Diversity Combining for DS CDMA System in a Rayleigh Fading Channel with Three Spreading Codes

الملخص

Fading problem is a major impairment of the wireless communication channel. In this paper we considers different diversity techniques to mitigate the fading problem in wireless channel for DS CDMA (Direct sequence Code Division Multiple Access) system.
Diversity is an effective method for increasing the received signal-to-noise ratio of a wireless communication system in a flat Rayleigh fading channel. Diversity branches can be established through frequency, time, antenna, or any combination of these diversity mechanisms.
The branch outputs can be processed using schemes such as selection combining, equal gain combining, or maximal ratio combining. The diversity combining technique used in this paper improved the performance of the DS CDMA system. For this system, three spreading code sequences are used to spread the spectrum of the signal namely, an M-sequence, a Gold sequence, and an Orthogonal Gold sequence. The BER performance in a two path flat Raleigh fading environment for DS CDMA system with diversity combining is evaluated using MATLAB 7 computer simulation software