一种适用于移动Ad hoc网络的无线P2P应用架构

移动AdHoc网络和P2P技术近年来迅速发展,各种新的应用层出不穷,向广大用户提供了多种新兴服务。相关研究表明,在现有的移动AdHoc网络中直接应用P2P技术,会影响整个网络的性能。本文采用跨层思想,提出新型的无线P2P应用架构,包括了资源搜索和文件传输的整个过程,实现了基于存储内容的分布式网络资源管理。该架构设计了适用于移动AdHoc网络的P2P拓扑结构,定义了各节点内部的模块功能和算法流程。本文还引入用户偏好和信用记录的机制,更好的满足了无线自组织网络中各种P2P应用的不同QoS需求以及每位用户的需求。     

Spiralchord： a space-filling curve based location awareness, cross-layering P2P file sharing system in WMNs

The common characteristics of peer-to-peer (P2P) overlay networks and wireless multi-hop network, such as self-organization, decentralization, hop-by-hop message transmission mode and high degree of dynamicity, lead to research of operating wired P2P applications on wireless multi-hop networks. Wireless mesh network (WMN) as a relative static multi-hop wireless network which is extended from Ad-Hoc networks, has become one of the key technologies for providing increased network coverage of Internet infrastructures. This paper investigates the problem of enabling P2P file sharing in WMNs. A special chord algorithm-spiralchord is proposed to address the major problem in wireless file sharing system-how to efficiently find resources currently available. Spiralchord put forward an identifier (ID) assignment technique based on spiral space-filling curve to integrate location-awareness with cross-layering. Location awareness aims at alleviating the mismatch of physical network topology and overlay network topology, and requires close-by IDs in logical ring of neighboring peers, while cross-layering aims at speeding up resource lookup operations, requires faraway IDs of neighboring peers. Spiralchord uses spiral curve to assign peers’ IDs which meet the contradictory requirements of location-awareness and cross-layering. The simulation results show spiralchord is effective in reducing message overhead, and increasing lookup performance with respect to basic chord.     

On Localized Application-Driven Topology Control for Energy-Efficient Wireless Peer-to-Peer File Sharing

Wireless peer-to-peer (P2P) file sharing is widely envisioned as one of the major applications of ad hoc networks in the near future. This trend is largely motivated by the recent advances in high-speed wireless communication technologies and high traffic demand for P2P file sharing applications. To achieve the ambitious goal of realizing a practical wireless P2P network, we need a scalable topology control protocol to solve the neighbor discovery problem and network organization problem. Indeed, we believe that the topology control mechanism should be application driven in that we should try to achieve an efficient connectivity among mobile devices in order to better serve the file sharing application. We propose a new protocol, which consists of two components, namely, adjacency set construction (ASC) and community-based asynchronous wakeup (CAW). Our proposed protocol is shown to be able to enhance the fairness and provide an incentive mechanism in wireless P2P file sharing applications. It is also capable of increasing the energy efficiency.     

Mitigating file‐sharing misbehavior with movement synchronization to increase end‐to‐end availability for delay sensitive streams in vehicular P2P devices

When dealing with wireless connectivity in a mobile peer‐to‐peer (MP2P) environment, there are many concerns about the offered efficiency and availability of the requested resources and concerns about practicality considerations. These considerations deal with the movement and deployment of continuous connectivity. The intermittent connectivity is a major factor for object sharing misbehavior because it aggravates the connectivity and reliability. MP2P environments are in need of specialized placement algorithms where structured index‐centric solutions will be able to provide efficiency and object location determination over intermittent connectivity and communication. Replication of any requested object and redundancy face the requests' failures because they create severe duplications, and aggravate the capacity of the end‐to‐end path. This work proposes a framework that enables mitigation between the file sharing misbehavior in contrast to the movement synchronization, and it quantifies the parameters that affect the end‐to‐end efficient transmission by taking into consideration the synchronization between moving peers to assign the requested resources in the end‐to‐end path. Resilience metrics are introduced to enable reliability in cooperative file sharing procedure. The proposed scheme considers synchronization and assignment of the moving mobile Infostation peer with certain object indices to a certain vehicle via a synchronized cooperative scheme where the file sharing process is performed through the message ferry mobile peer. In addition, a resource assignment cooperation engine is developed taking into consideration the social cooperation model and the end‐to‐end capacity of the relay path. The proposed resource exchange apparatus for file chunks' migration is performed to enable delay sensitive streaming. The proposed model is evaluated through experimental simulation taking measures for the throughput and the reliability offered and for the robustness for sharing resources of any capacity in dynamically changing MP2P wireless environments under synchronized movements. Copyright © 2012 John Wiley & Sons, Ltd.     

