**A**lhussein** Abouzeid Research:**

*Interests*

Systems: Communication Networks; Wireless Ad Hoc and Sensor Networks;
Peer-to-Peer Networks.

Applied Theory: Stochastic Processes; Algorithm and Protocol
Complexity; Multi-layer Optimization; Information Theory; Queuing Theory.

*Project "**Randomized**":**Randomized
Algorithms for Overlay and Disconnected Networks*

Locating
a resource/ service or a peer efficiently is one of the most important issues
related to unstructured decentralized networks. The objective of a search
mechanism is to successfully locate resources while incurring low overhead and
low delay. In order to fulfill this objective, several random walk based search
algorithms have been proposed. However, no analytical model has been proposed
to quantify the effect of parameters of random walk, such as the number and
time to live (TTL) of random walkers, on the performance of search algorithms.

In
this work we develop a mathematical model for random walk search in a
peer-to-peer network. Using the model we derive analytical expressions for the
performance metrics, such as delay, overhead and success rate, of the search in
terms of the popularity of the resource being searched for and the parameters
of random walk. We propose an algorithm that uses the analytical expressions in
order to adaptively set the parameters of random walk so that it maintains a
certain minimum level of performance. The algorithm is called Equation Based
Adaptive Search (EBAS). We also propose a method for maintaining popularity
estimates of the resources in the network. The work is based on an important
recent observation regarding the relationship between random walk and uniform sampling.
The work is currently being extended to utilize location information. This
extension is specifically useful for delay tolerant networks (DTNs).

*Presentations:*

*Key Publications:*

N.
Bisnik and A.A. Abouzeid, “Optimizing Random Walk Search
in P2P Networks,” *Computer Networks*, in press,
available online (ScienceDirect) 18 September 2006. (Conference version in
HoTP2P 2005).