Title :
A turbo coded DS/CDMA system with embedded Walsh-Hadamard codewords: coder design and performance evaluation
Author :
van Wyk, D.J. ; Linde, L.P.
Author_Institution :
Lab. for Adv. Eng., Pretoria Univ., South Africa
Abstract :
This paper presents the design of a turbo encoding scheme with embedded Walsh-Hadamard (WH) codewords, and a suitable decoder structure based on an iterative decoding technique, akin to the work on “superorthogonal” turbo codes presented by Pehkonen and Komulainen (see ISSSTA´96: International Symposium on Spread Spectrum Techniques & Applications, Mainz, Germany, p.580-4, 1995). The main contribution of this paper is a detailed design of the turbo decoder structure required to perform the required decoding steps, omitted by Pehkonen et al. The performance of the proposed iterative turbo coded DS/CDMA receiver is then studied in an mobile radio environment. Attention is focused on an 8-state rate 2/64 coded QPSK DS/CDMA system, in agreement with the rate offered by the IS-95 coding scheme. The bit error rate performance of the proposed coding scheme is evaluated by means of simulation and compared to that of a DS/CDMA system employing the IS-95 front-end coder for the reverse link channel
Keywords :
Hadamard codes; code division multiple access; error statistics; iterative decoding; land mobile radio; multiuser channels; quadrature phase shift keying; radio links; radio receivers; spread spectrum communication; turbo codes; 8-state coded QPSK; BER; IS-95 coding scheme; bit error rate performance; code rate; coder design; embedded Walsh-Hadamard codewords; front-end coder; iterative decoding; iterative turbo coded DS/CDMA receiver; mobile radio environment; performance evaluation; reverse link channel; simulation; superorthogonal turbo codes; turbo coded DS/CDMA system; turbo decoder structure; turbo encoding; Africa; Design engineering; Forward error correction; Iterative decoding; Land mobile radio; Multiaccess communication; Quadrature phase shift keying; Receivers; Telecommunication standards; Turbo codes;
Conference_Titel :
Spread Spectrum Techniques and Applications, 1998. Proceedings., 1998 IEEE 5th International Symposium on
Conference_Location :
Sun City
Print_ISBN :
0-7803-4281-X
DOI :
10.1109/ISSSTA.1998.723806
