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Article
Distance Estimation Based on RSSI and Log-Normal Shadowing Models for ZigBee Wireless Sensor Network

Author: Salim Latif Mohammed
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2016 Volume: 34 Issue: 15 Part (A) Engineering Pages: 2950-2959
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

In the last few years, a mobile wireless sensor and its application in wireless sensor network (WSN) are commonly used. Localization of a mobile sensor node is considered a critical issue in some WSN applications. In this paper, an outdoor environments experiment was carried out to measure the distance between the mobile node and the coordinator node in a simple point-to-point ZigBee WSN. The distance was determined based on the measured Received Signal Strength Indicator (RSSI) of the mobile node by the coordinator node. In addition, a Log-Normal Shadowing Model (LNSM) was derived for outdoor condition. Moreover, the parameters of the propagation channel such as standard deviation and a path loss exponent were estimated. The RSSI was measured and analysed for outdoor environments for a distance range 1-100 m. The measurements were carried out by using 2.4 GHz ZigBee wireless protocol based on XBee series 2 modules. The results disclosed that the mean absolute error (MAE) of 3.44 and 6.72 m for a distance range 0-65 m and 0-100 m, respectively. These results point that the LNSM is only suited for short distance.

Keywords

Distance estimation --- LNSM --- RSSI --- WSN --- ZigBee.


Article
A localization Approach for Sensor Networks by Using Round Trip Time
طريقة تحديد الموقع لشبكات الاستشعار بواسطة طريقة حساب الذهاب والاياب

Author: Ahmed A. Mohsin احمد محسن
Journal: Iraqi Journal of Information Technology المجلة العراقية لتكنولوجيا المعلومات ISSN: 19948638/26640600 Year: 2017 Volume: 7 Issue: 4 اللغة الانكليزية Pages: 29-51
Publisher: iraqi association of information الجمعية العراقية لتكنولوجيا المعلومات

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Abstract

Node localization is a crucial requirement in wireless sensor networks (WSNs). Localization is known as the estimation of the precise physical location of the sensor node. The position of each sensor node in WSNs could be determined by attaching GPS to each node or manually by a human, but both of these are unrealistic in large WSNs due to cost and human efforts. Round trip time (RTT) is one of position estimation methods in WSN for assisting sensor nodes in determining their location. This paper proposes an approach to get a precise estimation of the distance between sensor nodes for one of the aspects of self-management, which is self-locating. The proposed approach presents an algorithm to refine the measurements. Different factors that affect the measured RTT values are studied. Furthermore, the results of two ways of estimating distance are discussed, simulated and evaluated. Finally, the simulation results show that considerable improvement in localization determination can be achieved with the proposed method.

تحديد موقع جهاز الاستشعار هو متطلب اساسي في شبكات الاستشعار اللاسلكية . تحديد الموقع يعرف بتقدير الموقع الفعلي الدقيق لجهاز الاستشعار. موقع كل جهاز استشعار في شبكات الاستشعار اللاسلكية يمكن ان يحدد بربطه بجهاز تحديد الموقع او يدويا بواسطة الانسان, كلتا الطريقتين غير عملية في شبكات الاستشعار اللاسلكية الكبيرة نتيجة التكلفة والجهد المطلوب. هذا البحث يقترح طريقة جديدة باستخدام طريقة حساب الذهاب والاياب لتخمين المسافة بين اجهزة الاستشعار في الشبكة لمفهوم واحد من مفاهيم الادارة الذاتية في الشبكات, وهو تحديد الموقع ذاتيا. عوامل مختلفة تأثر على قيم حساب طريقة الذهاب والاياب المقاسة. بالاضافة الى ذلك, نتائج طريقتين لتقدير المسافة تم مناقشتها, محاكاتها وتقييمها. بالنهاية, نتائج المحاكاة تبين بان هناك تحسنا واضحا في طريقة تحديد الموقع ممكن تحقيقه مع هذه الطريقة المقترحة.

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