Improved soft handoff and macro-diversity for mobile radio

This paper presents a new combining scheme for soft handoff techniques in the uplink. In comparison to hard handoff schemes, soft handoff or macro-diversity combining, respectively, offers significant improvements concerning coverage as well as capacity for cellular mobile radio systems. Besides that, it increases signal transmission quality and avoids the "ping-pong" effect occurring when a mobile near the cell boundaries switches from one base station to its neighbor back and forth. Simulation results establish that the proposed new combining scheme performs up to 5 dB better than conventional soft handoff methods based on the selection of speech frames. The additional expense in bandwidth on the links between base stations and combining unit is moderate since only hard quantized bits plus side information once per frame need to be transmitted.