References & Further Reading

References

  1. Q. Wu and R. Zhang, Intelligent Reflecting Surface Enhanced Wireless Network via Joint Active and Passive Beamforming, 2019

    The founding paper of the AO-based joint beamforming framework. Every RIS optimization chapter of this book builds on its Algorithm 1.

  2. C. Pan, H. Ren, K. Wang, W. Xu, M. Elkashlan, A. Nallanathan, and L. Hanzo, Multicell MIMO Communications Relying on Intelligent Reflecting Surfaces, 2020

    Extension of the AO framework to multi-cell MU-MIMO with multiple RIS panels. The quadratic-form reformulation of Section 5.4 is stated here.

  3. Q. Shi, M. Razaviyayn, Z.-Q. Luo, and C. He, An iteratively weighted MMSE approach to distributed sum-utility maximization for a MIMO interfering broadcast channel, 2011

    The WMMSE framework used inside every AO active update. Chapters 4, 5, 7 all rely on this reformulation.

  4. S. S. Christensen, R. Agarwal, E. de Carvalho, and J. M. Cioffi, Weighted sum-rate maximization using weighted MMSE for MIMO-BC beamforming design, 2008

    Earlier WMMSE paper specific to the MIMO broadcast channel. Complements Shi et al. 2011.

  5. D. P. Bertsekas, Nonlinear Programming, Athena Scientific, 2nd ed., 1999

    The reference for block coordinate descent convergence theory (Section 2.7). Every AO paper cites this.

  6. Q. H. Spencer, A. L. Swindlehurst, and M. Haardt, Zero-forcing methods for downlink spatial multiplexing in multiuser MIMO channels, 2004

    Classical ZF precoding. A useful simpler baseline for the active subproblem.

  7. X. Yu, D. Xu, Y. Sun, D. W. K. Ng, and R. Schober, Robust and Secure Wireless Communications via Intelligent Reflecting Surfaces, 2020

    Manifold-optimization-based passive update. Section VI discusses algorithm selection tradeoffs across N, K.

  8. Z.-Q. Luo, W.-K. Ma, A. M.-C. So, Y. Ye, and S. Zhang, Semidefinite relaxation of quadratic optimization problems, 2010

    The tutorial reference for SDR of QCQP. The optimality-gap theorem of Section 5.5 is from this paper.

  9. Y. Zhang, B. Di, H. Zhang, J. Lin, C. Xu, D. Zhang, Y. Li, and L. Song, Beyond Cell-Free MIMO: Energy Efficient Reconfigurable Intelligent Surface Aided Cell-Free MIMO Communications, 2021

    AO framework applied to RIS-aided cell-free systems. Good illustration of warm-starting and fast convergence in multi-RIS settings.

  10. C. Huang, A. Zappone, G. C. Alexandropoulos, M. Debbah, and C. Yuen, Reconfigurable intelligent surfaces for energy efficiency in wireless communication, 2019

    Complementary framework using AO for energy efficiency (not rate). Shows the framework's flexibility.

  11. Q. Wu and R. Zhang, Towards smart and reconfigurable environment: Intelligent reflecting surface aided wireless network, 2020

    Accessible magazine-style introduction. Good for orientation before the technical papers.

Further Reading

Resources for deeper study of the joint optimization framework.

  • WMMSE for RIS under imperfect CSI

    Z. Peng et al., 'Robust joint beamforming design for intelligent reflecting surface assisted wireless systems,' IEEE TCOM, 2020

    Extends the AO framework to imperfect CSI via WCEM (worst-case error minimization).

  • AO with multi-group multicast

    H. Guo et al., 'Reconfigurable intelligent surface enhanced multi-group multicast systems,' IEEE TWC, 2022

    Shows how the AO framework adapts when the active subproblem is non-trivial (multicast beamforming).

  • BCD convergence in non-convex optimization

    M. Razaviyayn, M. Hong, and Z.-Q. Luo, 'A unified convergence analysis of block successive minimization methods for nonsmooth optimization,' SIAM J. Optim., 2013

    Modern theoretical analysis of BCD convergence. Useful for rigorous treatment of AO variants.

  • Deep-learning-accelerated joint optimization

    S. Shen et al., 'Transformer-empowered 6G intelligent networks,' IEEE JSAC, 2023

    Replaces the inner AO iterations with a transformer network trained to mimic the optimal beamformer. Faster at inference than AO.

  • Joint beamforming for wideband OFDM-RIS

    Y. Yang, B. Zheng, S. Zhang, and R. Zhang, 'Intelligent reflecting surface meets OFDM: Protocol design and rate maximization,' IEEE TCOM, 2020

    Extension to OFDM. Each subcarrier has a different effective channel; the joint problem becomes over all subcarriers simultaneously.

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