Energy Efficient Reliable Multi-path Data Transmission in WSN for Healthcare Application

In healthcare applications of WSN, the data loss due to congestion may cause death alarm for a patient in critical condition. Therefore, an efficient congestion avoidance or otherwise an efficient congestion control mechanism is required. In this paper, we present an energy efficient reliable multi-path data transmission protocol for reliable data transport over WSN for the health care application. The emergency data and sensitive data packets are transmitted through an alternate path having minimum correlation with transmission interference during congestion. The proposed protocol attempts to avoid congestion by computing the probability of congestion at the intermediate nodes and transmission rate at the intermediate node is adjusted. The buffer of each node is partitioned to support fair and efficient data delivery. The reliability of the proposed protocol is achieved through hop-by-hop loss recovery and acknowledgement. The performance of the proposed protocol is evaluated through extensive simulations. The simulation results reveal that it outperforms the existing congestion control protocols for healthcare application in terms of energy efficiency, reliability and end-to-end delivery ratio.     

Adaptive Load-Aware Congestion Control Protocol for Wireless Sensor Networks

Congestion control in wireless sensor networks (WSNs) is crucial. In this article, we discuss congestion control and the adaptive load-aware problem for sensor nodes in WSNs. When the traffic load of a specific node exceeds its the available capacity of the node, a congestion problem occurs because of buffer memory overflow. Congestion may cause serious problems such as packet loss, the consumption of power, and low network throughput for sensor nodes. To address these problems, we propose a distributed congestion control protocol called adaptive load-aware congestion control protocol (ALACCP). The protocol can adaptively allocate the appropriate forwarding rate for jammed sensor nodes to mitigate the congestion load. Through the buffer management mechanism, the congestion index of neighboring sensor nodes, and an adjustment of the adaptive forwarding rate, the degree of congestion is alleviated markedly. The performance in allocating the forwarding rate effectively to neighboring sensor nodes also improves. The ALACCP can avoid packet loss because of traffic congestion, reduce the power consumption of nodes, and improve the network throughput. Simulation results revealed that the proposed ALACCP can effectively improve network performance and maintain the fairness of networks.     

基于拥塞预知的WSN多径寻优路由协议

针对无线传感器网络中常出现传输拥塞的问题,该文提出了一种基于拥塞预知的多径寻优路由协议(MOPC)。该协议基于主动避免拥塞的设计思想,依据节点的拥塞预知度、剩余能量和最小跳数建立路径满意度模型,实现了最优路径的选取;通过设定最优路径上节点的转发满意度变化率阈值,实现局部路由的动态维护。仿真结果表明,该协议具有良好的实时性和可靠性,并能显著提高能量利用率,延长网络生命期。     

基于Hadoop的交通数据分析系统

为了保证交通数据处理的实时性和存储的扩展性,文中设计并实现了一种交通大数据分析系统,其中Hadoop平台利用MapReduce并行分布式计算对车辆数据进行统计分析;另一个Storm平台利用其流计算组件对实时路况进行分析,两个模块协同作用,能对缓解城市交通拥堵起到一定的作用。通过测试表明,系统可靠性
较高、计算速率快,能达到支持决策的作用。     

A comparison of mechanisms for improving TCP performance overwireless links

Reliable transport protocols such as TCP are tuned to perform well in traditional networks where packet losses occur mostly because of congestion. However, networks with wireless and other lossy links also suffer from significant losses due to bit errors and handoffs. TCP responds to all losses by invoking congestion control and avoidance algorithms, resulting in degraded end-to end performance in wireless and lossy systems. We compare several schemes designed to improve the performance of TCP in such networks. We classify these schemes into three broad categories: end-to-end protocols, where loss recovery is performed by the sender; link-layer protocols that provide local reliability; and split-connection protocols that break the end-to-end connection into two parts at the base station. We present the results of several experiments performed in both LAN and WAN environments, using throughput and goodput as the metrics for comparison. Our results show that a reliable link-layer protocol that is TCP-aware provides very good performance. Furthermore, it is possible to achieve good performance without splitting the end-to-end connection at the base station. We also demonstrate that selective acknowledgments and explicit loss notifications result in significant performance improvements     

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.     