移动P2P信息交互的实现

随着移动终端设备和网络的发展，移动对等实体间的信息共享已引起越来越广泛的关注。介绍了通过包括移动代理服务器（Mobile proxy）的对等网络及扩展eDonkey体系实现移动对等实体及其他移动环境中的信息共享方法，最后给出了对其发展前景的预测。     

Extending P2PMesh: topology‐aware schemes for efficient peer‐to‐peer data sharing in wireless mesh networks

Wireless mesh networks (WMNs) have emerged as a promising technology that provides low‐cost broadband access to the Internet for fixed and mobile wireless end users. An orthogonal evolution in computer networking has been the rise of peer‐to‐peer (P2P) applications such as P2P data sharing. It is of interest to enable effective P2P data sharing in this type of networks. Conventional P2P data sharing systems are not cognizant of the underlying network topology and therefore suffer from inefficiency. We argue for dual‐layer mesh network architecture with support from wireless mesh routers for P2P applications. The main contribution of this paper is P2PMesh: a topology‐aware system that provides combined architecture and efficient schemes for enabling efficient P2P data sharing in WMNs. The P2PMesh architecture utilizes three schemes: (i) an efficient content lookup that mitigates traffic load imbalance at mesh routers; (ii) an efficient establishment of download paths; and (iii) a data transfer protocol for multi‐hop wireless networks with limited capacity. We note here that the path establishment and data transfer schemes are specific to P2P traffic and that other traffic would use routes determined by the default routing protocol in the WMN. Simulation results suggest that P2PMesh has the potential to improve the performance of P2P applications in a wireless multi‐hop setting; specifically, we focused on data sharing, but other P2P applications can also be supported by this approach. Copyright © 2011 John Wiley & Sons, Ltd.     

一种支持MD无线接入的新型混合式P2P模型

混合式P2P软件是目前互联网上广泛应用的P2P文件共享软件，但混合式P2P协议并没有特别考虑移动设备（Mobile Device）线接入的问题。文章将在混合式P2P模型的基础上，针对MD计算能力、存储能力的限制和无线连接的特点．提出一种支持MD无线接入的新型混合式P2P网络模型。它通过扩展移动支持节点的功能，使用移动代理代表MD接入P2P网络共享资源。并利用客户机缓存技术进行优化，有效的减少了MD自身的开销以及无线通信的开销．同时对MD的移动性和无线连接的断接性提供了很好的支持。     

Enabling Efficient Peer-to-Peer Resource Sharing in Wireless Mesh Networks

Wireless mesh networks are a promising area for the deployment of new wireless communication and networking technologies. In this paper, we address the problem of enabling effective peer-to-peer resource sharing in this type of networks. Starting from the well-known Chord protocol for resource sharing in wired networks, we propose a specialization that accounts for peculiar features of wireless mesh networks: namely, the availability of a wireless infrastructure, and the 1-hop broadcast nature of wireless communication, which bring to the notions of location awareness and MAC layer cross-layering. Through extensive packet-level simulations, we investigate the separate effects of location awareness and MAC layer cross-layering, and of their combination, on the performance of the P2P application. The combined protocol, MeshChord, reduces message overhead of as much as 40 percent with respect to the basic Chord design, while at the same time improving the information retrieval performance. Notably, differently from the basic Chord design, our proposed MeshChord specialization displays information retrieval performance resilient to the presence of both CBR and TCP background traffic. Overall, the results of our study suggest that MeshChord can be successfully utilized for implementing file/resource sharing applications in wireless mesh networks.     

