Joint User Association and Beamforming in Integrated Satellite-HAPS-Ground Networks

Shasha Liu, Hayssam Dahrouj, Mohamed Slim Alouini

Research output: Contribution to journalArticlepeer-review


This paper proposes and evaluates the benefit of, one particular hybrid satellite-high-altitude-platform-station (HAPS)-ground network, where one HAPS connected to one geo-satellite assists the ground base stations (BSs) at serving ground-level users. The paper assumes that the geo-satellite is connected to the HAPS using free-space-optical backhaul links. The HAPS, equipped with multiple antennas, aims at transmitting the geo-satellite data to the users via radio-frequency (RF) links using spatial-multiplexing. Each ground BS, on the other hand, is equipped with multiple antennas, but directly serves the users through the RF links. The paper then focuses on maximizing the network-wide throughput, subject to HAPS payload connectivity constraint, HAPS and BSs power constraints, and backhaul constraints, so as to jointly determine the user-association strategy of each user (i.e., user to geo-satellite via HAPS, or user to BS), and their associated beamforming vectors. We tackle such a mixed discrete-continuous optimization problem using an iterative approach, where the user-association is determined using a combination of integer linear programming and generalized assignment problems, and where the beamforming strategy is found using a weighted-minimum-mean-squared-error approach. The simulations illustrate the appreciable gain of our proposed algorithm, and highlight the prospects of augmenting the ground networks with beamforming-empowered HAPS for connecting the unconnected, and super-connecting the connected.

Original languageEnglish (US)
Pages (from-to)1-17
Number of pages17
JournalIEEE Transactions on Vehicular Technology
StateAccepted/In press - 2023


  • Array signal processing
  • backhaul
  • Backhaul networks
  • beamforming
  • High altitude platform station
  • Interference
  • Optimization
  • Payloads
  • Radio frequency
  • satellite-HAPS-ground network
  • Throughput
  • throughput
  • user association

ASJC Scopus subject areas

  • Automotive Engineering
  • Aerospace Engineering
  • Computer Networks and Communications
  • Electrical and Electronic Engineering


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