John Sucec

Clustering overhead for hierarchical routing in mobile ad hoc networks

Numerous clustering algorithms have been proposed that can support routing in mobile ad hoc networks (MANET). However, there is very little formal analysis that considers the communication overhead incurred by these procedures. Further, there is no published investigation of the overhead associated with the recursive application of clustering algorithms to support hierarchical routing. This paper provides a theoretical upper bound on the communication overhead incurred by a particular clustering algorithm for hierarchical routing in MANET. It is demonstrated that, given reasonable assumptions, the average clustering overhead generated per node per second is only polylogarithmic in the node count. To derive this result, novel techniques to assess cluster maintenance overhead are employed.

Hierarchical routing overhead in mobile ad hoc networks

Hierarchical techniques have long been known to afford scalability in networks. By summarizing topology detail via a hierarchical map of the network topology, network nodes are able to conserve memory and link resources. Extensive analysis of the memory requirements of hierarchical routing was undertaken in the 1970s. However, there has been little published work that assesses analytically the communication overhead incurred in hierarchical routing. This paper assesses the scalability, with respect to increasing node count, of hierarchical routing in mobile ad hoc networks (MANETs). The performance metric of interest is the number of control packet transmissions per second per node (/spl Phi/). To derive an expression for /spl Phi/, the components of hierarchical routing that incur overhead as a result of hierarchical cluster formation and location management are identified. It is shown here that /spl Phi/ is only polylogarithmic in the node count.

Location management for hierarchically organized mobile ad hoc networks

A geography-based grid location service (GLS), proposed elsewhere, has resulted in a scalable location management service for mobile ad hoc networks (MANETs) where packet forwarding decisions are based on geographic position. A similarly scalable location management strategy has been devised for MANETs that employ hierarchical link state routing. Both approaches employ hierarchical principles to facilitate scalability. However, currently proposed approaches for hierarchical link state routing rely on a designated subset of nodes for location management. Such nodes represent potential sites of hot spot contention. In this paper, it is proposed that by applying the distributed database selection technique of GLS, a hierarchical location management scheme may be realized for MANETs based on link state routing that equitably distributes location server functionality among network nodes. Second, it is shown that location registration overhead per node for hierarchical location management is only logarithmic in the node count.

An application of parameter estimation to route discovery by on-demand routing protocols

To discover a route to a peer node, an on-demand routing protocol may initiate a flood-search procedure known as route discovery. By selecting the correct query radius, the number of packet transmissions required for route discovery can be minimized. This paper presents methods to estimate the geographic radius (R/sub G/) and the number of currently active pairs of communicating nodes (P) in a mobile ad-hoc network. The methods are entirely distributed and incur little communication overhead. Network nodes can apply the estimated parameters to predict the probability mass function (PMF) of the route discovery hop distance. An accurate prediction of the PMF aids the selection of an appropriate query radius for the route discovery process. A computationally lightweight procedure to select an appropriate query radius, based only on an estimate of P, is also proposed. Simulation results show that this procedure facilitates a sensible tradeoff between the route request packet overhead and the route reply delay.

Location management handoff overhead in hierarchically organized mobile ad hoc networks

Control overhead in a mobile ad hoc network may be reduced through hierarchical routing. However, to facilitate packet forwarding in a hierarchically organized network, each datagram must specify the hierarchical address of the destination. Maintaining and acquiring hierarchical addresses represents a location management (LM) problem and incurs control overhead in addition to that of a routing protocol. This paper considers the LM overhead due to handoff. That is, the transfer of LM data due to node mobility and volatility of the clustered hierarchy. It is shown that handoff overhead is only polylogarithmic in the node count.

A query scope agent for flood search routing protocols

Flood-search on-demand routing has received considerable interest for its application to mobile ad hoc networks. To alleviate the effects of flooding the network with control packets to discover a route, the concept of an expanding ring search (ERS) has been proposed elsewhere for reducing the packet transmission overhead of the route discovery process. Essentially, ERS consists of incrementally increasing the allowable hop radius of the flood search until a route to the target node is returned. However, ERS incurs additional latency to successfully complete the route discovery procedure. This paper presents a query scope agent (QSA) that assists in the selection of an appropriate ERS. The QSA accepts as input, from the user or network application, a maximum allowable value for route discovery delay. The QSA then estimates network parameter values to determine an ERS approach that satisfies the delay requirement while reducing expected packet transmission overhead. Simulation results show that it successfully achieves this objective. Further, the QSA incurs little communication and computation overhead, and operates in a distributed and asynchronous fashion.

Capacity compatible 2-level link state routing for ad hoc networks with mobile clusterheads

The throughput of a mobile ad hoc network (MANET) is determined by the transceiver link capacity available at each node and the type of traffic pattern that is prevalent in the network. In order for a routing protocol to be scalable, its control overhead must not exceed transceiver link capacity. To achieve capacity compatible routing, hierarchical techniques may be employed. This paper describes how link state routing, with a single layer of hierarchy, provides sufficient scalability for MANETs where the traffic pattern consists of unicast communication between arbitrary pairs of nodes.