Abstract:
fIndoor wireless local area networks (LAN's) and personal area networks (PAN’s) have evolved very rapidly in the recent past. The indoor wireless LAN's are mainly dominated by narrow-band technologies like the IEEE 802.11a,b which are short range and provide data rates of 1 Mbps to 54 Mbps. The Bluetooth has become the standard for low-data rate WPAN’s. Ultra-wideband (UWB), though an old technology, has generated a lot of interest lately to be a contender for the high data rate indoor applications. A UWB system could span multi-GHz bandwidth, which enables it to pro- vide a very high capacity. The IEEE is developing the standards for the high data rate indoor environments and the approach is tending towards multi-band UWB. This thesis studies the system architecture and error performance of pulse-based UWB systems with multiple transmitter and receiver antennas for indoor environments. Performance of space-time coded multiple antenna pulse-based UWB and space-time-frequency coded multiple-antenna pulse-based multi-band UWB are analyzed. For the multi-band sys- tem, the 7.5 GHz UWB spectrum specified by the FCC is divided into sub-bands of 528 MHz each, and multiple sub-bands can be simultaneously used for data transmission. We design codes that maximize coding and diversity gains for multiple-antenna systems over the frequency- selective UWB channels and provide detailed detection and decoding procedures. The proposed multi-antenna multi-band UWB system could dramatically increase link throughput as compared to existing schemes over non-line-of-sight (NLOS) dense multipath channels.
