Power allocation in OFDM cognitive radio relay networks with outdated channel state information

Abstract

SUMMARYIn this paper, we study power allocation in OFDM cognitive radio (CR) relay networks. The objective of power allocation is to maximize the instantaneous capacity of the CR network. It is assumed that the available channel state information between the secondary and primary users is an outdated but correlated version of the actual instantaneous channel state information. Optimal power allocation schemes are developed for both decode-and-forward and amplify-and-forward relay assisted CR transmission, assuming that the primary users are subject to average interference constraints and the CR transmitters are subject to maximum transmit power constraint. In addition, suboptimal power allocation schemes with reduced complexity are also proposed. Performance of the proposed schemes is compared with uniform power allocation and numerical results confirm that the proposed power allocation schemes achieve significant capacity improvement in comparison to uniform power loading. Furthermore, the proposed suboptimal power allocation schemes can be used as less complex alternatives for optimal power allocation with some capacity degradation.

Energy‐efficient power allocation for cognitive radio networks with minimal rate requirements

“…In , the authors propose a simplified algorithm to select relay and allocate power to maximize the capacity under the interference constraint. Biyanwilage et al aim to maximize the instant capacity of the CR system with optimal power distribution schemes, while Nouri and Noori propose power allocation to maximize usage efficiency of the secondary network in which SUs transmit data through the same spectral band that has been assigned to the PUs. Biyanwilage et al study the optimal power allocation schemes to maximize the capacity of the CR system, where the average interference constraints should be reached for the PUs, and the CR transmitters have maximum transmit power constraints.…”

A low‐complexity resource allocation algorithm in OFDMA‐based cooperative cognitive radio networks

“…However, in OFDMA-based cooperative cognitive radio networks, the complexity of resource allocation, including relay selection, subcarrier assignment and power allocation is prohibitive. In [15], optimal power allocation has been studied in OFDM cognitive radio relay networks for both decode-and-forward (DF) and amplify-and-forward relay assisted secondary users transmission, also suboptimal power allocation algorithms with reduced complexity are proposed with some capacity degradation. In [13], a joint subcarrier and power allocation algorithm is presented for cooperative multiuser orthogonal frequency division multiplexing cognitive radio systems.…”

“…In [14], it is assumed that, with the cooperation of PUs, the resource allocation for the PUs is known to the SUs, and then based on duality theory, a partially distributed algorithm is proposed in an OFDMA-based downlink cognitive radio network. In [15], optimal power allocation has been studied in OFDM cognitive radio relay networks for both decode-and-forward (DF) and amplify-and-forward relay assisted secondary users transmission, also suboptimal power allocation algorithms with reduced complexity are proposed with some capacity degradation. However, in this work, it is assumed that the direct link between the SU-Tx and the SU-Rx is blocked by obstacles, and there is no direct link between source and destination.…”