Event-to-sink reliable transport in wireless sensor networks

Wireless sensor networks (WSNs) are event-based systems that rely on the collective effort of several microsensor nodes. Reliable event detection at the sink is based on collective information provided by source nodes and not on any individual report. However, conventional end-to-end reliability definitions and solutions are inapplicable in the WSN regime and would only lead to a waste of scarce sensor resources. Hence, the WSN paradigm necessitates a collective event-to-sink reliability notion rather than the traditional end-to-end notion. To the best of our knowledge, reliable transport in WSN has not been studied from this perspective before. In order to address this need, a new reliable transport scheme for WSN, the event-to-sink reliable transport (ESRT) protocol, is presented in this paper. ESRT is a novel transport solution developed to achieve reliable event detection in WSN with minimum energy expenditure. It includes a congestion control component that serves the dual purpose of achieving reliability and conserving energy. Importantly, the algorithms of ESRT mainly run on the sink, with minimal functionality required at resource constrained sensor nodes. ESRT protocol operation is determined by the current network state based on the reliability achieved and congestion condition in the network. This self-configuring nature of ESRT makes it robust to random, dynamic topology in WSN. Furthermore, ESRT can also accommodate multiple concurrent event occurrences in a wireless sensor field. Analytical performance evaluation and simulation results show that ESRT converges to the desired reliability with minimum energy expenditure, starting from any initial network state.     

Stable routing algorithm for mobile ad hoc networks using mobile agent

Wireless ad hoc networks are growing important because of their mobility, versatility, and ability to work with fewer infrastructures. The mobile ad hoc network is an autonomous system consisting of mobile nodes connected with wireless links. Establishing a path between two nodes is a complex task in wireless networks. It is still more complex in the wireless mobile ad hoc network because every node is no longer as an end node and an intermediate node. In this paper, it focuses on design of connectionless routing protocol for the wireless ad hoc networks based on the mobile agent concept. The proposed model tries to discover the best path taking into consideration some concerns like bandwidth, reliability, and congestion of the link. The proposed model has been simulated and tested under various wireless ad hoc network environments with the help of a different number of nodes. The results demonstrate that the proposed model is more feasible for providing reliable paths between the source and destination with the minimum control message packets over the network. It has delivered more number of packets to the destination over the network. Copyright © 2012 John Wiley & Sons, Ltd.     

On Packet Switches with Infinite Storage

Most prior work on congestion in datagram systems focuses on buffer management. We find it illuminating to consider the case of a packet switch with infinite storage. Such a packet switch can never run out of buffers. It can, however, still become congested. The meaning of congestion in an infinite-storage system is explored. We demonstrate the unexpected result that a datagram network with infinite storage, first-in, first-out queueing, at least two packet switches, and a finite packet lifetime will, under overload, drop all packets. By attacking the problem of congestion for the infinite-storage case, we discover new solutions applicable to switches with finite storage.     

基于蚁群优化算法的路由协议的研究

生物仿真学群集算法在路由中有广泛的的应用,为了充分利用网络资源,降低拥塞程度,提出了一种基于蚁群优化算法的Ad Hoc网络负载均衡路由算法Pro-antnet,通过对蚂蚁收集到的网络信息所对应的参数赋予不同加权值的方法对路由表进行控制,有效地缓解了网络的拥塞问题。该算法具有良好的分布式特性,能为网络提供多条备用路径,增强网络的抗毁性。     

Delay aware reliable transport in wireless sensor networks

Wireless sensor networks (WSN) are event‐based systems that rely on the collective effort of several sensor nodes. Reliable event detection at the sink is based on collective information provided by the sensor nodes and not on any individual sensor data. Hence, conventional end‐to‐end reliability definitions and solutions are inapplicable in the WSN regime and would only lead to a waste of scarce sensor resources. Moreover, the reliability objective of WSN must be achieved within a certain real‐time delay bound posed by the application. Therefore, the WSN paradigm necessitates a collective delay‐constrained event‐to‐sink reliability notion rather than the traditional end‐to‐end reliability approaches. To the best of our knowledge, there is no transport protocol solution which addresses both reliability and real‐time delay bound requirements of WSN simultaneously. In this paper, the delay aware reliable transport (DART) protocol is presented for WSN. The objective of the DART protocol is to timely and reliably transport event features from the sensor field to the sink with minimum energy consumption. In this regard, the DART protocol simultaneously addresses congestion control and timely event transport reliability objectives in WSN. In addition to its efficient congestion detection and control algorithms, it incorporates the time critical event first (TCEF) scheduling mechanism to meet the application‐specific delay bounds at the sink node. Importantly, the algorithms of the DART protocol mainly run on resource rich sink node, with minimal functionality required at resource constrained sensor nodes. Furthermore, the DART protocol can accommodate multiple concurrent event occurrences in a wireless sensor field. Performance evaluation via simulation experiments show that the DART protocol achieves high performance in terms of real‐time communication requirements, reliable event detection and energy consumption in WSN. Copyright © 2007 John Wiley & Sons, Ltd.     

