Privacy-preserving telecardiology sensor networks: toward a low-cost portable wireless hardware/software codesign.

Recently, a remote-sensing platform based on wireless interconnection of tiny ECG sensors called Telecardiology Sensor Networks (TSN) provided a promising approach to perform low-cost real-time cardiac patient monitoring at any time in community areas (such as elder nursing homes or hospitals). The contribution of this research is the design of a practical TSN hardware/software platform for a typical U.S. healthcare community scenario (such as large nursing homes with many elder patients) to perform real-time healthcare data collections. On the other hand, due to the radio broadcasting nature of MANET, a TSN has the risk of losing the privacy of patients' data. Medical privacy has been highly emphasized by U.S. Department of Health and Human Services. This research also designs a medical security scheme with low communication overhead to achieve confidential electrocardiogram data transmission in wireless medium.     

Power-aware routing protocols in ad hoc wireless networks

An ad hoc wireless network has no fixed networking infrastructure. It consists of multiple, possibly mobile, nodes that maintain network connectivity through wireless communications. Such a network has practical applications in areas where it may not be economically practical or physically possible to provide a conventional networking infrastructure. The nodes in an ad hoc wireless network are typically powered by batteries with a limited energy supply. One of the most important and challenging issues in ad hoc wireless networks is how to conserve energy, maximizing the lifetime of its nodes and thus of the network itself. Since routing is an essential function in these networks, developing power-aware routing protocols for ad hoc wireless networks has been an intensive research area in recent years. As a result, many power-aware routing protocols have been proposed from a variety of perspectives. This article surveys the current state of power-aware routing protocols in ad hoc wireless networks.     

Pervasive Healthcare and Wireless Health Monitoring

With an increasingly mobile society and the worldwide deployment of mobile and wireless networks, the wireless infrastructure can support many current and emerging healthcare applications. This could fulfill the vision of “Pervasive Healthcare” or healthcare to anyone, anytime, and anywhere by removing locational, time and other restraints while increasing both the coverage and the quality. In this paper, we present applications and requirements of pervasive healthcare, wireless networking solutions and several important research problems. The pervasive healthcare applications include pervasive health monitoring, intelligent emergency management system, pervasive healthcare data access, and ubiquitous mobile telemedicine. One major application in pervasive healthcare, termed comprehensive health monitoring is presented in significant details using wireless networking solutions of wireless LANs, ad hoc wireless networks, and, cellular/GSM/3G infrastructure-oriented networks. Many interesting challenges of comprehensive wireless health monitoring, including context-awareness, reliability, and, autonomous and adaptable operation are also presented along with several high-level solutions. Several interesting research problems have been identified and presented for future research.     

Quality-of-service in ad hoc carrier sense multiple access wirelessnetworks

Carrier sense multiple access (CSMA) is one of the most pervasive medium access control (MAC) schemes in ad hoc, wireless networks. However, CSMA and its current variants do not provide quality-of-service (QoS) guarantees for real-time traffic support. This paper presents and studies black-burst (BB) contention, which is a distributed MAC scheme that provides QoS real-time access to ad hoc CSMA wireless networks. With this scheme, real-time nodes contend for access to the channel with pulses of energy-so called BBs-the durations of which are a function of the delay incurred by the nodes until the channel became idle. It is shown that real-time packets are not subject to collisions and that they have access priority over data packets. When operated in an ad hoc wireless LAN, BB contention further guarantees bounded and typically very small real-time delays. The performance of the network can approach that attained under ideal time division multiplexing (TDM) via a distributed algorithm that groups real-time packet transmissions into chains. A general analysis of BB contention is given, contemplating several modes of operation. The analysis provides conditions for the scheme to be stable. Its results are complemented with simulations that evaluate the performance of an ad hoc wireless LAN with a mixed population of data and real-time nodes     

