Capture effect in wireless LANs with RAKE reception of DSSS/DPSK signals

In this paper, we present the performance analysis of the RAKE receiver being exposed to simultaneous DSSS/DPSK transmissions from multiple stations, which introduces the possibility for occurrence of the capture effect. Given a frequency-selective Rayleigh-faded channel, we determined bounds on the capture probability by analytically estimating the probability of correct reception of a single frame's preamble. In the case of an idealized simultaneous arrival of both the reference and interference signals, the correlated gaussian interference noise is introduced by the delay-product circuit in each finger of the RAKE receiver, which leads to the upper bound on capture probability. Zero correlation of the interference noise is achieved if the preambles’ arrival moments are randomized, thus leading to the lower bound on capture probability.