Load balancing routing for single-layered satellite networks

The varying population density leads to imbalanced utilization rate of satellites. To ensure an intelligent engineering of traffic over satellite networks, a distributed routing scheme for single-layered satellite network, load balancing routing protocol based on mobile agent (LBRP-MA) is proposed. For LBRP-MA, mobile agents explore route by migrating autonomously. Upon arriving at destination, mobile agents migrate back. On each intermediate satellite, mobile agents evaluate path cost considering satellite geographical position as well as inter-satellite link (ISL) cost, and finally take ISL congestion index into account to update routing tables. Through simulations on the Courier-like constellation, the proposed approach is shown to achieve guaranteed end-to-end delay bound and decrease packet loss ratio with better throughput, which is especially suitable for data transferring in case of high traffic load. Moreover, results of the complexity analysis demonstrate that LBRP-MA can have low onboard signaling, storage and computation requirements. Furthermore, issues of LBRP-MA such as ISL congestion index and cost modification factor are discussed.     

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.     

A Novel Routing Protocol for Supporting QoS for Ad Hoc Mobile Wireless Networks

The main purposes of this article are to lessen the influence of the fastchanging network topology, rapidly varying bandwidth information, and the increasing size of routing tables onquality of service routing. Based on DSDV (Destination-Sequenced Distance-Vector) routing protocol formaintaining up-to-date routing information, the related research has to update routing tables when networktopology changes; moreover, the routing tables must be updated periodically even though the networktopology has not changed. To put emphasis on QoS routing, they also have to exchange routing tables by thetime of bandwidth information changes. Furthermore, the size of routing tables increases with the numberof mobile nodes; therefore, the precious wireless bandwidth is wasted on transmitting the large-scalerouting tables. In this article, we propose an on-demand-based QoS routing protocol to mitigate theseproblems and to achieve the QoS requirement. The goal of this article is to discover an optimal routewith minimum time delay for transmitting real-time data from a source node hop by hop to adestination node under some predefined constraints. Our contributions are as follows: our researchprovides a rigorous bandwidth definition and bandwidth application, a broad view of bandwidth calculationand reservation, minimizing the size of control packets and the number of control packet transmissions,and an efficient QoS routing protocol.     

低轨卫星星座网的切换研究

提出了一种适用于装备有星际链路的低轨卫星星座网的切换策略——最小跳数切换策略。该策略以端到端连接的跳数为基础,充分利用了低轨星座网的特点,将切换过程与路由有机地结合为一体,有效解决了不同卫星之间的切换问题。仿真结果表明,同已有的切换策略相比,该策略能够提供一定程度的QoS保障,获得较好的系统性能,如较低的传播延时和较小的切换频率,具有很好的实用价值。     

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.     

ATM-based routing in LEO/MEO satellite networks with intersatellitelinks

An asynchronous transfer mode (ATM)-based concept for the routing of information in a low Earth orbit/medium Earth orbit (LEO/MEO) satellite system including intersatellite links (ISLs) is proposed. Specific emphasis is laid on the design of an ATM-based routing scheme for the ISL part of the system. The approach is to prepare a virtual topology by means of virtual path connections (VPCs) connecting all pairs of end nodes in the ISL subnetwork for a complete period in advance, similar to implementing a set of (time dependent) routing tables. The search for available end-to-end routes within the ISL network is based on a modified Dijkstra (1959) shortest path algorithm (M-DSPA) capable of coping with the time-variant topology. With respect to the deterministic time variance of the considered ISL topologies, an analysis of optimization aspects for the selection of a path at call setup time is presented. The performance of the path search in combination with a specific optimization procedure is-by means of extensive simulations-evaluated for example LEO and MEO ISL topologies, respectively     

Fuzzy Logic QoS Dynamic Source Routing for Mobile Ad Hoc Networks

Considering the characters of dynamic topology and the imprecise state information in mobile ad hoc network,we propose a Fuzzy Logic QoS Dynamic Source Routing(FLQDSR)algorithm based on Dynamic Source Routing(DSR)protocol while adopting fuzzy logic to select the appropriate QoS routing in multiple paths which are searched in parallel.This scheme considers not only the bandwidth and end-to-end delay of routing,but also the cost of the path.On the otherhand the merit of using fuzzy logic is that it can be implemented by hardware.This makes the realization of the schemeeasier and faster.However our algorithm is based on DSR,the maximal hop count should be less than 10,i.e.,the scaleof mobile ad hoc network should not be very large.Simulation results show that FLQDSR can tolerate a high degree of in-formation imprecision by adding the fuzzy logic module which integrates the QoS requirements of application and the rout-ing QoS parameters to determine the most qualified one in every node.     

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.     

