Abstract
5G millimeter-wave (mmW) systems rely on electronically steerable antenna arrays to support directional communications. Directionality complicates the initial access (IA) process, whereby a base station (BS) announces itself to nearby user equipments (UEs), giving them the opportunity to associate with this BS. Existing approaches for IA suffer from long discovery time and/or nonnegligable probability of missing UEs. In this paper, we propose FastLink, an efficient IA protocol for mmW systems, in which discovery beacons are transmitted/received using the narrowest possible beams, allowing for high beamforming gains and low misdetection rate, while maintaining low discovery time. Fastlink executes a unique algorithm, called 3-dimensional peak finding (3DPF), to find the best beam in logarithmic time. We formulate the beam-finding process as a sparse problem and use compressive sensing to determine the minimum number of measurements needed for this process. We first study FastLink for the discovery of a single UE and then extend our analysis to a multi-user scenario. Both simulations and over-the-air experiments based on a custom mmW testbed are used to evaluate FastLink. Our results verify its efficiency, and show that it can reduce the search time by 90% compared to the scanning approach used in 802.11ad systems.
Original language | English (US) |
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Article number | 8962355 |
Pages (from-to) | 2504-2514 |
Number of pages | 11 |
Journal | IEEE Transactions on Wireless Communications |
Volume | 19 |
Issue number | 4 |
DOIs | |
State | Published - Apr 1 2020 |
Keywords
- Millimeter-wave
- analog beamforming
- beam finding
- compressive sensing
- initial access
ASJC Scopus subject areas
- Computer Science Applications
- Electrical and Electronic Engineering
- Applied Mathematics