Performance Analysis of Interconnected Communication Networks

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Topology-aware peer-to-peer overlay network for Ad-hoc

The mismatch between the structured peer-to-peer (P2P) overlay network, which is based on Hashing, and the actual physical network, leads to query repeatedly passing through some nodes in the actual route when it is applied in Ad-hoc networks. An approach of getting an appropriate node identifier (ID) bearing its local physical information is proposed, in which the traditional theory of getting node ID through Hashing the node's Internet protocol (IP) address is abandoned, and a topology-aware overlay network suiting Ad-hoc networks is constructed. The simulation results show that the overlay network constructed in the proposed method can avoid the route being iteratively accessed. Meanwhile, it can effectively minimize the latency and improve the load balance.     

Age-based anonymity: a randomized routing approach to communication unobservability

Providing anonymous communication on networks of interconnected computers is an active area of research which aims to enhance the privacy of the users of such networks. Communication unobservability, stronger property compared to anonymity, attempts to guarantee that legitimate messages are not discernible from dummy traffic. A network with an active global adversary is one which it is assumed that all nodes in the network are potentially being monitored at all times, and also that at any time any node could be an adversary. This paper introduces a set of anonymous system design requirements for providing enhanced communication unobservability. A new anonymous networking system was designed based on these requirements to provide both sender and receiver anonymity. The proposed system has a structured peer-to-peer network architecture and a randomized routing algorithm to obfuscate the detection of communication paths and the message routing patterns. An age-based method is proposed to prevent even the first node after the sender from identifying the original sender. A simulation program was designed and implemented to test the proposed system. The effect of different parameters on the proposed algorithm is demonstrated using a simulation program.     

Resource-Cardinality Based Scheme to Reduce Resource Lookup Cost in Structured P2P Networks

A P2P (peer-to-peer) network is a distributed system dependent on the IP-based networks, where independent nodes join and leave the network at their drive. The files (resource) are shared in distributed manner and each participating node ought to share its resources. Some files in P2P networks are accessed frequently by many users and such files are called popular files. Replication of popular files at different nodes in structured P2P networks provides significant reduction in resource lookup cost. Most of the schemes for resource access in the structured P2P networks are governed by DHT (Distributed Hash Table) or DHT-based protocols like Chord. Chord protocol is well accepted protocol among structured P2P networks due to its simple notion and robust characteristics. But Chord or other resource access protocols in structured P2P networks do not consider the cardinality of replicated files to enhance the lookup performance of replicated files. In this paper, we have exploited the cardinality of the replicated files and proposed a resource cardinality-based scheme to enhance the resource lookup performance in the structured P2P networks. We have also proposed the notion of trustworthiness factor to judge the reliability of a donor node. The analytical modelling and simulation analysis indicate that the proposed scheme performs better than the existing Chord and PCache protocols.

     

基于无线传感器网络的农业环境监测系统

针对当前农业环境在线监测的需要,提出了一种利用具有自组织特性的无线传感器网络(wireless sensor networks,WSN)对温度、土地湿度和土壤的PH值等环境变量进行在线监测的方法.该方法采用了对等式网络体系结构、低功耗微小网络节点、基于拓扑树的网络初始化配置算法.实验测试表明节点能够有效地采集和处理数据,并可以在节点间成功地进行通信.     

On the design of node architectures and MAC protocols for optical burst-switched ring networks

Efficient multiple-token-based MAC protocols have been proposed for optical burst-switched (OBS) unidirectional ring networks using a TT-TR-based node architecture in our previous research. However, the unidirectional OBS ring network is difficult to scale to larger networks. As wavelengths accessibilities are dominated by tokens, network performance is restricted by the frequency of capturing a token. If the network is too large, it takes a long time for tokens to rotate. Thus, a destination queue may wait for a long time to be served, which results in large queuing delays and inefficiency of network resource utilization. In order to improve network efficiency and scalability for OBS ring networks using multiple tokens, this work is extended to a bidirectional ring system that uses the tunable transmitter and tunable receiver (TT-TR)-based node architecture with two pairs of transceivers, so that each queue can be served by tokens from both directions. Furthermore, two kinds of node architectures differing in sharing the two pairs of transceivers, either shared or not, are proposed. Then, two MAC protocols considering different queue scheduling algorithms are proposed for the ring network using the proposed node architectures, in order to use the network resources more efficiently. They are improved from general round-robin (GRR) and termed as half-ring round-robin (HfRR) and co-work round-robin (CoRR), respectively. The network performance of the two proposed node architectures and the two proposed MAC protocols for the networks using them as well as the network scalability are evaluated with the OPNET simulator.     

