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2 Journal of Telecommunications and Information Technology

2 2001

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Walsh-chirp sequences for wireless applications

Wysocki B. J., Wysocki T. A., Zepernick H.-J.

Journal of Telecommunications and Information Technology

2001

nr 3

24-28

This paper deals with a new method to design polyphase spreading sequences for DS CDMA wireless applications. The method is based on weighting symbols of the orthogonal Walsh sequences by the complex factors being symbols of baseband chirp sequences. The resulting sequences possess good aperiodic correlation properties, while maintaining the orthogonality. Because of the parametric design, the sequences can be optimized to achieve desired characteristics.

Performance of CDMA systems with Walsh and PN coding

Gajewski P., Dołowski J.

Journal of Telecommunications and Information Technology

2001

nr 2

41-45

Wideband CDMA method has been recently investigated for its using in the future communication systems. Such systems capacity depends on many factors, the main is multi-access interference (MAI). MAI is an inherent CDMA property connected to correlation characteristics of codes used to access and to spreading. The influence on CDMA performance of these codes families and parameters is presented in this paper. The standard Gaussian approximation has been used for interference analysis. Bit error rate (BER) on detector output is a measure of interference influence on transmission quality. It can be used for SNR(i) evaluation on receiver input for channel assignment and handover procedures. The results of interference analysis for the pseudo-noise sequences (M-sequences, Gold, de'Bruin and Jennings) as well as for the Walsh orthogonal mapping are presented in this paper.