频域时间反转多用户系统的信干噪比和误比特率分析

为了更有效地将时间反转技术应用到正交频分复用系统中，推导了多天线频域时间反转预编码多用户系统的平均信干噪比和误比特率的表达式。通过推导信号功率均值的表达式和用户间干扰信号功率均值的近似表达式，得到用户的平均接收信干噪比的近似表达式，进而得到二进制相移键控调制下的平均误比特率的一个下界和近似表达式。仿真结果表明，推导的平均信干噪比的近似值与仿真结果很接近，近似BER值与仿真得到的平均BER值较为接近;通过增大速率回退因子和天线数，可明显提高平均信干噪比，降低误比特率。

Analysis of SINR and BER for frequency-domain time-reversal multi-user systems

By precoding signals in frequency domain, time reversal technology can be applied to OFDM systems. In this paper, the expressions of average signal to interference plus noise ratio and bit error rate of MISO frequency-domain time-reversal multi-user system are derived. First, the expressions of average signal power and the approximation of inter-user interference signal power are derived, and the approximate expressions of average received SINR of users are obtained. Based on the derived approximation, a lower bound of the average bit error rate under binary phase-shift keying modulation is obtained, and an approximation of bit error rate is derived. Finally, the theoretical derivation is verified by simulation. Simulation results show that the derived average SINR approximation is close to the simulation results and BER approximation is relatively close to the average BER results obtained by simulation. The results also show that by increasing the rate back-off factor and the number of antennas, the average SINR increases and the bit error rate can be reduced.