Tomoaki Shirakawa

A genetic algorithm for generating multiple paths on mesh maps

Path generation is an optimization problem mainly performed on grid square maps that combines generation of paths with minimization of their cost. Several methods that belong to the class of exhaustive searches are available; however, these methods are only able to obtain a single path as a solution for each iteration of the search. Hence, this paper proposes a new method using genetic algorithms for this problem with the goal of simultaneously searching for multiple candidate paths.

Fading Analysis in Land Mobile Reception of TV Waves.

This paper analyzes the basic properties of reception of TV waves by land mobile systems. A precise TV wave propagation model is developed, fading is analyzed mathematically, and a received-signal equation is derived. This analysis treats all kinds of signals as well as TV signals. Doppler effects made by multipath distortion are introduced to both carrier and modulation signals for wide-band signal transmission. The resulting expression for the received signal is numerically evaluated. The characteristics of wide-band signals such as TV wave transmission are different from those of narrow-band signal tramsmission. The time correlation has almost zero value when the distance is half λc or less. (λc is the carrier wavelength); and the carrier frequency correlation has almost a constant value when the carrier frequency distance between received signals is further than a certain threshold. The correlation coefficient between wide-band received signals and narrow-band received signals has a low value. Therefore, for land mobile reception wide-band signals and narrow-band signals cannot be treated in the same way.