A Survey of Service Discovery Protocols in Multihop Mobile Ad Hoc Networks

An in-depth review of service discovery protocols (SDPs) in multihop mobile ad hoc networks analyzes SDP building blocks and determines SDP suitability based on architecture, mobility, and network size. Mobile ad hoc networks (manets) include a variety of devices, such as cell phones, PDAs, laptops, and other relatively larger devices. These devices can move at high or low speeds or even remain stationary, entering and leaving the system when switched on or off. Such a variety of devices also offers a variety of services. A service is any tangible or intangible facility a device provides that can be useful for any other device. Services comprise those for software and hardware. A software service, for example, can be a simple file, such as an MP3 file, or a software implementation of an algorithm, such as converting one audio file format to another. A hardware service, for example, can be a printer that a mobile device can use wirelessly. To benefit from these services, a device must be able to both locate them in the network and invoke them. Service discovery protocols (SDPs) enable these capabilities.     

Gradient Clock Synchronization in Dynamic Networks

Over the last years, large-scale decentralized computer networks such as peer-to-peer and mobile ad hoc networks have become increasingly prevalent. The topologies of many of these networks are often highly dynamic. This is especially true for ad hoc networks formed by mobile wireless devices.     

Middleware services for P2P computing in wireless grid networks

Advances in network architecture are changing application and service delivery. The wireless industry, for example, now talks of service grids - collections of separate wireless services collated from across the network. However, with current limitations in mobile device capabilities, a scalable and efficient middleware platform is essential. The authors' new middleware architecture, called scalable inter-grid network adaptation layers (signal), integrates mobile devices with existing grid platforms to conduct peer-to-peer operations through proxy-based systems. Combining mobile P2P applications with grid technologies could ultimately give mobile devices the power of supercomputers.     

一种基于地理定位信息的Ad Hoc分簇算法

Ad hoc网络的分簇机制目的是为了利用网络的分级结构来管理众多的移动设备。为了创建和维持一个当节点高速移动时仍然有效的分级结构,必须满足下面的需求:(1)分级结构中每个移动设备能够根据本地信息自动转换它的角色;(2)分级结构的管理负载要小,每个簇内的节点数目要尽可能地相同。该文提出了一个基于地理定位系统的自适应的多跳分簇机制,试验结果表明新的算法不依赖于节点的移动速度和传播范围,满足上面两个要求。     

Service discovery in mobile ad hoc networks: A field theoretic approach

Service discovery in mobile ad hoc networks is challenging because of the absence of any central intelligence in the network. Traditional solutions as used in the Internet are hence not well suited for mobile ad hoc networks. In this paper, we present a novel decentralized service discovery mechanism for ad hoc networks. The basic idea is to distribute information about available services to the network neighborhood. We achieve this by using the analogy of an electrostatic field: A service is modelled by a (positive) point charge, and service request packets are seen as (negative) test charges which are attracted by the service instances. In our approach, we map the physical model to a mobile ad hoc network in a way where each network element calculates a potential value and routes service requests towards the neighbor with the highest potential, hence towards a service instance. Our approach allows for differentiation of service instances based on their capacity. We define the required protocols and methods which we implemented in a network simulator. Using extensive simulations, we evaluate the performance and robustness of the mechanisms. The results indicate good performance and convergence even in highly mobile environments. We believe that this technique can and should be further exploited, e.g., as a routing protocol in mobile ad hoc networks.     

DaaS: Cloud-based mobile Web service discovery

The proliferation of smartphones and the recent advancement in ubiquitous wireless access have made mobile Web services more possible than ever before. However, finding relevant Web services that can match requests and fit user context remains a major concern. The challenges facing Web service discovery are further magnified by the stringent constraints of mobile devices and the inherit complexity of wireless heterogeneous networks. Cloud computing, with its flexible design and theoretically unlimited computing resources, is a viable approach to bootstrapping Web service discovery. The cloud can build bridges between mobile devices, as a convenient ubiquitous interface, and a backbone infrastructure with abundant computing resources. This paper introduces “Discovery as a service (Daas)”, a novel cloud-based discovery framework that addresses the core components of mobile Web service discovery. The DaaS framework lays the foundation of efficient mobile Web service discovery that takes into consideration user preferences and context. The experimental validation and performance evaluation demonstrate that DaaS can effectively rank relevant services according to the various user context and preferences, in addition to enhancing the precision of the discovered services. The prototype also shows that Web service clustering for discovery significantly improves the overall response time, while the cloud maintains scalability according to prespecified performance criteria.     

