UE based conditional enabling of ULTD

1. A method for uplink transmit diversity, comprising:

transmitting, by a user equipment (UE), an uplink on a first antenna of the UE;

determining that a serving node has conditionally authorized uplink transmit diversity;

measuring a value; and

transmitting, by the UE, the uplink, at least in part, on a second antenna of the UE for uplink transmit diversity in response to determining that the serving node has conditionally authorized uplink transmit diversity and determining that an enabling condition based on the value is satisfied.

2. The method of claim 1 , further comprising determining by the user equipment that uplink transmit diversity is conditionally authorized.

3. The method of claim 1 , further comprising measuring the value by the user equipment.

4. The method of claim 1 , further comprising determining by a serving node that uplink transmit diversity is conditionally authorized.

5. The method of claim 1 , further comprising measuring the value by a serving node.

6. The method of claim 1 , further comprising transmitting the uplink at least in part on the second antenna for Switched Antenna Transmit Diversity (SATD).

7. The method of claim 6 , further comprising:

wherein measuring the value comprises determining a value of time elapsed since switching between transmitting on the first antenna and the second antenna; and

enabling switching between the first antenna and the second antenna in response to comparing the value of time elapsed to the enabling condition of a minimum elapsed time threshold.

8. The method of claim 7 , wherein the enabling condition prevents switching between the first antenna and the second antenna more than a configurable value.

9. The method of claim 6 , further comprising disabling switching between the first antenna and the second antenna for Switched Antenna Transmit Diversity (SATD) in response to determining that the user equipment is configured for Dual Carrier High-Speed Uplink Packet Access (DC-HSUPA).

10. The method of claim 1 , further comprising transmitting the uplink at least in part on a second antenna for Beamforming Transmit Diversity (BFTD).

11. The method of claim 10 , further comprising disabling BFTD in response to determining that the user equipment is configured for Dual Carrier High-Speed Uplink Packet Access (DC-HSUPA).

12. The method of claim 1 , wherein determining that the enabling condition based on the value is satisfied further comprises comparing the value comprising power headroom of the user equipment to an enabling threshold.

13. The method of claim 1 , wherein determining that the enabling condition based on the value is satisfied further comprises comparing the value comprising an active set size of the user equipment to an active set threshold.

14. The method of claim 13 , wherein the active set threshold is one (1).

15. The method of claim 1 , wherein determining that the enabling condition based on the value is satisfied further comprises comparing the value comprising Common Pilot Channel (CPICH) Received Signal Code Power (RSCP) to an enabling threshold.

16. The method of claim 1 , wherein determining that the enabling condition based on the value is satisfied further comprises comparing the value comprising Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA) carrier Received Signal Strength Indication (RSSI) to an enabling threshold.

17. The method of claim 1 , wherein determining that the enabling condition based on the value is satisfied further comprises comparing the value comprising Chip Energy divided by Noise Density (Ec/No) of a downlink from a serving node to an enabling threshold.

18. The method of claim 1 , further comprising determining that the enabling condition based on the value is satisfied further comprises comparing the value comprising transmit power by the user equipment to an enabling threshold.

19. The method of claim 18 , wherein the determining that the enabling condition is satisfied further comprises determining that only a W-CDMA Release 1999 Dedicated Channel (DCH) is configured on the user equipment.

20. The method of claim 1 , wherein determining that the enabling condition based on the value is satisfied further comprises comparing the value comprising speed of the user equipment to an enabling threshold.

21. The method of claim 1 , wherein determining that the enabling condition based on the value is satisfied further comprises comparing the value comprising distance of the user equipment from a serving node to an enabling threshold.

22. The method of claim 1 , wherein determining that the enabling condition based on the value is satisfied further comprises comparing the value comprising an average data rate transmitted by the user equipment to an enabling threshold.

23. The method of claim 1 , wherein determining that the enabling condition based on the value is satisfied further comprises comparing the value comprising duration of a Radio Resource Management (RRM) operation to an enabling threshold.

24. The method of claim 1 , wherein determining that the enabling condition based on the value is satisfied further comprises comparing the value comprising duration of an interference management operation to an enabling threshold.

25. The method of claim 1 , wherein determining that the enabling condition based on the value is satisfied further comprises comparing the value comprising a traffic characteristic of a served plurality of user equipment to an enabling threshold.

26. The method of claim 1 , wherein determining that the enabling condition is satisfied further comprises comparing the value comprising a number of antenna switches within a selected amount of time to an enabling threshold.

27. The method of claim 1 , further comprising disabling uplink transmit diversity in response to determining that a disabling condition based on the value is satisfied, wherein the disabling condition comprises a disabling threshold that equals the enabling condition comprising an enabling threshold with a threshold adjustment for hysteresis.

28. An apparatus for uplink transmit diversity, comprising:

means for transmitting, by a user equipment (UE), an uplink on a first antenna of the UE;

means for determining that a serving node has conditionally authorized uplink transmit diversity;

means for measuring a value; and

means for transmitting, by the UE, the uplink, at least in part, on a second antenna of the UE for uplink transmit diversity in response to determining that the serving node has conditionally authorized uplink transmit diversity and determining that an enabling condition based on the value is satisfied.

29. An apparatus for uplink transmit diversity, comprising:

a transmitter for transmitting, by a user equipment (UE), an uplink on a first antenna;

an uplink transmit diversity controller for determining that a serving node has conditionally authorized uplink transmit diversity;

a receiver for measuring a value; and

the transmitter further for transmitting, by the UE, the uplink, at least in part, on a second antenna of the user equipment for uplink transmit diversity in response to the uplink transmit diversity controller for determining that the serving node has conditionally authorized uplink transmit diversity and determining that an enabling condition based on the value is satisfied.