RFID based IoT Sensor Communication System with ESPAR Antenna

The electronically steerable parasitic array radiator (ESPAR) antenna offers low cost and low complexity relative to conventional array antennas. Because of the low complexity of the antenna there is only a single-port output for processing the signals impinging on the antenna elements. Since a reactance-domain MUSIC algorithm for ESPAR antennas has been proposed, the practical problem of estimating the direction of arrival of signals impinging toward an ESPAR antenna can be tackled. In this paper, two experimental methods of estimating the arrival signal angles are proposed. A method of solving the practical problem of calibrating the ESPAR antenna output signal model is also shown. The experimental results show that for one impinging signal the direction of arrival can be estimated with precision of 3 degrees.

최근 대용량, 초고속 통신 서비스의 비중이 높아짐에 따라 배열 안테나를 사용하는 MIMO(Multi-Input Multi-Output) 시스템의 활용이 중요하게 평가되고 있다. 하지만 기존의 MIMO 시스템은 다수의 안테나를 사용하기 때문에 안테나의 개수만큼 RF(Radio Frequency) 체인이 요구되며, 이로 인해 복잡도와 전력 소모가 크다는 단점을 가진다. 이러한 기존 MIMO 시스템의 단점을 해결하기 위해서 단일 능동 소자와 다수의 기생 소자를 이용하는 방식의 ESPAR(Electronically Steerable Parasitic Array Radiator) 안테나를 사용하는 빔 공간 MIMO 시스템에 대한 연구가 활발히 진행되고 있다. ESPAR 안테나를 사용하는 빔 공간 MIMO 시스템은 단일 RF 체인으로 구성되어 있기 때문에 기존 MIMO 시스템의 단점을 해결할 수 있다. 본 논문에서는 시스템의 보안성을 향상시키기 위해 QPSK(Quadrature Phase Shift Keying) 변조 방식의 ESPAR 안테나를 사용하는 빔 공간 MIMO 시스템에 비예측성, 비주기성, 구현의 용이성, 민감한 초기조건 등의 특징을 가지고 있는 카오스 통신 알고리즘을 적용하여 QPSK 변조 방식의 ESPAR 안테나를 사용하는 카오스 빔 공간 MIMO 시스템을 구성하고 성능을 평가한다. Recently, utilization of MIMO(Multi-Input Multi-Output) system using array antennas is evaluated significantly according to the extension of high-capacity and high-speed communication services. However, MIMO system has disadvantages such as high-complexity and high-power-consumption, because RF(Radio Frequency) chain is required as antenna number, and several array antenna is used in conventional MIMO system. In order to solve these problems, research about beamspace MIMO system using ESPAR(Electronically Steerable Parasitic Array Radiator) antenna that has single RF chain by using one active antenna and several parasitic elements has been studied actively. Beamspace MIMO system using ESPAR antenna is possible to solve the problems of conventional MIMO system, because this system is composed by single RF chain. In this paper, in order to improve the system security, chaos communication algorithm that has characteristics such as non-periodic, non-predictability, easy implementation and initial condition is applied to QPSK (Quadrature Phase Shift Keying) modulated beamspace MIMO system. We design the chaos QPSK modulated beamspace MIMO system, and evaluate SER performance of this system.

SummaryIn this paper, in order to improve the received signal strength (RSS) and signal quality, three arrays of electronically steerable parasitic array radiator (ESPAR) antennas are suggested for the ultra‐high frequency (UHF) radio frequency identification (RFID) communication and sensing system applications. Instead of the single antenna, the array antennas have recently been widely used in many communication systems because of their peak gains, better radiation patterns, and higher radiation efficiency. Also, there are some important issues to use the antenna array like high data rates in wireless communication systems and to better understand the many targets or sensors. In this article, a wireless sensor network (WSN) is being investigated to overcome multipath fading and interference by antenna nulling technology that can be achieved through beam control ESPAR array antennas. The proposed ESPAR array antennas exhibit higher gains like 9.63, 10.2, and 12 dBi and proper radiation patterns from one array to another. Moreover, we investigate the mutual coupling effect on the performance of array antennas with different spacing (0.5λ, 0.75λ, λ) and configurations. It is found that the worst mutual coupling reduced by −28 to −34 dB for 2 × 2 array, −3 to −43 dB for 2 × 3 array, and finally −42 dB to −51 dB due to the antenna spacing from 0.5λ to λ. Thus, these suggested antennas could effectively be applied in the WSN communication systems, internet of things (IoT) networks, and massive wireless and backscatter communication systems.

This paper studies the electronically steerable parasitic array radiator (ESPAR) antenna as a solution for beam pattern switching to implement blind interference alignment (BIA). The ESPAR antenna uses a single radio-frequency (RF) chain, and its beamforming is achieved by simply tuning the reactance loads of parasitic elements. Furthermore, ESPAR's beam pattern can be designed to enhance the received signal-to-noise ratio (SNR), thereby improving the performance of BIA. The focus of this work is the design of the ESPAR beam pattern to realize and improve BIA. In the first approach, each receiver ESPAR antenna dynamically selects the proper beam patterns from among the sector beam patterns, which are pre-designed to access different angular sectors with constant optimal antenna efficiency. We also propose a singular value decomposition (SVD) beamforming method, by means of the available channel state information at the receiver and a dynamic matching network for a high antenna efficiency. The simulation results illustrate the improvement of BIA with proposed methods, especially in the low and moderate SNR region, due to ESPAR's beamforming capability.

