Research on hierarchical architecture and routing of satellite constellation with IGSO‐GEO‐MEO network

In this paper, a three‐layered medium Earth orbit (MEO), geostationary Earth orbit (GEO), and inclined geosynchronous orbit (IGSO) satellite network (IGMSN) is presented. Based on the idea of time‐slot division, a novel dynamic hierarchical and distributed QoS (quality of service) routing protocol (HDRP) is investigated, and an adaptive bandwidth‐constrained minimum‐delay path for IGSO/GEO/MEO hierarchical architecture constellation (BMDP‐HAC) algorithm is developed to calculate routing tables efficiently using the QoS metric information composed of delays and bandwidth. The performance of the IGMSN and HDRP is evaluated through simulations and theoretical analysis. And then, the paper further analyzes the performance of the IGMSN structure and the BMDP‐HAC algorithm with failure satellites.     

Performance of delay‐sensitive traffic in multi‐layered satellite IP networks with on‐board processing capability

In this article, performance of delay‐sensitive traffic in multi‐layered satellite Internet Protocol (IP) networks with on‐board processing (OBP) capability is investigated. With OBP, a satellite can process the received data, and according to the nature of application, it can decide on the transmission properties. First, we present a concise overview of relevant aspects of satellite networks to delay‐sensitive traffic and routing. Then, in order to improve the system performance for delay‐sensitive traffic, specifically Voice over Internet Protocol (VoIP), a novel adaptive routing mechanism in two‐layered satellite network considering the network's real‐time information is introduced and evaluated. Adaptive Routing Protocol for Quality of Service (ARPQ) utilizes OBP and avoids congestion by distributing traffic load between medium‐Earth orbit and low‐Earth orbit layers. We utilize a prioritized queueing policy to satisfy quality‐of‐service (QoS) requirements of delay‐sensitive applications while evading non‐real‐time traffic suffer low performance level. The simulation results verify that multi‐layered satellite networks with OBP capabilities and QoS mechanisms are essential for feasibility of packet‐based high‐quality delay‐sensitive services which are expected to be the vital components of next‐generation communications networks. Copyright © 2007 John Wiley & Sons, Ltd.     

双层卫星网络中的自适应路由算法

The rapid advancement of communication and satellite technology drives broadband satellite networks to carry different traffic loads. However, traffic class routing of satellite cannot be provided by the existing 2 layerd satellite networks. In this paper, a 2 layered satellite network composed of low Earth orbit and medium Earth orbit satellite networks is presented, and a novel Self adapting Routing Protocol (SRP) is developed. This scheme aims to adopt self adapting routing algorithm to support different traffic classes. Meanwhile, the path discovery processing is invoked independently for each individual origin/destination pair. Simulation results are provided to evaluate the performance of the new scheme in terms of end to end delay, normalized data throughput, delay jitter and delivery ratio.     

Congestion management techniques for disruption‐tolerant satellite networks

Delay and disruption‐tolerant networks are becoming an appealing solution for extending Internet boundaries toward challenged environments where end‐to‐end connectivity cannot be guaranteed. In particular, satellite networks can take advantage of a priori trajectory estimations of nodes to make efficient routing decisions. Despite this knowledge is already used in routing schemes such as contact graph routing, it might derive in congestion problems because of capacity overbooking of forthcoming connections (contacts). In this work, we initially extend contact graph routing to provide enhanced congestion mitigation capabilities by taking advantage of the local traffic information available at each node. However, since satellite networks data generation is generally managed by a mission operation center, a global view of the traffic can also be exploited to further improve the latter scheme. As a result, we present a novel strategy to avoid congestion in predictable delay‐ and disruption‐tolerant network systems by means of individual contact plans. Finally, we evaluate and compare the performance improvement of these mechanisms in a typical low Earth orbit satellite constellation.     

LEO multi-service routing algorithm based on multi-objective decision making

In low earth orbit(LEO) satellite networks,in view of the unbalanced link resource,it's difficult to meet differentiated quality of service(QoS) requirements and easily lead to reduce the efficiency of the whole network.A routing algorithm based on multi-objective decision making was proposed which defined LEO satellite network transmission service as the delay sensitive,sensitive bandwidth and reliability sensitive three categories.It used the eigenvector method to calculate service weights,and used the consistency ratio to determine whether it can be accepted.Based on the multi-objective decision making theory,it combined with the actual state of satellite network nodes and links and the specific requirements of the business,calculating the path that meets the QoS requirements of the service,so as to realize the LEO satellite network multi objective dynamic routing optimization.Established simulation platform based on the iridium network system simulated network delay,the uncertain characteristics like the residual bandwidth and packet error rate,route planning for the randomly generated three classes of business.The simulation results show that,the algorithm not only satisfies the QoS constrain while balancing the traffic load of the satellite link effectively,but also improves the performance on the throughput.     