QoS routing based on multi-class nodes for mobile ad hoc networks

In this paper, we present a new quality of service (QoS) routing protocol for mobile ad hoc networks (MANETs). Most of the existing routing protocols assume homogeneous nodes in MANETs, i.e., all nodes have the same communication capabilities and characteristics. However, in many ad hoc networks, nodes are not the same. Some nodes have longer transmission range, larger transmission bandwidth, and are more reliable and robust than other nodes. We take advantage of the non-homogeneous property to design more efficient QoS routing protocol. And node location information is used to aid routing. We also develop a new algorithm to calculate end-to-end bandwidth for a given path. Our QoS routing protocol contains end-to-end bandwidth calculation and bandwidth reservation. QoS route is discovered and setup only when it is needed. Extensive simulation studies demonstrate the good performance of the QoS routing protocol.     

Efficient QoS Partition and Routing of Unicast and Multicast

In this paper, we study problems related to supporting unicast and multicast connections with quality of service (QoS) requirements. We investigate the problem of optimal routing and resource allocation in the context of performance dependent costs. In this context, each network element can offer several QoS guarantees, each associated with a different cost. This is a natural extension to the commonly used bi-criteria model, where each link is associated with a single delay and a single cost. This framework is simple yet strong enough to model many practical interesting networking problems. An important problems in this framework is finding a good path for a connection that minimizes the cost while retaining the end-to-end delay requirement. Once such a path (or a tree, in the multicast case) is found, one needs to partition the end-to-end QoS requirements among the links of the path (tree). We consider the case of general integer cost functions (where delays and cost are integers). As the related problem is NP complete, we concentrate on finding efficient epsiv-approximation solutions. We improve on recent previous results by Erguumln Lorenz and Orda, and Raz and Shavitt, both in terms of generality as well as in terms of complexity of the solution. In particular, we present novel approximation techniques that yield the best known complexity for the unicast QoS routing problem, and the first approximation algorithm for the QoS partition problem on trees, both for the centralized and distributed cases     

基于卫星时变网络的时延受限最小费用路由算法

卫星网络是一种特殊的时变网络,其QoS路由问题比地面网络QoS路由问题更为复杂.本文利用卫星拓扑的可预测性,通过引入业务的中断概率和费用模型来描述链路切换对业务QoS以及网络的影响,并给出时延受限最小费用路由(SDCMCR)算法来解决在卫星链路时延长的情况下寻找满足时延限制条件且受切换影响最小的路径的问题,该算法可兼顾网络业务中断率和业务阻塞率等性能,且计算复杂度低,可适应星上设备处理能力的要求.仿真表明算法在计算复杂性、业务请求被阻塞的概率等方面都优于同类算法.     

Route Stability Based QoS Routing in Mobile Ad Hoc Networks

To provide high quality communications service among mobile wireless devices is basically a challenging task in wireless ad hoc networks. In this paper, we propose a Route Stability based QoS Routing (RSQR) protocol in Mobile Ad Hoc Networks (MANETs) which is an extension of QoS routing with throughput and delay constraints. Ensuring a data path to be valid for sufficiently longer period of time is a very difficult problem in MANET due to its highly dynamic nature. We propose a simple model for computing link stability and route stability based on received signal strengths. By including some extra fields in route request/reply packets, the route stability information can be utilized to select a route with higher stability among all the feasible routes between a given source destination pair. Further, inclusion of a signal strength based admission control enhances the performance of the routing. Results of our experiments show performance improvements in terms of packet delivery ratio, control overhead and average end-to-end delay in comparison with a QoS routing protocol proposed by Q. Xue and A. Ganz.     

QoS routing in networks with uncertain parameters

We consider the problem of routing connections with quality of service (QoS) requirements across networks when the information available for making routing decisions is inaccurate. Such uncertainty about the actual state of a network component arises naturally in a number of different environments. The goal of the route selection process is then to identify a path that is most likely to satisfy the QoS requirements. For end-to-end delay guarantees, this problem is intractable. However, we show that by decomposing the end-to-end constraint into local delay constraints, efficient and tractable solutions can be established. Moreover, we argue that such decomposition better reflects the interoperability between the routing and reservation phases. We first consider the simpler problem of decomposing the end-to-end constraint into local constraints for a given path. We show that, for general distributions, this problem is also intractable. Nonetheless, by defining a certain class of probability distributions, which includes typical distributions, and restricting ourselves to that class, we are able to establish efficient and exact solutions. We then consider the general problem of combined path optimization and delay decomposition and present efficient solutions. Our findings are applicable also to a broader problem of finding a path that meets QoS requirements at minimal cost, where the cost of each link is some general increasing function of the QoS requirements from the link     

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.     

