Optimized Design Schemes Of Precoders And Decoders In Cognitive Radio Networks Based On Interference Alignment

Cognitive radio networks based on interference alignment is currently a hot researchtopic in the field of communications,it can dramatically improve the spectrum utilization.Although interference alignment can effectively remove interference of secondary users to primary users,it reduces the signal-to-noise ratio of primary users,which affects their performance.Thus,this paper will research optimized design schemes of precoders and decoders in cognitive radio networks based on interference alignment,the specific work is as follows:(1)Focus on CR networks with single primary user,this paper proposed two algorithms.On the basis of the application of full interference alignment,the first algorithm re-design the precoding matrix of primary user on the principle of optimal rates,it can optimize the performance of primary user through sacrificing partial performance of secondary users,which ensures the priority of primary user.The second algorithm optimized precoder of primary user on the principle of completely removing interference among different data streams.Compared to the first algorithm,although the second proposed algorithm has some performance degradation,it provides extremely low time consumption,which has more actual application meanings.Simulation results show that the two proposed algorithms both can achieve the desired effects and have better performance compared to simply using classical interference alignment algorithms.(2)In CR networks with multiple primary users,based on different demands between primary networks and secondary networks,this paper proposed an unidirectional iterative optimization algorithm based on orthogonalization.This algorithm firstly utilizes maximal signal to interference plus noise ratio algorithm to improve the communication quality of primary users,then it optimizes precoding and decoding matrices through orthogonal space updating algorithm to completely eliminate interference of secondary users to the other users.From the comparison results,it can be seen that the proposed algorithm not only has much lower complexity,but also can improve the sum rate of the whole system effectively.