A Reconfigurable Viterbi Traceback for Implemenation on Turbo Decoding Array

The trace back operation as used in Viterbi decoding is presented. The trace back is used for a new large constraint length, soft decision Viterbi decoder designed to be implemented reusing components of turbo decoding array. The Viterbi decoder can be reconfigured for standards such as CDMA2000, WCDMA (UMTS), ADSL, IEEE 802.11 and GSM. The proposed trace back operation supports all of these multiple standards. The Viterbi decoding is made reconfigurable between different trellis types, constraint lengths and rates that can be reconfigured for the desired standard. The reconfigurable fabric is implemented as a subset of turbo decoder array on a 180 nm UMC process technology.