Opportunistic relay selection with outdated CSI: outage probability and diversity analysis

• Published in: IEEE transactions on wireless communications Vol. 8; no. 6; pp. 2872 - 2876
• Main Authors: Vicario, J.L., Bel, A., Lopez-Salcedo, J.A., Seco, G.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.06.2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Access methods and protocols, osi model; Applied sciences; Approximation; Capacity planning; Channel state information; Channels; Closed-form solution; Cooperative communications; Decoding; Detection, estimation, filtering, equalization, prediction; diversity gain; Diversity methods; Exact sciences and technology; Exact solutions; Extreme values; Information analysis; Information, signal and communications theory; Mathematical analysis; MIMO; opportunistic relay selection; Outages; outdated CSI; Power system relaying; Relay; Relays; Signal and communications theory; Signal, noise; System performance; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Teleprocessing networks. Isdn; Transmission and modulation (techniques and equipments); Wireless communication; Parameter estimation; Relay; Outage; Diversity; Transmission protocol; diversity gain; Cooperative communications; Accuracy; opportunistic relay selection; Channel estimation; Numerical simulation; Routing protocols; Signal to noise ratio; outdated CSI
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2009.081561

In this paper, we analyze the outage probability and diversity order of opportunistic relay selection in a scenario based on decode and forward and where the available channel state information (CSI) is outdated. The study is conducted analytically by obtaining a closed-form expression for the outage probability, which is defined as the probability that the instantaneous capacity is below a target value. We derive high-SNR approximations for the outage probability. By doing so, we demonstrate that the diversity order of the system is reduced to 1 when CSI is outdated, being this behavior independent of the level of CSI accuracy. A physical explanation for this extreme loss of diversity is provided along with numerical results to support the analytical study.