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Achievable Rate and Capacity of Amplify-and-Forward Multi-Relay Networks with Channel State Information

Tran, Tuyen X
http://rave.ohiolink.edu/etdc/view?acc_num=akron1376743091

Abstract Details

2013, Master of Science, University of Akron, Electrical Engineering.
Cooperative relaying is an effective approach to enhance the reliability and data-rate of wireless channels, where network nodes assist each other by relaying transmissions. Among different cooperative relaying protocols, the amplify-and-forward (AF) scheme is popular due to its performance and the ease of implementation. This thesis investigates the cooperative AF half-duplex multi-relay systems from an information-theoretic point of view where multiple relays use channel state information (CSI) to cooperate with the source and destination. The first part of the thesis is dedicated to the orthogonal AF (OAF) protocol where the source and relays using orthogonal channels for transmission. For a given input covariance matrix at the source, an optimal power allocation scheme among the relays is first developed via the optimal instantaneous power amplification coefficients to maximize the end-to-end achievable rate. The optimization problem is concave and is solved by Karush-Kuhn-Tucker conditions. The ergodic channel capacity is then derived by jointly optimizing the input covariance matrix at the source and the power sharing scheme among the relays. This is a bi-level non-convex optimization problem and can be solved using Tammer decomposition method. Furthermore, the capacity-achieving input covariance matrix is analyzed in high and low signal-to-noise ratio (SNR) regimes. At high SNRs, it is demonstrated that the transmit power should be distributed equally to all broadcasting phases at the source. On the other hand, at low SNRs, the optimal way is to use only a relay having the strongest cascaded source-relay and relay-destination channels and the source spends all the power in the broadcasting phase corresponding to that relay. The second-part of the thesis extends the results and analysis to the non-orthogonal AF (NAF) protocol, which is considered as a general description of AF relaying. Given the nature of broadcasting and receiving collisions in NAF, the optimization problem to maximize the achievable rate is non-convex. A novel method is proposed by evaluating the achievable rate in different sub-domains of the vector channels to obtain the globally optimal solution. The ergodic channel capacity is then established by using Tammer decomposition method. Finally, focusing on the asymptotic behavior, it is show that at high SNRs, the transmit power at the source should be equally distributed in all broadcasting and cooperative phases. At low SNRs, similar to the OAF, the source should spend all its power in the broadcasting phase associated with a relay having the strongest cascaded source-relay and relay-destination channels.
Nghi Tran, Dr. (Advisor)
Hamid Bahrami, Dr. (Committee Member)
S.I. Hariharan, Dr. (Committee Member)
109 p.
Electrical Engineering
Achievable rate; channel state information; distributed water filling; ergodic capacity; multiple relays; non orthogonal amplify and forward; power adaptation; relay channel

Recommended Citations

Citations

  • Tran, T. X. (2013). Achievable Rate and Capacity of Amplify-and-Forward Multi-Relay Networks with Channel State Information [Master's thesis, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1376743091

    APA Style (7th edition)

  • Tran, Tuyen. Achievable Rate and Capacity of Amplify-and-Forward Multi-Relay Networks with Channel State Information. 2013. University of Akron, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1376743091.

    MLA Style (8th edition)

  • Tran, Tuyen. "Achievable Rate and Capacity of Amplify-and-Forward Multi-Relay Networks with Channel State Information." Master's thesis, University of Akron, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=akron1376743091

    Chicago Manual of Style (17th edition)

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This open access ETD is published by University of Akron and OhioLINK.