Title :
Adaptive multidimensional coded modulation over flat fading channels
Author :
Hole, Kjell J. ; Holm, Henrik ; Øien, Geir E.
Author_Institution :
Dept. of Inf., Bergen Univ., Norway
fDate :
7/1/2000 12:00:00 AM
Abstract :
We introduce a general adaptive coding scheme for Nakagami multipath fading channels. An instance of the coding scheme utilizes a set of 2L-dimensional (2L-D) trellis codes originally designed for additive white Gaussian noise (AWGN) channels. Any set of 2L-D trellis codes for AWGN channels can be used, Sets for which all codes can be generated by the same encoder and decoded by the same decoder are of particular interest. A feedback channel between the transmitter and receiver makes it possible to transmit at high spectral efficiencies under favorable channel conditions and respond to channel degradation through a smooth reduction of the spectral efficiency. We develop a general technique to determine the average spectral efficiency of the coding scheme for any set of 2L-D trellis codes. As an illustrative example, we calculate the average spectral efficiency of an adaptive codec utilizing eight 4-D trellis codes. The example codec is based on the International Telecommunications Union´s ITU-T V.34 modem standard.
Keywords :
adaptive codes; channel coding; codecs; fading channels; feedback; mobile radio; multipath channels; trellis coded modulation; 2L-D trellis codes; AWGN channels; ITU-T V.34 modem standard; Nakagami multipath fading channels; adaptive codec; adaptive coding scheme; adaptive multidimensional coded modulation; additive white Gaussian noise channels; channel degradation; feedback channel; flat fading channels; spectral efficiencies; spectral efficiency; trellis codes; AWGN channels; Adaptive coding; Additive white noise; Codecs; Convolutional codes; Decoding; Fading; Feedback; Modulation coding; Multidimensional systems;
Journal_Title :
Selected Areas in Communications, IEEE Journal on