Coherence Bandwidth of Rice Channels for Millimeter Wave and Sub-Terahertz Applications

Abstract

6G research in the millimeter wave and sub-Terahertz domain is targeting very wideband systems with significantly higher data throughput than for 5G systems. Multipath propagation under shadowing conditions is affecting radio propagation, where multipath propagation results in frequency-selective fading, which is characterized by the coherence bandwidth and the time variation by the coherence time. In these frequency ranges shadowing can be overcome by additional means in the network deployment such as reflectors, RIS arrays or repeaters, which provide at the receiver a channel impulse response with a strong component (Rice type channel). Coherence bandwidth and coherence time are well-known for Rayleigh channels. However, both parameters for Rice channels versus the Rice factor K′ are not available. This paper is investigating the coherence bandwidth and time for Rice channels based on an approximative approach for the fading statistics. With the proposed correlation criterion, the coherence bandwidth and time tend to infinity from a Rice factor around K′≥4=ˆ6 dB. These relations are provided by approximative functions for K′≥0 starting at the Rayleigh channel.