Cross-layer design of P2P file sharing over mobile ad hoc networks

Peer-to-peer file sharing over mobile ad hoc networks (MANET) has become a popular application due to the rapid growing number of mobile devices. However, the fact that mobile nodes in a MANET dynamically alter their locations and join/leave the P2P system has posted many challenges in designing a robust and scalable P2P system. Although, in the literature, flooding-based P2P approach has been shown to be robust in a highly dynamic network, it leads to poor efficiency in terms of bandwidth usage and scalability. A new design is required in which cross-layer designs and cognitive approaches could be applied such that it could interact with the requests of users and respond to dynamic change of network topology. In this paper, we propose an efficient and scalable P2P file sharing system over MANET based on Swarm Intelligence, referred to as P2PSI. By applying the cognitive behaviour of the real ant colonies, P2PSI owns the capability of adaptive learning of routing path and is able to cope with mobility problem without flooding. Moreover, P2PSI also adopts cross-layer design to reduce the redundant message overhead and query latency. Performance of P2PSI is evaluated and compared to two existing cross-layer design service discovery protocols through simulations. Our simulation results show that P2PSI achieves better performance in terms of control overhead and request success ratio.     

P2P网络中稳定节点会话序列特征分析

给出稳定节点的形式化定义,提出一个从所有节点中分离稳定节点的方法以及分析稳定节点会话序列特征的数学模型。针对KAD中的稳定节点得到以下新的重要结论:稳定节点数目仅约占总节点数目的0.6%;约70%的稳定节点通过多次会话保证长时间在线,且会话时长之间的差异很大;其余约30%的稳定节点的总会话时长远低于前者,但是它们很少离线且平均会话时长约为前者的1.8倍。这两类稳定节点可作为超级节点,发挥各自长处构造层次P2P网络。     

Reliability-oriented ant colony optimization-based mobile peer-to-peer VoD solution in MANETs

Mobile peer-to-peer (MP2P) has emerged as a state-of-the-art technology for video resource sharing in mobile ad-hoc networks (MANETs), building on the advantages of P2P data exchange and providing a feasible solution for large-scale deployment of media streaming services. Fast search for video resources and low maintenance overhead of overlay networks to support the mobility of nodes are key factors in MP2P video on demand solutions. In this paper, we propose a novel reliability-oriented ant colony optimization (ACO)-based MP2P solution to support interactivity for video streaming in MANETs (RACOM). RACOM makes use of highly innovative algorithms such as the peer status-aware mechanism and peer-centric overlay maintenance mechanism to support high-efficiency video resource sharing. The peer status-aware mechanism includes the user reliability measure model which is used to identify the peers having reliable playback status in order to find stable potential resource suppliers and a new ACO-based prediction model of playback behavior which provides the accurate prediction of playback content in the future to ensure the smooth experience and optimize the distribution of resources. In order to balance the fast supplier discovery and low maintenance overhead, RACOM makes use of peer-centric overlay maintenance mechanism composed of the time window-based detection strategy and encounter-based synchronization strategy to reduce the maintenance overhead of reliable peers, obtain quasi real-time status of peers and support the mobility of mobile nodes. Simulation results show how RACOM achieves higher hit ratio, lower seek delay, lower server stress, lower peer load and less overlay maintenance overhead in comparison with another state of the art solution.     