QoS routing based on mobile agent for LEO satellite IP networks

Current quality of service (QoS) routing schemes for low earth orbit (LEO) satellites IP networks either neglect the varying population density or fail to guarantee end-to-end delay. As a remedy, QoS routing protocol based on mobile agent (QoSRP-MA) is proposed. QoSRP-MA is a source-based routing protocol. Once connection requests arrive, QoS mobile agents are dispatched from ingress satellite to explore routes, which migrate using satellite routing tables. Upon arriving in egress satellite, QoS mobile agents migrate back towards ingress satellite to reserve bandwidth. To construct satellite routing tables, load balancing routing algorithm based on mobile agent (LBRA-MA) is presented. In LBRP-MA, at regular intervals mobile agents launched on all satellites migrate autonomously to evaluate path cost and update routing tables. Moreover, path cost between source and destination is evaluated considering satellite geographical position as well as inter-satellite link (ISL) cost. Furthermore, ISL congestion index is considered to update routing table. Through simulations on a Courier-like constellation, it shows that QoSRP-MA can achieve guaranteed end-to-end delay bound with higher throughput, lower connection failing ratio and signaling overhead compared to high performance satellite routing (HPSR) scheme.     

A multicast routing algorithm for LEO satellite IP networks

Satellite networks provide global coverage and support a wide range of services. Since low Earth orbit (LEO) satellites provide short round-trip delays, they are becoming increasingly important for real-time applications such as voice and video traffic. Many applications require a mechanism to deliver information to multiple recipients. A multicast routing algorithm for datagram traffic is introduced for LEO satellite IP networks. The new scheme creates multicast trees by using the datagram routing algorithm. The bandwidth utilization and delay characteristics are assessed through simulations     

Q-Win – A New Admission and Handoff Management Scheme for Multimedia LEO Satellite Networks

Low Earth Orbit (LEO) satellite networks are deployed as an enhancement to terrestrial wireless networks in order to provide broadband services to users regardless of their location. In addition to global coverage, these satellite systems support communications with hand-held devices and offer low cost-per-minute access cost, making them promising platform for Personal Communication Services (PCS). LEO satellites are expected to support multimedia traffic and to provide their users with the negotiated Quality of Service (QoS). However, the limited bandwidth of the satellite channel, satellite rotation around the Earth and mobility of end-users makes QoS provisioning and mobility management a challenging task. One important mobility problem is the intra-satellite handoff management. The main contribution of this work is to propose Q-Win, a novel call admission and handoff management scheme for LEO satellite networks. A key ingredient in our scheme is a companion predictive bandwidth allocation strategy that exploits the topology of the network and contributes to maintaining high bandwidth utilization. Our bandwidth allocation scheme is specifically tailored to meet the QoS needs of multimedia connections. The performance of Q-Win is compared to that of two recent schemes proposed in the literature. Simulation results show that our scheme offers low call dropping probability, providing for reliable handoff of on-going calls, good call blocking probability for new call requests, while maintaining bandwidth utilization high.     

Next‐generation global satellite system with mega‐constellations

Mega satellite constellations in low earth orbit (LEO) will provide complete global coverage; rapidly enhance overall capacity, even for unserved areas; and improve the quality of service (QoS) possible with lower signal propagation delays. Complemented by medium earth orbit (MEO) and geostationary earth orbit (GEO) satellites and terrestrial network components under a hybrid communications architecture, these constellations will enable universal 5G service across the world while supporting diverse 5G use cases. With an unobstructed line‐of‐sight visibility of approximately 3 min, a typical LEO satellite requires efficient user terminal (UT), satellite, gateway, and intersatellite link handovers. A comprehensive mobility design for mega‐constellations involves cost‐effective space and ground phased‐array antennas for responsive and seamless tracking. An end‐to‐end multilayer protocol architecture spanning space and terrestrial technologies can be used to analyze and ensure QoS and mobility. A scalable routing and traffic engineering design based on software‐defined networking adequately handles continuous variability in network topology, differentiated user demands, and traffic transport in both temporal and spatial dimensions. The space‐based networks involving mega‐constellations will be better integrated with their terrestrial counterparts by fully leveraging the multilayer 5G framework, which is the foundational feature of our hybrid architecture.     

