Modeling and evaluation of beam tracking in mobile millimeter wave communication

The most critical challenge facing mobile millimeter wave communication is the precise projection of high-gain and narrowly focused radiation toward the multi-paths leading to a device as it moves and rotates in the field. In order to design and evaluate such beam tracking mechanism, an accurate model of the propagation environment is required. Unfortunately, conventional channel models for system operating in carrier frequency lower than 6 GHz are typically statistically based with time-invariant parameters and thus inadequate to simulate the dynamics in spatial characteristics the millimeter wave channel may exhibit. In this paper, such shortcoming is overcome by the introduction of certain time-varying parameters to a widely adopted geometry based stochastic model. With the revised model, we proceed to tune its parameters to fit the statistics extracted from the latest measurement data and subsequently investigate the model´s capability in evaluating beam tracking performance. The beam tracking algorithms are generic in nature and only assume certain imperfect knowledge of the channel´s spatial profile. It is found that at 28 GHz carrier frequency, beam tracking can be maintained at a moving speed of 60 kmph and an angular speed of 720°/sec with around 20% loss comparing with the stationary reference if the spatial profile is updated at a rate of 50 Hz.