流控制传输协议研究

文章介绍了流控制传输协议(SCTP)的主要特点:支持多穴主机,支持消息的无序递交,提供端到端的可靠性,提供面向消息的传输,提供相对TCP增强的流量控制和拥塞控制,提供更好的安全性和可扩展性;分析了SCTP的主要应用,强调作为一种通用的传输层协议SCTP是今后发展的方向;综合考察了当前SCTP的研究进展,并给出了相关结论,认为SCTP是一种功能强大的传输层协议.     

Management of cognitive radio ad hoc networks using a congestion‐based metric

In this paper, we propose a new network management protocol to address the unique challenges of managing cognitive radio ad hoc networks that have distributed, multihop architectures with dynamic spectrum availability. We focus on performance management for these networks, and address the problem of network congestion for secondary users, because of its significant impact on data throughput. Specifically, we define a performance metric, the average congestion level of the network, and derive it analytically as a function of the primary users’ activities and the secondary users’ strategy. For practical implementation, we further propose a cluster‐based management architecture that utilizes a designated central manager and cluster heads that function as distributed managers. The cluster heads collect information from multiple layers of the protocol stack using new MIB (management information base) variables to capture the characteristics of cognitive radio ad hoc networks, such as the location‐dependent spectrum availability. The objective of the management action is to utilize a network‐level view of the congestion situation in the network by directing the secondary users to select the highest‐quality links available and avoid congested clusters. This hierarchical networkmanagement design allows us to take advantage of its scalability to achieve near‐real‐time management. Numerical results demonstrate the effectiveness of the proposed scheme. Copyright © 2013 John Wiley & Sons, Ltd.     

Optimized Congestion Management Protocol for Healthcare Wireless Sensor Networks

The application of Wireless Sensor Networks (WSNs) in healthcare is dominant and fast growing. In healthcare WSN applications (HWSNs) such as medical emergencies, the network may encounter an unpredictable load which leads to congestion. Congestion problem which is common in any data network including WSN, leads to packet loss, increasing end-to-end delay and excessive energy consumption due to retransmission. In modern wireless biomedical sensor networks, increasing these two parameters for the packets that carry EKG signals may even result in the death of the patient. Furthermore, when congestion occurs, because of the packet loss, packet retransmission increases accordingly. The retransmission directly affects the lifetime of the nodes. In this paper, an Optimized Congestion management protocol is proposed for HWSNs when the patients are stationary. This protocol consists of two stages. In the first stage, a novel Active Queue Management (AQM) scheme is proposed to avoid congestion and provide quality of service (QoS). This scheme uses separate virtual queues on a single physical queue to store the input packets from each child node based on importance and priority of the source’s traffic. If the incoming packet is accepted, in the second stage, three mechanisms are used to control congestion. The proposed protocol detects congestion by a three-state machine and virtual queue status; it adjusts the child’s sending rate by an optimization function. We compare our proposed protocol with CCF, PCCP and backpressure algorithms using the OPNET simulator. Simulation results show that the proposed protocol is more efficient than CCF, PCCP and backpressure algorithms in terms of packet loss, energy efficiency, end-to-end delay and fairness.     

