An ad-hoc network is the cooperative engagement of a collection of mobile nodes without the required intervention of any centralized access point or existing infrastructure. We present Ad-hoc On Demand Distance Vector Routing (AODV), a novel algorithm for the operation of such ad-hoc networks. Each mobile host operates as a specialized router, and routes are obtained as needed (i.e., on-demand) with little or no reliance on periodic advertisements. Our new routing algorithm is quite suitable for a dynamic self starting network, as required by users wishing to utilize ad-hoc networks. AODV provides loop-free routes even while repairing broken links. Because the protocol does not require global periodic routing advertisements, the demand on the overall bandwidth available to the mobile nodes is substantially less than in those protocols that do necessitate such advertisements. Nevertheless we can still maintain most of the advantages of basic distance vector routing mechanisms. We show that our algorithm scales to large populations of mobile nodes wishing to form ad-hoc networks. We also include an evaluation methodology and simulation results to verify the operation of our algorithm.

/pdf/ad-hoc-on-demand-distance-vector-routing-3w61wv0p1h.pdf

Ad-hoc on-demand distance vector routing

Broadcasting is a common operation in a network to resolve many issues. In a mobile ad hoc network (MANET) in particular, due to host mobility, such operations are expected to be executed more frequently (such as finding a route to a particular host, paging a particular host, and sending an alarm signal). Because radio signals are likely to overlap with others in a geographical area, a straightforward broadcasting by flooding is usually very costly and will result in serious redundancy, contention, and collision, to which we call the broadcast storm problem. In this paper, we identify this problem by showing how serious it is through analyses and simulations. We propose several schemes to reduce redundant rebroadcasts and differentiate timing of rebroadcasts to alleviate this problem. Simulation results are presented, which show different levels of improvement over the basic flooding approach.

/pdf/the-broadcast-storm-problem-in-a-mobile-ad-hoc-network-2ovgqt6pyc.pdf

The broadcast storm problem in a mobile ad hoc network

It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity. >

On the capacity of a cellular CDMA system

We present a suite of algorithms for self-organization of wireless sensor networks in which there is a scalably large number of mainly static nodes with highly constrained energy resources. The protocols further support slow mobility by a subset of the nodes, energy-efficient routing, and formation of ad hoc subnetworks for carrying out cooperative signal processing functions among a set of the nodes.

http://mae.engr.ucdavis.edu/dsouza/Protocolsforself-orgWSN.pdf

Protocols for self-organization of a wireless sensor network

A wireless network consisting of a large number of small sensors with low-power transceivers can be an effective tool for gathering data in a variety of environments. The data collected by each sensor is communicated through the network to a single processing center that uses all reported data to determine characteristics of the environment or detect an event. The communication or message passing process must be designed to conserve the limited energy resources of the sensors. Clustering sensors into groups, so that sensors communicate information only to clusterheads and then the clusterheads communicate the aggregated information to the processing center, may save energy. In this paper, we propose a distributed, randomized clustering algorithm to organize the sensors in a wireless sensor network into clusters. We then extend this algorithm to generate a hierarchy of clusterheads and observe that the energy savings increase with the number of levels in the hierarchy. Results in stochastic geometry are used to derive solutions for the values of parameters of our algorithm that minimize the total energy spent in the network when all sensors report data through the clusterheads to the processing center.

/pdf/an-energy-efficient-hierarchical-clustering-algorithm-for-574o6gyna1.pdf

An energy efficient hierarchical clustering algorithm for wireless sensor networks

A multi-cluster, multi-hop packet radio network architecture for wireless adaptive mobile information systems is presented. The proposed network supports multimedia traffic and relies on both time division and code division access schemes. This radio network is not supported by a wired infrastructure as conventional cellular systems are. Thus, it can be instantly deployed in areas with no infrastructure at all. By using a distributed clustering algorithm, nodes are organized into clusters. The clusterheads act as local coordinators to resolve channel scheduling, perform power measurement/control, maintain time division frame synchronization, and enhance the spatial reuse of time slots and codes. Moreover, to guarantee bandwidth for real time traffic, the architecture supports virtual circuits and allocates bandwidth to circuits at call setup time. The network is scalable to large numbers of nodes, and can handle mobility. Simulation experiments evaluate the performance of the proposed scheme in static and mobile environments.

Multicluster, mobile, multimedia radio network

A distributed, mobile network infrastructure for wireless multimedia applications is presented. This network is not constrained by a fixed backbone network as conventional cellular systems are. By using a clustering algorithm, nodes are organized into clusters. The access scheme relies on both time/code division inside a cluster and code separation across clusters. Clustering enhances the spatial reuse of time slots and codes. A TDMA structure provides bandwidth guarantee for real time traffic. Using different codes for different clusters by appropriate power control algorithms can increase the channel capacity. A fast reservation virtual circuit scheme allows us to extend the bandwidth guarantee also to mobile environments. Simulation experiments evaluate the performance of the proposed scheme.

A distributed, mobile wireless infrastructure for multimedia applications

Rajeev Jam, Abeer Aiwan,MarioGerla, Len Kleinrock, John Villasenor,Ben Beizer, Walter Boring, Steve Molloy, Sean Nazareth, Marcio Siqueira, Joel Short, Jack TsaiSchool of Engineering and Applied SciencesUniversity of California, Los Angeles*ABSTRACTCurrent wireless network systems (eg metropolitan cellular) are constrained by fixed bandwidth allocations and support only anarrow range of services (voice and low bit-rate data) To overcome these constraints and advance the state of the art in wirelessmultimedia communications, we are developing variable-rate video and speech compression algorithms, and wireless node archi-tectures that will enable peer-to-peer multimedia networking even with very low bandwidthTo support this objective, each wireless node must support new applications (for multimedia), advances in networking and sourcecoding to support multimedia under limited bandwidth conditions (wireless), advances in physical layer design to support robust,low power, high packet throughput links, low power DSP for multimedia compression, and an architectural strategy to integratethese components into an efficient node The algorithms and architectures to support this functionality are presented here,together with some preliminary results on network performanceKeywords: multimedia networking, wireless systems1 ITTRODUCTIONCurrent wireless systems (eg metropolitan cellular) are constrained by fixed bandwidth allocations, fixed network configura-tions, and reliance on a tethered infrastructure In addition, existing systems support only a narrow range of services (voice andlow bit-rate data) To overcome these constraints and advance the state of the art in wireless multimedia communications, we aredeveloping new multimedia applications, video/speech compression and network control algorithms, and wireless node architec-tures that will enable peer-to-peer multimedia networking amongst an arbitrary grouping of mobile nodes To support this objec-tive, each wireless node must support the functionality shown in Fig 1, ie new applications (for multimedia), advances innetworking to support mobility and multimedia under limited bandwidth conditions (wireless), advances in physical layer designto support robust, low power, high packet throughput links, low power DSP for multimedia compression, and an architecturalstrategy to integrate these components into an efficient nodeThe algorithms and architectures to support this functionality are pre-sented below, together with some preliminary results on network performance2 ALGORITHMS

https://www.lk.cs.ucla.edu/data/files/Jain/Multimedia%20Wireless%20Networking.pdf

Jack Tzu-Chieh Tsai

Papers

Multicluster, mobile, multimedia radio network

A distributed, mobile wireless infrastructure for multimedia applications

Multimedia wireless networking