Increasing indoor spectrum sharing capacity using smart reflect-array

Abstract

The radio frequency (RF) spectrum becomes overly crowded in some indoor environments due to the high density of users and bandwidth demands. To accommodate the tremendous wireless data demands, efficient spectrum-sharing approaches are highly desired. To this end, this paper introduces a new spectrum sharing solution for indoor environments based on the usage of a reconfigurable reflect-array in the middle of the wireless channel. By optimally controlling the phase shift of each element on the reflect-array, the useful signals for each transmission pair can be enhanced while the interferences can be canceled. As a result, multiple wireless users in the same room can access the same spectrum band at the same time without interfering each other. Hence, the network capacity can be dramatically increased. To prove the feasibility of the proposed solution, an experimental testbed is first developed and evaluated. Then, the effects of the reflect-array on transport capacity of the indoor wireless networks are investigated. Through experiments, theoretical deduction, and simulations, this paper demonstrates that significantly higher spectrum-spatial efficiency can be achieved by using the smart reflect-array without any modification of the hardware and software in the users' devices.

Communication Through a Large Reflecting Surface With Phase Errors

“…. , n, are irrelevant to the distribution of |H|, as this depends only on the average magnitudes (1). The individual coefficients may even have different distributions, as long as they are mutually independent and have the respective means.…”

“…Furthermore, by endowing such devices with interconnection capability, they can be introduced in control loops that enable adaptation to the changing conditions of the wireless network, thus creating a smart radio environment. Examples of reconfigurable devices that can manipulate EM waves include tunable reflect-arrays [4], [1], frequency-selective surfaces [5], or meta-surfaces consisting of a thin layer of metamaterials [6].…”

“…The focus of this paper is on the concept of a large reflective surface (LRS) which, irrespective of the building technology, can be abstracted into an array of passive reflector elements that induce adjustable phase shifts on the reflected signals. An LRS placed somewhere between a source and a destination can greatly enhance the communication between the two when the phase shifts are appropriately configured such that the reflected waves combine coherently at the destination [1], [7], [8], [9]. Most of the studies assume the phase shifts induced by the composite propagation channel through the LRS are perfectly known and the reflector phases are set to the ideal values, with no errors.…”

Secrecy Rate Maximization for Intelligent Reflecting Surface Assisted Multi-Antenna Communications

“…Intelligent reflecting surface (IRS), which consists of a large number of low-cost passive reflecting elements with adjustable phase shifts, has recently been advocated as a costeffective solution to significantly enhance the performance of wireless communications [1], [2]. Owing to the tunable phase shifts of all the reflecting elements, the functions of signal enhancement and interference suppression can be achieved by the IRS without the use of active transmitters.…”

“…Compared to the well known massive multiple-input multiple-output (MIMO) technique, one appealing advantage of applying the IRS is to reduce the system energy consumption and achieve sustainable green 5G and beyond wireless networks. IRS can be implemented via conventional reflectarrays [1]- [3], liquid crystal metasurfaces [4], or software defined metamaterials [5]. We highlight that the IRS is passive, operates under the full-duplex mode without self-interference and has no noise amplification, which is different from the relay system.…”