Improving Connection Stability for Robust UAV Control
- 주제(키워드) UAV , Network
- 발행기관 고려대학교 대학원
- 지도교수 김황남
- 발행년도 2020
- 학위수여년월 2020. 8
- 학위구분 박사
- 학과 대학원 전기전자공학과
- 세부전공 컴퓨터공학 전공
- 원문페이지 106 p
- UCI I804:11009-000000232099
- DOI 10.23186/korea.000000232099.11009.0001176
- 본문언어 영어
- 제출원본 000046048413
초록/요약
Various unmanned aerial vehicles (UAVs) have been developed based on advance hardware and software technology. Service providers in diverse areas have tried to utilize UAVs to create more effective solutions. In many cases, employing multiple UAVs are more effective to perform a given mission than using a single UAV. UAV network composed of multiple UAVs allow wide operating radius and various tasks to be performed. However, UAV network mostly suffers from high probability of transmission failure due to interference or mobility. To utilize multiple UAVs, the UAVs should be strongly connected, and it is critical to construct reliable and efficient network. In this dissertation, we describe three solutions for improving UAV connectivity and maintaining stable network for UAV. First, we propose an algorithm to improve the transmission performance of UAV network through TCP with Slow-Start threshold (Ssthresh) value adjusted. The adjustment algorithm is called Adaptive Ssthresh Reviser for flying Ad hoc Network (ASRAN) that quickly restores unnecessary decrease of transmission speed in UAV network. Nodes connected to the network often experience connection loss and segment loss caused by frequent node mobility and routing update. Since congestion is not the only cause of data loss in UAV networks, the TCP congestion control should not be run if there is a possibility of transient link instability unless a reduction in transmission speed is required. Second, we propose ConClone as a scheme for control packet transmission. ConClone duplicates control packets and then transmits them over multiple network connections to increase the probability of successful control packet transmission. We implemented ConClone using real equipment, and its performance was verified through experiments and theoretical analysis. UAV is being applied to various applications. In order to perform repetitive and accurate tasks, it is more efficient for the operator to perform the tasks through an integrated management program rather than controlling the UAV one by one through a controller. In this environment, control packets must be reliably delivered to the UAV to perform missions stably. However, wireless communication has the risk to lose packet or delayed packet propagation. Typical network communications can respond to situations in which packets are lost by retransmitting lost packets. However, in the case of UAV control, delay due to retransmission is fatal, so control packet loss and delay should not occur. Because UAV has a fast moving speed, if the control packets are lost or delayed, there is a high risk in accidents. Therefore, eliminating the instability of packet transmission and increasing the flight control stability of UAV is necessary. Last, we propose an Enhanced Ground Control System routing protocol (Enhanced GCS routing) to provide reliable and efficient multi-UAV control system. GCS is the essential component of flying ad-hoc network (FANET) and can obtain information of UAVs. Using this information, Enhanced GCS routing can provide more effective routing, predict any topology changes, and react immediately. Enhanced GCS routing does not issue any periodic HELLO message for neighbor discovery or link cost estimation, which significantly enhances network performance. We applied Enhanced GCS routing to UAV fleets, as well as simulations to evaluate Enhanced GCS routing performance. The results clearly identify the advantages of the proposed routing protocol for UAV networks compared with current routing protocols.
more목차
Chapter 1 Introduction . . . . . . . . . . . . . . . . . . . . . 1
Chapter 2 Related Work . . . . . . . . . . . . . . . . . . . . 9
2.1 TCP scheme for multi-hop network . . . . . . . . . . . . . . 9
2.2 Connection stabilization scheme . . . . . . . . . . . . . . . . 12
2.3 Reliable routing scheme . . . . . . . . . . . . . . . . . . . . 14
Chapter 3 Adaptive TCP Transmission Adjustment for UAV Network Infrastructure. . . . . . . 17
3.1 Adaptive Ssthresh Reviser for flying Ad hoc Network (ASRAN). . . . . . . . .. . . . . . . . . . . 17
3.2 ASRAN throughput Model . . . . . . . . . . . . . . . . . . 25
3.3 Performance Evaluation . . . . . . . . . . . . . . . . . . . . 28
Chapter 4 MPTCP-based Transmission Scheme for Improving Control Stability of Unmanned Aerial Vehicle . . . . 37
4.1 ConClone . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4.2 Theoretical analysis . . . . . . . . . . . . . . . . . . . . . . 41
4.3 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Chapter 5 Ground Control System Based Routing for Reliable and Efficient Multi-UAV Control System . . . . . . 56
5.1 Enhanced GCS routing Design . . . . . . . . . . . . . . . . 56
5.2 Theoretical analysis . . . . . . . . . . . . . . . . . . . . . . 59
5.3 Performance Evaluation . . . . . . . . . . . . . . . . . . . . 64
Chapter 6 Conclusions . . . . . . . . . . . . . . . . . . . . . . 76
6.1 Summary and Contribution . . . . . . . . . . . . . . . . . . 76
6.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . 78
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