TCP Unfairness in Ad Hoc Wireless Networks and a Neighborhood RED Solution

Significant TCP unfairness in ad hoc wireless networks has been reported during the past several years. This unfairness results from the nature of the shared wireless medium and location dependency. If we view a node and its interfering nodes to form a “neighborhood”, the aggregate of local queues at these nodes represents the distributed queue for this neighborhood. However, this queue is not a FIFO queue. Flows sharing the queue have different, dynamically changing priorities determined by the topology and traffic patterns. Thus, they get different feedback in terms of packet loss rate and packet delay when congestion occurs. In wired networks, the Randomly Early Detection (RED) scheme was found to improve TCP fairness. In this paper, we show that the RED scheme does not work when running on individual queues in wireless nodes. We then propose a Neighborhood RED (NRED) scheme, which extends the RED concept to the distributed neighborhood queue. Simulation studies confirm that the NRED scheme can improve TCP unfairness substantially in ad hoc networks. Moreover, the NRED scheme acts at the network level, without MAC protocol modifications. This considerably simplifies its deployment.Kaixin Xu is a Ph.D student of the computer science department at UCLA. He joined the Network Research Lab. (NRL) of UCLA at 2000. His research focuses on the ad hoc wireless networking especially protocols at MAC, Network and Transport layers. His recently work includes enhancing TCP performance in multihop ad hoc networks, TCP performance in IEEE 802.11 MAC based ad hoc networks, as well as MAC protocols for utilizing directional antennas and mobility track. He’s also working on network protocols for building hierarchical ad hoc networks. E-mail: xkx@cs.ucla.eduMario Gerla was born in Milan, Italy. He received a graduate degree in engineering from the Politecnico di Milano, in1966, and the M.S. and Ph.D. degrees in engineering from UCLA in 1970 and 1973, respectively. He joined the Faculty of the UCLA Computer Science Department in 1977. His research interests cover the performance evaluation, design and control of distributed computer communication systems; high speed computer networks; wireless LANs (Bluetooth); ad hoc wireless networks. He has been involved in the design, implementation and testing of wireless ad hoc network protocols (channel access, clustering, routing and transport) within the DARPA WAMIS, GloMo projects and most recently the ONR MINUTEMAN project. He has also carried out design and implementation of QoS routing, multicasting protocols and TCP transport for the Next Generation Internet. He is currently an associate editor for the IEEE Transactions on Networking. E-mail: gerla@cs.ucla.eduLantao Qi received her B.E. and M.S. from the department of computer science at Tianjin University China in 2003. From 2000 to 2003 she engaged in research programs in the field of computer networks. Her major research focuses on buffer management, DIFFServ networks as well as mobile ad hoc networking. She has published many technical papers in this field. He recently joined the Agricultural Bank of China. E-mail: ltqi@tju.edu.cnYantai Shu is a professor of the computer science department at Tianjin University, China. He received his B.E., M.S., and Ph. D. degree in the electronics engineering department at Tianjin University. From 1974 to 1991, he was working as a researcher in the Institute of Plasma Physics, Academia Sinica. He has been serving as the vice president of the university from 1993 to 1997. His current research interests are focused on computer communication networks, wireless networks, real-time systems, modeling and simulation. He is a member of the IEEE and the ACM. He has published more than 120 papers and contributed to one book. E-mail:ytshu@tju.edu.cn     

The integration of ad hoc sensor and cellular networks for multi-class data transmission

This paper targets mobile telemedicine applications that can be supported using third generation (3G) cellular networks, to provide highly flexible medical services. On the other hand, large-scale Ad hoc Sensor Networks (ASN), when deployed among mobile patients who may carry different kinds of micro-sensors to measure ECG, blood pressure, basal temperature or other physiological data, can provide a dynamic data query architecture to allow the medical specialists to monitor patients at any place. So far very little research has been conducted to explore the possibility of integrating ASN with mobile telemedicine. In this paper: 1. we suggest an integrated architecture that takes advantage of the low cost mobile sensor networks and 3G cellular networks to support multimedia medical calls with differentiated Quality-of-Service (QoS) requirements. 2. We propose a low-energy, distributed, concentric-zone-based data query mechanism that has the advantages of both proactive and reactive ad hoc routing algorithms to collect medical results from large-scale mobile patients for medical specialists who use cellular network to report patient data to the medical center. 3. In order to minimize the ambulance wireless call-dropping rate, we adopt accurate resource reservation call admission control (CAC) scheme to allocate the necessary bandwidth in the destination cell. 4. In order to meet the QoS requirements of patients’ wireless calls, we use dynamic guard channel CAC scheme to keep their handoff-call dropping rate below a certain threshold. We evaluate the validity of our schemes through simulations and analyze their performance. Our results clearly indicate the efficiency of the proposed CAC and sensor network query algorithms to meet the multimedia telemedicine QoS requirements.     

