Sequential Beam Searching for mmWave Cell Discovery

Investigate sequential beam searching strategies for initial cell search in millimeter-wave cellular networks that use periodic primary synchronization signal transmissions, and determine their detection performance, timing acquisition accuracy, and overhead relative to omnidirectional transmission and random directional scanning under the generalized likelihood ratio test detectors considered in this work.

Background

The paper studies initial cell discovery at millimeter-wave frequencies, where highly directional beamforming is required but complicates synchronization. It derives GLRT-based detectors for analog and digital beamforming at the user equipment and evaluates two base station transmission strategies for the synchronization signal: omnidirectional transmission and random directional scanning.

Simulations using realistic parameters and channel models indicate that omnidirectional transmission generally outperforms random directional scanning, and that digital beamforming at the receiver substantially improves detection over analog beamforming. The authors note that while these two strategies were analyzed, the alternative of sequential (structured) beam searching was not examined and remains an open direction for investigation.