Improving mobile ad hoc network routing with satellite out‐of‐band signaling

Routing in mobile ad hoc networks is a complex task due to the mobility of the nodes and the constraints linked to a wireless multihop network (e.g., limited bandwidth, collisions, and bit errors). These adverse conditions impair not only data traffic but also routing signaling traffic, which feeds route computation. In this contribution, we propose to use satellite communications to help in the distribution of mobile ad hoc network routing signaling. The optimized link‐state routing (OLSR) is chosen among several routing protocols to be extended with satellite‐based signaling, yielding a version we call OLSR hybrid signaling (OLSR‐H). This new scheme is evaluated through simulations and yields improvements of approximately 10% in the data delivery ratio compared with a regular OLSR. This evaluation is conducted using two different network topology models, one being fit for representing forest firefighting operations. Copyright © 2013 John Wiley & Sons, Ltd.     

Simulation analyses of weighted fair bandwidth‐on‐demand (WFBoD) process for broadband multimedia geostationary satellite systems

Advanced resource management schemes are required for broadband multimedia satellite networks to provide efficient and fair resource allocation while delivering guaranteed quality of service (QoS) to a potentially very large number of users. Such resource management schemes must provide well‐defined service segregation to the different traffic flows of the satellite network, and they must be integrated with some connection admission control (CAC) process at least for the flows requiring QoS guarantees. Weighted fair bandwidth‐on‐demand (WFBoD) is a resource management process for broadband multimedia geostationary (GEO) satellite systems that provides fair and efficient resource allocation coupled with a well‐defined MAC‐level QoS framework (compatible with ATM and IP QoS frameworks) and a multi‐level service segregation to a large number of users with diverse characteristics. WFBoD is also integrated with the CAC process. In this paper, we analyse via extensive simulations the WFBoD process in a bent‐pipe satellite network. Our results show that WFBoD can be used to provide guaranteed QoS for both non‐real‐time and real‐time variable bit rate (VBR) flows. Our results also show how to choose the main parameters of the WFBoD process depending on the system parameters and on the traffic characteristics of the flows. Copyright © 2005 John Wiley & Sons, Ltd.     

A distributed QoS routing based on ant algorithm for LEO satellite network

Low Earth Orbit (LEO) satellites provide short round-trip delays and are becoming in- creasingly important. One of the challenges in LEO satellite networks is the development of specialized and efficient routing algorithms. To satisfy the QoS requirements of multimedia applications, satellite routing protocols should consider handovers and minimize their effect on the active connections. A distributed QoS routing scheme based on heuristic ant algorithm is proposed for satisfying delay bound and avoiding link congestion. Simulation results show that the call blocking probabilities of this al- gorithm are less than that of Shortest Path First (SPF) with different delay bound.     

非静止轨道卫星系统考虑通信中断的服务质量分析

基于Globalstar和Odyssey两个Walker delta星座,建立星间链路网络,重点分析网络中的不同轨道间星间链的动态特性,特别是与星上跟瞄系统密切相关的俯仰角、方位角和链路长度变化,为卫星网络路由提供依据.对传统的卫星路由策略作了改进,利用卫星系统的冗余覆盖的特性,选择不同策略下的最优路径.针对用户不能忍受通信中断的情况,提出考虑消除中断的路由策略,进行服务质量的分析比较.同时也比较在消除中断的路由策略下,LEO同MEO网络差异之处.消除通信中断是以其它QoS性能下降为代价.     

A survivable routing protocol for two-layered LEO/MEO satellite networks

Due to the rapid development of space communication, satellite networks will be confronted with more complex space environment in future, which poses the important demand on the design of the survivable and efficient routing protocols. Among satellite networks, two-layered Low Earth Orbit (LEO)/Medium Earth Orbit (MEO) satellite networks (LMSNs) have become an attractive architecture for their better communication service than single-layered satellite networks. To determine the topological dynamics of LMSN, the satellite group and group manager (SGGM) method is a prevalent strategy. However, it can not precisely capture the topological dynamics of the LEO layer, which may result in the unreliability of data transmission. Besides, most existing routing protocols based on the SGGM method will collapse once any top satellite fails. To overcome both limitations, this paper proposes a new topology control strategy for LMSNs. The proposed strategy determines the snapshot in terms of the topological change of the LEO layer, which ensures the topological consistency of routing calculation. Moreover, a new survivable routing protocol (SRP) is presented for LMSNs by combining both centralized and distributed routing strategies. The SRP can provide strong survivability under the LEO or MEO satellite failure. Besides, it can also achieve the minimum delay routing provided the MEO layer can effectively work. The performance of SRP is also evaluated by simulation and analysis.     