In this paper, we have introduced a new method to improve overall efficiency of direction-of-arrival (DoA) estimation scheme relying on received signal strength (RSS) values measured at the output port of electronically steerable parasitic array radiator (ESPAR) antenna. The proposed approach uses software-defined radio (SDR) setup and power pattern cross-correlation (PPCC) estimator involving multiple calibration planes. By placing the calibration planes using the proposed SDR-based iterative method, it has been possible to obtain more optimal form of the PPCC estimator, than originally proposed in the literature. Anechoic chamber measurements of our ESPAR antenna prototype indicate that one can keep the expected overall accuracy of DoA estimation results in a wide span of incoming signal elevation angles and, simultaneously, decrease the number of required calibration planes by more than half, which will shorten the time required for RSS-based DoA estimation process and also for the initial calibration procedure within an anechoic chamber.

Phased array antenna’s radiation pattern can be electronically controlled, making them a relevant solution for multipath interference. Electronically Steerable Parasitic Array Radiator (ESPAR) antenna systems are part of the family of phased array antennas under the umbrella of aerial beam-forming antennas. Generally ESPAR antenna system design considers the quarter wavelength approach. In practice there are a significant number of multiband systems with many applications integrated in a single device. This paper looks at the design of a dual-band ESPAR antenna. The design is limited to the ESPAR antenna’s structural parameter modification through the loading of its element with inductance load (circuitry). This results in an antenna system which operates in both 2.4GHz and 5.8 GHz bands of the IEEE 802.11 WLAN (Wireless Local Area Network) suitable for rural areas. The approach employed in this work consists of different stages of structural modification with careful optimization processes. The two adopted process are the quarter wavelength design and the optimization process, conducted through the genetic optimization algorithm.KeywordsESPAR Antenna systemWLANGenetic Algorithm

n this paper, a small size electronically steerable parasitic array radiator (ESPAR) antenna composed of six inverted F-type antennas (IFAs) that covers the frequency band from 2.4 to 2.5 GHz is proposed. Each of the IFAs can be reconfigured either as a driven element or a parasitic element equally. The radius of the proposed ESPAR antenna is 11.5 mm, which enables handheld wireless devices such as mobile phone and walkie talkie to employ a smart antenna. Despite its small size, the proposed ESPAR antenna achieves a gain of 3.5 dBi and a front-back ratio of 7 dB. The beam forming can be achieved by tuning the reactive load of varactors on each IFA radiator.

Electronically steerable parasitic array radiator (ESPAR) antenna is well known for its low-power consumption, small-size antenna. In this paper, a novel fourth-order MUSIC algorithm using a 13-element ESPAR antenna for direction of fourth-order MUSIC algorithm is that it is insensitive to additive Gaussian noise regardless of whether it is white or colored so it can improve the precision of the DOA estimation. By comparing with the conventional algorithm, our proposed algorithm can obtain more than 45dB gain under SNR=10dB, which can obviously show an outstanding performance improvement. Finally, computer simulation results show that the novel algorithm can resolve up to one impinging signal with less than 0.15° under SNR=0dB and provide an estimation with less than 0.6° under SNR=5dB for two impinging signals coming from different angles.

In this paper, the miniaturized electronically steerable parasitic array radiator (ESPAR) antenna is presented. The size reduction was obtained by embedding its active and passive elements in polylactic acid (PLA) plastic material commonly used in low-cost 3D printing. The influence of 3D printing process imperfections on the ESPAR antenna design is investigated and a simple yet effective method to compensate them has been proposed. An antenna prototype was fabricated and measured, which showed that the experimental and simulated results are in good agreement. Realized antenna is characterized by 5.6 dBi peak gain and reflection coefficient of -17.6 dB. Base radius reduction of 23% and occupied area reduction of 40% were achieved.

This paper studies the energy efficiency (EE) of the cloud radio access network (C-RAN), consisting of multiple remote radio heads (RRHs) equipped with electronically steerable parasitic array radiator (ESPAR) antennas, which provide multiple antenna functionality with a single radio frequency (RF) chain. An EE optimization problem is formulated to obtain the configuration of ESPAR and the closed-form expressions of the voltage feeding and the loadings are derived for signal transmission at each RRH. Specifically, we obtain the closed-form expressions for precoder and power allocation that are applicable not only for the ESPAR based system but also for standard MIMO antenna (SMA) system with multiple RF chains. It is shown that EA system can be configured with less complexity compared with SMA system in block fading channel. Furthermore, symbol error rate (SER) and EE performances are compared for EA and SMA based systems. It is shown that the system with EA provides better EE performance while providing similar SER performance. From our results, it is proved that EA system can provide better performance to satisfy the requirement of 5G wireless communication networks.