D-PRMA：一种新的无线Ad Hoc网络资源预留MAC机制

支持资源预留的介质访问控制(MAC)机制是无线ad hoc网络提供服务质量保证的关键。本文在分析分组预留多址接入(PRMA)的基础上，给出了一种新的支持资源预留的无线ad hoc网络MAC机制：分布式PRMA(D-PRMA)。D—PRMA的主要特点是分布式的，这适合无线ad hoc网络无中心的特点，同时，D—PRMA具有很短的碰撞持续时间，支持不同速率的实时业务，避免了对分组的分片和重组。通过仿真，本文进一步分析了D—PRMA的性能，仿真结果表明D—PRMA能保证实时业务的带宽和时延。     

Multicasting with Localized Control in Wireless Ad Hoc Networks

This paper investigates how to support multicasting in wireless ad hoc networks without throttling the dominant unicast flows. Unicast flows are usually congestion-controlled with protocols like TCP. However, there are no such protocols for multicast flows in wireless ad hoc networks and multicast flows can therefore cause severe congestion and throttle TCP-like flows in these environments. Based on a cross-layer approach, this paper proposes a completely-localized scheme to prevent multicast flows from causing severe congestion and the associated deleterious effects on other flows in wireless ad hoc networks. The proposed scheme combines the layered multicast concept with the routing-based congestion avoidance idea to reduce the aggregated rate of multicast flows when they use excessive bandwidth on a wireless link. Our analysis and extensive simulations show that the fully-localized scheme proposed in this paper is effective in ensuring the fairness of bandwidth sharing between multicast and unicast flows in wireless ad hoc networks.     

An integrated communications framework for context aware continuous monitoring with body sensor networks

This paper deals with a wireless pervasive communication system to support advanced healthcare applications. The proposed system is based on an ad hoc interaction of mobile body sensor networks with independent wireless sensor networks already deployed within the environments in order to allow a continuous and context aware health monitoring for patients along their daily life scenarios with an unprecedented precision and flexibility of sensing. After an accurate protocol characterization, simulation results are provided, underlining remarkable performance with respect to existing solutions, for different mobility models and node density values.     

Pervasive, secure access to a hierarchical sensor-based healthcare monitoring architecture in wireless heterogeneous networks

This study presents a healthcare monitoring architecture coupled with wearable sensor systems and an environmental sensor network for monitoring elderly or chronic patients in their residence. The wearable sensor system, built into a fabric belt, consists of various medical sensors that collect a timely set of physiological health indicators transmitted via low energy wireless communication to mobile computing devices. Three application scenarios are implemented using the proposed network architecture. The group-based data collection and data transmission using the ad hoc mode promote outpatient healthcare services for only one medical staff member assigned to a set of patients. Adaptive security issues for data transmission are performed based on different wireless capabilities. This study also presents a monitoring application prototype for capturing sensor data from wireless sensor nodes. The implemented schemes were verified as performing efficiently and rapidly in the proposed network architecture.     

Intrusion detection techniques in mobile ad hoc and wireless sensor networks

Mobile ad hoc networks and wireless sensor networks have promised a wide variety of applications. However, they are often deployed in potentially adverse or even hostile environments. Therefore, they cannot be readily deployed without first addressing security challenges. Intrusion detection systems provide a necessary layer of in-depth protection for wired networks. However, relatively little research has been performed about intrusion detection in the areas of mobile ad hoc networks and wireless sensor networks. In this article, first we briefly introduce mobile ad hoc networks and wireless sensor networks and their security concerns. Then, we focus on their intrusion detection capabilities. Specifically, we present the challenge of constructing intrusion detection systems for mobile ad hoc networks and wireless sensor networks, survey the existing intrusion detection techniques, and indicate important future research directions.     

An energy-efficient MAC protocol based on IEEE 802.11 in wireless ad hoc networks

Energy efficiency is a measure of the performance of IEEE 802.11 wireless multihop ad hoc networks. The IEEE 802.11 standard, currently used in wireless multihop ad hoc networks, wastes bandwidth capacity and energy resources because of many collisions. Therefore, controlling the contention window size at a given node will increase not only the operating life of the battery but also the overall system capacity. It is essential to develop effective backoff schemes for saving power in IEEE 802.11 wireless multihop ad hoc networks. In this paper, we propose an energy-efficient backoff scheme and evaluate its performance in an ad hoc network. Our contention window mechanism devised by us grants a node access to a channel on the basis of the node’s percentage of residual energy. We use both an analytical model and simulation experiments to evaluate the effective performance of our scheme in an ad hoc network. Our extensive ns-2-based simulation results have shown that the proposed scheme provides excellent performance in terms of energy goodput, end-to-end goodput, and packet delivery ratio, as well as the end-to-end delay.     

