Broadband wireless local-area networks at millimeter waves around 60 GHz

During the past few years, research covering propagation, channel characterization, and wireless system performance has yielded a substantial knowledge of the 60 GHz channel. The unlicensed 60 GHz frequency band presents many attractive properties for wireless communications. This paper addresses some wideband propagation characteristics for broadband wireless LANs (BWLANs). Important system-design characteristics, from measured results obtained from two wideband 60 GHz LOS radio links, are presented. Measurements were undertaken using the swept-frequency channel-sounding method. Analysis from the complex frequency responses in a worst-case scenario has yielded a lower-coherence-bandwidth value of 5 MHz. Minimum and maximum B_0.9 coherence bandwidths, obtained with a directional-horn transmitting antenna and an omnidirectional receiving antenna, were 1.10 MHz and 105.33 MHz, respectively. It was observed that the coherence bandwidth fluctuated significantly with the location of the receiver with respect to the base station. These results can be used for the modeling and design of future BWLANs.