Outdoor Millimeter-Wave Channel Modeling for Uniform Coverage Without Beam Steering

Diverse performance requirements of the emerging 5G cellular systems and their deployment challenges motivate researchers to explore high frequency millimetre wave (mmWave) spectrum as a potential solution. The allocation and utilization of mmWave spectrum in cellular communication is a new frontier. In this paper, we investigate a directional mmWave small cell outdoor propagation channel by exploiting its deterministic nature; using ray tracing method. Estimates on specific attenuation measurements and free space propagation parameters reveal that directional transmission is inevitable and would result in a channel model divergent from that of an omnidirectional propagation model. In addition, we examine the effect of antenna tilting in the access links to establish highly directional adaptive link. Capacity of the sparsely faded channel is also analyzed. Results exemplify that, beyond 50 m propagation range, the received signal strength in mmWave small cells employing base stations of height 5 m as opposed to macro cells with base station height of 20 m is independent of beam steering. A simplified geometry devoid of the complexity of adaptive beam steering is hence proposed to provide uniform signal strength in an outdoor small cell channel to affirm low latency.