Differential Modulation-Based Buffer-Aided Cooperative Relaying Network

Abstract

In this article, we consider a multirelay cooperative network using a differential modulation technique. The given set-up consists of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$K$</tex-math></inline-formula> decode-and-forward (DF) relays, each equipped with a buffer of size <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$L$</tex-math></inline-formula> . All transceiver nodes in the considered cooperative network apply differential modulation for the transmission of data, hence, channel-state information is not required for decoding of the data at the receiving nodes. A priority-based max link selection approach is used for the selection of the best links for the transmission and reception of data. The Markov chain approach is used to derive the state-transition matrix of the system, which is then further used to model the evolution of buffer status. Analytical expressions of the outage probability and average bit error rate are obtained with the help of the state-transition matrix. The performance of the considered system is analyzed for different buffer sizes and a number of relays. The performance is then further compared with that of a coherent buffer-aided network and also with the nonbuffer-aided differential amplify-and-forward and DF systems. As compared to the coherent buffer-aided network, the considered buffer-aided differential system suffers a negligible signal-to-noise ratio penalty in the scenario when more than one buffer-aided relay is present in the network, which is a significant improvement when compared with the nonbuffer-aided differential cooperative systems, which suffer a performance penalty of approximately 3 dB as compared to their coherent counterpart.