Procedure for the spatial resolution of multipath signals in urban radio links

The growing use and demand for microwave communication systems has led to an increase in system density, especially in urban areas where the abundant presence of potential obstacles increases the risk of propagation. For efficient frequency planning, knowledge of the multipath geometries involved is required. This can be obtained by resolving the multipath field into its constituent components, yielding their amplitudes and angles of arrivals at a receiver terminal. Investigations into the resolution of multipath height gain curves are documented in the literature. These generally concentrate on resolving the two predominant signal components. In an urban environment, the number of distinct signal paths generally exceeds two. Resolution of more than two components is more complex and requires considerably more effort. The paper presents a component resolution procedure which determines the individual amplitudes and angles of arrival of the constituent signal paths. The procedure is applied to the spatial amplitude envelope observed when displacing a receiver incrementally over a distance of a few wavelengths through a multipath field. The presented solution has the advantages of relatively simple measurements and post-processing of measured data. In stationary measurement environments and discrete ray distributions, the solution requires only the recording of envelope amplitude values and no phase information. The performance of the resolution procedure was evaluated using a receiver with a standard antenna. Examples including simulated and experimental radio paths supported by measurements are presented