Revisiting Incremental Relaying and Relay Selection for Underlay Cognitive Radio

Abstract

Cooperative relaying combined with selection exploits spatial diversity to improve the performance of interference-constrained secondary users in an underlay cognitive radio network. While a relay improves the signal-to-interferenceplus-noise ratio, it requires two hops and also generates interference to the primary. Therefore, in underlay cognitive radio, new criteria are needed to determine which relay to select. We present an optimal relay selection rule that maximizes the fading-averaged transmission rate of an average interferenceconstrained underlay secondary network. It differs from the many rules proposed in the literature. We then analyze its fadingaveraged channel capacity. Numerical results show that the proposed rule outperforms direct transmission and several other rules, such as incremental relaying, proposed in the literature.

Throughput analysis and optimization of cognitive radio networks using incremental relaying

“…Incremental relaying for Cognitive Radio Networks (CRN) was studied in [14][15][16][17][18][19][20][21][22][23][24]. Cooperative beamforming combined with incremental relaying was considered in [14] in order to improve spectrum efficiency.…”

“…The asymptotic outage probability, diversity and coding gains were evaluated in [20] in the presence of multiple DF relays. The average fade duration was studied in [21] when incremental AF relaying is implemented. Relaying for multihop CRN has been studied in [22][23][24].…”

“…-Study incremental relaying with partial and reactive relay selection. Only opportunistic relaying was previously studied [14][15][16][17][18][19][20][21]. -Consider multihop multibranch incremental relaying.…”

“…-Optimize the secondary throughput by choosing an appropriate value of β. Previous studies have not optimized β [14][15][16][17][18][19][20][21]. -We take into account the interference from primary transmitter to secondary nodes as well as interference from secondary nodes to primary receiver.…”