Optimal Hopping Patterns And Their Applications In Distributed MIMO Systems

People's demand has become diversified with the rapid development of mobile communication,that requires higher capacity and speed of communication system.The emergence of MIMO technology is a major breakthrough in the history of mobile communication.The distributed MIMO system combines the MIMO technology with the distributed antenna system,which fully demonstrates the advantages of the two technologies,and overcomes the problems of the traditional MIMO system such as the too large antenna correlation and signal access distance.Combined with the distributed architecture,more antennas can be used to transmit and receive at the same time,so as to improve the communication system capacity.Distributed MIMO system not only improves the signal coverage and channel capacity,reduces the transmission power and prolongs the service life of the device,but also improves the performance of anti large-scale fading.However,due to the combination of distributed antenna,multiple-access interference,multipath time delay,Doppler frequency shift have become the influencing factors of distributed MIMO communication system.Compared with the traditional constant carrier frequency communication,frequency-hopping communication has great advantages in anti-interference,anti-fading,easy networking,improving frequency utilization ratio and expanding system channel capacity.The key of frequency hopping communication is to construct frequency hopping sequence.Because Costas sequence has ideal auto-correlation but not ideal cross-correlation,this paper focuses on the construction method of optimal frequency-hopping graph with ideal auto-correlation and cross-correlation.Because of its ideal auto-correlation and cross-correlation,the optimal frequency-hopping graph has been widely used in aerospace telemetry,radar,OFDM or(and)MIMO cellular mobile communication and other fields.In this paper,based on the Welch Coasts sequence,the optimal frequency hopping chart with ideal auto-correlation and cross-correlation characteristics is constructed by using two-dimensional cyclic shift.Through simulation analysis,the optimal frequency hopping chart can effectively reduce the interference caused by Doppler frequency shift or multipath time delay in MIMO system.Compared with the traditional frequency hopping system,it can improve the information transmission rate and system capacity.The research results include important reference value for reducing the interference in thedistributed MIMO system.