References & Further Reading
References
- R. Long, Y.-C. Liang, Y. Pei, and E. G. Larsson, Active Reconfigurable Intelligent Surface-Aided Wireless Communications, 2021
The first paper to formalize active RIS architecture. Section II.B defines the model; Section III derives the optimization framework used in Section 9.2.
- Z. Zhang, L. Dai, X. Chen, C. Liu, F. Yang, and R. Schober, Active RIS vs. Passive RIS: Which Will Prevail in 6G?, 2023
Definitive comparison. Theorem 1 and its proof are the basis of Section 9.3's crossover analysis. Excellent section on practical deployment.
- E. Björnson, Ö. Özdogan, and E. G. Larsson, Intelligent Reflecting Surface Versus Decode-and-Forward: How Large Surfaces Are Needed to Beat Relaying?, 2020
Classical comparison of passive RIS with AF/DF relays. Section II introduces the relay reference model used in Section 9.4.
- Q. Wu and R. Zhang, Intelligent Reflecting Surface Enhanced Wireless Network via Joint Active and Passive Beamforming, 2019
The original passive RIS framework. Section 9 extends this to active RIS by relaxing the unit-modulus constraint.
- G. Caire and I. Atzeni, Active RIS with Tight Power Constraints, 2023
CommIT contribution. Optimal per-element power allocation for active RIS under realistic DC budget. The algorithmic refinement adopted in Section 9.4.
- J. Zhao, Y. Cui, X. You, C. Pan, and S. Jin, Sum-Rate Maximization for Active RIS-Aided Downlink Multiuser MIMO Systems, 2022
Multi-user extension of active RIS with WMMSE + active subproblem. Practical multi-user active RIS algorithmic framework.
- M. H. Khoshafa, T. M. N. Ngatched, M. H. Ahmed, and A. R. Ndjiongue, Active Reconfigurable Intelligent Surfaces-Aided Wireless Communication System, 2021
Active RIS for simple single-user scenario; useful pedagogical introduction.
- J. Lyu and R. Zhang, Hybrid Active/Passive Wireless Network Aided by Intelligent Reflecting Surface, 2020
Early hybrid active/passive concept. Relevant to Exercise 9.15's design discussion.
- D. M. Pozar, Microwave Engineering, Wiley, 4th ed., 2012
Chapter 13 covers power-amplifier basics: gain, noise figure, 1-dB compression. Essential background for Section 9.1's hardware model.
- S. Loyka and G. Levin, On physically-based normalization of MIMO channel matrices, 2009
Normalization conventions for MIMO channels including relay scenarios. Relevant for carefully comparing active RIS with AF relay.
- J. N. Krieger and E. B. Hogenauer, Amplifier noise and its impact on wireless receivers, 2008
Tutorial on amplifier noise figure and its system-level implications. Relevant to Section 9.3's crossover analysis.
- M. Di Renzo et al., Smart Radio Environments Empowered by Reconfigurable Intelligent Surfaces, 2020
Comprehensive survey. Section VI.B discusses active vs. passive RIS deployment considerations.
Further Reading
Resources for deeper study of active RIS.
Prototype active RIS demonstrations
Staat et al. (2023), 'Intelligent Reflecting Surface with Integrated Power Amplifiers: A Practical Demo,' IEEE Vehicular Technology Conference
Empirical validation of active RIS on actual hardware; bridges the theory-practice gap.
Active RIS for ISAC
Liu et al. (2023), 'Active RIS-Aided Integrated Sensing and Communication with Robust Design,' IEEE TSP
Extends active RIS to the joint communication-sensing scenario of Chapter 13. Shows how amplification helps sensing accuracy in the radar path.
Hybrid active-passive architectures
Exercise 9.15 and references therein (Lyu and Zhang 2020, etc.)
A promising research direction combining the best of both worlds.
Power-constrained active RIS
Caire and Atzeni (2023), 'Active RIS with Tight Power Constraints' (CommIT contribution)
Practical extension for real-world deployments where total DC budget matters.
Amplifier hardware for active RIS
Pozar (2012), Microwave Engineering, Ch. 13 (ch09 reference)
Classical microwave engineering text with comprehensive treatment of power amplifier design — the hardware backbone of active RIS.