One-to-many multicast restoration based on dynamic core-based selection algorithm in WDM mesh networks

This paper proposes a novel dynamic core-based selection (DCS) algorithm for the multicast restoration in WDM mesh networks. The core-based fault tolerance scheme provides a flexible way to control a number of core nodes with less control overheads for searching the routing path, wavelength assignment (RWA), and restoration paths when fault occurs in the one-to-many multicast domain. Compared with the source-based scheme, core-based schemes are easier to maintain, and specifically scalable in large-scale topologies. In the core-based fault tolerance scheme, k-tuple domination nodes are selected to form a minimum sized vertex subset such that each vertex in the graph is dominated by at least k vertices, where the k is defined as two in this paper. The proposed DCS algorithm is defined as each node in multicast tree session must be directly connected to at least one core node in multicast tree session and also has to be directly connected to at least one core node out of multicast tree session. The primary aim of this work is to provide the scalable and fast local survivability based on the information from core nodes. Simulation results show that the proposed algorithm outperforms the Dual Tree and MRLR algorithms in terms of total hop counts needed for all recovery paths and blocking probability for different network topologies.     

QoS provisioning dynamic connection-admission control for multimedia wireless networks using a Hopfield neural network

This paper presents a quality-of-service (QoS) provisioning dynamic connection-admission control (CAC) algorithm for multimedia wireless networks. A multimedia connection consists of several substreams (i.e., service classes), each of which presets a range of feasible QoS levels (e.g., data rates). The proposed algorithm is mainly devoted to finding the best possible QoS levels for all the connections (i.e., QoS vector) that maximize resource utilization by fairly distributing wireless resources among the connections while maximizing the statistical multiplexing gain (i.e., minimizing the blocking and dropping probabilities). In the case of congestion (overload), the algorithm uniformly degrades the QoS levels of the existing connections (but only slightly) in order to spare some resources for serving new or handoff connections, thereby naturally minimizing the blocking and dropping probabilities (it amounts to maximizing the statistical multiplexing gain). The algorithm employs a Hopfield neural network (HNN) for finding a QoS vector. The problem itself is formulated as a multi-objective optimization problem. Hardware-based HNN exhibits high (computational) speed that permits real time running of the CAC algorithm. Simulation results show that the algorithm can maximize resource utilization and maintain fairness in resource sharing, while maximizing the statistical multiplexing gain in providing acceptable service grades. Furthermore, the results are relatively insensitive to handoff rates.     

Performance evaluation of p-cycle based protection methods for provisioning of dynamic multicast sessions in mesh WDM networks

Network survivability is crucial to both unicast and multicast traffic. Up to now, extensive research has been done on unicast traffic protection. Recently, due to the rapid growth of multicast applications, such as video-conferencing, high definition television (HDTV), distance learning, and multi-player on-line gaming, the problem of multicast traffic protection has started to draw more research interests. The preconfigured protection cycle (p-cycle) method proposed by Grover offers fast speed in restoration (because p-cycles are pre-cross-connected) and high efficiency in resource utilization (because p-cycles protect both on-cycle and straddling links). So far p-cycles based protection approaches have been intensively studied for unicast traffic protection, but have been rarely investigated for multicast traffic. We propose to apply p-cycles to dynamic protection provisioning of multicast traffic, and evaluate the blocking performance in comparison to other existing multicast protection schemes. We consider three different p-cycle based multicasting protection methods, namely dynamic p-cycle (DpC) design, p-cycle based protected working capacity envelope (PWCE) design, and hybrid DpC and PWCE design. We show that p-cycle-based multicast protection approaches offer much better blocking performance, as compared with other existing multicast protection schemes. The main reasons for the much better blocking performance are attributed to the facts that (i) the selection of p-cycles is independent of the routing of the multicast light trees, (ii) there are no path/segment disjoint constraints between the selected p-cycles and the multicast light trees to be protected, (iii) the selected p-cycles are the most efficient p-cycles.

