高阶调制下Turbo-BLAST系统性能

Turbo-BLAST Performance with Multi-Level Modulation

将高阶调制技术用于Turbo-BLAST系统,提出一种结合高阶调制的Turbo-BLAST系统模型。在发送端级联卷积编码、高阶调制和V-BLAST结构,以提高系统的数据传输速率和频谱利用率;在接收端采用软干扰抵消的最小均方误差(Minimum mean square error,MMSE)检测器和软输入软输出(Soft input soft output,SISO)信道译码器相级联,并利用Turbo译码思想进行迭代检测,以提高系统增益。在Turbo-BLAST迭代接收机中,需要由SISO信道译码器反馈的比特似然度来估计软干扰抵消的符号。本文还提出了一种格雷星座映射下直接由各个比特的似然度恢复MMSE检测所需反馈符号的方法,并对不同调制方式以及不同天线数目的系统性能进行了仿真,仿真结果表明,采用高阶调制可以显著提高系统的传输速率和频谱利用率。

Applying multi-level modulation technique to Turbo-BLAST system, a Turbo- BLAST system module for multi-level modulation is proposed. On the transmitter, the V- BLAST structure is employed by following convolutional code and multi-level modulation to achieve high data rate and improve the spectral efficiency. On the receiver, soft-input soft-out- put （SISO） channel decoder is used following minimum mean square error （MMSE） soft interference cancellation detector, and the turbo-like idea is used for the iterative detection to improve the system efficiency. During every iterative process, the symbol estimation based on LLR feed back from SISO decoder is needed for the soft interference cancellation, and how to estimate the symbol from LLR straightly is proposed based on gray constellation. The different modulations, different antennas and different channel coding are simulated. Simulation results show that the Turbo-BLAST system combined with multi-level modulation achieves a high data rate, thus improving the spectral efficiency.