Abstract
This letter proposes a novel hybrid relay and Intelligent Reflecting Surface (IRS) assisted system for future wireless networks. We demonstrate that for practical scenarios where the amount of radiated power and/or the number of reflecting elements are/is limited, the performance of an IRS-supported system can be significantly enhanced by utilizing a simple Decode-and-Forward (DF) relay. Tight upper bounds for the ergodic capacity are derived for the proposed scheme under different channel environments, and shown to closely match Monte-Carlo simulations.
Highlights
W ITH the ever-increasing demand of data traffic over wireless networks, Intelligent Reflecting Surface (IRS) technology was recently proposed as a low-cost solution to enhance the performance and capacity of communications systems by smartly reconfiguring the propagation environment of wireless channels [1], [2]
Our results provide an insight into the performance of such hybrid schemes in terms of power optimization, mode selection, relay placement, as well as relay/IRS pairing for future networks
The Signal-to-Noise Ratio (SNR) is defined as P/σw2, and the simulations were averaged over 104 different channel realizations
Summary
W ITH the ever-increasing demand of data traffic over wireless networks, Intelligent Reflecting Surface (IRS) technology was recently proposed as a low-cost solution to enhance the performance and capacity of communications systems by smartly reconfiguring the propagation environment of wireless channels [1], [2]. A typical IRS array contains a large number of passive reflecting elements that are integrated on a planar surface and controlled by an IRS controller Unlike other technologies such as well-known massive multiple-input multiple-output systems, IRS does not require radio-frequency chains. Several authors have focused their research on showing the efficiency of IRSs and/or comparing their performances to well-known technologies, such as relays or multiantenna systems Motivated by this fact, and unlike the works in [7] and [11] which deal with the IRS and the relays as two separate ways to enhance link quality, in this letter, we investigate the performance gain of a novel hybrid scheme that amalgamates the benefits of both the IRS and the relay. Notations: Matrices and vectors are represented by bold-face upper-case and lower-case letters, respectively. |x| and E[x] are the absolute and expected values of x, respectively. aT is the transpose of a; while [a]i is the ith element of a. diag(a) is a diagonal matrix whose diagonals are the elements of a; while arg(x) is the phase of a complex number x
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