Sum-Rate Analysis for High Altitude Platform (HAP) Drones with Tethered Balloon Relay

P. G. Sudheesh, Mohammad Mozaffari, Maurizio Magarini, Walid Saad, P. Muthuchidambaranathan

Research output: Contribution to journalArticlepeer-review

42 Citations (Scopus)


High altitude platform (HAP) drones can provide broadband wireless connectivity to ground users in rural areas by establishing line-of-sight links and exploiting effective beamforming techniques. However, at high altitudes, acquiring the channel state information (CSI) for HAPs, which is a key requirement to perform beamforming, is challenging. In this paper, by exploiting an interference alignment (IA) technique, a novel method for achieving the maximum sum-rate in HAP-based communications without CSI is proposed. In particular, to realize IA, a multiple-antenna tethered balloon is used as a relay between multiple HAP drones and ground stations (GSs). Here, a multiple-input multiple-output X network system is considered. The capacity of the considered M × N X network with a tethered balloon relay is derived in closed-form. Simulation results corroborate the theoretical findings and show that the proposed approach yields the maximum sum-rate in multiple HAPs-GSs communications in absence of CSI. The results also show the existence of an optimal balloon's altitude for which the sum-rate is maximized.

Original languageEnglish
Pages (from-to)1240-1243
Number of pages4
JournalIEEE Communications Letters
Issue number6
Publication statusPublished - 06-2018

All Science Journal Classification (ASJC) codes

  • Modelling and Simulation
  • Computer Science Applications
  • Electrical and Electronic Engineering


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