Dynamic voltage and frequency scaling in wireless modems
Methods and apparatuses are described in which dynamic voltage and frequency scaling may be used to save power when processing packets in a wireless communications device. In some cases, inframe detection may allow the device to determine whether to transition from a first (e.g., lower) voltage level to a second (e.g., higher) voltage level to process one or more packets of a received frame. For some packet types the first voltage level may be maintained. In other cases, the device may determine a bandwidth to use from among multiple bandwidths supported by the device. The bandwidth may be determined based on channel conditions. A voltage level may be identified that corresponds to the determined bandwidth and a processing voltage may be scaled to the identified voltage level. The device may be configured to operate in wireless local area network (WLAN) and/or in a cellular network (e.g., LTE).
1. A method for wireless communications, comprising:
operating at a first voltage level in a wireless communications device;
detecting, based at least in part on information within a first portion of a received frame, a throughput category corresponding to a bandwidth of one or more packets of the received frame; and
determining whether to transition, during processing of the first portion of the received frame, to a second voltage level to process at least a portion of the one or more packets including a second portion of the received frame based at least in part on the detected throughput category, wherein the transition to the second voltage level occurs during processing of the first portion of the received frame, and wherein the second portion of the received frame is subsequent to the first portion of the received frame.
2. The method of claim 1 , further comprising:
detecting, based at least in part on the information within the first portion of the received frame or information within the second portion of the received frame, one or more of a destination of a packet, a transmission grant, and a reception grant.
3. The method of claim 1 , further comprising:
scaling from the first voltage level to the second voltage level, the second voltage level being greater than the first voltage level.
4. The method of claim 1 , further comprising:
scaling from the second voltage level to the first voltage level for a next received frame after processing the at least a portion of the one or more packets including the second portion of the received frame at the second voltage level.
5. The method of claim 1 , wherein the detecting comprises:
detecting the throughput category within a preamble of the received frame.
6. The method of claim 1 , wherein:
the one or more packets in the received frame is an IEEE 802.11 packet.
7. The method of claim 6 , wherein:
the one or more packets is a very high throughput (VHT) packet, and
the detecting comprises detecting the throughput category during the VHT short training field (VHT-STF) of the received VHT packet.
8. The method of claim 7 , further comprising:
scaling from the first voltage level to the second voltage level within the VHT packet, the second voltage level being greater than the first voltage level.
9. The method of claim 1 , further comprising:
determining whether the received frame is destined for the wireless communications device; and
operating at the first voltage level when the received frame is not destined for the wireless communications device.
10. The method of claim 9 , wherein the determining comprises:
identifying a media access control (MAC) portion of the received frame; and
determining a destination of the received frame from the MAC portion of the received frame.
11. The method of claim 9 , wherein the determining comprises:
identifying a pAID field or a GID field in the received frame; and
determining a destination of the received frame from the pAID field or the GID field.
12. The method of claim 1 , wherein the one or more packets is a high throughput (HT) packet, the method comprising:
scaling from the first voltage level to the second voltage level to process at least a portion of the HT packet, the second voltage level being greater than the first voltage level.
13. The method of claim 1 , wherein the one or more packets is a legacy packet, the method comprising:
maintaining the first voltage level for processing the legacy packet.
14. The method of claim 1 , further comprising:
identifying a bandwidth associated with the one or more packets of the received frame; and
scaling from the first voltage level to the second voltage level based at least in part on the throughput category and the identified bandwidth.
15. The method of claim 14 , further comprising:
identifying a different bandwidth associated with the one or more packets of the received frame; and
scaling from the second voltage level to a third voltage level based at least in part on the throughput category and the identified different bandwidth.
16. The method of claim 1 , further comprising:
scaling from a first clock frequency to a second clock frequency based at least in part on the throughput category, the second clock frequency being greater than the first clock frequency.
17. The method of claim 1 , wherein:
the received frame is an LTE sub-frame comprising a first slot and a second slot, the first slot comprising a region with physical downlink control channel (PDCCH) information, and
the detecting comprises detecting the throughput category within the region in the first slot.
18. The method of claim 17 , further comprising:
determining from the throughput category whether a portion of the received frame is to be decoded by an LTE modem; and
scaling from the first voltage level to the second voltage level to process the portion of the received frame when a determination is made that the portion of the received frame is not to be decoded by the LTE modem.
19. The method of claim 1 , further comprising:
applying the second voltage level to one or more subsystems of the wireless communications device.
20. An apparatus for wireless communications, comprising:
means for operating at a first voltage level in a wireless communications device;
means for detecting, based at least in part on information within a first portion of a received frame, a throughput category corresponding to a bandwidth of one or more packets of the received frame; and
means for determining whether to transition, during processing of the first portion of the received frame, to a second voltage level to process at least a portion of the one or more packets including a second portion of the received frame based at least in part on the detected throughput category, wherein the transition to the second voltage level occurs during processing of the first portion of the received frame, and wherein the second portion of the received frame is subsequent to the first portion of the received frame.
21. A wireless communications device, comprising:
a processor; and
a memory in electronic communication with the processor, instructions stored in the memory being executable by the processor to:
operate at a first voltage level in the wireless communications device;
detect, based at least in part on information within a first portion of a received frame, a throughput category corresponding to a bandwidth of one or more packets of the received frame; and
determine whether to transition, during processing of the first portion of the received frame, to a second voltage level to process at least a portion of the one or more packets including a second portion of the received frame based at least in part on the detected throughput category, wherein the transition to the second voltage level occurs during processing of the first portion of the received frame, and wherein the second portion of the received frame is subsequent to the first portion of the received frame.
22. A wireless communications device, comprising:
a detector configured to detect, based at least in part on information within a first portion of a received frame, a throughput category corresponding to a bandwidth of one or more packets of the received frame; and
a voltage adjuster configured to:
operate at a first voltage level, and
determine whether to transition, during processing of the first portion of the received frame, to a second voltage level to process at least a portion of the one or more packets including a second portion of the received frame based at least in part on the detected throughput category, wherein the transition to the second voltage level occurs during processing of the first portion of the received frame, and wherein the second portion of the received frame is subsequent to the first portion of the received frame.
23. A computer program product, comprising:
a non-transitory computer-readable medium comprising:
code for causing at least one computer to operate at a first voltage level in a wireless communications device;
code for causing the at least one computer to detect, based at least in part on information within a first portion of a received frame, a throughput category corresponding to a bandwidth of one or more packets of the received frame; and
code for causing the at least one computer to determine whether to transition, during processing of the first portion of the received frame, to a second voltage level to process at least a portion of the one or more packets including a second portion of the received frame based at least in part on the detected throughput category, wherein the transition to the second voltage level occurs during processing of the first portion of the received frame, and wherein the second portion of the received frame is subsequent to the first portion of the received frame.