COMBINING ECHO CANCELLATION AND DECISION FEEDBACK EQUALIZATION

被引:16
作者
MUELLER, KH [1 ]
机构
[1] BELL TEL LABS INC, MURRAY HILL, NJ 07974 USA
来源
BELL SYSTEM TECHNICAL JOURNAL | 1979年 / 58卷 / 02期
关键词
D O I
10.1002/j.1538-7305.1979.tb02229.x
中图分类号
TM [电工技术]; TN [电子技术、通信技术];
学科分类号
0808 ; 0809 ;
摘要
A system for two‐wire, full‐duplex data transmission is proposed. It consists of two adaptive transversal filters, one accepting the transmitted symbols and working as an echo canceller, the other accepting the received symbols and functioning as a decision feedback equalizer. A joint stochastic adjustment algorithm (updates at each baud) is analyzed, and it is shown that the sum of the mean‐squared errors in the coefficients of both filters can be decoupled from its difference by selecting identical gain constants in each loop. The optimum gain equals the reciprocal of the sum of the taps of both loops. Convergence is exponential, and its time is 0.23 adjustments/db/tap. This is completely independent of all channel parameters. Implementation of the proposed structure requires neither multipliers nor A/D converters. Promising applications are seen in channels with moderate precursor distortion, such as highpass channels (dc‐restoration), two‐wire pbx systems with a need for high‐speed, full‐duplex communication, limited distance cable channels, and, most important, two‐wire digital subscriber lines for digital voice/data terminals. © 1979 The Bell System Technical Journal
引用
收藏
页码:491 / 500
页数:10
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