Etude comparative d'un recepteur numerique a conversion directe a technologie six-port dans la bande 2.45GHz adapte a la modulation QPSK (French text)

We have seen a huge development in telecommunications systems and in particular wireless local area networks (WLAN) over the last decade. Nowadays such networks are gaining widespread use for both large world area networks and small pico networks. This expansion demands changes in the communications system infrastructure to increase the rate of the transmission by use of higher carrier frequencies and increased spectral efficiency with multiple access techniques.; WLAN with IEEE802.11 a&b standards require miniaturized receivers to be integrated into hand-held devices such as pocket PCs. These receivers must guarantee high data rates and be robust in the presence of interfering signals and noise. New receiver architectures such as the direct conversion six-port digital receiver is examined and studied in this project in an attempt to improve quality and lower costs of WLAN.; The proposed digital receiver uses six-port technology operating at 2.45GHz with 40Mb/s and QPSK modulation. Comparative measurements and results with a commercial direct digital receiver using a zero-IF quadrature standard architecture operating at 2.45GHz in the ISM band are presented. (Abstract shortened by UMI.)...