Methods and apparatus for a transmit path with frequency hopping phase locked loop

1. An apparatus for frequency hopping uplink transmission, comprising:

a transmit path;

a plurality of local oscillators (LO); and

a control unit configured to:

receive an upcoming resource block (RB) allocation;

determine whether the upcoming RB allocation is the same as a current RB allocation; and

in response to determining that the upcoming RB allocation is different than the current RB allocation:

select an unused LO of the plurality of LOs;

determine whether a number of allocated RBs associated with the upcoming RB allocation is greater than a threshold; and

in response to determining that the number of allocated RBs associated with the upcoming RB allocation is not greater than the threshold, tune the selected LO to a frequency corresponding to the upcoming RB allocation.

2. The apparatus of claim 1 , wherein the control unit is further configured to provide an output signal from the selected LO to transmit data via the transmit path according to the upcoming RB allocation.

3. The apparatus of claim 2 , further comprising a phase locked loop (PLL) selector configured to receive one or more control signals from the control unit;

wherein each of the plurality of LOs comprise a PLL and a corresponding voltage controlled oscillator (VCO) (PLL/VCO).

4. The apparatus of claim 3 , wherein a first PLL/VCO of the plurality of PLL/VCOs is coupled with a first divider and a second PLL/VCO of the plurality of PLL/VCOs is coupled with a second divider, and wherein the PLL selector is further configured to switch from a first output signal of the first divider to a second output signal of the second divider to provide the second output signal to the transmit path based at least in part on the one or more control signals from the control unit.

5. The apparatus of claim 4 , wherein the control unit is further configured to cause the switch to be performed while a first symbol is transmitted via the transmit path according to the upcoming RB allocation.

6. The apparatus of claim 4 , wherein the control unit is further configured to cause the switch to be performed during a transmission of a cyclic prefix (CP).

7. The apparatus of claim 3 , wherein a first PLL/VCO of the plurality of PLL/VCOs and a second PLL/VCO of the plurality of PLL/VCOs are coupled with a shared divider, and wherein the PLL selector is configured to switch from an output signal of the first PLL/VCO to the output signal of the second PLL/VCO to provide the output signal of the second PLL/VCO to the shared divider based at least in part on the one or more control signals from the control unit.

8. The apparatus of claim 7 , wherein the control unit is further configured to cause the switch to be performed while a first symbol is transmitted via the transmit path according to the upcoming RB allocation.

9. The apparatus of claim 7 , wherein the control unit is further configured to cause the switch to be performed during a transmission of a cyclic prefix (CP).

10. The apparatus of claim 1 , wherein the transmit path comprises a baseband filter (BBF) and a mixer.

11. The apparatus of claim 10 , wherein the BBF is configured to generate a baseband signal based on a tuned frequency of the selected LO and a required frequency of the upcoming RB allocation, and wherein the mixer is configured to modulate a signal at the tuned frequency of the selected LO with the baseband signal from the BBF.

12. The apparatus of claim 1 , wherein the control unit is further configured to:

in response to determining that the number of allocated RBs associated with the upcoming RB allocation is greater than the threshold, tune the selected LO to a frequency corresponding to an assigned channel.

13. The apparatus of claim 12 , wherein the frequency corresponding to the assigned channel comprises a center frequency of the assigned channel.

14. The apparatus of claim 1 , wherein the control unit is further configured to:

in response to determining that the upcoming RB allocation is the same as the current RB allocation, continue to utilize a currently used LO to transmit data according to the current RB allocation.

15. The apparatus of claim 1 , wherein the control unit is further configured to tune the selected LO at least in part by performing coarse tuning (CT) calibration and allowing the selected LO to settle to the frequency corresponding to the upcoming RB allocation.

16. The apparatus of claim 1 , wherein the control unit is further configured to tune the selected LO at least in part by performing coarse tuning (CT) calibration and two-point modulation (TPM).

17. An apparatus for frequency hopping uplink transmission, comprising:

means for providing an output signal from a plurality of local oscillators (LO); and

control means for receiving an upcoming resource block (RB) allocation and for determining whether the upcoming RB allocation is the same as a current RB allocation;

the control means in response to determining that the upcoming RB allocation is different than the current RB allocation:

selects an unused LO of the plurality of LOs;

determines whether a number of allocated RBs associated with the upcoming RB allocation is greater than a threshold; and

in response to determining that the number of allocated RBs associated with the upcoming RB allocation is not greater than the threshold, tunes the selected LO to a frequency corresponding to the upcoming RB allocation.

18. A non-transitory computer readable medium having stored thereon instructions for causing one or more processors to perform operations comprising:

receiving an upcoming resource block (RB) allocation;

determining whether the upcoming RB allocation is the same as a current RB allocation; and

in response to determining that the upcoming RB allocation is different than the current RB allocation:

selecting an unused local oscillator (LO) of a plurality of LOs not currently in use;

determining whether a number of allocated RBs associated with the upcoming RB allocation is greater than a threshold; and

in response to determining that the number of allocated RBs associated with the upcoming RB allocation is not greater than the threshold, tuning the selected LO to a frequency corresponding to the upcoming RB allocation.