MLSR: a novel routing algorithm for multilayered satellite IPnetworks

Several IP-based routing algorithms have been developed for low-Earth orbit (LEO) satellite networks in recent years. The performance of the satellite IP networks can be improved drastically if multiple satellite constellations are used in the architecture. A multilayered satellite IP network is introduced that consists of LEO, medium-Earth orbit (MEO) and geostationary Earth orbit (GEO) satellites. A new multilayered satellite routing (MLSR) algorithm is developed that calculates routing tables efficiently using the collected delay measurements. The performance of the multilayered satellite network and MLSR is evaluated through simulations and analysis     

A sustainable heuristic QoS routing algorithm for pervasive multi-layered satellite wireless networks

Due to the recent developments in wireless technology and electronics, it is feasible to develop pervasive algorithms for satellite environments. Multi-Layered Satellite Networks (MLSNs) that consist of low earth orbit and medium earth orbit satellites are becoming increasingly important since they have higher coverage and better service than single-layered satellite networks. One of the challenges in MLSNs is the development of specialized and efficient routing algorithms. In this paper, we improved the virtual topology strategy and import heuristic algorithm to satisfy the QoS requirements of the MLSN users. The QoS requirements include end to end delay; link utilization, bandwidth, and package loss rate are mainly focused in this paper. To satisfy the QoS requirements is a multi-parameter optimization problem, and it is convinced as a Non-deterministic Polynomial Complete problem already. As a solution, three typical heuristic algorithms—Ant Colony Algorithm, Taboo Search Algorithm and Genetic Algorithm are applied in the routing scheme in order to reduce package loss, link congestion and call blocking. Simulation results show that heuristic routing algorithm can provide more QoS guarantees than shortest path first algorithm on package loss rate, link congestion and call blocking.     

Modelling and analysis of routing and resource allocation techniques in multi‐service networks

In this paper a novel call level model based on the extension of the classical Erlang multi‐rate model for broadband integrated services networks is proposed. We use the model to study routing strategies in multi‐service networks where service classes with/without QoS guarantees coexist. Examples for such networks include ATM and IP‐based integrated networks. In ATM, the CBR and VBR service classes provide QoS guarantees, while the ABR and UBR service classes are of the best effort type. In IP, traditional TCP/IP traffic is of the best effort type, while new protocols like the RSVP or the differentiated services with central resource handling attempt to support QoS parameters. The coexistence of guaranteed and best effort traffic gives rise to new challenging problems since for a given elastic (best effort) connection the bottleneck link determines the available bandwidth and thereby puts constraints on the bandwidth at the other links along the connection's path. Since the available bandwidth fluctuates in time following the load on the links, routing and link allocation in this environment together with blocking probability calculations and fairness issues need to be studied. By means of our proposed model we are able to conduct a survey of various routing and link allocation techniques as well as to develop a modified shortest path routing algorithm which, according to the numerical examples, performs well in this environment. Copyright © 1999 John Wiley & Sons, Ltd.     

多层卫星通信网络自适应路由策略

单层卫星网络由于轨道高度和覆盖能力的不同,以至构成通信的单层系统往往不能满足不同业务服务质量的需求。分析了Walkerdelta型星座构建多层卫星通信网络的拓扑结构和ISL性能,提出了在统计分布模型下的多层卫星自适应路由策略,综合考虑了路径时延和ISL链路负载。仿真结果表明了多层网络自适应路由策略能够更加有效地分配网络通信量,网络具有较小的丢包率、网络平均归一化链路负载和特定路径综合路径权重,有利于降低网络平均阻塞概率和特定路径阻塞概率,获得更高的可靠性,较传统的单层非自适应路由更加有效、可靠。     

Class Dependent Traffic Allocation in a LEO Satellite Network

Traffic allocation strategy becomes a significant factor in optimization of bandwidth usage of telecommunication resources, especially with increasing use of broadband applications. Allocation strategy in dynamic LEO (Low Earth Orbital) satellite communication network is studied, to improve their Quality of Service (QoS). Traffic allocation control is performed to provide a near optimal utilization of their Inter Satellite Links (ISLs). A combination of two algorithms is used to allocate traffic in ISLs. Empirical analysis is performed to examine performance of the proposed algorithm, GALPEDA. Result shows that the proposed algorithm is useful for traffic allocation of multiclass traffic in LEO satellite communication.