安全保障：无线Mesh网络中支持QoS的DSR路由协议的改进与实现

随着无线Mesh网络传输多媒体业务需求的增加,要求网络支持服务质量（QoS）,本文基于DSR协议设计了一个支持QoS的路由协议算法QDSR（QoS-DSR）。该算法保证了数据流的带宽、时延的QoS需求,根据路径跳数和节点拥塞情况定义路由代价函数,选择最优路径。仿真结果表明,与DSR相比,QDSR提高了网络吞吐量,降低了平均端到端延时,提高了网络利用率,更好地满足业务的QoS需求,并且具有更强的适用性和可扩展性。     

On the performance analysis of the minimum-blocking and bandwidth-reallocation channel-assignment (MBCA/BRCA) methods for quality-of-service routing support in mobile multimedia ad hoc networks

Quality-of-service (QoS) routing is the key to support multimedia services in wireless multihop networks. The goal of QoS routing is to find satisfactory paths that support the end-to-end QoS requirements of the multimedia flows. Previous work has demonstrated a framework for supporting QoS routing in mobile ad hoc networks, where two novel mechanisms for dynamic channel assignment, called the minimum-blocking and bandwidth-reallocation channel-assignment (MBCA/BRCA) algorithms, were proposed. MBCA/BRCA are on-demand channel assignment methods that reactively provide a differentiated service treatment to multimedia traffic flows at the link level using novel techniques for end-to-end path QoS maximization. Efficient QoS routing is then accomplished by giving the routing mechanism access to QoS information, thus coupling the coarse grain (routing) and fine grain (congestion control) resource allocation. In this paper, the specifics and individual mechanisms of the MBCA/BRCA algorithms are presented, whereas their effectiveness and the manner in which they interact in order to contribute to the overall protocol performance is examined and documented. The system performance is studied through simulations experiments under various QoS traffic flows and network scenarios. The protocol's behavior and the changes introduced by variations on some of the mechanisms that make up the protocol is further investigated. As demonstrated, the MBCA/BRCA methods are able to increase system's aggregate traffic by 2.8 Kb/s, on average, comparing to a non-MBCA/BRCA dynamic channel-allocation scheme.     

QoS Handover Management in LEO/MEO Satellite Systems

Low Earth Orbit (LEO) satellite networks are foreseen to complement terrestrial networks in future global mobile networks. Although space segment topology of a LEO network is characterized by periodic variations, connections of mobile stations (MSs) to the satellite backbone network alter stochastically. As a result the quality of service delivered to users may degrade. Different procedures have been proposed either as part of a resource allocation mechanism or as part of an end-to-end routing protocol to manage transitions of MSs from one satellite to another (handover). All of these techniques are based on the prioritization of requested handovers to ease network operation and therefore enhance provision of service. This paper proposes a new handover procedure that exploits all geometric characteristics of a satellite-to-MS connection to provide an equable handover in systems incorporating onboard processing satellites. Its performance is evaluated by simulations for a variety of satellite constellations to prove its general applicability. This revised version was published online in July 2006 with corrections to the Cover Date.     

MANET网络中基于移动虚拟节点的QoS路由算法

讨论了一种基于移动虚拟节点(VMN)的QoS路由算法—QoSRAVMN,通过移动WAVE在VMN节点间交换网络信息,允许在没有网络拓扑状态信息精确描述的情况下而能快速地发现路由。测试结果表明该算法路由开销低于HDP协议,算法产生的移动WAVE能很好地满足所有源和目的节点路径的QOS要求。     

Agent Driven Delay and Power Constrained Multicast Routing in Mobile Ad Hoc Networks by Using ANFIS

Group communication applications in Mobile Ad hoc NETworks (MANETs) require stringent bounds on Quality of Service (QoS) parameters. In this paper, we propose an agent driven QoS mesh based multicast routing scheme in MANET that satisfies the user requirements with good reasoning by using adaptive neuro-fuzzy inference system (ANFIS). Four types of agents are used in the scheme: Multicast administer, ANFIS, Route inventing and Guard agents. The proposed scheme operates in following steps. (1) ANFIS agent at the source node optimizes membership functions of QoS parameters according to the user QoS requirement. It also computes QoS factor for different combinations of parameter values from optimized membership functions. (2) Route inventing mobile agent carries the QoS requirement, set of parameter values and their corresponding QoS factors to reach multicast receivers through intermediate nodes by using selective flooding and agent cloning. Multicast administer agent (MAA) at the intermediate node decides its QoS satisfiability. (3) Route inventing mobile agents trace back the traversed path by marking QoS nodes. They facilitate MAA at the source node to construct QoS mesh between source and destinations. (4) MAA at the source node selects a shortest path to reach each of the multicast receivers from the constructed QoS mesh, and (5) Guard mobile agent is employed for the link/node failures and management of the group. Our proposed scheme performs better than fuzzy based, and autonomic QoS multicast routing schemes.     

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。