基于GMPLS的动态分布式WDM网状网恢复路由选择算法研究

提出了一种在GMPLS体系下的分布式业务路径和恢复路径在线选路算法，以使光网络在动态业务请求下能有效的利用波长资源。由于该算法对业务路径和恢复路径的选择进行了联合优化，其性能更优于独立业务路径恢复算法(SSPR)。仿真结果表明，利用该算法时业务路径和恢复路径占用的网络总资源明显小于SSPR算法，而恢复时间只比SSPR算法略有增加。     

网孔形光传输网络失败恢复机制的分析与优化

分析了目前基于光传输的通信网络中恢复机制的体系结构,结合目前使用最普遍和发展最快的SDH、WDM为主的网孔形光传输网,进行了网络层式分割,并在分层体系结构中,分析、总结服务层、逻辑层和光路层主要采用的恢复机制,比较了恢复速度和冗余容量的优缺点,以优化各种环境下的网络性能.     

Incremental survivable network design against node failure in SDH/SONET mesh networks

Network survivability is becoming more and more important for the plenty of information each single fiber carries. Extra network resources are needed to increase network survivability level. In this paper, we investigate the problem of how to augment the network topology with adding new links and allocate spare capacity to maximize the service restorability against node failures in SDH/SONET mesh networks. A scheme called maximal node-disjoint backup paths provisioning with topology augmentation is proposed to tackle the problem, and another scheme called globally optimized path provisioning with topology augmentation, which allows adjusting the existing working paths of network flows, is investigated to optimize the augmented network globally. Both schemes are formulated as mixed integer linear programming models. Furthermore, heuristic algorithms are investigated to be implemented in software. Three algorithms, i.e., added links searching method, successive maximal survivable routing method, and random sequence routing convergence method, are designed and compared. Simulation results show the effectiveness of the algorithms.     

Incremental survivable network design with topology augmentation in SDH/SONET mesh networks

An incremental capacity allocation with topology augmentation problem is investigated in this article to maximize the service restorability in SDH/SONET mesh networks. To tackle the optimal design problem, two schemes are proposed, i.e., minimal backup path provisioning with topology augmentation (MBPP-TA), and global path pair provisioning with topology augmentation (GPPP-TA). Both schemes are formulated as integer linear programming (ILP) models, and are implemented using the proposed two-step linear programming (LP) approaches. Numerical results show that the two-step LP approaches achieve better solutions with significantly less execution time than the direct ILP approach. Moreover, results show that GPPP-TA provides better solutions than MBPP-TA at the cost of longer computation time.     

Rule-based network design: application to packet radio networks

A heuristic, rule-based approach to network design is presented. The problem of designing high-performance packet radio networks by altering individual radio powers (i.e. by altering network connectivity) is considered. It is assumed that node locations, traffic requirements, and a multiaccess protocol are specified. The focus is on the dependence of capacity on connectivity for two reasons: connectivity is always a design parameter, whereas radio locations, protocol, and traffic may not always be; and the relationship between capacity and connectivity is well documented in the literature, even though the exact nature of this reliance remains unclear. Packet radio performance analysis models found in the literature are used for performance evaluation     

Extending end-to-end optical service provisioning and restoration in carrier networks: opportunities, issues, and challenges

In this article, we address the opportunities, issues and challenges associated with end-to-end optical service provisioning and restoration in carrier networks. A number of scenarios are analyzed from a practical perspective, considering important aspects relevant to the management and control planes. Along the lines of three basic dimensions, to which we refer as locality, granularity, and ownership, we discuss the complexity associated with provisioning and restoring end-to-end optical services in regional (local scale) and national (global scale) networking scenarios. We identify a number of challenges in integrating a unified control plane solution and vendor-specific management and control planes with legacy carrier management systems.     

