Intelligent Reflecting Surface‐Aided Communications for 6G

Recently, Intelligent Reflecting Surface (IRS), a.k.a., Reconfigurable Intelligent Surface (RIS) attract a lot of interests from both academia and industry. This chapter discusses the basic concept of the IRS, the technical advantages of IRS-aided wireless communications, and its potential applications. It discusses the fundamentals of IRS-aided single-antenna transmission, including the cascaded IRS channel, the signal model of passive beamforming, optimal reflecting coefficients, and a special feature called the product-distance path loss. The chapter details the fundamentals of IRS-aided multi-antenna transmission, including joint active and passive beamforming, and joint precoding and reflecting optimization. It then provides an introduction of the dual-beam IRS technique, the forming of dual beams over hybrid analog-digital transceivers, and the optimization design.