Mahdi Lotfinezhad

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In wireless sensor networks, clustering allows the aggregation of sensor data. It is well known that leveraging the correlation between different samples of the observed data will lead to better utilization of energy reserve. However, no previous work has analyzed the effect of non-ideal data aggregation in multi-hop sensor networks. In this paper, we(More)
Recently wireless sensor networks featuring direct sink access have been studied as an efficient architecture to gather and process data for numerous applications. We focus on the joint effect of clustering and data correlation on the performance of such networks. We propose a novel cluster-based data collection scheme for sensor networks with direct sink(More)
It is well known that for ergodic channel processes the Generalized Max-Weight Matching (GMWM) scheduling policy stabilizes the network for any supportable arrival rate vector within the network capacity region. This policy, however, often requires the solution of an NP-hard optimization problem. This has motivated many researchers to develop sub-optimal(More)
In this paper, we study the delay performance of CSMA policies in wireless networks, where the delay is defined as the average time that a silent wireless link needs to wait until it accesses the channel for packet transmission. It is well-known that CSMA policies can incur an access delay that may be correlated over time and may grow exponentially with the(More)
Wireless sensor networks with mobile access points are effective tools for collecting data in a variety of environments. Mobile agents are powerful hardware units with sophisticated transceivers. Low-cost and low-power sensors in the reachback operation contend for the channel to transmit their own data packets to the mobile agent. This data communication(More)
In this paper, we consider the problem of optimal control for throughput utility maximization in cognitive radio networks with dynamic user arrivals and departures. The cognitive radio network considered in this paper consists of a number of heterogeneous sub-networks. These sub-networks may be power-constrained and are required to operate in such a way(More)
Throughput optimal scheduling policies in general require the solution of a complex and often NP-hard optimization problem. Related literature has shown that in the context of time-varying channels, randomized scheduling policies can be employed to reduce the complexity of the optimization problem but at the expense of a memory requirement that is(More)
CSMA policies are examples of simple distributed scheduling algorithms in wireless networks. In this paper, we study the delay properties of CSMA in the limit of large networks. We first define an ideal network under which CSMA becomes memoryless in that the delay to access the channel becomes an exponential r.v. independent of the past. We then show that,(More)
We consider CSMA policies for multihop wireless networks. CSMA policies are simple policies that can be easily implemented in a distributed manner. However, the delay performance of CSMA policies can be very poor as the delay can grow exponentially in the network size. As a result, CSMA policies are not practical for delay-sensitive traffic even for(More)