Re-synchronization of temporary UE IDs in a wireless communication system
Techniques for re-synchronizing Cell Radio Network Temporary Identifiers (C-RNTIs) in a wireless communication system are described. In one design, a user equipment (UE) sends a random access preamble for random access. A base station receives the random access preamble, assigns a Temporary C-RNTI to the UE, and sends a random access response including the Temporary C-RNTI. The UE uses the Temporary C-RNTI as a C-RNTI for itself if a valid C-RNTI is not already available. The UE discards the Temporary C-RNTI and uses the valid C-RNTI if available. The UE sends a transmission after receiving the random access response, and the transmission may include the valid C-RNTI if available. For handover, the base station (a target base station) receives a handover request from a source base station, assigns the valid C-RNTI to the UE, and sends the valid C-RNTI to the source base station for forwarding to the UE.
1. An apparatus for wireless communication, comprising:
at least one processor configured to send a random access preamble for random access by a user equipment (UE), to receive a random access response including a Temporary Cell Radio Network Temporary Identifier (C-RNTI), to use the Temporary C-RNTI as a C-RNTI for the UE if a valid C-RNTI is not already available, and to discard the Temporary C-RNTI and use the valid C-RNTI if available; and
a memory coupled to the at least one processor;
wherein the at least one processor is configured to send the random access preamble for timing synchronization update when the valid C-RNTI is available, and to discard the Temporary C-RNTI and continue to use the valid C-RNTI.
2. The apparatus of claim 1 , wherein the at least one processor is configured to send a transmission after receiving the random access response, the transmission including the valid C-RNTI if available.
3. The apparatus of claim 1 , wherein the at least one processor is configured to send the random access preamble for initial system access when the valid C-RNTI is not available, and to use the Temporary C-RNTI as the C-RNTI for the UE.
4. The apparatus of claim 1 , wherein the at least one processor is configured to send the random access preamble for transition from an idle state to an active state when the valid C-RNTI is not available, and to use the Temporary C-RNTI as the C-RNTI for the UE.
5. A method for wireless communication, comprising:
sending a random access preamble for random access by a user equipment (UE);
receiving a random access response including a Temporary Cell Radio Network Temporary Identifier (C-RNTI);
using the Temporary C-RNTI as a C-RNTI for the UE if a valid C-RNTI is not already available; and
discarding the Temporary C-RNTI and using the valid C-RNTI if available;
wherein the sending the random access preamble includes sending the random access preamble for timing synchronization update when the valid C-RNTI is available, and wherein the Temporary C-RNTI is discarded and the valid C-RNTI is used.
6. The method of claim 5 , further including:
sending a transmission after receiving the random access response, the transmission including the valid C-RNTI if available.
7. The method of claim 5 , wherein the sending the random access preamble includes sending the random access preamble for initial system access or for transition from an idle state to an active state when the valid C-RNTI is not available, and wherein the Temporary C-RNTI is used as the C-RNTI for the UE.
8. An apparatus for wireless communication, comprising:
at least one processor configured to receive a random access preamble for random access by a user equipment (UE), to assign a Temporary Cell Radio Network Temporary Identifier (C-RNTI) to the UE, to send a random access response including the Temporary C-RNTI, to use the Temporary C-RNTI as a C-RNTI for the UE if a valid C-RNTI is not already available at the UE, and to release the Temporary C-RNTI and use the valid C-RNTI if received from the UE; and
a memory coupled to the at least one processor;
wherein the at least one processor is configured to receive the random access preamble from the UE for timing synchronization update when the UE already has the valid C-RNTI, to receive a transmission including the valid C-RNTI from the UE after sending the random access response, and to release the Temporary C-RNTI and use the valid C-RNTI for the UE.
9. The apparatus of claim 8 , wherein the at least one processor is configured to receive a transmission from the UE after sending the random access response, the transmission including the valid C-RNTI if available at the UE.
10. The apparatus of claim 8 , wherein the at least one processor is configured to receive the random access preamble from the UE for initial system access, and to use the Temporary C-RNTI as the C-RNTI for the UE.
11. The apparatus of claim 8 , wherein the at least one processor is configured to receive the random access preamble from the UE for transition from an idle state to an active state, and to use the Temporary C-RNTI as the C-RNTI for the UE.
12. A method for wireless communication, comprising:
receiving a random access preamble for random access by a user equipment (UE);
assigning a Temporary Cell Radio Network Temporary Identifier (C-RNTI) to the UE;
sending a random access response including the Temporary C-RNTI;
using the Temporary C-RNTI as a C-RNTI for the UE if a valid C-RNTI is not already available at the UE; and
releasing the Temporary C-RNTI and using the valid C-RNTI if received from the UE;
wherein the receiving the random access preamble includes receiving the random access preamble from the UE for timing synchronization update when the UE already has the valid C-RNTI, wherein the method further includes receiving a transmission including the valid C-RNTI from the UE after sending the random access response, and wherein the Temporary C-RNTI is released and the valid C-RNTI is used for the UE.
