LEO satellite communication networks—a routing approach

In the modern world of telecommunications, the concept of wireless global coverage is of the utmost importance. However, real global coverage can only be achieved by satellite systems. Until recently, the satellites were in geostationary orbit and their high altitude could not allow real‐time communication such as cellular networks. The development of LEO satellite networks seems to overcome this limit. However, LEO satellite systems have specific characteristics that need to be taken into account. In the same manner, the TCP/IP standard was developed for terrestrial network. The need is then to come up with a solution that would permit the use of TCP/IP on LEO satellite networks without losing too many packets. The idea is to develop a routing algorithm that maximizes the RTT delays compared to the TCP timer granularity. For that matter, we use an FSA‐based link assignment that simulates the satellite constellation as a fixed network for a predetermined time interval. In this configuration, the problem becomes a static routing problem where an algorithm can find the best solution. Copyright © 2003 John Wiley & Sons, Ltd.     

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     

A distributed routing algorithm for datagram traffic in LEOsatellite networks

Satellite networks provide global coverage and support a wide range of services, low Earth orbit (LEO) satellites provide short round-trip delays and are becoming increasingly important. One of the challenges in LEO satellite networks is the development of specialized and efficient routing algorithms. In this work, a datagram routing algorithm for LEO satellite networks is introduced. The algorithm generates minimum propagation delay paths. The performance of the algorithm is evaluated through simulations. The robustness issues of the algorithm are also discussed     

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.     

A Distributed Multicast Routing Scheme for Multi-Layered Satellite IP Networks

In this paper, a distributed multicast routing scheme is introduced for multi-layered satellite IP networks, which include GEO, MEO, and LEO layers. This scheme aims to minimize the total cost of multicast trees in the satellite network. Multicast trees are constructed and maintained in the dynamic satellite network topology in a distributed manner. Simulation results are provided to evaluate the performance of the new scheme in terms of end-to-end delay and multicast tree cost.     

Performance evaluation of adaptive routing algorithms in packet‐switched intersatellite link networks

This paper addresses the performance evaluation of adaptive routing algorithms in non‐geostationary packet‐switched satellite communication systems. The dynamic topology of satellite networks and variable traffic load in satellite coverage areas, due to the motion of satellites in their orbit planes, pose stringent requirements to routing algorithms. We have limited the scope of our interest to routing in the intersatellite link (ISL) segment. In order to analyse the applicability of different routing algorithms used in terrestrial networks, and to evaluate the performance of new algorithms designed for satellite networks, we have built a simulation model of a satellite communication system with intersatellite links. In the paper, we present simulation results considering a network‐uniform source/destination distribution model and a uniform source–destination traffic flow, thus showing the inherent routing characteristics of a selected Celestri‐like LEO satellite constellation. The updates of the routing tables are centrally calculated according to the Dijkstra shortest path algorithm. Copyright © 2002 John Wiley & Sons, Ltd.     

适于低轨卫星IP网络的特定源组播算法

为了解决低轨卫星IP网络中现有特定源组播算法的信道资源浪费问题,本文提出了一套新的特定源组播算法,即基于核心群的特定源组播算法(CSSM)和加权的CSSM算法(w-CSSM).CSSM算法以源节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,所得的树代价最小,从而大大提高了网络的带宽利用率和传输效率.在w-CSSM算法中,加权因子可以自适应调整以适度增大树代价、降低端到端传播时延,以支持某些有严格端到端时延要求的实时组播业务.通过与低轨卫星IP网络中典型特定源组播算法MRA的仿真比较,可以看出CSSM和w-CSSM算法的树代价性能比MRA有较大改善,不过端到端传播时延略高.     

LEO/MEO卫星网络中运用自组网思想的动态路由算法

分析了基于星际链路的LEO/MEO路由算法的特点及卫星网与自组网的相同之处，借鉴了自组网路由协议中适用于卫星网的部分，提出了LEO/MEO卫星网络中运用自组网思想的动态路由算法，并对算法进行了模型仿真和性能分析，这种算法增强了卫星网络的自适应性，使网络具有自治性强，功能更全面、系统开销小、适用范围广等特点。     

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 dynamic routing concept for ATM-based satellite personalcommunication networks

Satellite systems are going to build a part of the future personal communications infrastructure. The first-generation candidates for satellite personal communication networks (S-PCN) will rely on low Earth orbit (LEO) and medium Earth orbit (MEO) constellations. A noticeable trend in this field is toward broadband services and the use of ATM. For LEO satellite systems employing intersatellite links (ISLs), this paper proposes an overall networking concept that introduces the strengths of ATM to their operation. The core of the paper is the design of a new routing scheme for the periodically time-variant ISL subnetwork, discrete-time dynamic virtual topology routing (DT-DVTR), and its ATM implementation. DT-DVTR works completely off line, i.e., prior to the operational phase of the system. In a first step, a virtual topology is set up for all successive time intervals of the system period, providing instantaneous sets of alternative paths between all source-destination node pairs. In the second step, path sequences over a series of time interval are chosen from that according to certain optimization procedures. An ATM-based implementation of DT-DVTR in LEO satellite ISL networks is presented with some emphasis on the optimization alternatives, and the performance in terms of delay jitter is evaluated for an example ISL topology     

Load balancing multipath routing protocol for mass remote sensing data downlink in LEO satellite network

LEO satellite networks can provide seamless real-time data communication for all kinds of users,which developed rapidly in recent years.At the mean time,the massive payload data down-link system of space data sources,such as remote sensing satellites,still make use of traditional storage and forward mode.The real-time performance of space mission data will be improved effectively,if such satellites are connected to LEO satellite networks equipped with inter satellite links.However,it is necessary to design a specialized satellite network load balancing routing algorithm.Satellite parallel edge-disjoint multipath routing protocol (SPEMR) was designed for remote sensing satellite real-time down-link applications.OPNET simulation results indicate that the performance degradation index(DI) of the multipath scheme implemented by SPEMR is 0.32,which is only 32% of the TLR and 21% of the traditional DSP scheme.It is demonstrated that SPEMR has the better capability of transmitting massive data in real time.     

