Abstract
The paper presents a joint subcarrier-pair based resource allocation algorithm in order to improve the efficiency and fairness of cooperative multiuser orthogonal frequency division multiplexing (MU-OFDM) cognitive radio (CR) systems. A communication model where one source node communicates with one destination node assisted by one half-duplex decode-and-forward (DF) relay is considered in the paper. An interference-limited environment is considered, with the constraint of transmitted sum-power over all channels and aggregate average interference towards multiple primary users (PUs). The proposed resource allocation algorithm is capable of maximizing both the system transmission efficiency and fairness among secondary users (SUs). Besides, the proposed algorithm can also keep the interference introduced to the PU bands below a threshold. A proportional fairness constraint is used to assure that each SU can achieve a required data rate, with quality of service guarantees. Moreover, we extend the analysis to the scenario where each cooperative SU has no channel state information (CSI) about non-adjacent links. We analyzed the throughput and fairness tradeoff in CR system. A detailed analysis of the performance of the proposed algorithm is presented with the simulation results.
Highlights
Cognitive radio technology (CR) has been proposed as a relatively new concept for improving the overall utilization of spectrum bands
In contrast with [36], where large channel fluctuations are intentionally created with “dumb” antennas for long-term proportional fairness resource allocation, this paper proposes a subcarrier-pair based resource allocation algorithm to maintain proportional rates among secondary users (SUs) for each channel realization, which ensures the rates of different SUs to be proportional in any time scale of interest
We have developed a novel subcarrier-pair based resource allocation algorithm that maximizes the transmission data rate while the interference introduced to the primary users (PUs) remains within a given limit
Summary
Cognitive radio technology (CR) has been proposed as a relatively new concept for improving the overall utilization of spectrum bands. Chandrashekar et al [24] proposed an algorithm which is capable of maximizing the total transmitted data rate and achieving a high proportional fairness index This algorithm cannot be applied to the CR network where we must adjust the interference introduced to the PU bands below. Nader et al in [29] considered the practical case in which only partial CSI for the wireless channel between the secondary base station and SUs is available at the secondary base station They formulated the resource allocation problem in the secondary network as an optimization problem in which the objective was to maximize the weighted sum rate of the secondary users. The proposed subcarrier-pair based resource allocation algorithm ensures the rates of different SUs to be proportional in any time scale of interest, simulation results shown that a high transmitted data rate for all SUs (even those with poor channel gains) can be achieved. Denotes the expectation operator, and denotes the optimal value when only partial CSI can be obtained by SUs
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