Patent ID: 6449481
Filing Date: 2002-09-10
Classification: H04W

Abstract:
A method for determining the execution time of an inter-frequency hard handoff in a mobile telecommunication system divided into a plurality of sectors, said telecommunication system including at least one mobile station providing a subscriber with mobile telecommunication services, a plurality of base transceiver stations (BTSs) each servicing one of said plurality of sectors, each BTS transmitting a unique pilot signal identifying said BTS, and a base station controller managing a sub-cell, the method comprising the steps of:(a) receiving a pilot strength measurement message (PSMM) from the mobile station by the base station controller (BSC), the PSMM including a plurality of pilot signals each having a pilot signal strength; (b) upon receiving the PSMM by the BSC, determining whether all sub-cells with which the mobile station is currently in communication are border frequency sub-cells; (c) if it least one sub-cell is determined not to be a border frequency sub-cell, executing a general handoff; (d) if all sub-cells are determined to be border frequency sub-cells, periodically ordering the PSMM from all sub-cells with which the mobile station is currently in communication by the BSC; (e) analyzing a received PSMM transmitted from the mobile station in response to the PSMM order issued by the BSC to determine whether the pilot signal strengths received from all sub-cells are lower than a predetermined power level, T_DOWN, and activating a timer set to a predetermined time, T_TDOWN if said determination is satisfied; (f) if the timer expires normally ordering the mobile station to execute an intra-cell inter-frequency hard handoff to a common frequency that all base transceiver stations service.