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

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

The SWAP specification for wireless voice and data networking within the home will enable a new class of mobile consumer devices that draw from the power and content of the Internet and the home PC. If cable modems and xDSL represent the "last mile" access to the home, then HomeRF/sup TM/'s mission with SWAP could be called the "very last 150 feet" within and around the home. HomeRF has the broad backing of the major corporate stakeholders for networking within the home and is optimized specifically for the cost/performance point needed for consumers. The technology leverages the existing PC-industry infrastructure around the Internet, TCP/IP, and Ethernet, and adds a standard way to connect to the PSTN for voice telephony. First products should appear in late 1999, and future versions with enhanced features and/or higher data rates should follow in one to two years.

HomeRF: wireless networking for the connected home

The Shared Wireless Aaccess Protocol (SWAP) specification for wireless voice and data networking within the home will enable a new class of mobile consumer devices that draw from the power and content of the Internet and the Home PC. If cable modems and xDSL represent the "last mile" access to the home, then HomeRFTM's mission with SWAP could be called the "very last 150 feet" within and around the home. HomeRFTM has the broad backing of the major corporate stakeholders for networking within the home and is optimized specifically for the cost/performance point needed for consumers. The technology leverages the existing PC-industry infrastructure around the Internet, TCP/IP and Ethernet and adds a standard way to connect to the Public Switched Telephone Network (PSTN) for voice telephony. First products should appear in late 1999 and future versions with enhanced features and/or higher data rates should follow by 1--2 years.

HomeRF™ and SWAP: wireless networking for the connected home

A combined IEEE 1394-2000 and ethernet network allows devices on the network to operate according to both the IEEE 1394-2000 protocol and the ethernet protocol. The devices within the network are able to send IEEE 1394-2000 isochronous data, IEEE 1394-2000 asynchronous data and ethernet data. Both IEEE 1394-2000 and ethernet devices within the network are coupled to modified hubs (MHubs) to form a local cluster. The MHubs are coupled to an ethernet switch which controls communications between devices in different local clusters. The ethernet switch and the MHubs obey an isochronous interval in which all isochronous data transfers will be allowed. Preferably, on a regular and reoccurring period, the ethernet switch sends an isotick signal to begin the isochronous interval. Any bandwidth left after the isochronous interval is then allocated to the traditional ethernet traffic and the IEEE 1394-2000 asynchronous traffic, until the start of the next isochronous interval.

Method of and apparatus for providing isochronous services over switched ethernet including a home network wall plate having a combined IEEE 1394 and ethernet modified hub

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

C. Romans

Papers

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