Title :
Soft output detector for parity bit selected CDMA system
Author :
Mirzaee, Alireza ; Amours, Claude D.
Author_Institution :
Sch. of Inf. Technol. & Eng., Univ. of Ottawa, Ottawa, ON
Abstract :
This paper investigates the performance of the parity bit selected code division multiple access (PB-CDMA) system when a soft output detector based on log likelihood ratio (LLR) calculation is employed. In this system, information bits are convolutionally encoded prior to being used in the parity bit selected direct sequence spread spectrum (DS-SS) system. Reliability of the detected bits in the receiver is calculated in the form of LLRs and then used as the input of a soft input Viterbi decoder. The performance of the proposed system is compared to conventional coded spread spectrum systems where no parity bit selected spreading sequence is used. Numerical results show that the proposed system can be used to improve the capacity of a code division multiple access (CDMA) system in terms of the number of simultaneously transmitting users.
Keywords :
Viterbi decoding; code division multiple access; Viterbi decoder; code division multiple access; direct sequence spread spectrum system; log likelihood ratio calculation; parity bit selected CDMA system; soft output detector; Bit error rate; Block codes; Convolutional codes; Decoding; Detectors; Matched filters; Multiaccess communication; Spread spectrum communication; Transmitters; Vectors; CDMA; Spread spectrum communication; error control coding; log likelihood ratio;
Conference_Titel :
Information Theory, 2009. CWIT 2009. 11th Canadian Workshop on
Conference_Location :
Ottawa, ON
Print_ISBN :
978-1-4244-3400-8
Electronic_ISBN :
978-1-4244-3401-5
DOI :
10.1109/CWIT.2009.5069547
