Research On Signal Subspace Orthogonalreconstruction Algorithm For Two-way Relay

With the increasing demand for wireless communication in modern life,limited spectrum resources have become one of the important factors limiting the development of communication services,and increasing the transmission signal bandwidth or using broadband signals cannot guarantee the demand for the continuous development of communication services.Therefore,in the background of current spectrum resources,the effective use of spectrum resources and the improvement of transmission efficiency are the research directions that communication researchers are paying close attention to.In recent years,in order to suppress co-channel interference and ensure the reliability of transmitted signals,physical layer network coding(PNC)and Signal Space Alignment(SSA)techniques are proposed.At present,the research on these two technologies focuses on combining with other advanced technologies and applying them to more channel models,while the technology itself has less research on improving system reliability.Therefore,this paper aims to study the transmission reliability of interference utilization in relay communication systems.The main research application scenarios in this paper are two-way relay system and MIMO Y channel model.These two typical system models are used as communication scenarios,and corresponding improvement schemes are proposed for physical layer network coding and signal space alignment in relay cooperative communication.In order to improve the transmission efficiency and bit error rate performance of the communication system,and ensure the reliability of information transmission.The main research contents of this paper are:Firstly,for the fuzzy detection problem caused by the relay mapping of the high-order modulation physical layer network coding,the high-order mapping design is performed according to the coding criterion of the physical layer network coding.On the one hand,the amplitude of the modulated signal is controlled,and the modulation and demodulation mapping rules are designed to achieve the purpose of separating the coincident constellation points;on the other hand,the appropriate mapping rule is found from the Euclidean distance between adjacent constellation points in the superimposed signal constellation.Then,this chapter makes a comparative analysis of the performance of the two proposed solutions from different angles.Secondly,the importance of orthogonal alignment of signal subspace is analyzed.With the help of redundancy of user antennas,the signal subspace random orthogonal alignment algorithm is initially achieved,and the limitations of the scheme are pointed out.It is found that the worst transmission channel is the most critical factor that restricts system performance.By improving the transmission quality of the worst channel by algorithm design,the system performance can be significantly improved.Therefore,the corresponding user transmit power of the worst transmission channel is preferentially guaranteed,and the spatial alignment direction formed by corresponding interactive signal should be first determined in the relay.The selection gain of the signal space is used to compensate for the impact caused by the poor performance of the system.In addition,as a premise to improve the overall performance,a method for judging the quality of channel transmission in the system is designed to realize the criterion for determining the spatial alignment direction of the transmission channel from the worst to the best.Applying this result to the Multiple Access Channel(MAC)precoding orthogonal reconstruction optimization scheme makes the improved scheme easier to generalize to the multi-user channel model.Finally,in the multi-user MIMO Y channel,the signal subspace orthogonal alignment under high-order modulation is proposed,which is combined the improved high-order modulation physical layer network coding relay mapping scheme with the optimized signal subspace orthogonal reconstruction algorithm.The implementation steps of the algorithm from the MAC to the broadcast(Broadcast Channel,BC)are described.The proposed algorithm is simulated by related performance,which verifies the reliability and effectiveness of the algorithm.