Impact of Beamforming on Delay Spread in Wideband Millimeter-wave Systems

Berk Akgun, Marwan Krunz, David Manzi

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

The harsh propagation environment at millimeter-wave (mmW) frequencies can be countered by using large antenna arrays, which can be steered electronically to create directional beams. Knowledge of the key channel characteristics in this environment, including the delay spread, the coherence time, and the coherence bandwidth, plays a significant role in optimal adaptation of the transmission waveform. In this paper, we focus on analyzing the delay spread of a directional mmW channel. A high delay spread causes inter-symbol interference (ISI), which can be mitigated by concatenating cyclic prefixes (CPs) to data symbols at the expense of lower spectral efficiency. Considering a single mmW link, whose transmitter (Tx) and receiver (Rx) are equipped with uniform planar arrays (UPAs), we study the impact of various beamforming attributes (e.g., antenna-array size, beamwidth, beam direction, and beam misalignment) on the average and root-mean-square delay spread. We use detailed simulations with accurate 3GPP channel models and conduct extensive experiments using a 4\times 8 UPA at 28 GHz to verify our analysis. Based on this analysis, we study the optimal beamforming configuration at the Rx for a given Tx beamformer so as to maximize the spectral efficiency. Our proposed beam selection method finds the best Rx beam direction that results in a low delay spread and high signal-to-noise ratio (SNR). Our extensive simulation and experimental results verify that this method significantly improves the spectral efficiency, almost doubling the data rate in some cases.

Original languageEnglish (US)
Title of host publication2020 International Conference on Computing, Networking and Communications, ICNC 2020
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages890-896
Number of pages7
ISBN (Electronic)9781728149059
DOIs
StatePublished - Feb 2020
Event2020 International Conference on Computing, Networking and Communications, ICNC 2020 - Big Island, United States
Duration: Feb 17 2020Feb 20 2020

Publication series

Name2020 International Conference on Computing, Networking and Communications, ICNC 2020

Conference

Conference2020 International Conference on Computing, Networking and Communications, ICNC 2020
CountryUnited States
CityBig Island
Period2/17/202/20/20

Keywords

  • Beamforming
  • Cyclic prefix
  • Delay spread
  • Millimeter-wave
  • Multipath
  • Single-carrier modulation

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Hardware and Architecture
  • Information Systems and Management
  • Control and Optimization

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  • Cite this

    Akgun, B., Krunz, M., & Manzi, D. (2020). Impact of Beamforming on Delay Spread in Wideband Millimeter-wave Systems. In 2020 International Conference on Computing, Networking and Communications, ICNC 2020 (pp. 890-896). [9049739] (2020 International Conference on Computing, Networking and Communications, ICNC 2020). Institute of Electrical and Electronics Engineers Inc.. https://doi.org/10.1109/ICNC47757.2020.9049739