探討感測元件最佳佈署高度範圍以提升室內定位的準確度

Analysis of the Influence of the Heights of Optimal Beacon Placements on the Accuracy of Indoor Positioning

洪浩翔(Hao-Hsiang Hung)

指導教授 ： 魯大德

健行科技大學/電資學院/資訊工程系碩士班/碩士(2016年)

摘要

由於室內定位可以便利地找到目標物或人員所在位置，使其具有一定的商業價值，在藍牙無線感測網路(Bluetooth-based wireless Sensor Network)的領域中為重要的應用之驗證明在相同的高度距離下，不同的佈署高度具有不同的訊號表現，我們提出一RSSI高度與距離關係模型，藉由此模型分析及各項實驗找出最佳的佈署高度範圍，使接收端獲得較佳之RSSI訊號值，進而提升藍牙RSSI-Based室內定位的準確度。其中，採用Received Signal Strength Indication (RSSI) Based定位技術，因具有低功耗(Bluetooth Low Energy)、不須過多的額外設備、易於分析等特性，在近年來的室內定位研究中被廣為使用，但最大的問題為RSSI訊號容易受到室內環境中周遭物理環境的影響，像是傢俱、牆壁、人體等，造成RSSI訊號的衰減，進而降低室內定位的準確度。
現有RSSI-Based定位研究都著重於演算法或是定位機制的改良，但是當接收到較差之RSSI訊號的前提下，所能提升定位的準確度是有限的。因此本文探討藍牙訊號發射器在室內環境中的佈署高度對RSSI訊號值的影響，利用實驗證明在相同的LOS距離下，不同的佈署高度具有不同的訊號表現。我們提出一RSSI高度與距離關係模型，藉由此模型分析及各項實驗找出最佳的佈署高度範圍，使接收端獲得較佳之RSSI訊號值，進而提升藍牙RSSI-Based室內定位的準確度。以訊號紋比對法作為實驗，結果顯示在1 m的誤差距離下non-line-of sight(NLOS)與line-of sight(LOS)環境中與未調整感測器佈署高度相比，調整後之感測器佈署高度其定位準確度分別提升了20%與8%。

關鍵字

Sensor placement ； Beacon ； RSSI ； RSSI-Based

並列摘要

Location services can use information from cellular, Wi-Fi, Zigbee, and iBeacon sources. Indoor localization can conveniently find the locations of objects or people. It’s one of important applications in Bluetooth-based wireless sensor networks. Received Signal Strength Indication-based (RSSI) positioning technology does not need too much extra equipment and is widely used in indoor localization research. However, RSSI signals are susceptible to attenuation from physical objects in indoor environments, such as furniture, walls, and bodies, which reduce the accuracy of indoor locations.
In recent years, RSSI-based localization research has focused on the improvement of the positioning localization mechanisms or algorithms. It is difficult to improve the accuracy of localization with inferior RSSI signals. Sensor placements affect the quality of indoor positioning. Therefore, we study various heights of sensors and mobile phone.
In this study, we proposed a RSSI height and distance relational model to find the optimal sensor height range. The results show that the cumulative distribution function (CDF) of accuracy is improved by 20% and 8%, with an error distance of 1m, in non-line-of sight (NLOS) and line-of sight (LOS) environments, respectively.

並列關鍵字

Sensor placement ； Beacon ； RSSI ； RSSI-Based

參考文獻

[1] Adewumi, O. G., et al., “RSSI Based Indoor and Outdoor Distance Estimation for Localization in WSN”, Industrial Technology (ICIT), pp. 1534-1539, 2013

[2] Alqudah, R., Basagni, S., ”On the Effects of Multiple Beacons on Localization for Wireless Sensor Networks”, Wireless Telecommunications Symposium, pp.304 – 309, 2008.

[3] Alrajeh, N. A., et al., “Localization Techniques in Wireless Sensor Networks”, International Journal of Distributed Sensor Networks, vol. 2013, 2013

[4] Bai, S. Q., et al., “Accurate Path-Loss Exponent Correcting Location Method”, Control Conference (CCC), pp. 472-475, 2014

[5] Chen, C. C., et al., “Range-Free Localization Scheme in Wireless Sensor Networks Based on Bilateration”, International Journal of Distributed Sensor Networks, vol. 2013, 2013