Performance comparison of UWB-IR using RAKE receivers in UWB channel models

Abstract

We evaluate the performance of the ultra wideband impulse radio with Walsh Hadamard BPSK (UWB-IR with WH-BPSK) using RAKE receivers in two channel models. The first channel model (J. Foerster and Q. Li (2002)) is referred to as an (A) model. The measurements characterize the channel over the frequency range of 2-8 GHz using 0.167 ns baseband pulses. The amplitudes of multipath are modeled with the lognormal fading distribution. The second channel model (D. Cassioli and M. Z. Win (2002)) is referred to as a (B) model, The measurements characterize the channel over the frequency range of 1.5-3 GHz using 2.0 ns baseband pulses. The amplitudes of multipath are modeled with the Nakagami distribution. We evaluate the signal to noise ratio (SNR) distribution of the RAKE combining output and the bit error rate (BER) of UWB-IR with WH-BPSK using the partial RAKE (PRAKE) receiver and the selective RAKE (SRAKE) receiver for the given number of fingers in the two channel models. We show that using the PRAKE receiver, the UWB-IR with WH-BPSK in the (B) model can achieve a better BER than that in the (A) model when the number of fingers is small (i.e., L = 2, 10) and vice versa when the number of fingers is large (i.e., L /spl ges/ 50). We also show that using the SRAKE receiver, the UWB-IR with WH-BPSK in the (A) model can achieve the better BER than that in the (B) model for any L. Therefore, we confirm that the performance of the UWB-IR using the RAKE receivers, particularly, the PRAKE receiver, depends largely on the channel model.