Patent ID: 6144656
Filing Date: 2000-11-07
Classification: H04B,H04W,Y02D

Abstract:
A method for synchronizing a telecommunications connection in a mobile communications system havingat least one base station communicating with mobile stations on time division multiple access system channels including of control channels and traffic channels whose uplink and downlink frequencies are divided into frames, a part of which may be defined dynamnically, by determining an energy economy mode start frame and length of an energy economy cycle, for a mobile station in the database as energy economy mode sleeping frames, during which the mobile station is not prepared to receive transmissions on downlink frequencies,at least a first mobile station communicating on a direct mode channel divided into frames and predisposed to operate in a dual watch mode both on a control channel of the mobile communications system and on the direct mode channel which comprises pre-emption frames, by which the mobile stations communicating on the direct mode channel request transmission turns for themselves, the method comprising:communicating from the at least first mobile station operating on the direct mode channel to the at least one base station a wish of the at least first mobile station to operate in the dual watch mode and to operate in an energy economy mode on the control channel of the mobile communications system;checking from the database (i) whether the energy economy mode start frame has been determined for the direct mode channel and (ii) the length of the energy economy cycle if the energy economy mode start frame has been determined for the direct mode channel, the checking from the database in response to a registration message associated with the at least first mobile station;determining and storing in the database the energy economy mode start frame and the length of the energy economy cycle wherein each of a number of pre-emption frames coincides with a corresponding number of sleeping frames of the energy economy mode, determining and storing if the energy economy mode start frame has not been determined for the direct mode channel;transmitting to the at least first mobile station information on a desired control channel of the at least one base station and timing information related to the desired control channel, and transmitting a command to switch to the energy economy mode, the command containing information on the energy economy mode start frame and the length of the energy economy cycle; andthe at least first mobile station switching to the dual watch mode and to the energy economy mode, to communicate either on the direct mode channel or the control channel so that the at least first mobile station can listen to the control channel between transmission time-slots of the direct mode channel while communicating on the direct mode channel, the at least first mobile station switching in response to the information on the desired control channel, the timing information related to the desired control channel, the information on the energy economy mode start frame, and the length of the energy economy cycle.