Improved Spectrum-Sharing Protocol for Cognitive Radio Networks With Multiuser Cooperation

Abstract

This paper proposes an improved spectrum-sharing protocol for multiuser cooperation in cognitive radio (CR) networks. In CR networks, a secondary user (SU) can access the licensed bands of a primary user (PU) as compensation for cooperative transmission. During cooperative transmission, the SU concurrently transmits its own signal and network-coded signal from the PUs. However, detection errors at the SU cause error propagation which degrades the performance of the PU and SU. To address this problem, we develop a cooperative maximalratio combining scheme that mitigates the error propagation and achieves diversity gain. To evaluate the combining scheme, we derive a diversity order and closed-form bit error rate (BER) expression for arbitrary M -QAM at high SNR. The analysis results show that the diversity order and BER depend on the fraction of the transmit power at the SU. Based on the dependency of the fraction factor, we propose an optimization problem to minimize the BER of the SU while guaranteeing the PU's BER. Further, we apply the BER-constrained optimization problem to the adaptive modulation system. Simulation results show that the proposed cooperation provides full diversity gain to the PU and thus improves its spectral efficiency by using the optimized fraction factor.Index Terms-Cognitive radio, overlay spectrum sharing, multiuser cooperation, network coding, bit error rate.

Cooperative Overlay Spectrum Access in Cognitive Radio Networks

“…El-Sherif et al [88] The joint design of routing and resource allocation algorithms in cognitive radio based wireless mesh networks. Kim et al [89] An improved spectrum-sharing protocol for multiuser cooperation in CR networks. Equilibrium is as follows: Let L be the number of players in a game, where the user-index is l, which obeys 0 < l ≤ L, while s l denotes a set of potentially available mixed strategies for player l, with s l ∈ S i being any possible strategy of player l. The Nash Equilibrium satisfies the following equation:…”