Development and performance evaluation of an antenna diversity module for industrial communication based on IEEE 802.15.4

In this paper, the influence of antenna diversity techniques adapted to the IEEE 802.15.4 radio technology are evaluated and the corresponding process gains are empirically examined. With the assumption of a WSSUS model and Rayleigh-distributed signal amplitudes, the minimum optimal antenna spacing relating to a 2D-propagation is calculated. A diversity module with three antennas, based on Freescale MC13193 transceivers, was developed by using the calculated antenna spacing. Different algorithms for signal combining were examined and evaluated with this module. The process gain of the particular algorithms was quantified by the corresponding error rate and by examination of the RSSI values. Additionally, the effects of the combining algorithms on the "digital" channel\´s memory were examined. For this purpose the parameters complementary error distance distribution F^c _a(a), block error density function P(m, n) and error correlation function R_ee(v) were used.