QoS provisioning in wireless video sensor networks: a dynamic power management framework

Recent technological advances in microelectronics and nano-systems technologies have made it feasible to equip wireless sensor nodes with small low-cost cameras to capture and transmit video. Wireless video sensor networks are gaining popularity due to numerous potential applications such as video surveillance, environmental and habitat monitoring, and so on. However, due to the limited battery available in wireless video sensor nodes, provisioning of QoS in such a network is a challenging task. We provide a survey on the major issues related to QoS provisioning in wireless video sensor networks and possible solution approaches. A dynamic power management framework is proposed for a wireless video sensor node to improve energy saving performance so that the lifetime of the sensor node can be increased. This framework considers the video traffic arrival process in the sensor node, the sleep and wakeup processes in the camera and wireless transceiver electronics, the queue status, and the wireless channel condition. Performance analysis results show that the proposed mechanism can achieve considerable energy saving in a sensor node while providing a target level of QoS performance.     

Survivable lightpath provisioning in WDM mesh networks under shared path protection and signal quality constraints

This paper addresses the problem of survivable lightpath provisioning in wavelength-division-multiplexing (WDM) mesh networks, taking into consideration optical-layer protection and some realistic optical signal quality constraints. The investigated networks use sparsely placed optical-electrical-optical (O/E/O) modules for regeneration and wavelength conversion. Given a fixed network topology with a number of sparsely placed O/E/O modules and a set of connection requests, a pair of link-disjoint lightpaths is established for each connection. Due to physical impairments and wavelength continuity, both the working and protection lightpaths need to be regenerated at some intermediate nodes to overcome signal quality degradation and wavelength contention. In the present paper, resource-efficient provisioning solutions are achieved with the objective of maximizing resource sharing. The authors propose a resource-sharing scheme that supports three kinds of resource-sharing scenarios, including a conventional wavelength-link sharing scenario, which shares wavelength links between protection lightpaths, and two new scenarios, which share O/E/O modules between protection lightpaths and between working and protection lightpaths. An integer linear programming (ILP)-based solution approach is used to find optimal solutions. The authors also propose a local optimization heuristic approach and a tabu search heuristic approach to solve this problem for real-world, large mesh networks. Numerical results show that our solution approaches work well under a variety of network settings and achieves a high level of resource-sharing rates (over 60% for O/E/O modules and over 30% for wavelength links), which translate into great savings in network costs.     

Context-based wireless mesh networks: a case for network virtualization

Wireless Mesh Networks (WMNs) have gained increasing attention as an attractive means to provide connectivity in complement to access as offered by regular Internet Service Providers (ISPs). Such a grass-root technique, however, often suffers from detrimental operating conditions and poor quality. Network virtualization, on the other hand, has been widely advocated as a possibility to overcome what has often been referred to as the ossification of the Internet. Combining the concept of network virtualization with WMN technology, therefore, appears to be promising and desirable. It is envisioned that well managed multiple Virtual Networks (VNs) may overcome shortcomings of WMNs on the one hand, and extend the reach of the Internet beyond its current confinement into the realm and control of the user on the other hand. In this paper, we argue for a context-based approach for an effective means to extend multi-VNs from the Internet domain into WMN environments. We describe both mobility and preferences as context models in order to create virtualized WMNs based on these types of context models. As a result, it is envisioned to achieve a comprehensive connectivity coverage, accompanied by high assurance in network quality. We further present a distributed solution to manage multi-VNs, and a mobility-aware context use case to demonstrate the usefulness of our approach.     

一种高速大容量SDH交叉连接芯片的设计与实现

介绍了一种高速大容量SDH交叉连接芯片及其各模块所完成功能的设计与实现,重点论述了如何利用T-S-T三级交换网络实现高速大容量的SDH数字交叉,讨论了设计中面临的问题和解决方法.该芯片通过高性能的FPGA器件进行仿真和综合,已经在SDH交叉设备上成功地完成测试和验证.     