13. The method of claim 12 , further including:
receiving a transmission from the UE after sending the random access response, the transmission including the valid C-RNTI if available at the UE.
14. The method of claim 12 , wherein the receiving the random access preamble includes receiving the random access preamble from the UE for initial system access or for transition from an idle state to an active state, and wherein the Temporary C-RNTI is used as the C-RNTI for the UE.
15. An apparatus for wireless communication, comprising:
means for sending a random access preamble for random access by a user equipment (UE);
means for receiving a random access response including a Temporary Cell Radio Network Temporary Identifier (C-RNTI);
means for using the Temporary C-RNTI as a C-RNTI for the UE if a valid C-RNTI is not already available; and
means for discarding the Temporary C-RNTI and using the valid C-RNTI if available;
wherein the means for sending the random access preamble includes means for sending the random access preamble for timing synchronization update when the valid C-RNTI is available, and wherein the Temporary C-RNTI is discarded and the valid C-RNTI is used.
16. The apparatus of claim 15 , further including:
means for sending a transmission after receiving the random access response, the transmission including the valid C-RNTI if available.
17. The apparatus of claim 15 , wherein then means for sending the random access preamble includes means for sending the random access preamble for initial system access or for transition from an idle state to an active state when the valid C-RNTI is not available, and wherein the Temporary C-RNTI is used as the C-RNTI for the UE.
18. A non-transitory machine-readable medium comprising instructions which, when executed by a machine, cause the machine to perform operations including:
sending a random access preamble for random access by a user equipment (UE);
receiving a random access response including a Temporary Cell Radio Network Temporary Identifier (C-RNTI);
using the Temporary C-RNTI as a C-RNTI for the UE if a valid C-RNTI is not already available; and
discarding the Temporary C-RNTI and using the valid C-RNTI if available;
wherein the sending the random access preamble includes sending the random access preamble for timing synchronization update when the valid C-RNTI is available, and wherein the Temporary C-RNTI is discarded and the valid C-RNTI is used.
19. The non-transitory machine-readable medium of claim 18 , wherein the operations further include sending a transmission after receiving the random access response, the transmission including the valid C-RNTI if available.
20. The non-transitory machine-readable medium of claim 18 , wherein the sending the random access preamble includes sending the random access preamble for initial system access or for transition from an idle state to an active state when the valid C-RNTI is not available, and wherein the Temporary C-RNTI is used as the C-RNTI for the UE.
21. An apparatus for wireless communication, comprising:
means for receiving a random access preamble for random access by a user equipment (UE);
means for assigning a Temporary Cell Radio Network Temporary Identifier (C-RNTI) to the UE;
means for sending a random access response including the Temporary C-RNTI;
means for using the Temporary C-RNTI as a C-RNTI for the UE if a valid C-RNTI is not already available at the UE; and
means for releasing the Temporary C-RNTI and using the valid C-RNTI if received from the UE;
wherein the means for receiving the random access preamble includes means for receiving the random access preamble from the UE for timing synchronization update when the UE already has the valid C-RNTI, wherein the apparatus further includes means for receiving a transmission including the valid C-RNTI from the UE after the random access response is sent, and wherein the Temporary C-RNTI is released and the valid C-RNTI is used for the UE.
22. The apparatus of claim 21 , further including:
means for receiving a transmission from the UE after sending the random access response, the transmission including the valid C-RNTI if available at the UE.
23. The apparatus of claim 21 , wherein the means for receiving the random access preamble includes means for receiving the random access preamble from the UE for initial system access or for transition from an idle state to an active state, and wherein the Temporary C-RNTI is used as the C-RNTI for the UE.
24. A non-transitory machine-readable medium comprising instructions which, when executed by a machine, cause the machine to perform operations including:
receiving a random access preamble for random access by a user equipment (UE);
assigning a Temporary Cell Radio Network Temporary Identifier (C-RNTI) to the UE;
sending a random access response including the Temporary C-RNTI;
using the Temporary C-RNTI as a C-RNTI for the UE if a valid C-RNTI is not already available at the UE; and
releasing the Temporary C-RNTI and using the valid C-RNTI if received from the UE;
wherein the receiving the random access preamble includes receiving the random access preamble from the UE for timing synchronization update when the UE already has the valid C-RNTI, wherein the operations further include receiving a transmission including the valid C-RNTI from the UE after sending the random access response, and wherein the Temporary C-RNTI is released and the valid C-RNTI is used for the UE.
25. The non-transitory machine-readable medium of claim 24 , wherein the operations further include receiving a transmission from the UE after sending the random access response, the transmission including the valid C-RNTI if available at the UE.
26. The non-transitory machine-readable medium of claim 24 , wherein the receiving the random access preamble includes receiving the random access preamble from the UE for initial system access or for transition from an idle state to an active state, and wherein the Temporary C-RNTI is used as the C-RNTI for the UE.