TDMA burst-mode mobile radio communication system with forward error correction

摘要

A method of receiving digitised data encoded to permit forward error correction, for example convolutionally encoded data transmitted in a burst-mode radio communications system such as GSM. Prior to transmission a set of first data elements (bits) relating to a first message which may be associated with a first channel type (e.g. a traffic channel (TCH) in GSM) has selected bits substituted or stolen by data elements (bits) relating to a second message which may be associated with a second channel type (e.g. a fast associated channel (FACCH) in GSM). At the receiver the second message is recovered by extracting the substitute data elements. In order to improve bit error rate performance the received data is then modified by replacing the substitute data elements with low-or zero-valued "soft decisions", i.e. further data elements comprising respective components indicative of the low level of confidence associated therewith relative to the original data element. The modified data is decoded using, for example a Viterbi decoder (4) sensitive to the soft decisions to estimate the most likely set of data elements comprising the first message.