Method and apparatus for change of primary cell during carrier aggregation
View Patent ↗Methods for performing change of primary cell during carrier aggregation operation are described. A mobile station (MS) receives a message to change a primary cell and to perform a random access communication with a new primary cell. Upon receiving a random access response message from the new primary cell, the MS starts transmitting a control channel to the new primary cell. In one embodiment, the MS releases the configuration of an uplink control channel and transmits uplink control information through an uplink shared channel. Upon completion of the primary cell change procedure, the MS starts transmission of an uplink control channel to the new primary cell.
1. A method in a mobile station for transmitting uplink control information, the method comprising:
configuring a first uplink control channel for transmitting uplink control information from the mobile station to a first primary cell;
configuring one or more uplink shared channels for transmitting uplink data;
receiving a message directing a change of primary cell to a second primary cell, the second primary cell distinct from the first primary cell;
releasing the first uplink control channel configuration and transmitting uplink control information using the one or more uplink shared channels after having released the first uplink control channel configuration;
configuring a second uplink control channel for transmitting uplink control information from the mobile station to the second primary cell; and
transmitting a message indicating successful configuration of the second uplink control channel,
wherein the message indicating the change of primary cell further includes a new mobile station identifier, and
wherein when it is determined that a mobile station identifier used by the mobile station prior to the change is used for communication between the second primary cell and another mobile station, the second primary cell and the mobile station use the new mobile station identifier for communication upon change to the second primary cell.
2. The method according to claim 1 , wherein uplink control information includes at least one of ACK/NACK indicators for downlink transmissions, Channel Quality Indicator information, or scheduling requests.
3. The method according to claim 1 wherein configuring an uplink control channel comprises
configuring time-frequency resources for transmission of the uplink control channel; and
transmitting uplink control information using the configured time-frequency resources.
4. The method according to claim 1 wherein the release of the configuration of the uplink control channel comprises performing at least one of following:
release of any time-frequency resources associated with the uplink control channel;
resetting of any stored parameters associated with the uplink control channel;
modifying the configuration of the mobile station such that the uplink control channel cannot be transmitted;
modifying the configuration of the mobile station such that the uplink control channel is transmitted at a zero power level; or
suspension of transmission of part or all of the uplink control information using the resources associated with the uplink control channel.