Effects of ISI and satellite channel nonlinearity on Viterbi demodulation/decodingIt is shown that, for convolutionally coded transmission over bandwidth-constrained channels, a mere reversal of the switching direction at the encoder output produces a change in the system bit error probability performance. This change is significant when the Viterbi demodulator/decoder is matched to the total channel memory and is more significant for linear channels than for nonlinear ones. The reversal of switching direction is a simple demonstration of the fact that the well-known optimum codes for the linear AGWN channel are no longer necessarily optimum for a bandwidth-constrained channel with or without the addition of channel nonlinearity. It is concluded that potentially significant performance improvement can be obtained by matching the encoder (through the appropriate choice of tap weights and modulo-2 summers) to the channel in addition to matching the demodulator/decoder to the channel for a given encoder.
Document ID
19840066495
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Divsalar, D. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Simon, M. K. (California Institute of Technology, Jet Propulsion Laboratory, Pasadena CA, United States)