Hamid Aghvami

Analysis of Proxy Assisted P2P Services

In recent years peer-to-peer communications has developed into a powerful networking model for real-time applications. Its slow adoption by the wireless community can be attributed to several factors including resource limitations of portable devices and restrictive pricing models employed by operators. The mobility management strategy proposed in [1] alleviates some of these problems by allowing migration of proxy services to the local vicinity of a mobile peer whilst helping to reduce the traffic transmitted over the wireless link. In this paper, we analytically evaluate the above-mentioned scheme by formulating the performance metrics of registration cost and message delivery cost. Specifically we employ the random walk model to represent the motion of a mobile peer moving between different subnets. Our results show that considerable performance improvements, up to 80% in some cases, can be achieved in most mobility scenarios.

IEEE Vehicular Technology Conference (VTC), Fall 2006

In this paper, a family of integer linear programs is formulated for performing collision free scheduling in Spatial-TDMA wireless mesh networks. We extend previous formulations for power aware STDMA scheduling to include discrete power transmission and multi-rate support via adaptive constellation selection. Despite the theoretical attractiveness of these (mixed) integer linear programs, STDMA scheduling problems are in general intractable (NP-hard problems). Thus, the practicality of providing optimal solutions is rather limited. To this end, we study approximation algorithms that are based on linear programming relaxation and randomized rounding. Based on these approximation algorithms we focus our study on the trade-off between optimality of the solution and feasibility. Conducted numerical investigations aim to vindicate the claim regarding the strength of randomized algorithms. In that respect the performance of the approximation algorithms under different scenarios, such as the number of active links and number of nodes in the mesh network, is investigated.