EVALUATION OF RECEIVED SIGNAL STRENGTH INDICATION OF BLUETOOTH LOW ENERGY ON DISTANCE ESTIMATION

Abstract

The concept of using short-range radio technologies to connect group of small devices to internet or capillary networks are significant on IoT. On certain use case, such as localization, BLE (Bluetooth Low Energy) as novel wireless short range radio technology has tremendous potential for enabling coverage of localization network. However, due to its wireless nature, it runs into phenomena such as multipath effect. Therefore, analysis of radio propagation model plays important role in performance evaluation on both theoretical and practical aspect. There are several theoretical evaluations of path loss exponent on different place in the literature. However, there is a lack of experimental evaluation. In this paper, we experiment the measurement in free space, indoor hall, and closed room, where BLE nodes are generally deployed. Log normal model is used in order to evaluate the experimental analysis. Path loss exponent are measured by means of Received Signal Indicator or RSSI. Those parameter are compared with theoretical analysis, which is available in literature. Overall, we obtained minimum MAE (Mean Absolute Error) on indoor hall environment 1.9974 meter for practical PLE, while on PLE theoretical, we obtained 6.2494 meter. This difference shows importance of PLE calibration in RSSI distance estimation..

Keywords: Bluetooth Low Energy, Path Loss Exponent, RSSI

 

Abstrak

Konsep penggunaan teknologi short range radio untuk menghubungkan perangkat-perangkat kecil ke internet atau disebut capillary networks berperan sangat penting pada perkembangan IoT (Internet of Things). Pada kasus tertentu, seperti penentuan lokasi, BLE (Bluetooth Low Energy) sebagai teknologi wireless short range radio baru memiliki potensi yang cukup besar untuk memungkinkan coverage pada suatu localization network. Meskipun begitu, oleh karena sifat wireless-nya, sinyal BLE mengalami fenomena multipath. Oleh karena itu, analisis dari model propagasi radio memiliki peran yang cukup penting dalam evaluasi performansi teoritis dan praktis. Ada beberapa evaluasi teoritis terkait PLE (Path Loss Exponent) di dalam literatur. Meskipun begitu, terdapat kekurangan terhadap evaluasi experimental. Pada paper ini, kami mencoba melakukan pengukuran pada beberapa kondisi yaitu, free space, koridor dalam ruangan, dan ruangan tertutup, dimana node dari BLE umumnya dibangun. Model log normal digunakan untuk evaluasi secara eksperimental. PLE diukur dengan menggunakan RSSI (Received Signal Strength Indicator). Parameter tersebut dibandingkan dengan analisis teoritis yang ada di literatur. Secara keseluruhan, kami memperoleh MAE (Mean Absolute Error) minimum pada kondisi koridor di dalam ruangan sebesar 1.9974 meter untuk PLE praktis, sedangkan untuk PLE teoritis diperoleh MAE sebesar 6.2494 meter. Perbedaan ini memperlihatkan pentingnya kalibrasi PLE dalam estimasi jarak menggunakan metode RSSI.

Kata kunci: Bluetooth Low Energy, Path Loss Exponent, RSSI