Power-Efficient Beam Tracking during Connected Mode DRX in mmWave and Sub-THz Systems

Syed Hashim Ali Shah, Sundar Aditya, Sundeep Rangan

Research output: Contribution to journalArticlepeer-review


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 bandit algorithms for link tracking 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%.

Original languageEnglish (US)
Article number9398853
Pages (from-to)1711-1724
Number of pages14
JournalIEEE Journal on Selected Areas in Communications
Issue number6
StatePublished - Jun 2021


  • 5G
  • 6G
  • Discontinuous reception (DRX)
  • millimeter wave (mmWave) communications
  • multiple-play multi-armed bandits (MP-MAB)
  • power-efficient beam tracking
  • sub-terahertz (THz) communications

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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