多天线无线数据通信系统中多用户分集的研究

Analysis of multiuser diversity in the multiple-antenna wireless systems

研究当接收天线不少于发送天线时多输入多输出(MIMO)系统的多用户分集能力。首先从理论上分析了发送天线个数等于1和2时最大似然接收和迫零接收系统的平均吞吐量和调度增益,以及仿真分析了发送天线个数大于2时系统性能。理论分析和仿真表明:在多用户的MIMO系统中,接收的平均信噪比、用户个数、收发天线个数、接收机的结构等对于多用户分集有很大的影响。当发送天线个数为1时,接收天线较少(1,2,3)和平均信噪比为-10dB时调度增益很大,但调度增益随着天线个数和发送功率增大急剧下降。和最大似然接收相比,迫零接收具有更大的多用户分集增益,因此迫零接收机的吞吐量可以很容易超过最大似然接收机。

This paper address the problem of multiuser diversity in the multiple-input multiple-output (MIMO) antennas systems. The throughput and scheduling gain was studied through the analysis and simulation. It was shown that multiuser diversity is concerned with the number of transmit antennas, the number of receive antennas, receiver structure, the signal-to-noise ratio at the receiver and the number of users. When one transmit antenna is used and the number of receive antennas is less than 3, the scheduling gain is large, while the scheduling gain decreases quickly as the number of receive antennas increases. When the transmit power increases, the scheduling gain also decreases. The performance of zero-forcing receivers is similar with the system with only one transmit antenna. When the number of transmit antennas or receive antennas increases, the scheduling gain decreases. Finally, although the zero-forcing receiver is not optimal for single-user, through the scheduling, the throughput of zero-forcing receiver maybe is larger than that of the maximum likelihood receiver.