TRANSMISSION METHOD AND MOBILE STATION TO CARRY OUT THE METHOD
A method, in a cellular radio-communication system comprising a core network and an access network, the access network comprising base stations for providing wireless links to at least one mobile station, the mobile station being capable of operating in a first transmission mode in which beamforming transmit diversity is not used and in a second transmission mode in which beamforming transmit diversity is used. The method comprises switching from the second transmission mode to the first transmission mode upon determining that at least one predetermined criterion related to the mobile station operation in soft handover is satisfied.
1 . A method, in a cellular radio-communication system comprising a core network and an access network, the access network comprising base stations for providing wireless links to at least one mobile station, the mobile station being capable of operating in a first transmission mode in which beamforming transmit diversity is not used and in a second transmission mode in which beamforming transmit diversity is used, the method comprising switching from the second transmission mode to the first transmission mode upon determining that at least one predetermined criterion related to the mobile station operation in soft handover is satisfied.
2 . A method according to claim 1 wherein at least one predetermined criterion is satisfied if the number of base stations in the active set of the mobile station when operating in soft handover exceeds a predetermined threshold.
3 . A method according to claim 2 wherein at least one predetermined criterion is satisfied if the number of base stations in the active set of the mobile station when operating in soft handover, and for which the radio link with the mobile station exceeds a predetermined quality threshold, exceeds a predetermined threshold.
4 . A method according to claim 1 , wherein at least one predetermined criterion is satisfied if a request message for switching from the second transmission mode to the first transmission mode is received from the access network.
5 . A mobile station, in a cellular radio-communication system comprising a core network and an access network, the access network comprising base stations for providing wireless links to at least one mobile station, comprising:
an antenna system comprising at least two antennas for transmission in beamforming transmit diversity mode;
a radio module adapted for operating in a first transmission mode in which beamforming transmit diversity is not used and in a second transmission mode in which beamforming transmit diversity is used;
a control module adapted for determining that at least one predetermined criterion related to the mobile station operation in soft handover is satisfied and for, responsive to said determination, switching the operation of the radio module from the second transmission mode to the first transmission mode upon.
6 . A mobile station according to claim 5 wherein the control module is further adapted for determining that at least one predetermined criterion is satisfied if the number of base stations in the active set of the mobile station when operating in soft handover exceeds a predetermined threshold.
7 . A mobile station according to claim 6 wherein the control module is further adapted for determining that at least one predetermined criterion is satisfied if the number of base stations in the active set of the mobile station when operating in soft handover, and for which the radio link with the mobile station exceeds a predetermined quality threshold, exceeds a predetermined threshold.
8 . A mobile station according to claim 5 , wherein the control module is further adapted for determining that at least one predetermined criterion is satisfied if a request message for switching from the second transmission mode to the first transmission mode is received from the access network.
9 . A computer readable medium having processor executable instructions thereon for implementation by a processor, the instructions executing a method according to claim 1 .