[show abstract][hide abstract] ABSTRACT: Received power measurements at spatially distributed monitors can be usefully exploited to deduce various characteristics of active wireless transmitters. In this paper, we study the problem of “blind” estimation of a wireless node's transmit power utilizing solely received power measurements at spatially distributed monitors, without any prior knowledge about the transmitter's location or any statistical characterization of its transmit power. We first consider a deterministic setup and utilize a geometrical approach to obtain fundamental limitations on estimating the transmit power and location of an unknown wireless node. We show that a regular placement of monitors, though appealing, does not provide sufficient measurement diversity to yield a unique estimate. We then extend the setup to consider wireless fading and present a theoretical analysis of maximum likelihood (ML) estimate, which is analytically shown to be asymptotically optimal. Finally, we provide numerical results comparing the performance of the estimator through simulations and on a dataset of field measurements.
IEEE/ACM Transactions on Networking 09/2010; · 2.01 Impact Factor
[show abstract][hide abstract] ABSTRACT: In this paper, we analyze the connectivity dynamics of vehicular ad-hoc networks in a generic signalized urban route. Given the velocity profile of an urban route as a function of space and time, we utilize a fluid model to characterize the general vehicular traffic flow, and a stochastic model to capture the randomness of individual vehicle. From the fluid and stochastic models, we can acquire respectively the densities of the mean number of vehicles along the road and the corresponding distribution. With the knowledge of the vehicular density dynamics, we determine the probability that the communication network is fully connected, i.e., each node can communicate with every other node through a multi-hop path, and the problem is also investigated for a general case of a k-connected network. To closely approximate the practical road conditions, we use a density-dependent velocity profile to approximate vehicle interactions and capture the shockwave propagation at traffic signals. We confirm the accuracy of the connectivity analysis through simulations and show that the analytical results are good approximations even when vehicles interact with each other as their movement is controlled by traffic lights. We also illustrate that system engineering and planning for optimizing connectivity in the communication networks can be carried out with the results in this paper.
[show abstract][hide abstract] ABSTRACT: Received power measurements at spatially distributed, passive, monitors contain valuable information on the active wireless transmitters, which can be usefully exploited to make various inferences. In this paper, we study blind estimation of the number of active wireless sources, their transmission powers and their locations in the network based on received power measurements at multiple monitoring nodes, without assuming any prior knowledge or statistical characterization of these parameters. Utilizing geometrical analysis and algorithmic approach we present estimation algorithms for these parameters under signal combination from multiple transmitters. We present useful non-trivial insights regarding such inferences, and also present simulation results verifying the analysis and quantifying the performance of the estimation algorithms.
Military Communications Conference, 2008. MILCOM 2008. IEEE; 12/2008
[show abstract][hide abstract] ABSTRACT: Transmit-power estimation is an important part in power-aware designs of mobile ad-hoc networks (MANETs). In this paper, we consider the cooperation among multiple monitor-nodes to estimate the transmit power of other nodes. Utilizing a geometric approach, we characterize the theoretical performance of such cooperative monitoring schemes and propose transmit-power estimation techniques with different number of cooperating nodes. We introduce the novel concept of confidence region that provides a fundamental confidence level for the accuracy of the power estimation and enables the development of techniques for allocating network monitors. Finally, we present a simple, distributed cooperative estimation scheme for a large-scale wireless network and give illustrative simulation results to quantify its performance.
Wireless Communications and Networking Conference, 2008. WCNC 2008. IEEE; 05/2008