基於無線訊號接收強度之低複雜度低功耗室內定位系統

近年來，定位相關的應用越來越普及。由於全球定位系統(Global positioning system，GPS)的衛星訊號不能夠穿透建築物到室內，所以室內定位系統需要用其他的技術來設計。在本篇論文中，我們利用藍牙低功耗(Bluetooth low energy，BLE)設計了一個低功耗、低成本的室內定位系統。本篇論文提出的定位系統是由藍牙低功耗標籤(BLE tag)、藍牙低功耗/無線網路中繼器(BLE/Wi-Fi repeater)和伺服器(Fusion server)所構成。系統中的藍牙低功耗標籤負責廣播藍牙信標，中繼器則會接收標籤傳出的信標並萃取出接收到的訊號強度(Received signal strength，RSS)，萃取出的訊號強度資訊會透過無線網路(Wi-Fi)上傳到伺服器，之後伺服器會利用訊號強度相關的定位演算法來估測標籤的位置。本篇論文使用了接收訊號強度指紋(Received signal strength indication-fingerprint)與單位原點(Cell of origin，CoO)的混合式演算法來估測目標位置，並對個別的演算法做改良來提升精準度。為了驗證系統的效能，本篇論文實際考量了兩個不同的室內場景，第一個場景位於清華大學台達館8樓的休息區，第二個則是捷螺系統公司的辦公室，每個場景各被4個中繼器涵蓋，平均的定位誤差分別為1.2公尺及1.37公尺。除此之外我們使用的藍牙低功耗標籤大小半徑是1.7公分，厚度是0.5公分，可以非常簡易的黏貼在定位目標上。每個藍牙低功耗標籤的成本是3美元，對於需要大量的標籤來做多目標定位的應用不會造成太大的負擔。耗能的部分，標籤平均的消耗電流是50微安培，搭配上CR2025鋰電池可以連續使用136天。

關鍵字

藍牙；低功耗；低複雜度；室內定位；接收訊號強度

並列摘要

In recent years, applications of positioning have become more and more popular. Since the signals transmitted from global positioning system (GPS) satellites cannot penetrate inside the buildings, there are demands for indoor positioning systems with other technologies. In this thesis, we propose a indoor positioning system based on Bluetooth low energy (BLE) with characteristics of low power, low cost and high portability . The proposed system consists of BLE tags, BLE/WiFi repeaters and a fusion server. The BLE tag in our system is a device which broadcasts BLE beacons. The BLE/WiFi repeaters collect the beacons transmitted from the tag and extract the received signal strength (RSS). The RSS values are then transmitted to our fusion server through Wi-Fi, and the server will estimate the position of the BLE tag with RSS-based positioning algorithm. We propose a indoor positioning algorithm which is a hybrid from received signal strength indication (RSSI)-fingerprint and cell of origin (CoO). Some modifications are made to typical RSSI-fingerprint and CoO algorithm to get better accuracy. To verify the performance of our system, we take two indoor environments into considerate. The first is the rest area of Delta building in National Tsing-Hua University (NTHU). The second is the office of GYRO system company. Each environment is covered by four BLE/WiFi repeaters. The mean error distance of these two environments are 1.2 m and 1.37 m respectively. Moreover, the size of the BLE tag is 1.7 cm in radius and 0.5 cm thick, that can be easily attached to the localization target. Each BLE tag costs 3 US dollars. So it is friendly for those who need large amounts of them for multi-objects positioning. The current consumption of the tag is 50 A which can be used without charge for 136 days with a CR2025 battery.

並列關鍵字

Bluetooth ； low power ； BLE ； low complexity ； indoor positioning ； RSSI

參考文獻

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[8] H. Liu, H. Darabi, P. Banerjee, and J. Liu, “Survey of wireless indoor positioning techniques and systems,” IEEE Transactions on Systems, Man, and Cybernetics, Part C (Applications and Reviews), vol. 37, no. 6, pp. 1067–1080, Nov 2007.

[9] R. Want, “An introduction to RFID technology,” IEEE Pervasive Computing, vol. 5, no. 1, pp. 25–33, Jan 2006.

[10] S. Gezici, Z. Tian, G. B. Giannakis, H. Kobayashi, A. F. Molisch, H. V. Poor, and Z. Sahinoglu, “Localization via ultra-wideband radios: a look at positioning aspects for future sensor networks,” IEEE Signal Processing Magazine, vol. 22, no. 4, pp. 70–84,

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基於無線訊號接收強度之低複雜度低功耗室內定位系統

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