Paper encompasses formulation of mathematical model, simulation and later designing of ESPAR (Electronically Steerable Parasitic Array Radiator) antenna capable of dynamic tracking of active targets in 3D. Variable reactance set was loaded in array of elements surrounding center element. Reactance value for placement of maxima is specified direction in 3D axis is formulated using Quasi Newton Method. Using calculated values 3D beam steering is achieved. Around 8 dB gain is achieved in specified direction of Theta and Phi. Designed antenna is efficient in terms of size and cost as all the elements are placed at Lambda/4, thereby revolutionizing present day communication systems and replacing conventional Omni directional antennas in Radios, Laptops, Cell phones. Along with efficient beam forming designed antenna is a step forward towards green technology, operating at reduced powers without disrupting EIRP of antenna systems, thereby maintaining constant EIRP.

Industrial Internet-of-Things (IIoT) applications require reliable and efficient wireless communication. Assuming dense wireless sensor networks (WSNs) operating in a harsh environment, a concept of a time-division multiple access (TDMA)-based WSN enriched with electronically steerable parasitic array radiator (ESPAR) antennas is proposed and examined in this work. The utilized antenna provides one omnidirectional and 12 directional radiation patterns that can be electronically switched by the sensor node. We introduce a relay discovery algorithm, which selects those sensor nodes with an ESPAR antenna capable to act as relay. The selection of the relay nodes is based on a certain link quality threshold that algorithm uses as input. The outcome is a reduction in the number of layers or hops with a guaranteed Quality of Service (QoS). To emphasize the physical aspect of the wireless propagation, we introduce the measured antenna radiation patterns and consider two different path-loss propagation models representing blockage-free and blockage-prone industrial environments. A number of network simulations were performed and signal-to-noise ratio (SNR) as a link quality measure was examined with respect to the network density and different measured radiation pattern settings. The main outcomes show a tradeoff between SNR per link and the percentage of nodes that can serve as relays. As a result, we propose network design guidelines that take under consideration the QoS range with respect to SNR together with an optimal number of antenna radiation patterns that should be selected as a tradeoff between latency, energy consumption, and reliability in a network.

Accessing the spatial domain of wireless environments through antenna arrays has become key to improve the use of energy and, in light of this, there is an increasing need for low cost multi-antenna architectures. As one alternative, the Electronically Steerable Parasitic Array Radiator (ESPAR) was proposed as a coupling-based inexpensive option; allowing to significantly reduce the amount of required radio frequency (RF) front-ends. As a caveat, due to its inherent non-linear behavior, the required computational complexity can be prohibitive. Additionally, the unavailability of precise mutual coupling and channel state information (CSI) becomes a further issue difficult to avoid in practical setups. In this regard, the current work has two main contributions: a) it deals with the computational complexity by proposing the linearization of ESPAR’s system model through the truncated Taylor expansion of the admittance matrix; facilitating the spatial processing algorithm of interest. Also, the authors propose b) to face the mutual coupling and CSI unavailability issue via the joint estimation of the channel-ESPAR parameters as directly observed through the single RF front-end. Relying on the optimization of the linearized system model, the pilot-based algorithm to be introduced allows ESPAR to track the configuration that synthesizes coherent combination at a significantly low complexity. Particularly, as shown through Monte-Carlo simulation, the latter allows to obtain 4 dB of array gain with a single RF front-end via a 5-element ESPAR.

Fading or reflections strongly affect the receiver signal strength in the conventional UHF RFID communication system. In this paper, a new UHF RFID based wireless sensor network is considered to manage the interference and multipath fading by antenna nulling technology that can be made by beamforming control of ESPAR antenna. In addition, the proposed electronically steerable antenna's localization of passive UHF RFID tag and a stationary RFID reader is based on the Direction of Arrival and Angle of Arrival. To estimate the Link Budget (LB) and the Received Signal Strength (RSS) between the Sensor tag and the RFID reader are also investigated in this paper. ESPAR antenna exhibits higher gain and proper radiation pattern. The work can be applied into the wireless ECG monitoring system by providing better advantages.

Electronically steerable parasitic array radiator (ESPAR) antenna is a novel low-cost technique to gain comparable diversity order to that of using multiple antennas while maintaining one radio frequency (RF) front-end, low power consumption, and simple wiring at the mobile receiver. It has huge potential to realize high energy efficiency for multiple and massive antennas systems. The main drawback of the ESPAR based OFDM system is that the channel estimation (CE) usually should be realized in time-domain with a huge computational complexity (CC) because the received signal to each parasitic element is overlapped each other both in frequency and time domain. This article will propose three ways to reduce the complexity of CE for the ESPAR-OFDM system. The parallel multi-column compressive sensing (CS) algorithm was first introduced to detect all locations of channel impulse response simultaneously using one small segment of sensing matrix. Furthermore, by exploiting the symmetrical properties of Digital Fourier transform (DFT), the size of matrix to decrease the CC of matrix operation. Finally, by selecting a small set of row vectors of sensing matrix at the receiver side, the CC involved in CS algorithm can be reduced. From the analysis and simulated results, the proposed method can obtain more than 90% CC reduction for CE of ESPAR-OFDM receiver can be confirmed.