tailieunhanh - Báo cáo hóa học: " Selection combining for noncoherent decode-and-forward relay networks"

Tuyển tập các báo cáo nghiên cứu về hóa học được đăng trên tạp chí hóa hoc quốc tế đề tài : Selection combining for noncoherent decode-and-forward relay networks | Nguyen and Nguyen EURASIP Journal on Wireless Communications and Networking 2011 2011 106 EURASIP Journal on . http content 20ll l l06 Wireless Communications and Networking a SprlngerOpen Journal RESEARCH Open Access Selection combining for noncoherent decode-and-forward relay networks Ha X Nguyen and Ha H Nguyen Abstract This paper studies a new decode-and-forward relaying scheme for a cooperative wireless network composed of one source K relays and one destination and with binary frequency-shift keying modulation. A single threshold is employed to select retransmitting relays as follows a relay retransmits to the destination if its decision variable is larger than the threshold otherwise it remains silent. The destination then performs selection combining for the detection of transmitted information. The average end-to-end bit-error-rate BER is analytically determined in a closed-form expression. Based on the derived BER the problem of choosing an optimal threshold or jointly optimal threshold and power allocation to minimize the end-to-end BER is also investigated. Both analytical and simulation results reveal that the obtained optimal threshold scheme or jointly optimal threshold and power-allocation scheme can significantly improve the BER performance compared to a previously proposed scheme. Keywords cooperative diversity frequency-shift keying fading channel decode-and-forward protocol selection combining power allocation 1 Introduction Cooperative diversity has recently emerged as a promising technique to combat fading experienced in wireless transmissions. The basic idea behind this technique is that a source node cooperates with other nodes or relays in the network to form a virtual multiple antenna system 1-7 hence providing spatial diversity. Amplify-and-forward AF and decode-and-forward DF are two well-known protocols to realize cooperative diversity. In AF the relays amplify and forward the received signals to the .

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