Achievable Rate Optimization for Stacked Intelligent Metasurface-Assisted Holographic MIMO Communications

Anastasios Papazafeiropoulos, Jiancheng An, Pandelis Kourtessis, Tharmalingam Ratnarajah, Symeon Chatzinotas

Research output: Contribution to journalArticlepeer-review


Stacked intelligent metasurfaces (SIM) is a revolutionary technology, which can outperform its single-layer counterparts by performing advanced signal processing relying on wave propagation. In this work, we exploit SIM to enable transmit precoding and receiver combining in holographic multiple-input multiple-output (HMIMO) communications, and we study the achievable rate by formulating a joint optimization problem of the SIM phase shifts at both sides of the transceiver and the covariance matrix of the transmitted signal. Notably, we propose its solution by means of an iterative optimization algorithm that relies on the projected gradient method, and accounts for all optimization parameters simultaneously. We also obtain the step size guaranteeing the convergence of the proposed algorithm. Simulation results provide fundamental insights such the performance improvements compared to the single-RIS counterpart and conventional MIMO system. Remarkably, the proposed algorithm results in the same achievable rate as the alternating optimization (AO) benchmark but with a less number of iterations.
Original languageEnglish
Pages (from-to)1-14
Number of pages14
JournalIEEE Transactions on Wireless Communications
Publication statusPublished - 17 May 2024


  • Metasurfaces
  • Optimization
  • Transmitters
  • Receivers
  • MIMO communication
  • Reconfigurable intelligent surfaces
  • Covariance matrices
  • Holographic MIMO (HMIMO)
  • stacked intelligent metasurfaces (SIM)
  • reconfigurable intelligent surface (RIS)
  • gradient projection
  • 6G networks


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