Ericsson says it has a small solution to the big problem of weak mobile service in enterprises. On Wednesday, the world's largest cellular network vendor introduced a radio that can fit in the palm of your hand and hook up to a full-size base station via conventional LAN cables. The so-called Radio Dot System, due to ship late next year, will let carriers fill large and medium-sized buildings with strong voice and data signals while keeping their equipment and management costs low, Ericsson said.