Stavroula Siachalou

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The network planning problem of placing replicated servers with QoS constraints is considered. Each server site may consist of multiple server types with varying capacities and each site can be placed in any location among those belonging to a given set. Each client can be served by more than one location as long as the round-trip delay of data requests(More)
Sensor collision (interference) is studied in a large network of low bit-rate sensors that communicate via backscatter, i.e. modulate the reflection of a common carrier transmitted by a central reader. Closed-form analysis is provided, quantifying sensor collision (interference) in high-density, backscatter sensor networks (BSN), as a function of number of(More)
We consider the problem of routing in a network where QoS constraints are placed on network traffic. We provide two optimal algorithms that are based on determining the discontinuities of functions related to the optimization at hand. The proposed algorithms have pseudopolynomial worst case running time and for a wide variety of tested networks they have(More)
Careful planning and optimization of wireless networks for indoor operation require site-specific propagation predictions for several possible antenna-configurations in reasonable running time. In this paper, we propose treating each room as a single entity, where estimations of the mean received power, as well as the minimum and maximum values of the mean(More)
We consider the problem of precomputing constrained widest paths and multicast trees in a communication network. Precomputing and storing of the relevant information minimizes the computational overhead required to determine an optimal path when a new connection request arrives. We evaluate algorithms that precompute paths with maximal bandwidth (widest(More)
This letter proposes a computationally inexpensive, site-specific propagation model, useful in coverage evaluation of radio frequency identification (RFID) networks with passive tags. The parameters of a Rice distribution for each point in the volume of interest are computed using site-specific approximations that address overall space geometry, materials,(More)
This work analytically quantifies and attempts to alleviate the collision induced by a number of tags that operate via backscatter communication, i.e. modulate the reflection of a common carrier transmitted by a central hub. For omni hub antenna, it is shown that acceptable anti-collision performance can be engineered only when appropriate modulation at(More)
In this paper, we propose a model to calculate the probability of successful identification of passive UHF RFID tags in a given environment. The validity of the proposed model is verified by comparison with analytical ray-tracing results and measurements. The model can be included in automated RFID network planning algorithms to evaluate the identification(More)
In this paper, a solution for automated passive RFID network planning is proposed. The proposed scheme comprises two parts; i) a fast site specific stochastic propagation model that extracts the probabilities of successful identification for any possible reader-antenna configuration, ii) a particle swarm optimization (PSO) algorithm that selects a subset of(More)
In this paper a maximum likelihood estimator of the locations of passive RFID tags is presented, exploiting the Received Signal Strength Information (RSSI) collected at the reader. The reader-antenna is fixed on a moving cart and collects RFID data in the area of interest. Locations of the reader-antenna and of the target-objects are obtained by the RSSI of(More)