scholarly journals Cooperative beamforming for a double-IRS-assisted wireless communication system

Author(s):  
Guodong Tian ◽  
Rongfang Song

AbstractIntelligent reflecting surface (IRS) has emerged as an innovative and disruptive solution to boost the spectral and energy efficiency and enlarge the coverage of wireless communication systems. However, the existing literature on IRS mainly concentrates on wireless communication systems assisted by single or multiple distributed IRSs, which are not always effective. In view of this issue, this paper considers a special double-IRS-assisted wireless communication system, where IRS1 and IRS2 are deployed near the base station (BS) and the user, respectively, and the transmitted signals reach the user via the cascaded BS-IRS1-IRS2-user channel only. We cooperatively optimize transmit and passive beamforming on the two IRSs based on the particle swarm optimization (PSO) algorithm to maximize the received signal power. Simulation indicates that despite no direct line-of-sight (LoS) path from the BS to the user, an excellent signal-to-noise ratio (SNR) is available at the receiver with the aid of two IRSs, which demonstrates that it is feasible to assist communication by double reflection links composed of two IRSs. Additionally, we unexpectedly find that when the positions of the two IRSs are fixed, by exchanging the positions of the BS and the user, the obtainable SNRs are similar.

2021 ◽  
Author(s):  
Xiaoyan Hu ◽  
Liang Jin ◽  
Yangming Lou ◽  
Zhou Zhong ◽  
Xiaoli Sun

Abstract: The information security and functional safety of wireless communication systems have become the focus of current research. The endogenous security principle based on Dynamic Heterogeneous Redundancy provides a direction for the development of wireless communication security and safety technology. This paper introduces the concept of wireless endogenous security from the following four aspects. First, we sorts out the endogenous security problems faced by the current wireless communication system, and then analyzes the endogenous security and safety attributes of the wireless channel. After that, the endogenous security and safety structure of the wireless communication system is given, and finally the applications of the existing wireless communication endogenous security and safety functions are listed. <br>


2017 ◽  
Vol 6 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Dmytro Krush ◽  
Christoph Cammin ◽  
Ralf Heynicke ◽  
Gerd Scholl ◽  
Bernd Kaercher

Abstract. Custom-fit communication systems are key elements in modern cyber-physical sensor systems. Therefore a wireless communication system (WCS) for sensor/actuator communication has been developed to facilitate energy and environmental monitoring on the shop floor of industrial production sites. Initially, the distinct demands and requirements are described. As the WCS has been designed for new installations as well as for retrofitting already installed facilities, the WCS has to be able to coexist with other wireless communication systems already allocated in the same frequency band. The WCS handles measurement data from both, energy-autarkic sensors and fast line-powered sensors. Mobile users in the field equipped with mobile devices are served by the system, too. A modular hardware concept has been chosen for easy system modification or for the integration of new wireless standards. Finally, measured results for the coexistence capability are presented.


2021 ◽  
Author(s):  
Xiaoyan Hu ◽  
Liang Jin ◽  
Yangming Lou ◽  
Zhou Zhong ◽  
Xiaoli Sun

Abstract: The information security and functional safety of wireless communication systems have become the focus of current research. The endogenous security principle based on Dynamic Heterogeneous Redundancy provides a direction for the development of wireless communication security and safety technology. This paper introduces the concept of wireless endogenous security from the following four aspects. First, we sorts out the endogenous security problems faced by the current wireless communication system, and then analyzes the endogenous security and safety attributes of the wireless channel. After that, the endogenous security and safety structure of the wireless communication system is given, and finally the applications of the existing wireless communication endogenous security and safety functions are listed. <br>


Author(s):  
Maksim Sergeevich Demichev ◽  
Konstantin Eduardovich Gaipov ◽  
Alena Alekseevna Demicheva ◽  
Rinat Faitulovich Faizulin ◽  
Dmitrii Olegovich Malyshev

The subject of this research is the frequency planning algorithm for networks with an arbitrary topology of links over radio channels. The algorithm determines the total number of non-overlapping frequency ranges for the entire network and provides the distribution of each frequency range between communication nodes. The algorithm consists of two stages: at the first stage, there is a search and simultaneous distribution of frequency channels, the so-called main frequency range, as a result, only one frequency range is allocated to each node; at&nbsp;the second stage, additional frequency channels are searched for, which can be used by a separate subset of nodes, thus , some nodes can use more than one frequency range, but several at once. The novelty of this research lies in the developed frequency planning algorithm for wireless communication systems with an arbitrary topology of communications over radio channels. The result of the operation of the algorithm for a wireless communication system is the allocation of radio frequencies for communication nodes from the common frequency band allocated for the wireless communication system, in terms of reuse, eliminating the effect of interference. The result for communication nodes is the allocation of a baseband and an additional frequency band, taking into account the topology of the radio network, which can be used by a separate subset that makes wireless communication systems resistant to narrowband random interference.


Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1439
Author(s):  
Janghyuk Youn ◽  
Woong Son ◽  
Bang Chul Jung

Recently, reconfigurable intelligent surfaces (RISs) have received much interest from both academia and industry due to their flexibility and cost-effectiveness in adjusting the phase and amplitude of wireless signals with low-cost passive reflecting elements. In particular, many RIS-aided techniques have been proposed to improve both data rate and energy efficiency for 6G wireless communication systems. In this paper, we propose a novel RIS-based channel randomization (RCR) technique for improving physical-layer security (PLS) for a time-division duplex (TDD) downlink cellular wire-tap network which consists of a single base station (BS) with multiple antennas, multiple legitimate pieces of user equipment (UE), multiple eavesdroppers (EVEs), and multiple RISs. We assume that only a line-of-sight (LOS) channel exists among the BS, the RISs, and the UE due to propagation characteristics of tera-hertz (THz) spectrum bands that may be used in 6G wireless communication systems. In the proposed technique, each RIS first pseudo-randomly generates multiple reflection matrices and utilizes them for both pilot signal duration (PSD) in uplink and data transmission duration (DTD) in downlink. Then, the BS estimates wireless channels of UE with reflection matrices of all RISs and selects the UE that has the best secrecy rate for each reflection matrix generated. It is shown herein that the proposed technique outperforms the conventional techniques in terms of achievable secrecy rates.


2013 ◽  
Vol 380-384 ◽  
pp. 3505-3508
Author(s):  
Yi Peng Li ◽  
Hao Yang

Stacked Alamouti coding in MIMO wireless communication systems was analyzed through equivalent channel.We derive an upper bound on the portion of the ergodic capacity that the stacked Alamouti scheme can achieve, which is dependent on the ratio of number of transmit antennas to that of receive antennas in the high signal-to-noise ratio regime. As a conclusion, it is shown that the stacked Alamouti scheme can approach the channel capacity as long as the number of transmit antennas is no less than two times that of receive antennas.


Author(s):  
Essam Saleh Altubaishi

<span>Relay selection strategy under maximum-signal-to-noise ratio (MAX-SNR) criterion was proven to maximize performance but at the expense of losing fairness among the cooperative relays. In this work, the effect of controlling the MAX-SNR criterion on the spectral efficiency of cooperative wireless communication system with adaptive modulation is investigated. Specifically, the probability density function (PDF) of the end-to-end SNR for the considered system is derived when the controlled selection criterion is considered. Base on that PDF, the average spectral efficiency is then derived and investigated. The results show how the spectral efficiency of the system deteriorates as controlling the selection of a relay. Furthermore, the results of Monte Carlo simulation validate the derived expression.</span>


2020 ◽  
Vol 5 (5) ◽  
pp. 571-575
Author(s):  
Md. Razu Ahmed ◽  
Mohammad Osiur Rahman ◽  
Md. Jiabul Hoque

Smart home is a prime research interest among researchers around the globe due to the fact that it offers ample features to make people’s life effortless and efficient. People can lead their life smartly through the use of smart home technology [17]. There are numerous communication systems in both wired and wireless media exist that are used in smart home technology. However, not a single communication system itself can satisfy all the demands of secure, comfort and intelligent smart home system. Wireless communication is flexible, requires negligible number of instruments, cheap and easy to install but the key concerning issue for wireless communication system in smart home technology is the slow data rate. In contrast, wired communication provides better performance through the provision of higher data rate and uninterrupted connectivity; however, consumers have to pay substantial amount of payment for smart home services [3]. Therefore, it is essential for researchers to analyze both wired and wireless communication system in terms of data rate and area of coverage in order to find out the right communication system for right feature of smart home system. In this paper, authors reviewed and analyzed both wired and wireless communication methods that are commonly used in smart home technology. It can be seen after careful analysis that for majority of the services of smart home system can get better result through the use of wireless communication system even though wired communication system offers better data rate and greater coverage.


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