基于过采样的OFDM-MFSK系统分集方法

摘要

为了提高OFDM-MFSK系统误比特率性能,提出一种基于过采样的OFDM-MFSK系统分集方法.该方法在发送端对OFDM子载波进行分组MFSK调制,在接收端时域进行过采样,接收端频域利用逐载波等增益合并相关子载波能量,进行非相干能量检测.仿真结果表明,该方法通过时域过采样获得了分集增益,过采样倍数越大,系统误比特率性能越好.相比于相干检测,不用信道估计,在高信噪比下,具有更好的系统性能,且对时变信道具有很强的鲁棒性.%In order to improve bit error rate(BER)performance of OFDM-MFSK system,a diversity method based on over-sampling is proposed.Firstly the subcarriers of OFDM are divided into several groups at the transmitter,and each group of subcarrier employs MFSK modulation scheme.Then the receiving signals are sampled with a sampling frequency significant-ly higher than Nyquist rate at the receiver.At the end,an equal gain combination(EGC)is carried in frequency domain to accumulate related subcarriers'energy for non-coherent energy detection.Simulation results show that the proposed method can win the diversity gain,the greater the oversampling factor,the better BER performance.Compared with the coherent detection,no channel estimation is needed,and under the high signal-to-noise ratio,it not only has better system perform-ance,but also has strong robustness for the time-varying channel.