Influence of spatial‐wideband effects in evaluation of mm‐wave communications

Hybrid, mixed analogue/digital beam-forming architectures are a central research topic for the development of mm-wave communication for fifth generation. Most approaches are based on phase shifters in the analogue part, which are inherently narrowband. In this study, the authors evaluate the effects and performance of narrowband beam-steering on wideband signals using two different modelling approaches: spatial-narrowband model, in which the inter-antenna element delays are neglected, and spatial-wideband model, in which the inter-antenna element delays are considered. They show that neglecting the spatial-wideband effects on channel models overestimates the focusing of beam-forming, the expected delay spread reduction, and achievable data-rate with an increasing number of antennas and bandwidth. These effects are quantised by simulations using a realistic ray-tracing scenario at 60 GHz.