DiffServ resource allocation for fast handoff in wireless mobileInternet

The next-generation wireless networks are evolving toward a versatile IP-based network that can provide various real-time multimedia services to mobile users. Two major challenges in establishing such a wireless mobile Internet are support of fast handoff and provision of quality of service (QoS) over IP-based wireless access networks. In this article, a DiffServ resource allocation architecture is proposed for the evolving wireless mobile Internet. The registration-domain-based scheme supports fast handoff by significantly reducing mobility management signaling. The registration domain is integrated with the DiffServ mechanism and provisions QoS guarantee for each service class by domain-based admission control. Furthermore, an adaptive assured service is presented for the stream class of traffic, where resource allocation is adjusted according to the network condition in order to minimize handoff call dropping and new call blocking probabilities     

基于OpenFlow的移动自由空间光网络的控制架构(英文)

Mobile free space optical networks have aroused much attention due to the ability of providing high speed connectivity over long distance using the wireless laser links,while requiring relatively high available bandwidth resource and less energy consumption.However,maintaining the network with laserlinks is quite challenging due to a number of issues,such as the link fragility,the difficulty in pointingand tracking of the link,which also raises the great difficulty in the control of the network.In this paper,we present the methodology for the deployment of the mobile freespace optical networks based on our proposed OpenFlow-based control architecture.In addition,a new routing scheme is proposed and demonstrated on the testbed based on this control architecture.Delivery ratio,average delivery delay and time complexity are given to verify the performance of the OpenFlow-based control architecture.     

Vertical handoffs in wireless overlay networks

No single wireless network technology simultaneously provides a low latency, high bandwidth, wide area data service to a large number of mobile users. Wireless Overlay Networks - a hierarchical structure of room-size, building-size, and wide area data networks - solve the problem of providing network connectivity to a large number of mobile users in an efficient and scalable way. The specific topology of cells and the wide variety of network technologies that comprise wireless overlay networks present new problems that have not been encountered in previous cellular handoff systems. We have implemented a vertical handoff system that allows users to roam between cells in wireless overlay networks. Our goal is to provide a user with the best possible connectivity for as long as possible with a minimum of disruption during handoff. Results of our initial implementation show that the handoff latency is bounded by the discovery time, the amount of time before the mobile host discovers that it has moved into or out of a new wireless overlay. This discovery time is measured in seconds: large enough to disrupt reliable transport protocols such as TCP and introduce significant disruptions in continuous multimedia transmission. To efficiently support applications that cannot tolerate these disruptions, we present enhancements to the basic scheme that significantly reduce the discovery time without assuming any knowledge about specific channel characteristics. For handoffs between room-size and building-size overlays, these enhancements lead to a best-case handoff latency of approximately 170 ms with a 1.5% overhead in terms of network resources. For handoffs between building-size and wide-area data networks, the best-case handoff latency is approximately 800 ms with a similarly low overhead. This revised version was published online in June 2006 with corrections to the Cover Date.     

Adaptive video protection in large scale peer‐to‐peer video streaming over mobile wireless mesh networks

Because video streaming over mobile handheld devices has been of great interest, the necessity of introducing new methods with low implementation cost and scalable infrastructures is a strong demand of the service. In particular, these requirements are present in popular wireless networks such as wireless mesh networks (WMN). Peer‐to‐peer (P2P) networks promise an efficient scalable network infrastructure for video streaming over wired and wireless networks. Limited resources of the peers in P2P networks and high error rate in wireless channels make it more challenging to run P2P streaming applications over WMNs. Therefore, it is necessary to design efficient and improved error protection methods in P2P video streaming applications over WMNs. In this paper, we propose a new adaptive unequal video protection method specially intended for large scale P2P video streaming over mobile WMNs. Using this method, different frames have different priorities in receivers along the recovery process. Moreover, we precisely and completely evaluate different aspects related to frame protection in these networks using five important performance metrics including video distortion, late arrival distortion, end‐to‐end delay, overhead and initial start‐up delay. The results obtained from a precise simulation in OMNeT++ show that the proposed adaptive method significantly outperforms other solutions by providing better video quality on mobile wireless nodes. Copyright © 2015 John Wiley & Sons, Ltd.     

