An intelligent reflecting surface (IRS) at terahertz (THz) bands is expected to have a massive number of reflecting elements to compensate for the severe propagation losses. However, as the IRS size grows, the conventional far-field assumption starts becoming invalid and the spherical wavefront of the radiated waves should be taken into account. In this work, we consider a spherical wave channel model and pursue a comprehensive study of IRS-aided multiple-input multiple-output (MIMO) in terms of power gain and energy efficiency (EE). Specifically, we first analyze the power gain under beamfocusing and beamforming, and show that the latter is suboptimal even for multiple meters away from the IRS. To this end, we derive an approximate, yet accurate, closed-form expression for the loss in the power gain under beamforming. Building on the derived model, we next show that an IRS can significantly improve the EE of MIMO when it operates in the radiating near-field and performs beamfocusing. Numerical results corroborate our analysis and provide novel insights into the design and performance of IRS-assisted THz communication.
|Title of host publication||2021 IEEE International Conference on Communications Workshops, ICC Workshops 2021 - Proceedings|
|Publisher||Institute of Electrical and Electronics Engineers Inc.|
|Publication status||Published - 09 Jul 2021|
|Event||2021 IEEE International Conference on Communications Workshops, ICC Workshops 2021 - Virtual, Online|
Duration: 14 Jun 2021 → 23 Jun 2021
|Name||IEEE International Conference on Communications Workshops (ICC Workshops): Proceedings|
|Conference||2021 IEEE International Conference on Communications Workshops, ICC Workshops 2021|
|Period||14/06/2021 → 23/06/2021|
Bibliographical notePublisher Copyright:
© 2021 IEEE.
ASJC Scopus subject areas
- Artificial Intelligence
- Computer Networks and Communications
- Hardware and Architecture
- Information Systems and Management