Outage contours using a Voronoi diagram
ABSTRACT The outage contour is the boundary surrounding a cell, where the signal to interference plus noise ratio reaches a minimum acceptable value. In a mobile communication network, this contour is used in planning frequency reuse, dynamic or fixed channel allocation and cell breathing. This work presents these outage contours as a multiplicatively weighted Voronoi diagram. Each base station is a generating point of this diagram, with a corresponding weight. The weights are obtained by use of radio parameters as antenna heights, transmission power, receiver sensitivity and specific-environment propagation characteristics. The cells outage contours are represented by the edges of the Voronoi diagram, obtained by comparison between the ranges of the base stations radio signal from adjacent cells. The results show that the signal to interference plus noise ratio can be mapped to a distance ratio. The distance ratio, instead of power ratio, makes it possible to represent the outage, a signal service dependent parameter, by means of the outage contour, a geometric approach, using the geometric structure called Voronoi diagram.
Conference Proceeding: The weighted Voronoi diagram and its applications in least-risk motion planning[show abstract] [hide abstract]
ABSTRACT: The authors present a path-planning algorithm to find the least-cost path along the WVD (weighted Voronoi diagram) based on Dijkstra's shortest path algorithm, where the cost of an edge is, in this case, the risk of transversing the edge. By imposing a discrete graph over the area of interest, the authors obtain a reduction from a continuous problem to a combinatorial problem. If the start or goal position does not lie on this graph, it is retracted by either the path of shortest distance or the path of steepest descent. Unfortunately, the WVD is not connected in some cases, and they have to enforce connectivity. With a practical aim in mind, the authors give a simple and easily computed path, connecting the disconnected components by the shortest distance path or by a circular path. With suitable preprocessing, they keep the run-time cost of path planning to O( n <sup>2</sup> log n ), including the cost of retraction of both the start and goal positions and the cost of Dijkstra's shortest path (or least-cost) algorithm. The authors demonstrate a potential application of the weighted Voronoi diagram as a heuristic in least-risk motion planningComputers and Communications, 1989. Conference Proceedings., Eighth Annual International Phoenix Conference on; 04/1989
Conference Proceeding: Propagation loss prediction models for land mobile communications[show abstract] [hide abstract]
ABSTRACT: Propagation loss prediction models play a very important role in the design of cellular mobile radio communication systems by specifying the key system parameters such as transmission power and frequency reuse. Several prediction models have been proposed for cellular mobile radio systems operating in the quasi-microwave frequency band. Some of them were derived in a statistical manner based on measurement data, while the others were derived analytically by considering diffraction effects. Each model uses specific parameters to achieve reasonable prediction accuracy. This paper summarizes propagation loss prediction models used in land mobile communication system design, and discusses their applicability to various mobile propagation environments. It is also considered that the propagation characteristics in microwave and higher frequency bands are now necessary for multimedia mobile communication systemsMicrowave and Millimeter Wave Technology Proceedings, 1998. ICMMT '98. 1998 International Conference on; 02/1998
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ABSTRACT: Two unified expressions for computing the refined outage criterion (which considers the receiver noise) in cellular mobile radio systems are derived using the Laplace and Fourier inversion formulas. Since these expressions do not impose any restrictions on the signal statistics while being easy to program, they provide a powerful tool for outage analysis over generalized fading channels. We also assess compatibility and applicability of previously published approaches that treat noise as cochannel interference (noise-limited model) or consider a minimum detectable receiver signal threshold and receiver noise. The outage probability in an interference-limited case can be evaluated directly by setting the minimum power threshold to zero. The analysis of correlated interferers is presented. Results are also developed for a random number of interferers. Several new closed-form expressions for the outage probability are also derived. Some previous studies have suggested approximating Rician desired signal statistics by a Nakagami-m (1960) model (with positive integer fading severity index) to circumvent the difficulty in evaluating the outage in Rician fading. The suitability of this approximation is examined by comparing the outage performance under these two fading conditions. Surprisingly, some basic results for Nakagami-m channel have been overlooked, which has led to misleadingly optimistic results with the Nakagami-m approximation model. However, similar approximation for the interferer signals is validIEEE Transactions on Communications 03/2001; · 1.75 Impact Factor