Optimal Pilot Power Based Channel Estimation Improves the Throughput of Intelligent Reflective Surface Assisted Systems

• Published in: IEEE transactions on vehicular technology Vol. 69; no. 12; pp. 16202 - 16206
• Main Authors: An, Jiancheng, Wang, Li, Xu, Chao, Gan, Lu, Hanzo, Lajos
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.12.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Array signal processing; Beamforming; Channel estimation; channel estimation errors; Channels; Communication systems; Communications systems; Gallium nitride; High gain; intelligent reflecting surface; Radio signals; Rate improvement; Resource management; Signal to noise ratio; Throughput
• ISSN: 0018-9545; 1939-9359
• DOI: 10.1109/TVT.2020.3034478

Intelligent reflecting surfaces (IRS) have emerged as a promising technology of managing the radio signal propagation by relying on a large number of low-cost passive reflecting elements. In this letter, the optimal pilot power allocation required for accurate channel estimation of IRS-assisted communication systems is investigated. In contrast to conventional channel estimators, where pilot signals are usually designed to be constant-enveloped, we reconsider the pilot design to improve the passive beamforming performance thus resulting in an improved achievable rate. At first sight the result of our analysis appears counter-intuitive, suggesting that at a given total power, more power should be allocated to estimate low-gain channels, since the channel phase impairments are more severe than those of high-gain channels. Our simulation results show that when the number of IRS elements is 4, the rate improvement of our proposed channel estimation scheme over the conventional counterpart may be as high as <inline-formula><tex-math notation="LaTeX">25\%</tex-math></inline-formula>.