Pre-Rake performance for pulse based UWB system in a standardized UWB short-range channel

The pre-Rake scheme for pulse based ultrawideband (UWB) communications system is proposed in a standardized UWB channel model from IEEE 802.15 SG3a, which is based on an extensive set of indoor short-range channel measurements in this paper. The pre-Rake scheme is shown to contribute to the low-power, cost-effective UWB system designing as well as Rake combining gain. Instead of building a Rake receiver at the receiving side (e.g. portable unit), the transmitter (e.g. access point) can pre-diversity the UWB signal before transmission in the forward link estimating the channel impulse response from the reverse link. While the pre-Raked signal is convolved with the estimated channel impulse response, the function of Rake combining at the receiver is automatically performed. Monte-Carlo simulations are carried out to compare the pre-Rake with Rake results and show that pre-Rake scheme is as good as Rake combining. Then the mobile or portable unit with a conventional receiver can still achieve the diversity gain of Rake combining.