Optical dynamic intelligent network services (ODIN): an experimental control-plane architecture for high-performance distributed environments based on dynamic lightpath provisioning

Currently, many large-scale, resource-intensive applications and services are being developed that can be supported only with high-performance, highly distributed, heterogeneous infrastructures, including grids. This type of infrastructure is particularly effective for supporting applications and services that must quickly adjust to continuously changing conditions. Such processes require the flexibility of highly adaptive, dynamic, and deterministic resource provisioning. One such architecture is described here. To enhance the performance and flexibility of distributed environments, an experimental architecture for optical dynamic intelligent network (ODIN) services has been designed to enable core optical network capabilities to extend to edge processes, including applications. This architecture allows those processes to directly address arid control core network resources, for example, individual lightpaths on demand. This approach supports flexible and deterministic communications by integrating signaled requirements with adjustable network resources. An experimental prototype of ODIN has been designed, developed, and implemented on several optical network testbeds.     

无线mesh网的跨层设计及其应用

根据无线mesh网跨层设计的基本原理,分析了跨层设计系统中各模块的功能和各种需要考虑的因素。提出一种综合了无线mesh网高效的状态信息交换方法和先进路由算法的跨层设计实现方案,可根据网络当前链路状态、拥塞情况和能量等因素,合理选择传输路径。同时还给出了该方法在电网高压输电监控系统中的应用实例。仿真和实验表明所提方案在实际应用时在强壮性、吞吐量和时延等方面都有良好的性能。     

用于Mesh光网络快速保护恢复的GMPLS信令机制的扩展

分析了Mesh光网络保护机制和恢复机制,并对GMPLS信令机制进行了扩展,给出了扩展后实现保护恢复的协议格式和信令流程,最后依据实验数据给出扩展的GMPLS信令机制的保护、恢复时间的仿真结果.     

Applications of network coding to improve TCP performance over wireless mesh networks: a survey

There is growing interest in the use of wireless mesh network (WMN) as a last‐mile option for Internet access. Despite the many benefits of WMNs, the performance of Internet access may not be ideal. One of the main issues is the interaction of transmission control protocol (TCP) with the underlying network. The poor performance of TCP over multi‐hop networks is well‐documented, and extensive research exists, which addresses TCPs foible and enhance TCP performance for multi‐hop environments. This paper provides a thorough survey of TCP performance issues over WMNs and the available solutions to address these issues. Among the existing methods, we focused on network coding (NC) and the ways that TCP interacts with network coded systems. NC is a technique that encodes the received packets in each node before forwarding them towards the destination. The use of NC in the transport layer to address performance issues raised by wireless access is a recent research topic. This paper presents a detailed study of TCP interaction with NC. Some open research areas in this field are suggested. Copyright © 2012 John Wiley & Sons, Ltd.     

Service discovery in mobile ad hoc networks: an overall perspective on architectural choices and network layer support issues

Service discovery is indispensable to ad hoc networking where establishing a stand-alone and self-configurable communication environment is the main objective. In this paper, we first discuss possible service discovery architectures along with the required network support for their implementation in mobile ad hoc networks. We then propose a distributed service discovery architecture that relies on a virtual backbone for locating and registering available services within a dynamic network topology. Our proposal consists of two independent components: (i) formation of a virtual backbone and (ii) distribution of service registrations, requests, and replies. The first component creates a mesh structure from a subset of a given network graph that includes the nodes acting as service brokers and also a subset of paths (which we refer to as virtual links) connecting them. Service broker nodes (SBNs) constitute a dominating set, i.e. all the nodes in the network are either in this set or only one-hop away from at least one member of the set. The second component establishes sub-trees rooted at service requesting nodes and registering servers for efficient dissemination of the service discovery control messages. Extensive simulation results are provided for comparison of performance measures, i.e. latency, success rate, and control message overhead, when different architectures and network support mechanisms are utilized in service discovery.