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Multi-beam Handover Strategeis for Improving Resource Utilization of Satellite Networks

위성 네트워크 자원효율 향상을 위한 멀티빔 핸드오버 전략

초록/요약

From the network management standpoint, the utility of satellite resources has to be maximized in supporting a large population of terminals. On the other hand, the user Quality of Service (QoS) requirements should be maintained. In the multi-beam mobile satellite system, utility of satellite resources and QoS of a Return Channel via Satellite Terminal (RCST) are affected by number of new connection RCST and capacity request/allocation scheme and number of handover RCST. There have been many researches about capacity request and allocation scheme to increase resource utilization. However, new connection and capacity request are unpredictable. Thus, we concentrate on the handover strategy to increase satellite resource utilization. And by handover control, we could increase satellite resource utilization and QoS of a RCST. In the multi-beam satellite communication system, a number of spot beams can be formed by beam forming technology in the focused areas, and the coverage of adjacent beams are partially overlapped just like the overlay structure of terrestrial cellular systems. However, Received Signal Strength (RSS) does not differ largely between the center and boundary of the beam. Also, Satellite communication can be serviced in the outage of high RSS beam boundary cause by rain attenuation margin. RSS based handover detection algorithm is not benefit to the multi-beam satellite system as a terrestrial system. Thus, we proposed adaptive handover detection algorithm based on RCST mobility information. This scheme not only removes uncertainties of handover due to the temporary RSS variation, but also increase forward link throughput. Furthermore, It can support first step of Load balancing Beam Handover (LBH) decision strategy, which is explained in below. In general, multi-beam satellite employs uniform allocation of RF power and bandwidth to multi-beam. If unpredictable events like disaster, regional warfare, etc.occur in a spot beam. Distribution of RCSTs could be different in each multi-beam. And resource saturation of some spot beam will occur, while adjacent beam resources are available. Furthermore, it is hard to predict the new connection and capacity request of RCST. On the other hands, handover request can be predicted. Also, Network Control Center (NCC) can control all of RCST information and multi-beam resources.Therefore, Load balancing of multi-beam can be achieved by handing over RCST in advance when the resources saturation of some spot beam is expected. Thus, we propose a novel handover decision strategy to improve return link resource utilization using LBH. This LBH scheme achieved the lower new connection block probability, capacity request block rate, handover block probability and higher return link utilization compared to the conventional handover detection schemes. In the Network Centric Operational Environment (NCOE), satellite communication is attractive attention as a military Internet Protocol (IP) based broadband tactical network. Since, commercial DVB-RCS standard that support IP based interaction channel is successively implemented. There are many studies to adapt DVB-RCS standard to the military satellite system. In order to communicate between RCSTs in other spot beams, it is required to the multi-beam traffic switching for transmitting traffic to the other spot beam forward link. In the military networks, multicast traffic in the operation group is important while unicast interaction channel for individual RCST is important in the commercial networks. If a RCST in group is distributed to many beams, large amount of multicast traffic must be transmitted to the many spot beams. This can be cause of packet loss during the multi-beam traffic switching in the forwardlink. If we apply LBH for increasing return link utilization to the military situation, packet loss could occur during the forward link beam traffic switching process. Thus, we evaluate the inefficient situation in the multi-beam traffic switching process when multicast is applied, and proposed modified LBH to reduce packet loss rate.

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목차

1 INTRODUCTION 1
1.1Motivation 1
1.2 Original contributions 2
1.3 Outline of dissertation 4
2 BACKGROUND AND RELATED WORKS 5
2.1 DVB-S2/RCS Resource Management strategy 5
2.1.1 DVB-S/S2 forward link organization 6
2.1.2 DVB-RCS return link organization 8
2.2 DVB-RCS+M handover process 12
2.3 Characteristic of multi-beam satellite system 16
2.3.1 Characteristic of multi-beam satellite signal 16
2.3.2 Characteristic of multi-beam structure 21
2.4 Chapter summary 24
3 MULTI-BEAM HANDOVER DETECTION STRATEGY 25
3.1 Problem description 25
3.2 Handover detection algorithm based on RCST mobility information 28
3.2.1 Adaptive distance margin based handover detection algorithm 28
3.2.2 Multi-beam handover detection procedure 33
3.3 Simulation results 35
3.4 Chapter summary 45
4 MULTI-BEAM HANDOVER STRATEGY FOR LOAD BALANCING 46
4.1 Problem description 46
4.2 Load balancing Beam Handover strategy 49
4.2.1 Load balancing Beam Handover algorithm 49
4.2.2 Performance analysis of QoS 56
4.2.3 Simulation results 57
4.2.4 Conclusion 66
4.3 Adaptive Load balancing Beam Handover algorithm 67
4.3.1 Adaptive resource margin control for load balancing 68
4.3.2 Simulation results 72
4.3.3 Conclusion 83
4.4 Load balancing Beam Handover for NCOE 84
4.4.1 Problem description 84
4.4.2 Modified ALBH and handover decision algorithm 89
4.4.3 Simulation results 91
4.4.4 Conclusion 96
4.5 Chapter summary 97
5 CONCLUSIONS 99
References 102

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