The base stations of a cellular radio system direct their respective antennas effectively towards the terminal equipment with which they are respectively communicating. Each terminal equipment maintains and updates a list of base stations serving and potentially available to serve the respective terminal equipment. Updating is based on measuring signal strengths and directions, as well as directions of motion of the respective terminal equipment, so that each list, as updated includes only those base stations serving, and on the basis of forecast direction of movement of the terminal equipment, likely to be able to serve the respective terminal equipment. The terminal equipment measure signal strengths for the listed base stations, to determine the need for a handover.