A group-based data-driven approach for data synchronization in unstructured mobile P2P systems

This paper addresses the problem of data consistency on mobile peer-to-peer (MP2P) systems (or MP2P networks). The considered MP2P system is based on a mobile ad-hoc network, where the energy and connectivity on the mobile devices are limited. Since different mobile nodes may store copies of shared information, data synchronization on an MP2P system becomes crucial and challenging due to frequent disconnection and change on network topology caused by node mobility. We propose an effective approach to improving the performance of data synchronization with a dynamic inverted data indexing structure and group-based data-driven consistency management. The proposed approach can effectively synchronize the data items without using a central cache node in each group (or cluster) and perform well in terms of the coverage of successfully synchronized nodes and the number of redundant messages. Last, the proposed approach is validated through extensive simulation experiments.     

The throughput time delay function of anM/M/1queue (Corresp.)

A study of the design requirements of the data link control protocol leads us to consider a throughput time delay criterion as a performance measure for optimal flow control of computer communication networks. A closed network model consisting of acdot /M/1queuing system (the receiver node) controlled by an exponential queuing system with variable rate (the source node) is considered. The flow control maximizing the throughput of the M/M/1 queuing system in equilibrium under a bounded average time delay criterion is shown to be a window flow control mechanism. The window sizeLcan be easily derived from the maximum tolerated average time delayTand the maximum offered loadc. The dependence of the maximum throughput on the average time delay is also analyzed.     

航空电子系统中FC网络的仿真和延迟估计

对采用单交换机光纤通道(FC)网络的航空电子系统进行了描述,建立了网络的排队模型.根据M/G/1模型对FC网络的队列长度、服务时间等参数进行了分析和估计.在OPNET平台下对4种周边节点数不同的FC网络进行了仿真;通过仿真分析了FC网络端到端延迟和网络节点数关系,并对评估的数学模型进行了修正;研究了网络中的延迟"抖动"...     

Distributed and Energy-Aware MAC for Differentiated Services Wireless Packet Networks: A General Queuing Analytical Framework

We present a novel queuing analytical framework for the performance evaluation of a distributed and energy-aware medium access control (MAC) protocol for wireless packet data networks with service differentiation. Specifically, we consider a node (both buffer-limited and energy-limited) in the network with two different types of traffic, namely, high-priority and low-priority traffic, and model the node as a MAP (Markovian arrival process)/PH (phase-type)/1/K nonpreemptive priority queue. The MAC layer in the node is modeled as a server and a vacation queuing model is used to model the sleep and wakeup mechanism of the server. We study standard exhaustive and number-limited exhaustive vacation models both in multiple vacation case. A setup time for the head-of-line packet in the queue is considered, which abstracts the contention and the back-off mechanism of the MAC protocol in the node. A nonideal wireless channel model is also considered, which enables us to investigate the effects of packet transmission errors on the performance behavior of the system. After obtaining the stationary distribution of the system using the matrix-geometric method, we study the performance indices, such as packet dropping probability, access delay, and queue length distribution, for high-priority packets as well as the energy saving factor at the node. Taking into account the bursty traffic arrival (modeled as MAP) and, therefore, the nonsaturation case for the queuing analysis of the MAC protocol, using phase-type distribution for both the service and the vacation processes, and combining the priority queuing model with the vacation queuing model make the analysis very general and comprehensive. Typical numerical results obtained from the analytical model are presented and validated by extensive simulations. Also, we show how the optimal MAC parameters can be obtained by using numerical optimization     

