An Algorithm for Searching Pulse-Amplitude-Modulation Compatible Trellis Codes

H.-C. Yeh, J.-N. Wang, and C.-L. Chang (Taiwan)


trellis code searching, pulse amplitude modulation, SHDSL, coding and modulation.


In the paper, we propose an algorithm based on the distance spectrum to search Ungerboeck-type trellis code for pulse amplitude modulation (TC-PAM). The algorithm is efficient in finding codes with large constraint length, which generally require large memory and computational power. By showing the distance between any two paths equals to the distance from all zero path to a particular information stream, we can reduce our calculations of distance spectrum to considering the distances from all-zero path only. The Chinese remainder theorem is used to examine the catastrophic property of codes, which further reduces the number of codes to be considered. A practical search in novel single-pair high-speed digital subscriber line (SHDSL) system with 512-state codes is demonstrated as an example.

Important Links:

Go Back