Interference Alignment Based Resource Management in MIMO Cognitive Radio Systems

Abstract:
In this paper, interference alignment (IA) is utilized to obtain an efficient and fair resource allocation algorithm in MIMO cognitive radio (CR) systems. In the proposed algorithm, IA enables all secondary users to share the available spectrum without affecting the quality-of-service of the primary system. The considered methodology increases the total degrees-of-freedom of the CR systems and achieves fairness among CR users. An optimal power allocation based on IA is formulated in order to maximize the total sum-rate while keeping the interference introduced to the primary system lower than the prescribed interference threshold. Furthermore, a sub-optimal power allocation scheme is proposed to overcome the high computational complexity of the optimal scheme. Simulations reveal that IA technique achieves significant sum-rate increase of CR systems compared to frequency division multiple access (FDMA) CR systems. Moreover, the sub-optimal algorithm approaches the optimal sum-rate performance.