水声网络通信性能分析

该文根据水声信道传播特性及水声网络结构特征,建立了基于水声网络的通信性能分析模型,并仿真分析了对等网络和汇聚网络两种水声网络结构的通信性能与节点间距、网络规模、工作繁忙度以及发射功率等因素的联系,结果表明通过适当的网络设置和协议设计能够优化网络的通信性能,并且存在使通信带宽效率最优的水声网络节点间距。该文的研究成果对水声网络应用具有指导意义。     

GI/Geom/1 queue based on communication model for mesh networks

In mesh networks architecture, it should be permitted to visit the mobile client points. Whereas in mesh networks environment, the main throughput flows usually communicate with the conventional wired network. The so‐called gateway nodes can link directly to traditional Ethernet, depending on these mesh nodes, and can obtain access to data sources that are related to the Ethernet. In wireless mesh networks (WMNs), the quantities of gateways are limited. The packet‐processing ability of settled wireless nodes is limited. Consequently, throughput loads of mesh nodes highly affect the network performance. In this paper, we propose a queuing system that relied on traffic model for WMNs. On the basis of the intelligent adaptivenes, the model considers the influences of interference. Using this intelligent model, service stations with boundless capacity are defined as between gateway and common nodes based on the largest hop count from the gateways, whereas the other nodes are modeled as service stations with certain capacity. Afterwards, we analyze the network throughput, mean packet loss ratio, and packet delay on each hop node with the adaptive model proposed. Simulations show that the intelligent and adaptive model presented is precise in modeling the features of traffic loads in WMNs. Copyright © 2013 John Wiley & Sons, Ltd.     

Performance Analysis of Network Coding Based Two-Way Relay Wireless Networks Deploying IEEE 802.11

In this paper, we investigate the performance analysis of the IEEE 802.11 DCF protocol at the data link layer. We analyze the impact of network coding in saturated and non-saturated traffic conditions. The cross-layer analytical framework is presented in analyzing the performance of the encode-and-forward (EF) relaying wireless networks. This situation is employed at the physical layer under the conditions of non-saturated traffic and finite-length queue at the data link layer. First, a model of a two-hop EF relaying wireless channel is proposed as an equivalent extend multi-dimensional Markovian state transition model in queuing analysis. Then, the performance in terms of queuing delay, throughput and packet loss rate are derived. We provide closed-form expressions for the delay and throughput of two-hop unbalanced bidirectional traffic cases both with and without network coding. We consider the buffers on nodes are unsaturated. The analytical results are mainly derived by solving queuing systems for the buffer behavior at the relay node. To overcome the hidden node problem in multi hop wireless networks, we develop a useful mathematical model. Both models have been evaluated through simulations and simulation results show good agreement with the analytical results.     

Performance analysis of an improved dynamic power management model in wireless sensor node

The energy consumption in the wireless sensor networks is a very critical issue which attracts immediate attention for the sake of the growing demand of the billion dollar market in future. The Dynamic Power Management (DPM) technique is a way of controlling and saving the energy usage in a sensor node. Previously, researchers have proposed lifetime improving stochastic models for wireless sensor networks and limited work has been done focusing on the wireless sensor node. This paper proposes an analyser based Semi-Markov model for DPM in the event-driven sensor node. The power consumption comparison with previously proposed models without this analyser shows the analyser significant contributes to lifetime improvement. The improved model is more power efficient, presents how the DPM model observes the input event arrival and power states of the sensor node components, and then dynamically manages the power consumption of the overall system. Further, to observe the effect of event arrival, missed events, waiting time, processor utilization on the power consumption and lifetime, the proposed DPM system with the single server queuing model is developed.     

