15
ULTRA-WIDEBAND PERSONAL AREA NETWORKS: MIMO EXTENSIONS
The focus of this chapter is on short-range, wireless communication using so-called ultra-wideband (UWB) technology.* The purpose of the chapter is to illustrate the advantages that can be gained from using multiple transmit and (possibly) receive antennas in such systems when appropriate precoding, or beamforming, techniques are employed at the transmitter. Several precoder designs are considered, all of which are based on the optimization of some objective, such as minimizing biterror rate or maximizing the received signal-to-noise ratio or the mutual information between the transmitted and received signals. Importantly, these precoder designs adhere to the strict system and regulatory constraints that relate to UWB transmissions. In fact, these constraints cause the UWB precoder designs to be significantly different from precoders that are used in many narrowband scenarios. Despite the aforementioned restrictions, it will be shown that multi-antenna precoding is a promising practical method of achieving robust, high-rate communication in ultra-wideband networks.
15.1 INTRODUCTION
State-of-the-art ultra-wideband systems transmit data using bandwidths of hundreds of megahertz in frequency bands that are shared with many existing licensed narrowband devices. Transmission of UWB signals over licensed frequency bands will cause interference to the existing licensed ...
