This paper introduces a review article on indoor localization techniques and technologies. The paper starts with current localization systems and summarizes comparisons between these systems in terms of accuracy, cost, advantages, and disadvantages. Also, the paper presents different detection techniques and compare them in terms of accuracy and cost. Finally, localization methods and algorithms, including angle of arrival (AOA), time of arrival (TOA), and recived signal strength (RSS) are introduced. The study contains concepts, requirements, and specifications for each category of methods presents pros and cons for investigated methods, and conducts comparisons between them.

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A Review of Indoor Localization Techniques and Wireless Technologies

A microstrip patch antenna using a defected ground structure (DGS) to suppress higher order harmonics is presented. An H-shaped defect on the ground plane with only one or more unit lattices has been utilized and yielded bandstop characteristics. Compared with a conventional microstrip patch antenna without the DGS unit cell, the radiated power of the DGS patch antenna at harmonic frequencies has been drastically decreased.

Harmonics reduction with defected ground structure for a microstrip patch antenna

In pursuit of the accomplishment of certain position estimations of targets in outdoor places, finding the locations of the targets in indoor environments has been a significant topic. Exact position estimations of the objects for indoor places have potentials for the enhancement of several emerging Internet-of-Things (IoT) applications, such as smart manufacturing, smart home, public security, social networks, transportation, traveling, marketing applications, and information services lead to a huge demand on the designing of low-cost and high-accuracy localization and navigation solutions. On the other hand, the global positioning system (GPS) technology designed for outdoor positioning applications, is not suitable to indoor positioning systems. Making exact position detection with GPS is a compelling problem for indoor positioning methods. In this study, received signal strength (RSS)-based least-squares triangulation approach that utilizes existing infrastructure, is proposed. By increasing the number of access points (APs) and using line fitting algorithms to the RSS values, the triangulation method improves the certainty of location estimation. The utilization of the existing infrastructure turns the proposed approach into cheaper when compared to existing localization methods which require expensive components. The proposed least-squares lateration algorithm is compared with pure lateration (PL) in terms of accuracy error under different Gaussian noise parameters for varying number of APs and varying dimensions of the measurement area. Usage of the least-square algorithm with line fitting approaches provides significant performance improvements for all cases when it compared with PL.

Comprehensive Analysis on Least-Squares Lateration for Indoor Positioning Systems

In rectifying or active antenna systems, the higher order modes can hamper the system efficiency, and thus, the filter antennas are used to eliminate the harmonic radiation. In this paper, the distribution of standing wave fields in patch antenna having been presented and then the characteristic mode theory having been employed, the influences of feeding location and the indentation of patch edges on the suppression of higher order harmonics and their spurious modes are investigated. It is indicated that indenting the radiating edges of the patch element works more effectively on the control of spurious modes while indenting the non-radiating edges can eliminate the harmonics by shifting down the fundamental mode. By selecting feed position and indenting the patch edges, a microstrip patch antenna with both harmonic and spurious mode controls is proposed.

Control of Higher Order Harmonics and Spurious Modes for Microstrip Patch Antennas

IEEE 802.11b wireless Ethernet is becoming the standard for indoor wireless communication. This paper proposes the use of measured signal strength of Ethernet packets as a sensor for a localization system. We demonstrate that off-the-shelf hardware can accurately be used for location sensing and real-time tracking by applying a Bayesian localization framework.

On the feasibility of using wireless ethernet for indoor localization.

In this paper, the power input to the radiating element of an active microstrip patch antenna is measured using a small sensing patch, which is weakly coupled to a radiating edge. Combined with an estimate of patch radiation efficiency, this also yields a measurement of total radiated power. The method has advantages of convenience, insensitivity to room reflections, and a weakly frequency-dependent calibration factor.

A power and efficiency measurement technique for active patch antennas

A comparison between two indoor localization algorithms using received signal strength is carried out. The first algorithm is the vector algorithm; the second is the matrix algorithm. The comparison considered the effects of the reference points, the access point, and the frequency on the accuracy of the localization process. The experiments were carried out using ray tracing software and MATLAB. This paper justifies the use of adopting the matrix algorithm.

Indoor localization using received signal strength

In this paper, a balanced antenna for mobile handset applications with dual- frequency performance, covering the 2.4GHz and the entire 5GHz WLAN frequency bands, is investigated and discussed. The antenna is a thin-strip planar dipole with folded structure and a dual-arm on each monopole. For validation, the antenna prototype was fabricated and tested. The performance of this balanced antenna was verifled and characterised in terms of the antenna return loss, radiation pattern, power gain and surface current distribution of the proposed antenna. The predicted and measured results show good agreement.

https://www.piers.org/piersonline/pdf/Vol6No1Page11to15.pdf

Compact Dual-band Balanced Handset Antenna for WLAN Application

We have studied the performance of multidimensional signaling techniques using wavelets based modulation within an orthogonally multiplexed communication system The discrete wavelets transform and wavelet packet modulation techniques have been studied using Daubechies 2 and 8, Biothogonal15 and 31 and reverse Biorthognal 15 and 31 wavelets in the presence of Rayleigh multipath fading channels with AWGN Results showed that DWT based systems outperform WPM systems both in terms of BER vs SNR performance as well as processing The performances of two different equalizations techniques, namely zero forcing (ZF) and minimum mean square error (MMSE), were also compared using DWT When the channel is modeled using Rayleigh multipath fading, AWGN and ISI both techniques yield similar performance

E.A. Elkhazmi

Papers

A power and efficiency measurement technique for active patch antennas

Indoor localization using received signal strength

Compact Dual-band Balanced Handset Antenna for WLAN Application

Performance of different wavelet families using DWT and DWPT-channel equalization using ZF and MMSE

Indoor environment propagation review