Frame Structure Design and Analysis for Millimeter Wave Cellular Systems
Abstract: wave (mmWave) (mmWave) frequencies have attracted considerable The millimeter-wave attention for fifth generation (5G) cellular communication as they offer orders of magnitude greater bandwidth than current systems. However, the medium access control (MAC) layer may need to be significantly redesigned redesigned to support the highly directional transmissions, and the demand for ultra-low ultra low latencies and high peak rates expected in mmWave communication. To address these challenges, we present a novel mmWave MAC layer frame structure with a number of enhancements, ts, including flexible, highly granular transmission times, dynamic control signal locations, extended messaging, and the ability to efficiently multiplex directional control signals. Analytic formulas are derived for the utilization and control overhead aass a function of control periodicity, number of users, traffic statistics, signal-to-noise signal noise ratio, and antenna gains. Importantly, the analysis can incorporate various front front-end end MIMO capability assumptions assumptions-a critical feature of mmWave. Under realistic system and traffic assumptions, the analysis reveals that the proposed flexible frame structure design offers significant benefits over designs with fixed frame structures similar to current 4G long long-term evolution. It is also shown that the fully digital beamforming beamforming architectures offer significantly lower overhead compared with analog and hybrid beamforming under equivalent power budgets.