \sim 9, compared with the direct transmission in the absence of shadowing at E_{b}/N_{0} = -10 \ \hbox{dB} .