Power-efficient beam tracking during connected mode DRX in mmWave and
sub-THz systems
Abstract
Discontinuous reception (DRX), wherein a user equipment (UE) temporarily
disables its receiver, is a critical power saving feature in modern
cellular systems. DRX is likely to be aggressively used at mmWave and
sub-THz frequencies due to the high front-end power consumption. A key
challenge for DRX at these frequencies is blockage-induced link outages:
A UE will likely need to track many directional links to ensure reliable
multi-connectivity, thereby increasing the power consumption. In this
paper, we explore reinforcement learning-based link tracking policies in
connected mode DRX that reduce power consumption by tracking only a
fraction of the available links, but without adversely affecting the
outage and throughput performance. Through detailed, system level
simulations at 28 GHz (5G) and 140 GHz (6G), we observe that even
sub-optimal link tracking policies can achieve considerable power
savings with relatively little degradation in outage and throughput
performance, especially with digital beamforming at the UE. In
particular, we show that it is feasible to reduce power consumption by
75% and still achieve up to 95% (80%) of the maximum throughput using
digital beamforming at 28 GHz (140 GHz), subject to an outage
probability of at most 1%.