A novel QoS routing protocol for LEO and MEO satellite networks

The rapid advance of communication and satellite technology pushes broadband satellite networks to carry on multimedia traffic. However, the function of onboard routing cannot be provided in existing satellite networks with inter‐satellite links, and quality of service (QoS) of satellite networks cannot be reliably guaranteed because of great difficulties in processing of long distance‐dependent traffic. In this paper, a two‐layered low‐Earth orbit and medium‐Earth orbit satellite network (LMSN) is presented. A novel hierarchical and distributed QoS routing protocol (HDRP) is investigated, and an adaptive bandwidth‐constrained minimum‐delay path algorithm is developed to calculate routing tables efficiently using the QoS metric information composed of delays and bandwidth. The performance of LMSN and HDRP is also evaluated through simulations and theoretical analysis. Copyright © 2007 John Wiley & Sons, Ltd.     

适于低轨卫星IP网络的核心群合并共享树组播算法

为了解决低轨卫星IP网络中现有典型源组播算法的信道资源浪费问题,该文提出了一种低树代价的组播算法,即核心群合并共享树(CCST)算法,包括动态近似中心(DAC)选核方法和核心群合并组播路径构建方法。DAC方法基于逻辑位置形成的虚拟静态、结构规则的网络拓扑选择核节点。在核心群合并方法中,以核节点作为初始核心群,通过核心群和剩余组成员的最短路径方法逐步扩展直至整棵组播树构建完成,从而使得组播树的树代价最小,大大提高了网络的传输带宽利用率和组播传输效率。最后,与低轨卫星IP网络中的其他几种典型算法进行了性能对比,仿真结果说明,CCST算法的树代价性能比其它算法有较大改善,而端到端传播时延略高。     

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.     

Multi-objective routing algorithms for low-earth orbit satellite network

The low-earth orbit (LEO) satellite network, composed of a large number of satellite nodes, is a hot research topic at present. Due to the characteristics of the large-scale LEO satellite network, such as many satellite nodes, short orbit period, large dynamic change of topology, and unstable link-state, its communication quality of service (QoS) requirements are difficult to meet. Aiming at this problem, various factors that may affect data transmission are first analyzed. The network link selection problem is modeled as a multi-constraint optimization decision problem, a routing mathematical model based on linear programming (LP) is designed, and its solution is solved. Aiming at the problem of limited onboard computing resources, a multi-object optimization Dijkstra algorithm (MOODA) is designed. The MOODA finds the optimal path according to the comprehensive performance of the link. It solves the problems of poor comprehensive QoS performance and the low degree of load balancing of the paths found by the Dijkstra algorithm. The simulation results show that the paths found by the two algorithms have good QoS, robustness, and load balancing performance.     

A model for the handover traffic in low earth-orbiting (LEO) satellite networks for personal communications

The spectacular growth of cellular telephone networks has demonstrated the demand for personal communications. Communication systems based on low earth orbit (LEO) constellations of satellites seem to be an adequate approach to achieve a world-wide network. When defining the capacity in terms of satellite circuits, the network designer has to take into account the handover traffic. Unfortunately, in a LEO communication network where handover is most often due to the network nodes motion, handover traffic models for terrestrial cellular networks cannot be used. Hence specific models must be developed. This paper proposes an analytical model for the handover in LEO satellite networks. This model is applied to different network configurations and compared to discrete-time simulations. Simulation results agree with those obtained from the analytical model.     

一种基于分时的LEO卫星网络无环路由算法

在分析传统卫星网络路由算法的基础上，提出一种基于分时的LEO卫星网络无环路由算法(DTRA)。针对卫星在各时间片之间进行路由表切换时可能出现的路由环问题，算法采用平滑路由表切换策略消除由于切换前后网络状态信息不一致而产生环路的可能性，保证分组在任何时刻都能够沿无环最短时延路径被转发。同时，DTRA也能够通过使用无环备份路径处理可能出现的链路拥塞、节点失败等突发情况。通过复杂性分析可知，算法只需较小的星上存储开销和星上处理开销，而无需星问通信开销。仿真实验结果也表明算法能够提供数据最优传送，具有较好的端到端时延性能。     

Joint multi-QoS and energy saving routing for LEO satellite network

Low earth orbit(LEO) satellite network provides global coverage and supports a wide range of services. However, due to the rapid changes and energy-limitation of satellites, how to meet the demand of the quality of service(QoS) from ground traffic and prolong the lifetime of LEO satellite network is the research emphasis of the investigator. Hence, a routing algorithm which takes into account the multi-QoS requirements and satellite energy consumption(QER) of LEO satellite network is proposed. Firstly, the satellite intimacy degree(SID) and the path health degree(PHD) are introduced to obtain the path evaluation function according to the energy consumption and queue state of the satellite. Then, the distributed routing QER is established through the path evaluation function and the idea of genetic algorithm(GA), which enables each satellite to adjust traffic and realizes the network load balancing. Simulation results show that QER performs well in terms of end-to-end delay, delay jitter, and system throughput.