Title :
Trade-off between channel coding and spreading in multi-carrier CDMA systems
Author_Institution :
Inst. for Commun. Technol., German Aerosp. Res. Establ., Oberpfaffenhofen, Germany
Abstract :
The efficiency of multi-carrier code division multiple access (MC-CDMA) systems for mobile radio communications depends on the processing gain due to bandwidth expansion and on the gain offered by channel coding. This paper shows how to evaluate the optimal ratio between spreading code length and channel coding rate for MC-CDMA systems in the downlink. The investigations are carried out for conventional MC-CDMA detection with minimum mean square error (MMSE) equalization and joint detection with maximum likelihood sequence estimation (MLSE). The results obtained with MC-CDMA systems are compared with those achieved by multi-carrier frequency division multiple access (MC-FDMA) and by multi-carrier time division multiple access (MC-TDMA) systems. Furthermore, for channel coding using convolutional codes, simple approximations of the log-likelihood ratio for the Viterbi decoding algorithm are presented in the case of MC-CDMA
Keywords :
Viterbi decoding; channel coding; code division multiple access; convolutional codes; equalisers; estimation theory; frequency division multiplexing; land mobile radio; maximum likelihood detection; maximum likelihood estimation; pseudonoise codes; spread spectrum communication; MC-CDMA systems; MC-FDMA; MC-TDMA; MLSE; MMSE equalization; Viterbi decoding algorithm; bandwidth expansion; channel coding rate; convolutional codes; downlink; joint detection; log-likelihood ratio; maximum likelihood sequence estimation; minimum mean square error; mobile radio communication; multi-carrier code division multiple access; multi-carrier frequency division multiple access; multi-carrier time division multiple access; processing gain; spreading code length; Bandwidth; Channel coding; Downlink; Frequency conversion; Land mobile radio; Maximum likelihood detection; Maximum likelihood estimation; Mean square error methods; Mobile communication; Multicarrier code division multiple access;
Conference_Titel :
Spread Spectrum Techniques and Applications Proceedings, 1996., IEEE 4th International Symposium on
Conference_Location :
Mainz
Print_ISBN :
0-7803-3567-8
DOI :
10.1109/ISSSTA.1996.563617