A Termination Detection Protocol for Use in Mobile Ad Hoc Networks

As devices become smaller and wireless networking technologies improve, the popularity of mobile computing continues to rise. In today's world, many consider devices such as cell phones, PDAs, and laptops as essential tools. As these and other devices become increasingly independent of the wired infrastructure, new kinds of applications that assume an ad hoc network infrastructure are being deployed. Their development forces software engineers to revisit well understood problems in a setting in which existing solutions are no longer working. This paper illustrates one such attempt by focusing on an important problem in distributed computing, termination detection in diffusing computations, in an ad hoc network environment. We formulate an algorithmic solution amenable to usage in mobile ad hoc networks. Along the way, we highlight several important software engineering concerns one must address and design strategies one might employ in a mobile setting.     

Certification-based trust models in mobile ad hoc networks: A survey and taxonomy

A mobile ad hoc network is a wireless communication network which does not rely on a pre-existing infrastructure or any centralized management. Securing the exchanges in such network is compulsory to guarantee a widespread development of services for this kind of networks. The deployment of any security policy requires the definition of a trust model that defines who trusts who and how. There is a host of research efforts in trust models framework to securing mobile ad hoc networks. The majority of well-known approaches is based on public-key certificates, and gave birth to miscellaneous trust models ranging from centralized models to web-of-trust and distributed certificate authorities. In this paper, we survey and classify the existing trust models that are based on public-key certificates proposed for mobile ad hoc networks, and then we discuss and compare them with respect to some relevant criteria. Also, we have developed analysis and comparison among trust models using stochastic Petri nets in order to measure the performance of each one with what relates to the certification service availability.     

Secure and efficient key management in mobile ad hoc networks

In mobile ad hoc networks, due to unreliable wireless media, host mobility and lack of infrastructure, providing secure communications is a big challenge. Usually, cryptographic techniques are used for secure communications in wired and wireless networks. Symmetric and asymmetric cryptography have their advantages and disadvantages. In fact, any cryptographic means is ineffective if its key management is weak. Key management is also a central aspect for security in mobile ad hoc networks. In mobile ad hoc networks, the computational load and complexity for key management are strongly subject to restriction by the node's available resources and the dynamic nature of network topology. We propose a secure and efficient key management (SEKM) framework for mobile ad hoc networks. SEKM builds a public key infrastructure (PKI) by applying a secret sharing scheme and using an underlying multi-cast server groups. We give detailed information on the formation and maintenance of the server groups. In SEKM, each server group creates a view of the certificate authority (CA) and provides certificate update service for all nodes, including the servers themselves. A ticket scheme is introduced for efficient certificate service. In addition, an efficient server group updating scheme is proposed. The performance of SEKM is evaluated through simulation.     

Cost-effective mobile ad hoc networks management

As there are more and more mobile devices in use, different mobile networking models such as ad hoc or mesh are attracting a large research interest. Self-organizing mobile ad hoc networks (MANET) allow devices to share their services and resources without any central administration or Internet support. In this respect they can become the backbone of the wireless grid or the gateway to existing grids. To achieve these goals, MANET management must be as effective as that of wired networks. This is, however, a challenging task due to network features like mobility, heterogeneity, limited resources of hosts and feeble communication. This paper presents a set of simple, cost-effective and resilient procedures for the basic tasks of MANET creation and management.     

Ad Hoc网络与移动IPv6集成的设计与实现

提出了一种IPv6网络环境中移动IPv6与Ad hoc网络集成的设计方案并介绍了其软件实现方法.该方案将移动IPv6家乡代理的服务范围从传统单跳网络扩展为多跳Ad hoc网络,解决了Ad hoc网络的节点在不同网络之间漫游管理的问题.     

Minimum disruption service composition and recovery in mobile ad hoc networks

The dynamic nature of mobile ad hoc networks poses fundamental challenges to the design of service composition schemes that can satisfy the end-to-end quality of service requirements and minimize the effect of service disruptions caused by dynamic link and node failures. Although existing research on mobile ad hoc networks has focused on improving reliability, little existing work has considered service deliveries spanning multiple components. Moreover, service composition strategies proposed for wireline networks (such as the Internet) are poorly suited for highly dynamic wireless ad hoc networks.This paper proposes a new service composition and recovery framework designed to achieve minimum service disruptions for mobile ad hoc networks. The framework consists of two tiers: service routing, which selects the service components that support the service path, and network routing, which finds the optimal network path that connects these service components. Our framework is based on the disruption index, which is a novel concept that characterizes different service disruption aspects, such as frequency and duration, that are not captured adequately by conventional metrics, such as reliability and availability.Using the definition of disruption index, we formulate the problem of minimum-disruption service composition and recovery (MDSCR) as a dynamic programming problem and analyze the properties of its optimal solution for ad hoc networks with known mobility plan. Based on the derived analytical insights, we present our MDSCR heuristic algorithm for ad hoc networks with uncertain node mobility. This heuristic algorithm approximates the optimal solution with one-step lookahead prediction, where service link lifetime is predicted based on node location and velocity using linear regression. We use simulations to evaluate the results of our algorithm in various network environments. The results validate that our algorithm can achieve better performance than conventional methods.     