Efficient resource allocation for China's 3G/4G wireless networks

The all-IP DiffServ model is expected to be the most promising architecture for QoS provisioning in China's next-generation wireless networks, due to its scalability, convenience for mobility support, and capability of interworking heterogeneous radio access networks. This article focuses on efficient resource allocation in a wireless DiffServ architecture. Resource utilization efficiency is particularly important for China's wireless networks as the mobile user density in China is and will continue to be much higher than that in other countries. More specifically, we propose a novel buffer sharing scheme to provide assured service for real-time layer-coded multimedia traffic, which can guarantee the specific packet loss requirement of each layer with UDP as the transport layer protocol. An adaptive optimal buffer configuration can be applied to achieve maximum resource utilization over the time-varying channel. Assured service is also provided to TCP data traffic for guaranteed throughput, where the cross-layer coupling between the TCP layer and link layer is exploited to efficiently utilize the wireless resources.     

移动P2P流媒体中基于有效容量的邻居节点选择机制

For Peer-to-Peer (P2P) streaming services in mobile networks, the selection of appropriate neighbour peers from candidate peers with demanding data is an important approach to improve Quality-of-Service (QoS). This paper proposes a novel Effective Capacity Peer Se-lection (ECPS) scheme based on effective capacity. In the ECPS scheme, the neighbour peer selection problem was modeled using the Multiple Attribute Decision Making (MADM) theory, which considered multiple factors of candidate peers, including Signal to Interference and Noise Ratio (SINR), residen-cy time, power level, security, moving speed, and effective capacity. This model could increase the suitability of ECPS for wireless mobile environments. Then, the Technique for Order Preference by Similarity to Ideal Solu-tion (TOPSIS) was used to solve the MADM problem and identify the preferred neighbour peers. Simulation results show that the ECPS scheme can improve the network throughput, reduce packet delay by about 82%, and al-most double the packet delivery ratio of the mobile P2P streaming service.     

Heterogeneous Vehicular Communication Architecture and Key Technologies

Vehicular networks have traditionally been used in specific scenarios, such as Electronic Toll Collection (ETC). New vehicular networks, however, support communication of safety information between vehicles using self-organized ad-hoc technology. Because of limitations in network architecture, current vehicular networks only provide communication for mobile terminals in a vehicle cluster. Vehicles cannot exchange information with an Intelligent Traffic System (ITS) control center nor can they access broadband wireless networks. This paper proposes a novel heterogeneous vehicular wireless architecture based on Wireless Access in Vehicular Environment (WAVE, IEEE 802.11 p) and Worldwide Interoperability for Microwave Access (WiMAX,IEEE 802.16e). A new network infrastructure and system model is introduced, and key technologies are discussed. For WAVE, these technologies include adaptive multichannel coordination mechanism and scheduling algorithm; and for WiMAX, these technologies include group handover scheme and two-level resource allocation algorithm.     

Biased Random Walks in Uniform Wireless Networks

A recurrent problem when designing distributed applications is to search for a node with known property. File searching in peer-to-peer (P2P) applications, resource discovery in service-oriented architectures (SOAs), and path discovery in routing can all be cast as a search problem. Random walk-based search algorithms are often suggested for tackling the search problem, especially in very dynamic systems-like mobile wireless networks. The cost and the effectiveness of a random walk-based search algorithm are measured by the excepted number of transmissions required before hitting the target. Hence, to have a low hitting time is a critical goal. This paper studies the effect of biasing random walk toward the target on the hitting time. For a walk running over a network with uniform node distribution, a simple upper bound that connects the hitting time to the bias level is obtained. The key result is that even a modest bias level is able to reduce the hitting time significantly. This paper also proposes a search protocol for mobile wireless networks, whose results are interpreted in the light of the theoretical study. The proposed solution is for unstructured wireless mobile networks.