This paper describes two techniques that improve throughput in an ad hoc network in the presence of nodes that agree to forward packets but fail to do so. To mitigate this problem, we propose categorizing nodes based upon their dynamically measured behavior. We use a watchdog that identifies misbehaving nodes and a pathrater that helps routing protocols avoid these nodes. Through simulation we evaluate watchdog and pathrater using packet throughput, percentage of overhead (routing) transmissions, and the accuracy of misbehaving node detection. When used together in a network with moderate mobility, the two techniques increase throughput by 17% in the presence of 40% misbehaving nodes, while increasing the percentage of overhead transmissions from the standard routing protocol's 9% to 17%. During extreme mobility, watchdog and pathrater can increase network throughput by 27%, while increasing the overhead transmissions from the standard routing protocol's 12% to 24%.

/pdf/mitigating-routing-misbehavior-in-mobile-ad-hoc-networks-3fdj9bxaq3.pdf

Mitigating routing misbehavior in mobile ad hoc networks

Multi-frequency media access control has been well understood in general wireless ad hoc networks, while in wireless sensor networks, researchers still focus on single frequency solutions. In wireless sensor networks, each device is typically equipped with a single radio transceiver and applications adopt much smaller packet sizes compared to those in general wireless ad hoc networks. Hence, the multi-frequency MAC protocols proposed for general wireless ad hoc networks are not suitable for wireless sensor network applications, which we further demonstrate through our simulation experiments. In this paper, we propose MMSN, which takes advantage of multi-frequency availability while, at the same time, takes into account the restrictions in wireless sensor networks. In MMSN, four frequency assignment options are provided to meet different application requirements. A scalable media access is designed with efficient broadcast support. Also, an optimal non-uniform backoff algorithm is derived and its lightweight approximation is implemented in MMSN, which significantly reduces congestion in the time synchronized media access design. Through extensive experiments, MMSN exhibits prominent ability to utilize parallel transmission among neighboring nodes. It also achieves increased energy efficiency when multiple physical frequencies are available.

/pdf/mmsn-multi-frequency-media-access-control-for-wireless-1og1d8x7bs.pdf

MMSN: Multi-Frequency Media Access Control for Wireless Sensor Networks

Low voltage electrical wiring has largely been dismissed as too noisy and unpredictable to support high-speed communication signals. Advances in communication and modulation methodologies as well as in adaptive digital signal processing and error detection and correction have spawned novel protocols capable of supporting power line communication networks at speeds comparable to wired LANs. We motivate the use of power line LANs as a basic infrastructure for building integrated smart homes, wherein information appliances ranging from simple control or monitoring devices to multimedia entertainment systems are seamlessly interconnected by the very wires that provide them electricity. By simulation and actual measurements using "reference design" prototype commercial powerline products, we show that the HomePlug MAC and PHY layers can guarantee QoS for real-time communications, supporting delay-sensitive data streams for smart home applications.

A power line communication network infrastructure for the smart home

Future wireless networks must be able to coordinate services within a diverse-network environment. One of the challenging problems for coordination is vertical handoff, which is the decision for a mobile node to handoff between different types of networks. While traditional handoff is based on received signal strength comparisons, vertical handoff must evaluate additional factors, such as monetary cost, offered services, network conditions, and user preferences. In this paper, several optimizations are proposed for the execution of vertical handoff decision algorithms, with the goal of maximizing the quality of service experienced by each user. First, the concept of policy-based handoffs is discussed. Then, a multiservice vertical handoff decision algorithm (MUSE-VDA) and cost function are introduced to judge target networks based on a variety of user- and network-valued metrics. Finally, a performance analysis demonstrates that significant gains in the ability to satisfy user requests for multiple simultaneous services and a more efficient use of resources can be achieved from the MUSE-VDA optimizations.

