Double Differential Modulation for Buffer-Aided Cooperative Relaying with Priority-Based Max Link Selection

In this paper, we propose double differential (DD) modulation for a buffer-aided cooperative system, employing decode-and-forward relaying. The considered set-up does not require information of channel coefficients and carrier frequency offset at receiving nodes. A Markov chain approach is used to determine the state transition matrix which is used to model the evolution of buffer status. An analytical expression is derived for the steady state probability; outage probability and average bit error rate (ABER) of the system are evaluated with the help of steady state probability. With the help of the obtained ABER, the performance gap between the considered system and a coherent buffer-aided network is observed. The considered DD system experiences a signal-to-noise ratio (SNR) penalty of approximately 4 dB at BER level of 10
^-5
which is a significant improvement over non-buffer-aided DD system; which suffers an SNR penalty of 6 dB compared to coherent detection.