基于频域迭代判决反馈均衡的低复杂度FTN接收机

Low-complexity FTN receivers based on frequency domain iterative decision feedback equalization

超Nyquist(FTN,faster-than-Nyquist)信号传输能在不降低系统可靠性的情况下,提高系统的有效性,但其引入了严重的码间串扰,导致最佳接收的复杂度非常高。迭代块判决反馈均衡器(IBDFE,iterative block decision feedback equalizer)能以较低的复杂度达到与最佳接收相近的性能,有效降低了FTN接收机的复杂度,但其复杂度仍能进一步降低。因此,在IBDFE的基础上,简化了前馈和反馈滤波器的设计,为FTN通信系统提出了一种降低复杂度的IBDFE(RC-IBDFE,reduced-complexity IBDFE)。当加速因子为τ={0.8,0.7}时,数值结果和分析表明,与IBDFE相比,RC-IBDFE的顽健性更好,复杂度降低了{45.7%,25%},当误比特率为10-5时的性能增益为{0.605 4,0.193 6}dB;与已有的低复杂度IBDFE(LC-IBDFE,low-complexity IBDFE)相比,RC-IBDFE的顽健性更好,复杂度降低了{13.6%,-25.8%},当误比特率为10-5时的性能增益为{0.289 7,0.531 2}dB。

Faster-than-Nyquist（FTN） signaling can improve the system effectiveness without reducing the system reliability, but the fierce inter-symbol interference（ISI） introduced by it may cause that the complexity of the optimal receiver is intolerable. An effective low-complexity FTN receiver is iterative block decision feedback equalizer（IBDFE）, which can achieve performance close to the optimal receiver with much lower complexity, but its complexity can be further reduced. Therefore, a reduced-complexity IBDFE（RC-IBDFE） was proposed for FTN communication systems, which was based on IBDFE, but introduced a simplified method to design the feedforward and feedback filters. When packing factor is τ={0.8, 0.7}, numerical results and analysis indicate that, compared with IBDFE, RC-IBDFE has stronger robustness, its complexity is reduced by {45.7%, 25%}, and its performance gain is {0.605 4, 0.193 6} dB when the bit error rate（BER） is 10^-5. Compared with the existing low-complexity IBDFE（LC-IBDFE）, RC-IBDFE has stronger robustness, its complexity is reduced by {13.6%,-25.8%}, and its performance gain is {0.289 7, 0.531 2} dB when the BER is 10^-5.