几种多天线系统的信道容量比较

分布式天线、智能天线和扇区天线是三种能大大提高无线通信系统容量的技术,本文比较了这三种多天线系统的信道(Shannon)容量.假设每个用户在所有接收天线上的总功率相等,分析表明分布式天线和扇区天线的信道容量远大于智能天线的信道容量,而传统的观点认为智能天线在抑制干扰时要比扇区天线的性能更好,从而获得更大的系统容量.另外我们分析了分布式天线在渐近条件下的信道容量,即用户数K和载波数M都趋近无穷大,而保证α=K/M一定.分析表明在α较大时,分布式天线与比扇区天线的信道容量差趋近常数0.44比特/秒/维,但是如果考虑分布式天线的分集增益,那么分布式天线的信道容量要远大于扇区天线.

Channel Capacity Comparison of Several Multiple Antennas Systems

Distributed antenna,smart antenna and sector antenna are three techniques to improve the system capacity in wireless communication.In this paper,we compare the channel/Shannon capacity of multiple antennas in the three cases.Assuming the average received signal power in total antennas from each user is the same,we get that distributed antenna and sector antenna have much larger Shannon capacity than smart antenna.This is in contrast with that smart antenna has a better performance than sector antenna in suppressing interference,which results in an improvement in system capacity.We also analyze the capacity of distributed antenna in unlimited case,that is,with large number of users K and large number antennas M while keeping the number of users per dimension α constant.Analysis show that in case of large α,α1,the capacity of distributed antenna approaches to that of sector antenna with a constant addition 0.44bit/s/Hz/Dim.It should be noted that if diversity gain by distributed antenna is considered,its capacity is still much larger than that of sector antenna.