High-Performance Adaptive Receivers for Broadband Multi-User Communications

University Of California-Los Angeles, Los Angeles CA

Investigators

Abstract

High-Performance Adaptive Receivers for Broadband Multi-User Communications High speed communications over wireless channels has emerged as a key feature of future communications systems due in part to the explosive interest in information technology applications, including wireless sensor networks, mobile wearable systems, mobile computing, wireless location (E911), high-speed mobile internet, and video transmission over wireless channels. The demand for higher information capacity in these applications has motivated the use of broadband wireless channels in order to provide wider bandwidth and higher data rates. This demand has also motivated the development of multi-user communication schemes in order to allow users to share the same physical channel; thereby contributing to even higher data rates. A key challenge that limits the performance of such multi-user communications systems is the distortion introduced by the coupled communication channels, by the interference among users and by the channel fading conditions. This research aims at studying and developing adaptive receivers that can combat such distortions by adapting their performance in accordance to the communications environment. The research studies and develops efficient adaptive receivers for broadband multi-user communications by exploiting spatial, data, and model structures in order to reduce computational complexity and increase performance level. In so doing, it is expected that the resulting schemes will help increase data rates, lower overhead due to training, lower bit-error-rate, improve signal-to-noise ratio, and help mitigate the ombined effects of inter-symbol interference, inter-user interference, and noise. Such schemes would increase the capacity of broadband wireless networks by allowing multiple users to share the same time slot and frequency band in an efficient manner. This study focuses on both time-domain and frequency-domain equalization techniques, with the latter receiving increasing attention since it has been accepted as IEEE 802.16 Standard for Wireless Metropolitan Area Networks. The research is also relevant to other wireless applications such as wireless location (E911), which has emerged as an essential public safety component of future cellular systems. This is because this work enables the development of enhanced adaptive techniques that are robust to fast channel fading, low signal-to-noise ratio conditions, and severe multipath propagation situations, all of which are characteristic of the E911 environment