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提出了一种基于发射功率、发送比特和误码率均受限时规则和非规则LDPC频域编码MIMO-OFDM系统自适应调制算法。仿真比较了规则、非规则LDPC编码及未编码自适应调制MIMO-OFDM系统性能,比较了LDPC-SISO-OFDM、LDPC-MIMO-OFDM系统子载波数变化对系统BER性能的影响,比较了收发天线数变化对LDPC-MIMO-OFDM系统BER性能的影响。仿真表明自适应调制MIMO-OFDM系统比非自适应调制系统性能有所提高,规则、非规则LDPC编码自适应调制MIMO-OFDM系统比未编码系统性能有很大提高,非规则LDPC编码自适应调制MIMO-OFDM系统比规则码自适应调制系统性能有提高,但在高信噪比时有错误平层。结果证明,适当设计非规则LDPC频域编码自适应调制算法,可以大大改善MIMO-OFDM系统性能。
An adaptive modulation algorithm for MIMO-OFDM systems based on regular and irregular LDPC codes is proposed based on transmit power, transmission bit and bit error rate. The simulation compares the performance of regular, irregular LDPC codes and uncoded adaptively modulated MIMO-OFDM systems. The influence of subcarrier number changes on the BER performance of the system is compared with that of the LDPC-SISO-OFDM and LDPC-MIMO-OFDM systems. Effect of the number change on BER performance of LDPC-MIMO-OFDM system. The simulation results show that the performance of the adaptive modulation MIMO-OFDM system is better than that of the non-adaptive modulation system. The performance of the regular and irregular LDPC-coded MIMO-OFDM system is much higher than that of the un-coded system. The irregular LDPC coding adaptive modulation The performance of MIMO-OFDM system is better than that of regular code adaptive modulation system, but there is error leveling in high signal-to-noise ratio. The results show that proper design of adaptive LDPC modulation algorithm for frequency domain coding can greatly improve the performance of MIMO-OFDM system.