分布式天线系统MIMO信道容量分析

Analysis of MIMO channel capacity for distributed antenna system

结合了分布式天线系统和MIMO信道特点的分布式MIMO系统可以改善覆盖特性,提高系统容量。提出了包含路径损耗、快衰落和阴影衰落的两层分集分布式MIMO系统。对MIMO信道容量的分析表明,分布式MIMO系统具有良好的信道容量均匀覆盖特性。与传统集中式天线系统相比,分布式MIMO系统可以获得更好的小区平均信道容量。对下行信道容量的数值分析表明,由于“充水”方式功率分配可以充分利用MIMO信道信息,此时的分布式MIMO系统可以比等功率分配条件下的分布式天线系统多获得0.25bit/(s·Hz)每发送天线的信道容量增量。

A distributed MIMO system combining the characteristics of MIMO channel and distributed antenna system was proposed. Channel model considered the influences of path loss, fast fading and lognormal shadowing. First, MIMO channel capacity between distributed antenna （DA） systems and conventional centralized antenna （CA） systems were compared. Through the comparison, it was found that the DA systems could acquire equal coverage property in the cell, and achieve a better channel capacity than CA systems. Following that, two different power allocation strategies were analyzed for downlink. The numerical results show that, because of the knowledge of the MIMO channel, water-filling power allocation strategy can achieve a channel capacity increment of about 0.25bit/（s ·Hz） per transmission antenna.