An adaptive transmit diversity scheme based on spatial signal combining for TH-PPM UWB

We propose an adaptive transmit diversity scheme for UWB impulse radio (IR), based on free space signal combining, which provides a significant increase in performance compared to the conventional single antenna MRRC receiver. The proposed scheme employs multiple transmitters, which adjust their transmit delays adaptively, in order to achieve perfect overlapping of pulses in space. This scheme uses a single correlator module at the receiver, and hence reduces the hardware complexity significantly, compared to S-RAKE receivers. The purpose behind free space signal combining is to improve the signal strength without multiplying the noise energy at the output of the correlator detector. Therefore, the proposed scheme can provide higher throughput with less complexity.