A quantitative comparison of ad hoc routing protocols with and without channel adaptation

To efficiently support tetherless applications in ad hoc wireless mobile computing networks, a judicious ad hoc routing protocol is needed. Much research has been done on designing ad hoc routing protocols and some well-known protocols are also being implemented in practical situations. However; one major imperfection in existing protocols is that the time-varying nature of the wireless channels among the mobile-terminals is ignored; let alone exploited. This could be a severe design drawback because the varying channel quality can lead to very poor overall route quality in turn, resulting in low data throughput. Indeed, better performance could be achieved if a routing protocol dynamically changes the routes according to the channel conditions. In this paper, we first propose two channel adaptive routing protocols which work by using an adaptive channel coding and modulation scheme that allows a mobile terminal to dynamically adjust the data throughput via changing the amount of error protection incorporated. We then present a qualitative and quantitative comparison of the two classes of ad hoc routing protocols. Extensive simulation results indicate that channel adaptive ad hoc routing protocols are more efficient in that shorter delays and higher rates are achieved, at the expense of a higher overhead in route set-up and maintenance.     

Security issues of wireless sensor networks in healthcare applications

The emergence of wireless sensor networks (WSNs) in healthcare applications is gaining momentum through the increasing array of wearable vital sign sensors and location tags which can track both healthcare personnel and patient status/ location continuously in real-time mode. Despite the increased range of potential application frameworks — ranging from pre-hospital, in-hospital, ambulatory and home monitoring, to long-term database collection for longitudinal trend analysis — the security gap between existing WSN designs and the requirements of medical applications remains unresolved. Generally, WSN devices are extremely limited in terms of power, computation, and communication. They are often deployed in accessible areas, thus increasing security vulnerabilities. The dynamic ad hoc topology, multicast transmission, location awareness, critical data prioritisation, and co-ordination of diverse sensors of healthcare applications further exacerbate the security challenges. This paper presents an analysis of various WSN security mechanisms from the demanding perspective of healthcare applications, and considers the importance of security to the successful deployment of pervasive computing solutions in the healthcare industry.     

Ad hoc技术

Ad　hoc技术是从无线移动Ad　hoc网络(WMANET)抽象出来的一个一般性概念，该项技术所标称的是自组识、多跳的一个临时分布式系统，是一种网络构架技术。它要面临多项难题。本文就是从OSI模型的角度把Ad　hoc技术分层介绍，最后给出了一种WMANET应用方案。     

A secure mobile healthcare system using trust-based multicast scheme

Due to the introduction of telecommunication technologies in telemedicine services, the expeditious development of wireless and mobile networks has stimulated wide applications of mobile electronic healthcare systems. However, security is an essential system requirement since many patients have privacy concerns when it comes to releasing their personal information over the open wireless channels. For this reason, this study discusses the characteristics and security issues with wireless and pervasive data communications for a ubiquitous and mobile healthcare system which consists of a number of mobile devices and sensors attached to a patient. These devices form a mobile ad hoc sensor network and collect data that are sent to a hospital or healthcare center for monitoring. Subsequently, this paper discusses the innovation and design of a novel trust evaluation model. We then propose a secure multicast strategy that employs trust in order to evaluate the behavior of each node, so that only trustworthy nodes are allowed to participate in communications, while the misbehavior of malicious nodes is effectively prevented. We analyze the security properties of our multicast scheme and evaluate its performance based on simulation experiments. Our experimental results demonstrate that our scheme not only achieves the necessary data transmission in mobile environments, but also provides more security with reasonably little additional overhead.     

Multipath video transport over ad hoc networks

Real-time multimedia transport has stringent bandwidth, delay, and loss requirements. It is a great challenge to support such applications in wireless ad hoc networks, which are characterized by frequent link failures and congestion. Using multiple paths in parallel for a real-time multimedia session (called multipath transport) provides a new degree of freedom in designing robust multimedia transport systems. In this article, we describe a framework for multipath video transport over wireless ad hoc networks, and examine its essential components, including multistream video coding, multipath routing, and transport mechanisms. We illustrate by three representative examples how to extend existing video coding schemes in order to fully explore the potential of multipath transport. We also examine important mechanisms in different layers for supporting multipath video transport over ad hoc networks. Our experiments show that multipath transport is a promising technique for efficient video communications over ad hoc networks.     

窄带无线自组网在应急语音通信中的实战性应用研究

在现代通信技术快速发展的背景下,应急语音通信作为应对突发自然灾害的重要手段,近年来得到了广泛重视。结合应急通信的实战需求,探讨了新一代窄带自组网通信技术的在应急通信领域的创新应用。根据我国实际情况提出了现有窄带应急通信的问题和需求,然后介绍并分析了窄带自组网的原理和特点,其具有通信覆盖面积广、抗毁性强、维护简单以及成本低等优势,极好地满足了目前偏远地区窄带应急语音通信的需要。最后,结合实际案例阐述了窄带自组网作为应急语音通信网的应用优势,初步证明了该应用的可行性。