Adaptive beamwidth optimization under Doppler ICI and positioning errors at mmWave bands

The growing trends towards massive antenna arrays with focusing capabilities has enabled the use of higher frequencies at the cost of more complex systems. In the particular case of vehicular communications, millimeter-wave (mmWave) communications are expected to unleash a set of advanced use cases with stringent spectrum needs. However, dealing with very directive patterns and high frequencies entail additional challenges such as beam misalignment and Doppler effect. This paper presents a beam optimization procedure for vehicle-to-network (V2N) systems in which a base station communicates with high-speed users. Aided by the a priori knowledge of the vehicle location, the base station is able to estimate the average signal-to-interference-plus-noise ratio (SINR) until the next beam refresh considering the positioning accuracy and the Doppler inter-carrier interference (ICI). The estimation includes the antenna beamwidth, which can be optimized to maximize the achievable throughput. The numerical results indicate that the SINR can be significantly enhanced compared to beam sweeping with identical hierarchical codebooks while reducing the probability of outage.This work was partly funded by the Spanish Ministerio de Economía y Competitividad under the projects PID2019-107885GB- C31 and MDM2016-0600, the Catalan Research Group 2017 SGR 219, and “Industrial Doctorate” programme of the Agència de Gestió d’Ajuts Universitaris i de Recerca (2018-DI-084). The Spanish Ministerio de Universidades contributes via a predoctoral grant to the first author (FPU17/05561).Peer ReviewedPostprint (published version