LTE/WiFi 기반 소형 무인기용 영상 전송 시스템 개발

Development of Video Transfer System using LTE/WiFi for Small UAV

Abstract

본 논문에서는 25kg 급 이하의 소형 무인기에서 활용 가능한 LTE/WiFi 기반의 영상 전송 시스템 개발 결과를 소개한다. 개발된 영상 전송 시스템은 탑재통신장치와 지상통신장치로 구성되었으며 소형무인기가 촬영한 HD급 해상도 이상의 영상(720p/30fps, 1080p/30fps)을 전송하기 위해 LTE와 WiFi 데이터통신 방식을 활용하였다. 탑재통신장치는 H.264 영상처리보드를 내장하여 실시간 스트리밍 영상 전송이 효율적으로 가능하도록 설계되었다. 지상시험평가를 통해 근거리부터 비가시선 영역에까지 실시간 영상전송이 가능함을 확인하였다.

In this paper, we present the results of a developed LTE/Wi-Fi-based video transmission system which can be applied in small unmanned aerial vehicles of 25kg or less. The developed video transmission system comprised of airborne datalink terminal, ground datalink terminal, and used LTE and Wi-Fi wireless data communication technologies to transmit videos of resolution higher than HD (720p/30fps, 1080p/30fps) taken by small UAV. The airborne device is designed to efficiently transmit real-time streaming video through the incorporation of H.264 video processing board. Ground tests and evaluation indicated the possibility of the developed system to transmit real-time videos from close distance in regards to non-line-of-sight area.

Fig. 1 LTE/WiFi Video Transfer System Architecture of Testbed UAV Platform

Fig. 2 Components of Airborne Datalink Terminal

Fig. 3 Airborne Datalink Terminal (ADT)

Fig. 4 Ground Datalink Terminal (GDT)

Fig. 5 Software Architecture

Fig. 6 RTP packet format

Fig. 7 Network configuration for LTE communication connection

Fig. 8 Port Forwarding and Mapping Scheme using one M2M server in LTE network

Fig. 9 Packet transfer between ADT to M2M server

Fig. 10 Ground Test Configuration

Fig. 11 Network Performance Measurement by iPerf Program

Fig. 12 Testbed UAV Setup for Functional Test of Command & Control (C2) Data Transfer

Fig. 13 Parameters downloaded from Flight Controller using C2 Datalink

Fig. 14 Upload of Waypoints for Mission Planning

Fig. 15 Ground Test Setup for HD Video Transfer Function using LTE/WiFi Communication

Fig. 16 Display of Streaming Video on VLC Player using LTE Datalink

Fig. 17 Installation and Ground Test on Testbed UAV Platform

Fig. 18 Removal of WiFi antenna and cable for Automatic Link Switching Function Test

Table 1 Features of Airborne Datalink Terminal

Table 2 Serial Communication Setting for Flight Controller Interface

Table 3 Command Transfer and Operation Results in C2 Link Functional Test