DSL系统时域均衡训练中一种新的时延优化算法

在数字用户线(DSL)系统中,每个符号在进行传输时要加入循环前缀(CP)以消除符号间干扰。理论上,CP的长度等于信道冲激响应的记忆长度,较长的CP大大降低了DSL系统的数据传输效率。为了避免使用较长CP,通常在接收端采用时域均衡缩短信道冲激响应长度。但是,信道冲激响应最优缩短算法的复杂度很高,为此,提出了一种实用的时延优化算法,该算法将信道的冲激响应与矩形序列进行卷积,用得到的序列进行时延估计,使得算法的复杂度大幅下降,满足了系统的实时性要求,并且缩短信噪比的损失很小。

New time delay algorithm of time domain equalizer for DSL systems

In DSL systems, a cyclic prefix (CP) was inserted before every symbol being transmitted, to alleviate the interference between consecutive symbols. In theory, the length of the CP was equal to the memory length of the impulse response of the channel. Using a long CP reduced the data transmission rate of the system largely. To avoid using a long CP, a time domain equalizer was used to shorten the length of the channel impulse response. However, the optimal shortening algorithm of channel impulse response leaded to very high computational complexity. Therefor, a new time delay algorithm is presented, which estimates time delay with channel impulse response convolutes with rectangle sequence, which reduces the computational complexities greatly, real-time implement and shortening SNR is reduced slightly.