卫星数据接收站中网络协议的应用

卫星信号通过数据接收站传送到地面网络再分发给不同的用户。数据接收站将承担陆地观测卫星的接收任务,并继续承担国外相关卫星的接收、处理与分发的任务。延时长信道的传输速率受限降低了TCP协议拥塞控制和流量恢复策略的性能。主要讨论了卫星数据接收站采用组播的方式与数据存储或其他数据管理分系统互连,并通过TCP/IP协议与中心站互通。     

An overview of reliable multicast transport protocol II

This document provides an overview of the reliable multicast transport protocol II, RMTP-II. RMTP-II is a reliable multicast protocol, designed to reliably and efficiently send data from a few senders to large groups of simultaneous recipients. It works over both symmetric networks and asymmetrical network topologies such as those provided by satellite, cable modem, or ADSL carriers. Before sending, each sender must connect with a trusted top node to receive permission and control parameters for its data stream. The top node provides network managers with a single point of control for the senders, allowing them to monitor and control the traffic being sent. RMTP-II builds on a rich field of existing work, and adds to it the following novel contributions. It differentiates the roles of the nodes in the protocol, provides algorithms for smoothing and control of the return (TRACK) traffic, and provides explicit support for highly asymmetrical networks. It provides explicit network management controls through a centralized point of control, a fully distributed membership protocol that enables positive confirmation of data delivery, and fault recovery algorithms which are integrated to the reliability semantics of the protocol. It includes a novel reliability level called time bounded reliability, and offers a unique combination of TRACKs, NACKs, and FEC for increased scalability and real-time performance. Finally, it integrates distributed algorithms for RTT calculation to each receiver, and provides automatic configuration of receiver nodes     

基于模糊门限的分布式数据存储系统

如何在高速发展的网络环境下构建大规模、高性能、高可靠性及高可扩展性的分布式存储系统,是分布式存储技术面I临的新发展课题。利用Shamir门限方案分割秘密方法的重要思想对共享数据进行分割,并将得到不同的份额再根据模糊数学中的隶属度来构造出子数据集,而后将子数据集分发给各参与者进行存储,根据用户的需要进行数据恢复。核心是把分割生成的子数据扩充生成子数据集,以此来增强数据恢复的可靠性。     

Secure group key management for storage area networks

Storage area networks offer high availability, reliability, and scalability, and are a promising solution for large-scale storage needs of many enterprises. As with any distributed storage system, a major design challenge for SANs is to provide secure storage, which implies data integrity and data confidentiality. In this article we propose a solution that addresses these core security requirements. In particular, we focus on mechanisms that enable efficient key management for SAN entities and allow scalable data sharing. We use strong cryptographic techniques to achieve data security and integrity. Further, we delegate the bulk of the cryptographic processing to the SAN entities, thereby removing bottlenecks at disks and causing minimal inconvenience to hosts. By recognizing the peer nature of the group of SAN entities, we propose a novel security architecture for SAN that uses a secure group communication protocol to provide efficient group keying without involving any centralized servers. This fosters both scalability and fault tolerance.     

Improving stream control transmission protocol performance over lossy links

The current stream control transmission protocol (SCTP) does not work well over lossy links. To make SCTP congestion control algorithms robust in lossy networks, the paper first introduces a fine-tuned explicit congestion notification (ECN) mechanism for SCTP in such environment, and then discusses the ECN-D SCTP that can differentiate noncongestion losses from congestion losses. We identify the optimal value of the congestion window for an SCTP source in response to ECN messages in order to maximize the throughput and maintain relatively small end-to-end delay. A simple and practical method to achieve the optimal value is developed by carefully choosing the threshold of queues that support ECN. Because the total goodput performance of SCTP associations is not sensitive to window reduction policies when the network load is heavy, and because fine-tuning SCTP or transmission control protocols congestion window in response to congestion indications using complicated methods may not be worth the increase in complexity of the protocol, the simplified method becomes attractive in achieving the optimal congestion window.     

一种在接收端实现的TCP-Friendly拥塞控制机制

本文提出了一种基于速率的单播TCP-Friendly拥塞控制算法——RAAR(Rate Adaptation at Receivers)控制机制.RAAR是一种接收端的速率自适应算法,它抛弃了每包反馈机制,采用GAIMD(General Additive Increase Multiplicative Decrease)策略进行拥塞控制,其主要控制操作由接收方完成.本文建立了简化的数学模型对其进行吞吐量的分析,得到在RAAR中用于TCP-Friendly 的GAIMD拥塞控制中α与 β的关系.通过与TFRC及TEAR这两种重要的TCP-Friendly协议进行对比研究发现,RAAR协议在对TCP协议的友好性,协议内的公平性以及速率的平滑性等方面具有更好的综合性能.由于RAAR不需进行每包反馈,且主要功能在接收方实现,因此可方便地将该机制引入多媒体组播传输系统中.