Patent ID: 6108547
Filing Date: 2000-08-22
Classification: H04W

Abstract:
In a mobile communication system that includes a concentrator and base transceiver stations connected thereto, a method for carrying out a soft handoff between a mobile station and multiple base transceiver stations, comprising the steps of:(a) connecting in advance adjacent base transceiver stations via a communication line logically isolated from said concentrator; and(b) performing soft handoff control between said mobile station and said multiple base transceiver stations by using said communication line with the control taken by one of said multiple base transceiver stations, step b including the substeps of:(i) implementing a transfer from a normal communication mode in which said mobile station is connected only to a first base transceiver station via a radio channel, to a soft handoff mode controlled by said first base transceiver station in which said mobile station is connected also to a second base transceiver station via a radio channel, and in which reverse traffic information received by said second base transceiver station is transferred via said communication line to said first base transceiver station, while forward traffic information received from said concentrator by said first base transceiver station is transferred also to said second base transceiver station via said communication line;(ii) implementing a transfer from the soft handoff mode controlled by said first base transceiver station to a soft handoff mode controlled by said second base transceiver station; and(iii) implementing a transfer from the soft handoff mode controlled by said second base transceiver station to a normal communication mode in which said mobile station is connected only to said second base transceiver station via said radio channel.