Supporting Cooperative Software Processes in a Decentralized and Nomadic World

Recent advances in wireless networks enable decentralized cooperative and nomadic work scenarios where mobile users can interact in performing some tasks without being permanently online. Scenarios where connectivity is transient and the network topology may change dynamically are considered. Connectivity among nodes does not require the support offered by a permanent infrastructure but may rely on ad hoc networking facilities. In this paper, a scenario in which a nomadic group of software engineers cooperate in developing an application is investigated. The proposed solution, however, is not software process specific but holds for other cases where shared documents are developed cooperatively by a number of interacting nomadic partners. Support tools for these groups are normally based on a client-server architecture, which appears to be unsuitable in highly dynamic environments. Peer-to-peer solutions, which do not rely on services provided by centralized servers, look more promising. This paper presents a fully decentralized cooperative infrastructure centered around peer-to-peer versioning system (PeerVerSy), a configuration management tool based on a peer-to-peer architecture, which supports cooperative services even when some of the collaborating nodes are offline. Some preliminary experiences gained from its use in a teaching environment are also discussed     

Design and implementation of a smart system for personalization and accurate selection of mobile services

Wireless mobile services are computing applications that run on handheld wireless devices. Such applications must work within the daunting constraints of the devices, which include memory, processing power, input capabilities, and size of display. It is therefore important that mobile services take into account the user’s context, optimize resource usage, and minimize input effort imposed on the user. In this paper, we present the design and implementation of a smart agent-enabled system for personalizing wireless mobile services and advertisements for Java 2 Micro Edition (J2ME) or Java ME, and Wireless Application Protocol (WAP) enabled devices. We use software agents for context filtering because such autonomous software entities have characteristics that can benefit mobile devices and the wireless environment, and the Composite Capability/Preference Profiles (CC/PP) standard for defining profiles for user preferences and device capabilities. The system incorporates the use of artificial neural networks to adaptively and iteratively learn to select the best available service based on contextual information. The system is evaluated using practical operating scenarios, as well as empirical data and results show an 87% success rate in the selection of the best available service.     

Inter-Cluster Routing Authentication for Ad Hoc Networks by a Hierarchical Key Scheme

Dissimilar to traditional networks, the features of mobile wireless devices that can actively form a network without any infrastructure mean that mobile ad hoc networks frequently display partition due to node mobility or link failures. These indicate that an ad hoc network is difficult to provide ou-llne access to a trusted authority server. Therefore, applying traditional Public Key Infrastructure （PKI） security framework to mobile ad hoc networks will cause insecurities. This study proposes a scalable and elastic key management scheme integrated into Cluster Based Secure Routing Protocol （CBSRP） to enhance security and non-repudiation of routing authentication, and introduces an ID-Based internal routing authentication scheme to enhance the routing performance in an internal cluster. Additionally, a method of performing routing authentication between internal and external clusters, as well as inter-cluster routing authentication, is developed. The proposed cluster-based key management scheme distributes trust to an aggregation of cluster heads using a threshold scheme faculty, provides Certificate Authority （CA） with a fault tolerance mechanism to prevent a single point of compromise or failure, and saves CA large repositories from maintaining member certificates, making ad hoc networks robust to malicious behaviors and suitable for numerous mobile devices.     

基于移动Ad hoc网络的服务管理研究

本文基于移动Ad hoc网络的广播特性、分簇的普遍性等特点,在分析分布式服务发现协议GSD等的基础上,提出了新的服务发现机制,该机制考虑了各节点处理能力、存储能力以及所提供的服务种类等不可能完全相同的特性,克服了GSD同等对待所有节点的缺欠;另外,文中提出了基于优先级和两步资源预约的服务调度和QoS分配方式,依据服务所请求的QoS级别和资源情况来确定合适的端到端QoS级别,保证资源的充分利用,并给出了算法的一个实际应用的例子,该算法考虑了资源的抢占和两步方式的资源预约,比普通的确定QoS级别的算法具有更高的预约成功率,而比仅依据优先级的算法具有更高的资源利用率。     

A negotiation framework for content distribution in mobile transient networks

Transient networks are spontaneous networks that appear for a short period of time in order to provide basic services such as connectivity and content distribution among a small community. Nowadays mobile devices are becoming multimode by nature providing multiple connection paths. This paper investigates the efficiency and benefit of a mobile transient network where multiple nodes collaborate, offering a multihomed network with community services by means of intelligent agents. The paper concretely proposes an architecture able to fully support a peer-to-peer transient community during both negotiation and service steps for two different modes: file download and multimedia streaming. The first mode, implemented on intelligent and cooperative agents, provides two negotiation models (fair and dynamic) in order to guarantee wider flexibility for different possible scenarios and community models; the second one implements a content delivery system into transient community, taking advantage of multihomed features of mobile devices.