卫星通信系统双向中继转发自干扰消除算法
An Algorithm to Eliminate Self？？Interference of Bidirectional Relaying for Satellite Communication Systems

针对卫星通信系统频谱资源日益紧张、邻带干扰难以消除的问题,提出了一种双向中继转发自干扰消除算法。该算法对地面通信站上、下行频带采用相同的匹配频带,并通过中继卫星进行放大转发实现频率复用;利用地面通信站对自身发射信号已知的特点,通过延时寄存器对自身发射信号进行多抽头采样,然后根据各抽头采样对接收信号的干扰影响,对抽头采样进行加权处理并赋予不同权重,以减小自身发射信号的干扰;最后采用网络栅格方案对剩余信号进行解码。该算法可依据不同的信号调制方式和码延时长度动态调整网络栅格的大小,在保证误码率的情况下,能有效降低解码复杂度,从而缩短卫星通信链路的建立时间。仿真结果表明,与基于全网络栅格方案的双向中继转发通信相比,在16APSK调制下误码率为10-3时,信噪比为27 dB,但解码复杂度只相当于全网络栅格方案的10％。
An algorithm to eliminate self？？interference of bidirectional relaying for satellite communication system is proposed to deal with the problem that the spectrum resource strain is increasing and adjacent band interference is hard to remove in satellite communication systems. Both the uplink and downlink transmission in grand stations occupy the common matching band and the relaying satellite plays the role of amplification and forwarding to achieve frequency reuse. Since the self？？transmitted signal is known to certain ground terminal, the interference of its emission signal can be reduced by using the relay register to multitap sampling of itself transmitted signal, and calculating a weighted sum of the samples with the weights determined from interference of the multitap samples to received signal. The symbol is recovered from the residual signal by network grille. The algorithm dynamically adjusts the size of grille according the signal modulation and code delay length. The proposed algorithm can effectively reduce the decoding complexity, and shorten the satellite communication link establishment time, while the bit error rate is ensured. Simulation results and comparisons with the full network grille algorithm show that when the modulation is 16APSK the SNR are 27 dB and the bit error ratio is 10-3 for both methods but the decoding complexity of the proposed method is only 10％ of that of the full network grille algorithm