Abstract: In this study, a cross-layer design which combines
adaptive modulation and coding (AMC) and hybrid automatic repeat
request (HARQ) techniques for a cooperative wireless network is
investigated analytically. Previous analyses of such systems in the
literature are confined to the case where the fading channel is
independent at each retransmission, which can be unrealistic unless
the channel is varying very fast. On the other hand, temporal channel
correlation can have a significant impact on the performance of
HARQ systems. In this study, utilizing a Markov channel model
which accounts for the temporal correlation, the performance of
non-cooperative and cooperative networks are investigated in terms of
packet loss rate and throughput metrics for Chase combining HARQ
strategy.
Abstract: Cooperative spectrum sensing is a crucial challenge in
cognitive radio networks. Cooperative sensing can increase the
reliability of spectrum hole detection, optimize sensing time and
reduce delay in cooperative networks. In this paper, an efficient
central capacity optimization algorithm is proposed to minimize
cooperative sensing time in a homogenous sensor network using OR
decision rule subject to the detection and false alarm probabilities
constraints. The evaluation results reveal significant improvement in
the sensing time and normalized capacity of the cognitive sensors.