A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Teclmology

Thesis (M.Eng.) - Asian Institute of Technology, 2005

Ultra wide band system (UWB) provides a large bandwidth for high data rate communications at a lower cost and with power saving consumption. Given its operation in a wide range frequency, and thus not interfering with other existing systems according to FCC requirements, this system tends to transmit with low power. There are three types of UWB systems named time hoping UWB (TH-UWB), direct sequence spread spectrum UWB (DS-UWB), and multi band OFDM (MB-OFDM) UWB. The first two systems are carrierless, while the MB-OFDM is used with carrier for modulation. This specification is developed by IEEE 802.15.3a task group for Wireless Personal Area Network (WPAN). IEEE UWB channel model, fitting in with the real measurement data, is introduced for UWB systems based on Saleh-Valenzuela (S-V) model with some modifications. Lognormal distribution is used for multi path components. In addition, arrival rays are clustered in the model. In this thesis, space time code (STC) on IEEE UWB channels is used. This is a special type of diversity for better performance of MB OFDM on multi path environment. The simple MIMO scheme which is used here discusses Alamouti STC scheme with two transmitter antennas and one receiver antenna. We study bit error rate (BER) and packet error rate (PER) performance of MB-OFD\1 UWB for both ideal channel state information (CSI) and channel estimation using minimum mean square error (MMSE). Simulation performs on four scenarios of IEEE UWB channel model. CM1 is classified that its operating distance is from 0 to 4 meters and there is line of sight path. CM2 has the same operating system with CM 1 but there is no light of sight path. Operating in the distance from 4 to 4 meters, it is known as CM3 which has not line of sight too. The distance greater than 10 meters is called CM4. The result shows that STC for ideal channel model works a little better than the ideal channel model without space time code in ideal case for achieving 10'' BER or 10.2 PER. But with MMSE channel estimation, STC can achieve 0.5 dB better.