Abstract
Intelligent reflecting surface (IRS) is considered as a promising application in terahertz (THz) communications since it is able to enhance the THz communication with no additional power consumptions. In this letter, we consider the channel estimation problem for an IRS-aided THz multi-user multi-input single-output (MISO) system with lens antenna array. The main challenge of the problem is that we need to estimate multiple channels and some of the channels are cascaded. To deal with the problem, we propose a two-stage channel estimation scheme, where we set different IRS modes to estimate different channels for each stage. In stage 1, we set the IRS to an absorbing mode and estimate the channel without IRS. Removing the influence of the prior estimated channel, in stage 2, we estimate the channel with IRS by setting the IRS to a perfect reflecting mode. And we decompose the total channel estimation problem into a series of independent problems, where we estimate each independent channel component with a least square method.
Highlights
Intelligent reflecting surface (IRS), as a promising technique for future wireless systems, such as terahertz (THz) communications, has attracted growing research interest in both academia and industry over recent years [1, 2]
An IRS is a physical meta-surface consisting of a large number of reflecting elements, where each element is equipped with a simple low-cost sensor [3]
Previous works about the IRS are mainly focused on optimizing secrecy-rate and data-rate by designing the phase-shifts of the IRS while assuming perfect channel state information (CSI) is obtained by both the base station (BS) and the IRS [6,7,8,9,10]
Summary
Intelligent reflecting surface (IRS), as a promising technique for future wireless systems, such as terahertz (THz) communications, has attracted growing research interest in both academia and industry over recent years [1, 2]. To the best of our knowledge, there are limited literatures considering the channel estimation problem for the IRS-aided system. In this letter, we investigate the channel estimation problem for the IRS-aided THz multi-user multi-input single output (MISO) system with lens antenna array. We propose a two-stage channel estimation scheme, where we set different IRS modes for the channel estimation in different stages. In stage 1, we estimate the channel between the BS and the user by setting the IRS to an absorbing mode which is able to absorb all induced signals by the IRS. Removing the influence of the prior estimated channel, in stage 2, we set the IRS to a perfect reflecting mode, which can reflect all induced signals by the IRS with few losses. We decompose the total channel estimation problem into a series of independent problems, where we estimate each channel component with a least square method
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