On using peer-to-peer communication in cellular wireless data networks

A recent class of approaches for enhancing the performance of cellular wireless data networks has focused on improving the underlying network model. It has been shown that using the peer-to-peer network model, a mode of communication typically seen in ad hoc wireless networks, can result in performance improvements such as increased data rate, reduced transmission power, better load balancing, and enhanced network coverage. However, the true impact of adopting the peer-to-peer network model in such an environment is yet to be fully understood. In this paper, we investigate the performance benefits and drawbacks of using the peer-to-peer network model for Internet access in cellular wireless data networks. We find that, although the peer-to-peer network model has significantly better spatial reuse characteristics, the improved spatial reuse does not translate into better throughput performance. Instead, we observe that using the peer-to-peer network model as-is might actually degrade the throughput performance of the network. We identify and discuss the reasons behind these observations. Using the insights gained through the performance evaluations, we then propose two categories of approaches to improve the performance of the peer-to-peer network model: approaches that leverage assistance from the base station and approaches that leverage the relaying capability of multihomed hosts. Through simulation results, we show that using the peer-to-peer network model in cellular wireless data networks is a promising approach when the network model is complemented with appropriate mechanisms.     

基于对等网络的分布式存储系统的设计与实现

在基于节点分级的对等网络路由定位算法SP_Route的基础上实现一个分布式存储系统。通过采用可扩展的体系结构、稳定的通信协议、通信机制,简明的文件的组织和节点构造方式,在物理网络上叠加一个P2P网络层。将各个节点贡献的物理上分布的存储资源连接成对用户透明的文件存储系统。该系统能快速地搜索文件和进行路由定位,能为用户提供较稳定的存储服务。     

一种改进的无结构P2P网络搜索策略

点对点(Peer-to-Peer)网络已发展成为当今最为流行的资源共享系统之一.其中的资源搜索是一个关键性问题.但其常用的基于简单flooding机制的信息资源搜索方法造成了严重的通信消耗,本文借鉴人际传播中谣言传播机制,结合节点吸引因子(在真实系统中,新增节点不仅与网络中已有的度数较高的节点连接,而且与吸引因子较大的...     

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.     

Effect of Network Coding and Multi-packet Reception on Point-to-Multi-point Broadcast Networks

This paper addresses throughput and delay gains resulting from network coding (NC) used to complement multi-packet reception (MPR) in a single-relay multi-user wireless network in saturated and non-saturated traffic conditions. The cross-layer analytical framework is presented in analyzing the performance of the encode-and-forward (EF) relaying wireless networks, where employed at the physical layer under the conditions of unsaturated traffic and finite-length queue at the data link layer. Considering the characteristics of EF relaying protocol at the physical layer, first a model of a two-hop EF relaying wireless channel is proposed as an equivalent extended multi-dimensional Markovian state transition model in queuing analysis. We show that the initial transmissions and the back-filling process can be greatly sped up through a combination of NC and MPR. We provided closed-form expressions for two-hop unbalanced bidirectional traffic cases both with and without NC even if the buffers on nodes are unsaturated. The analytical results are mainly derived by solving queuing systems for the buffer behavior at the relay node. The model has been evaluated through simulations and in comparison with the existing analytical model. Simulation results show good agreement with the analytical results.     

An intelligent and knowledge‐based overlapping clustering protocol for wireless sensor networks

Overlapping is one of the topics in wireless sensor networks that is considered by researchers in the last decades. An appropriate overlapping management system can prolong network lifetime and decrease network recovery time. This paper proposes an intelligent and knowledge‐based overlapping clustering protocol for wireless sensor networks, called IKOCP. This protocol uses some of the intelligent and knowledge‐based systems to construct a robust overlapping strategy for sensor networks. The overall network is partitioned to several regions by a proposed multicriteria decision‐making controller to monitor both small‐scale and large‐scale areas. Each region is managed by a sink, where the whole network is managed by a base station. The sensor nodes are categorized by various clusters using the low‐energy adaptive clustering hierarchy (LEACH)‐improved protocol in a way that the value of p is defined by a proposed support vector machine–based mechanism. A proposed fuzzy system determines that noncluster heads associate with several clusters in order to manage overlapping conditions over the network. Cluster heads are changed into clusters in a period by a suggested utility function. Since network lifetime should be prolonged and network traffic should be alleviated, a data aggregation mechanism is proposed to transmit only crucial data packets from cluster heads to sinks. Cluster heads apply a weighted criteria matrix to perform an inner‐cluster routing for transmitting data packets to sinks. Simulation results demonstrate that the proposed protocol surpasses the existing methods in terms of the number of alive nodes, network lifetime, average time to recover, dead time of first node, and dead time of last node.