Coherence bandwidth characterisation and estimation for indoor Rician multipath wireless channels using measurements at 62.4 GHz

Abstract

Estimations of coherence bandwidth from wideband channel sounding measurements made in the 62.4 GHz band in two indoor environments in a university building are described. Results are intended for applications in high-capacity indoor wireless local area networks. The coherence bandwidth is estimated from measurements of the complex transfer function of the radio channel, performed with no motion in the channel. The 90th percentile of the estimated coherence bandwidth B0.9 at 0.9 correlation level in a long narrow corridor environment is below 38 MHz. Large variations in B0.9 were observed. In an empty room environment, B0.9 was 72 MHz for 90% of the time. The presence and layout of furniture appeared not to influence significantly the frequency correlation values. Replacing a directional receive antenna with an omnidirectional one did not appear to influence B0.9 significantly. In both corridor and room environments, the coherence bandwidth varied significantly with the transmitter–receiver distance. The paper relates the RMS delay spread to the coherence bandwidth, which in turn, affects the radio channel capacity. By limiting the extent of the picocell so that the RMS delay spread is restricted to 20 ns, higher data transmission rates can be achieved. With appropriate modulation schemes, these may approach the challenging 155 Mbit/s rate envisaged for a mobile broadband system (MBS).