Method and apparatus to trigger a random access procedure for carrier aggregation in a wireless communication network
A method and apparatus for a base station to trigger a random access procedure for carrier aggregation in a wireless communication system are disclosed. The method includes sending a dedicated radio resource control signal to configure a user equipment with a plurality of secondary component carriers (SCCs) that include uplink SCCs and/or downlink SCCs for carrier aggregation. The method further includes sending an activation signal to the user equipment to activate a configured downlink SCC. The method also includes transmitting a physical downlink control channel order only on the downlink primary CC to trigger a random access procedure.
1. A method for a base station to trigger a random access procedure for carrier aggregation in a wireless communication system, comprising:
sending a dedicated radio resource control (RRC) signal to configure a user equipment (UE) with a plurality of secondary component carriers (SCCs) that include uplink SCCs and/or downlink SCCs for carrier aggregation;
sending an activation signal to the UE to activate a configured downlink SCC; and
transmitting a physical downlink control channel (PDCCH) order only on a downlink primary component carrier (PCC) to trigger a random access procedure, wherein the downlink PCC is considered as always activated.
2. The method of claim 1 , further comprises:
using the activation signal to request the UE to initiate a random access procedure on the activated SCC to update a timing advance for uplink transmissions.
3. The method of claim 1 , further comprises:
maintaining separate timing advances (TAs) for different groups of uplink CCs via separate random access procedures.
4. The method of claim 1 , further comprises:
deactivating a downlink SCC when a corresponding timer expires.
5. The method of claim 1 , wherein the uplink PCC and the downlink PCC correspond to a serving cell with which a UE establishes or re-establishes an RRC connection.
6. The method of claim 1 , wherein the dedicated RRC signal is a RRC connection reconfiguration message.
7. The method of claim 1 , wherein the activation signal is a Medium Access Control (MAC) signal.
8. A method for a user equipment (UE) to initiate a random access procedure for carrier aggregation in a wireless communication system, comprising:
receiving a dedicated radio resource control (RRC) signal to configure a plurality of secondary component carriers (SCCs) that include uplink SCCs and/or downlink SCCs for carrier aggregation;
receiving an activation signal to activate a configured downlink SCC; and
monitoring a physical downlink control channel (PDCCH) order only on the downlink primary component carrier (PCC) and initiating a random access procedure in response to receipt of the PDCCH order, wherein the downlink PCC is considered as always activated.
9. The method of claim 8 , further comprises:
initiating a random access procedure on the activated SCC upon receipt of the activation signal to update the timing advance for uplink transmissions.
10. The method of claim 8 , further comprises:
maintaining separate timing advances (TAs) for different groups of uplink CCs via separate random access procedures.
11. The method of claim 8 , further comprises:
deactivating a downlink SCC when a corresponding timer expires.
12. The method of claim 8 , wherein the uplink PCC and the downlink PCC correspond to the serving cell with which a UE establishes or re-establishes an RRC connection.
13. The method of claim 8 , wherein the dedicated RRC signal is a RRC connection reconfiguration message.
14. The method of claim 8 , wherein the activation signal is a Medium Access Control (MAC) signal.
15. An apparatus to initiate a random access procedure for carrier aggregation in a wireless communication system, comprising:
a first module adapted to receive a dedicated radio resource control (RRC) signal to configure a plurality of secondary component carriers (SCCs) that include uplink SCCs and/or downlink SCCs for carrier aggregation;
a second module adapted to receive an activation signal to activate a configured downlink SCC; and
a third module adapted to monitor a physical downlink control channel (PDCCH) order only on the downlink primary component carrier (PCC), and to initiate a random access procedure in response to receipt of the PDCCH order, wherein the downlink PCC is considered as always activated.
16. The apparatus of claim 15 , further comprises:
a fourth module adapted to initiate a random access procedure on the activated SCC upon receipt of the activation signal to update the timing advance for uplink transmissions.
17. The apparatus of claim 15 , further comprises:
a fifth module adapted to maintain separate timing advances (TAs) for different groups of uplink CCs via separate random access procedures.
18. The apparatus of claim 15 , further comprises:
a sixth module adapted to deactivate a downlink SCC when a corresponding timer expires.
19. The apparatus of claim 8 , wherein the uplink PCC and the downlink PCC correspond to the serving cell with which a UE establishes or re-establishes an RRC connection.
20. The apparatus of claim 8 , wherein the activation signal is a Medium AccessControl (MAC) signal.