Initial Beam Association in Millimeter Wave Cellular Systems: Analysis and Design Insights

Ahmed Alkhateeb, Young Han Nam, Md Saifur Rahman, Jianzhong Zhang, Robert W. Heath

Research output: Contribution to journalArticlepeer-review

99 Scopus citations


Enabling the high data rates of millimeter wave (mmWave) cellular systems requires deploying large antenna arrays at both the basestations and mobile users. Prior work on coverage and rate of mmWave cellular networks focused on the case when basestations and mobile beamforming vectors are predesigned for maximum beamforming gains. Designing beamforming/combining vectors, though, requires training, which may impact both the SINR coverage and rate of mmWave systems. This paper evaluates mmWave cellular network performance while accounting for the beam training/association overhead. First, a model for the initial beam association is developed based on beam sweeping and downlink control pilot reuse. To incorporate the impact of beam training, a new metric, called the effective reliable rate, is defined and adopted. Using stochastic geometry, the effective rate of mmWave cellular networks is derived for two special cases: near-orthogonal pilots and full pilot reuse. Analytical and simulation results provide insights into the answers of two important questions. First, what is the impact of beam association on mmWave network performance? Then, should orthogonal or reused pilots be employed? The results show that unless the employed beams are very wide, initial beam training with full pilot reuse is nearly as good as perfect beam alignment.

Original languageEnglish (US)
Article number7880676
Pages (from-to)2807-2821
Number of pages15
JournalIEEE Transactions on Wireless Communications
Issue number5
StatePublished - May 2017
Externally publishedYes


  • Millimeter wave cellular systems
  • beam association
  • initial access
  • stochastic geometry

ASJC Scopus subject areas

  • Computer Science Applications
  • Electrical and Electronic Engineering
  • Applied Mathematics


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