San Diego-based Qualcomm Inc has been awarded US patent number 5,101,501 for its method of providing a soft hand-off in a Code Division Multiple Access digital cellular telephone system, a feature that is designed to enhance communications quality and reduce the chance of a dropped call: the system enables the call to be received from two cells simultaneously as the user crosses a cell boundary, avoiding the problems that arise in a hard handoff, when the first cell is dropped before the second is picked up; in the worst case, where both signal strengths are comparable, the system can flipflop between the two signals, breaking up the call; with Qualcomm’s system, the original cell only hands off the call when the mobile unit is firmly established in the new cell, resulting in an exchange that will be transparent to the user.
