Numerical Investigation of Algorithms for Multi-Antenna Radiolocation

This article follows upon the author´s work in radiolocation of mobile 802.11b communication devices. The need for radiolocation is dictated by two significant problems in radio communication: unknown location of interlocutors, and rapid loss of signal strength with distance. Radiolocation method described in earlier work addresses these problems, both of which are caused by the omnidirectional nature of radio transmission. In this work, the previously introduced iterative pattern-matching algorithm for radiolocation is analyzed, in order to determine how its performance is affected by the characteristics of the radiolocator´s antenna. The algorithm´s mathematical foundation is discussed, with emphasis on the choice of the variational error measure for pattern matching. Numerical accuracy and rate of convergence are investigated, for several variants of the error measure, and over a range of antennas´ lobe widths. The effect of sparse directional sampling (aliasing) is investigated. The analysis of radiolocation algorithm is applied to the helical antennas of the prototype radiolocator, and to two commercially available directional antennas. Design calculations are performed, of the type needed to guide the design of an actual radiolocator antenna.