Positions Of Access Points Research Articles

Locating Rogue Access Point Using Fine-Grained Channel Information

Rogue access point (AP) has emerged as an important security problem in WLANs. However, it is a challenge task to localize the rogue AP with both high accuracy and minimal infrastructure cost. Either expensive professional infrastructure (e.g., multiple wireless sniffers) or additional hardware (e.g., directional antenna) need to be pre-deployed for rogue AP localization with high cost. Moreover, existing methods using Received Signal Strength (RSS) result in a large error as RSS is suffered from the multipath and shadowing effects in complex wireless environment. In this work, we exploit the channel state information (CSI), which is readily available from commercial Wi-Fi devices, to locate the rogue AP with high accuracy. We use only a single off-the-shelf Wi-Fi device for rogue AP localization which involves minimal infrastructure requirement. Our proposed rogue AP localization framework consists of two components: direction determination and position estimation. The direction determination can be carried out by using the human blocking effect on the CSI amplitude or phase. The multiple antennas on the Wi-Fi devices can be further utilized to enhance the rogue AP direction estimation. Given the estimated direction, two schemes are proposed to pinpoint the position of the rogue AP: determining directions at multiple locations grounded on triangulation and walking towards the rogue AP with direction adjustment. Results from extensive experiments in both indoor and outdoor environments show that our framework can achieve more practical and accurate rogue AP localization when comparing with the existing RSS-based approach.

A Self-Adaptive Model-Based Wi-Fi Indoor Localization Method.

This paper presents a novel method for indoor localization, developed with the main aim of making it useful for real-world deployments. Many indoor localization methods exist, yet they have several disadvantages in real-world deployments—some are static, which is not suitable for long-term usage; some require costly human recalibration procedures; and others require special hardware such as Wi-Fi anchors and transponders. Our method is self-calibrating and self-adaptive thus maintenance free and based on Wi-Fi only. We have employed two well-known propagation models—free space path loss and ITU models—which we have extended with additional parameters for better propagation simulation. Our self-calibrating procedure utilizes one propagation model to infer parameters of the space and the other to simulate the propagation of the signal without requiring any additional hardware beside Wi-Fi access points, which is suitable for real-world usage. Our method is also one of the few model-based Wi-Fi only self-adaptive approaches that do not require the mobile terminal to be in the access-point mode. The only input requirements of the method are Wi-Fi access point positions, and positions and properties of the walls. Our method has been evaluated in single- and multi-room environments, with measured mean error of 2–3 and 3–4 m, respectively, which is similar to existing methods. The evaluation has proven that usable localization accuracy can be achieved in real-world environments solely by the proposed Wi-Fi method that relies on simple hardware and software requirements.

Implementation of WLAN N and Estimation of Co Channel and Adjacent Channel Interference

Implementation of WLAN N and Estimation of Co Channel and Adjacent Channel Interference An enhanced Wireless network pLAN is needed to replace the existing WLANs. The introduction of WLAN/N offers the flexibility to dynamically locate users and devices, and to provide scalability to the network. In this research paper, the signals over non-line-ofsight propagation of 802.11/g and 802.11/n in indoor environment of the multi storied building are examined. Usually, an IEEE 802.11 variation is chosen based on their bandwidth and their coverage premises. In addition, suitable positioning of access points (AP) is significant to determine the efficiency of the network. Test bed and experiment has been carried out in terms of RSSI (Received Signal Strength Indication), coverage area, and signal interference computation between channels. The signal levels were measured using Com view and Tamo Graph tools and were compared with the Motley-Keenan model. The observed results have shown considerable reduction of Co-channel and adjacent channel interference in using 802.11/n compared to 802.11/g. This study will be the advantage to the researchers to choose the best technology depending on their deployment and requirement.

Three dimensional compressed sensing for wireless networks‐based multiple node localization in multi‐floor buildings

AbstractIn wireless network‐based node localization, the received signals are hampered by complex phenomena, such as shadowing, noise, and multi‐path fading. In this work, the localization is stated as an ill‐posed problem that can be solved by compressed sensing (CS) technique. A three dimensional (3D)‐CS approach using the ratio of received signal strength (R2S2) and the time difference of arrival metrics was proposed to improve the localization accuracy of multiple target nodes in 3D wireless networks, and to reduce deployment complexity and processing time. Simulation and experimental tests were conducted in a large multi‐floors building using the strength of the received signals and the radio map of the localization area. The results indicated that the 3D‐CS approach is reliable for identifying the floor number and estimating the horizontal position. The localization precision is less affected by the propagation medium variation than the conventional 2D‐CS method. The localization mean error is lower when the number of access points increases, and the radio map spacing decreases. In addition, the accuracy of the 3D‐CS approach was assured as well as the building material characteristics, position of access points, and wireless‐terminal real transmission power are unknown. Copyright © 2015 John Wiley & Sons, Ltd.

Performance analysis of multi-gigabit wireless transmission at THz WLAN-type applications

Optimal position of access point (AP) is important for multi-gigabit wireless transmission in terahertz (THz) wireless local area network (WLAN)-type applications, where there exist the THz characteristic multiple clusters in channel propagation. By considering the multiple clusters in THz indoor communications, this paper investigates the optimal AP position when two APs are issued for increasing the system capacity. Numerical results reveal that the central position of each AP within each half service region, which offers the shortest cumulated path length for line-of-sight paths, is optimal to achieve the maximal system capacity.

Unsupervised Locating of WiFi Access Points Using Smartphones

WiFi positioning systems require radio maps in the form of either RF fingerprints or positions of WiFi access points (APs). In particular, knowledge of the AP positions is essential to enable a locating mechanism as well as to understand the nature of underlying WiFi networks, such as density, connectivity, interference characteristics, and so on. In this paper, we propose an approach called Serendipity, which locates WiFi APs in an unsupervised manner using radio scans collected by ordinary smartphone users. From the radio scans, we extract dissimilarities between all pairs of WiFi APs and estimate relative positions of APs by analyzing the dissimilarities based on a multidimensional scaling technique. We then find the absolute positions with additional radio scans whose positions are known. The discovered positions of WiFi APs are used for the positioning of smartphones or the management of the WiFi networks. To validate the proposed approach, we conducted experiments on several indoor locations.

Connectivity in a random interval graph with access points

We derive closed analytical formulae of connectivity for random interval graphs in the presence of fixed access points. We examine the influence of positions of access points on the graph accessible connectivity. The results developed in this paper are useful in the design and engineering of random wireless access network in the future.