/pdf/multiservice-vertical-handoff-decision-algorithms-3us4azur82.pdf

Multiservice vertical handoff decision algorithms

Sensor networks, usually built with a large number of small, low-cost sensor devices, are characterized by their large-scale and unattended deployment that invites many critical attacks, thereby necessitating high-level security support for their intended applications and services. However, making sensor networks secure is challenging due mainly to the fact that sensors are battery-powered and it is often very difficult to change or recharge their batteries. To address this challenge, we design, develop and evaluate Lightweight S ecurity Protocols (LiSP) that cooperatively build a unified, energy-efficient security framework for sensor networks. 
We present two (group-based and distributed) key management/sharing schemes that are tailored to local and remote transactions, respectively. While the group-based scheme achieves efficient and robust re-keying via key broadcasting/authentication/recovery, distributed key sharing enables the development of attack-tolerant routing protocols capable of gracefully resisting device compromises as well as replacing resource-expensive, public-key-cipher-based protocols with a purely symmetric-cipher-based alternative. 
The problem of attack-tolerance is further investigated for the development of a secure localization protocol. The proposed protocol uses mutual collaboration among sensors to achieve high-level attack-tolerance in terms of detecting/identifying/rejecting sources of attacks, if present. Accordingly, it plays the role of an anomaly-based intrusion detection system tailored to localization that safeguards the network from localization-targeted attacks. 
As a countermeasure against physically tampering with sensors, we develop a novel soft tamper-proofing technique that verifies integrity of the program residing in each sensor device whenever it joins the network, or is suspected to have been compromised. Unlike other techniques unsuitable for low-cost, resource-limited sensors, our technique augments such sensors to be usable for applications that require high-level security. 
Finally, the benefits of our protocols are demonstrated via analysis and evaluation of their capability to defeat known security attacks, and their performance in terms of processing, communication and memory overheads.

http://www.123seminarsonly.com/Seminar-Reports/037/Security-Protocols-for-Sensor-Network.pdf

Lisp: lightweight security protocols for wireless sensor networks

This paper presents a scheme to improve the efficiency of radio MAC protocols in the case of broadcast and multicast transmissions, like TCP/IP multicasting. First, the reliability problems with broadcast packets and their consequences are analysed. Then the robust broadcast scheme is presented, which decreases the probability of loss of broadcast packets over MAC protocols based on CSMA/CA. Finally, the new protocol is simulated against other simple solutions to show how it performs.

http://www.hpl.hp.com/techreports/98/HPL-98-38.pdf

Robust broadcast: improving the reliability of broadcast transmissions on CSMA/CA

This paper describes a novel approach to using peer to peer wireless links, such as IrDA, Bluetooth and 802.11b. We explain the concept of wireless diversity and its impact on developers and users. We also explore the limitations of classical vertical handoff protocols, such as the need of an infrastructure. We describe our connection diversity framework, upon which is built P-Handoff. We introduce P-Handoff, a new handoff protocol for peer to peer links with fine granularity, which complements vertical handoff and allows to optimise connectivity through multiple wireless links; P-Handoff doesn't require an infrastructure and uses link layer events. We describe some features of our implementation under Linux.

P-Handoff: a protocol for fine grained peer-to-peer vertical handoff

In this paper we present a medium access control (MAC) protocol for a wireless LAN which is designed to support both isochronous (voice) and asynchronous (data) traffic. The protocol is designed for use in a frequency hopping system and uses a TDMA access protocol to support voice and a CSMA/CA access protocol to support data. A wireless LAN using this protocol can be operated as either an ad-hoc network (in which case only the data service is supported) or as a managed network under the control of a control point or base station (in which case the voice service is also supported).

http://www.hpl.hp.com/techreports/98/HPL-98-35.pdf

A medium access protocol for wireless LANs which supports isochronous and asynchronous traffic

This paper introduces the concept of inter-domain mobility, to allow users to migrate their connectivity between different network domains. Most current mobility techniques are not well suited to handle inter-domain mobility. We present L7-mobility, a simple extension of the current mobility practices for inter-domain mobility, which adds support for both hot and policy mobility. L7-mobility makes extensive use of our connection diversity framework and its connection manager to simplify implementation. We implemented L7-mobility in an HTTP proxy, which allowed us to evaluate the complexity, deployment and performance of this new technique.

http://www.hpl.hp.com/techreports/2004/HPL-2004-31.pdf

J. Tourrilhes

Papers

Robust broadcast: improving the reliability of broadcast transmissions on CSMA/CA

P-Handoff: a protocol for fine grained peer-to-peer vertical handoff

A medium access protocol for wireless LANs which supports isochronous and asynchronous traffic

L7-mobility: a framework for handling mobility at the application level