Wideband channel measurement and characterisation for wireless local loops

The multipath characteristics of the wireless local loop (WLL) channel were studied over both short and long time periods in urban and sub-urban high-rise and small-house environments. Wideband measurements were performed at a centre frequency of 1.3 GHz with a sliding correlation measurement system using a chip rate of 15 MHz. The receiver was situated at regular cellular base stations, and the transmitter with an omnidirectional antenna was moved to several rooms in different buildings around the base station sites. During the recordings the movement of people in the measurement rooms was restricted. The short-term results show a high degree of similarity in the multipath characteristics of the WLL channel in urban and sub-urban high-rise environments. The maximum measured values of delay spreads for the urban and suburban high-rise environments were 410 ns and 360 ns, respectively. For the sub-urban small-house environment the data indicate lower values of delay spread. The channel was shown to be very slowly fading, being in most situations essentially static over short time periods of the order of several tens of seconds. The variation of the channel characteristics over long time periods was shown to be significant.