저전력 블루투스에서 안전 응용을 위한 CSMA 성능 향상 기법 = Enhanced CSMA for Safety Application using Bluetooth Low Energy

다국어 초록 (Multilingual Abstract)

Recently, the number of accidents between pedestrian and personal mobility is increasing year after year as the use of personal mobility is increasing. Due to the technological advancement, personal mobility with high speed is being invented even with a small labor. Furthermore, electric personal mobility using battery and electric motors has appeared. Nowadays, use of personal mobility is becoming a trend. There are electric wheel, electric bicycle and electric scooter. In the case of electric wheel, the movement speed can be up to 30 km/h. In the case of electric bicycle, the speed can be up to 35 km/h. Due to this reason accidents between pedestrians and personal mobility are very dangerous.

In recent years, research of communication-based safety application has been actively pursued to prevent such accidents. Previously I have proposed Bluetooth Low Energy (BLE) based safety application. In that proposed scheme three channels are used for the communication in BLE, and as it is asynchronous communication the reliability of safety application decreases. There can be high packet collision when there are multiple senders existing nearby. This also makes the reliability of safety application to be decreased. Moreover, as BLE devices send packets based on pure ALOHA there is a high possibility of packet collision.

Therefore, in this paper, enhanced CSMA (Carrier Sense Multiple Access) is proposed to improve the reliability of communication-based safety application using BLE. Furthermore, I also analyze the performance of existing scheme in BLE, existing CSMA and proposed enhanced CSMA through experiments using NS-3 (Network Simulator 3).

목차 (Table of Contents)

• 1. 서론
• 2. 관련 연구
• 2.1 Bluetooth Low Energy
• 2.1.1 Scanner
• 2.1.2 Advertiser
• 2.2 안전 응용
• 2.2.1 BLE 기반의 자전거와 보행자간 안전 응용
• 2.3 매체 접근 제어
• 2.3.1 Pure ALOHA
• 2.3.2 Slotted ALOHA
• 2.3.3 1-persistent CSMA
• 2.3.4 p-persistent CSMA
• 2.3.5 Non-persistent CSMA
• 2.3.6 CSMA/CD
• 2.3.7 CSMA/CA
• 3. BLE의 특징을 고려한 CSMA
• 3.1 BLE와 Advertising, 안전 응용의 특징
• 3.2 제안한 CSMA의 동작
• 4. 실험 및 성능 평가
• 4.1 시뮬레이션 환경
• 4.2 시뮬레이션 시나리오
• 4.3 시뮬레이션 결과
• 4.3.1 비컨 충돌 실험
• 4.3.2 에너지 소모 실험
• 4.3.3 안전 응용 신뢰성 실험
• 5. 구현
• 5.1 보행자 안전 장치
• 5.1.1 안드로이드 기반의 보행자 안전 장치
• 5.2 자전거 안전 장치
• 5.2.1 라즈베리파이 기반의 자전거 안전 장치
• 5.2.2 nRF52832 기반의 자전거 안전 장치
• 6. 결론