Adaptive channel state feedback based on channel estimation characteristics and reporting requirements

Patent metadata

Field	Value
Publication number	US-9816969-B2
Application number	US-201514950608-A
Country	US
Kind code	B2
Filing date	Nov 24, 2015
Priority date	May 15, 2012
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

Providing adaptive channel state feedback (CSF) reports in discontinuous reception (DRX) scenarios in a power-efficient manner. The described algorithm may be able to make adaptive decisions to carry over the CSF from previous DRX cycles based on a comparison between an offset at which CSF values are stable and an offset at which a CSF report is to be sent to a base station. If the CSF values are not stable by the time the CSF report is to be sent, a CSF report from a prior DRX cycle may be used. Alternatively, if the CSF value are stable by the time the CSF report is to be sent, a determination may be made to either generate a new CSF report or use a prior CSF report. The latter determination may be made based on various criteria, including channel conditions and DRX cycle length.

First claim

What is claimed is:

1. An apparatus, comprising:
a communications circuit configured to communicate over a channel during a plurality of reception cycles, wherein the communications circuit comprises:
a memory configured to store one or more prior channel state feedback (CSF) reports from one or more prior reception cycles; and
one or more processors configured to:
perform a comparison between a time when stable CSF values are expected to be available for a current reception cycle and a point in time at which a current CSF report for the current reception cycle is to be sent;
based on the comparison between the time when stable CSF values are expected to be available and the point in time, perform a selection, wherein the selection is between generating new content for the current CSF report for the current reception cycle and reusing prior content from at least one of the one or more prior CSF reports for the current CSF report for the current reception cycle; and
cause the current CSF report to be sent to a base station over the channel.

2. The apparatus of claim 1 , wherein the apparatus is a component of a mobile phone.

3. The apparatus of claim 1 , wherein the communications circuit further comprises an antenna configured to send the current CSF report to the base station via the channel.

4. The apparatus of claim 1 , wherein the communications circuit is configured to operate in a discontinuous reception mode.

5. The apparatus of claim 1 , wherein the one or more processors are configured to generate the new content for the current CSF report in response to determining that a point in time at which CSF values of the channel are predicted to be stable for the current reception cycle is earlier than the point in time at which the current CSF report is predicted to be sent.

6. The apparatus of claim 1 , wherein the one or more processors are configured to reuse the prior content for the current CSF report in response to determining that a point in time at which CSF values of the channel are predicted to be stable for the current reception cycle is later than the point in time at which the current CSF report is predicted to be sent.

7. The apparatus of claim 2 , wherein the mobile phone further comprises one or more different processors integrated in a system on chip of the mobile phone and configured to execute program instructions for the mobile phone.

8. The apparatus of claim 4 , wherein the current reception cycle is a discontinuous reception cycle.

9. A non-transitory computer readable storage medium storing program instructions that, when executed by one or more processors, cause the one or more processors to carry out operations comprising:
communicating over a channel during at least one prior reception cycle;
selecting content of a current channel state feedback (CSF) report of the channel for a current reception cycle, comprising:
performing a comparison between a first point in time at which CSF values of the current reception cycle are predicted to be stable and a second point in time at which the current CSF report for the current reception cycle is to be sent;
based on determining that the first point in time occurs before the second point in time, generating new content for the current CSF report for the current reception cycle; and
based on determining that the first point in time occurs after the second point in time, reusing prior content from at least one prior CSF report for the current CSF report for the current reception cycle; and

causing the current CSF report to be sent to a base station via the channel.

10. The non-transitory computer readable storage medium of claim 9 , wherein, to cause the current CSF report to be sent, the non-transitory computer readable storage medium and the one or more processors are configured to cause the current CSF report to be sent to an antenna associated with the one or more processors.

11. The non-transitory computer readable storage medium of claim 9 , wherein the operations further comprise, based on current conditions of the channel, reusing the prior content from the at least one prior CSF report for the current CSF report.

12. The non-transitory computer readable storage medium of claim 9 , wherein the current CSF report is not required within a first subframe of the current reception cycle.

13. The non-transitory computer readable storage medium of claim 9 , wherein the first point in time is based on a channel estimation warm-up time for the channel.

14. The non-transitory computer readable storage medium of claim 11 , wherein the operations further comprise determining a probability that the current conditions of the channel will fall within a particular quality range.

15. A method, comprising:
causing, by one or more processors, communications over a channel with a base station during one or more previous reception cycles;
selecting, by the one or more processors, content of a current channel state feedback report (CSF) for a current reception cycle, comprising:
determining, by the one or more processors, a first point in time at which CSF values of the current reception cycle are predicted to be stable;
performing, by the one or more processors, a comparison between the first point in time and a second point in time at which the current CSF report for the current reception cycle is to be sent; and
in response to determining that the first point in time occurs after the second point in time, identifying, by the one or more processors, a previous CSF report from a previous reception cycle; and

causing the previous CSF report to be sent as the current CSF report for the current reception cycle to a base station.

16. The method of claim 15 , further comprising:
subsequent to the current reception cycle, selecting, by the one or more processors, content of a second CSF report for a second reception cycle, comprising:
determining a third point in time at which CSF values of the second reception cycle are predicted to be stable;
performing a comparison between the third point in time and a fourth point in time at which the second CSF report is to be sent; and
in response to determining that the third point in time occurs before the fourth point in time, generating a new CSF report for the second reception cycle; and

causing the new CSF report to be sent as the second CSF report to the base station.

17. The method of claim 15 , wherein causing the previous CSF report to be sent comprises sending the current CSF report to communications circuitry associated with the one or more processors.

18. The method of claim 15 , wherein the current CSF report comprises a channel quality indicator (CQI) of the channel, a precoding matrix index (PMI), and a rank indication (RI).

19. The method of claim 15 , wherein the second point in time is calculated based on a time associated with a time-tracking loop converging, a time associated with a frequency tracking loop converging, a time associated with an automatic gain control loop converging, or any combination thereof.

20. The method of claim 15 , wherein identifying the previous CSF report is performed in response to determining that a channel error rate of the channel is below an error rate threshold and a channel throughput of the channel is above a throughput threshold.

Assignees

• Apple Inc

Inventors

• Ji Zhu
• Damji Navid
• Sebeni Johnson O

Classifications

• H04W72/541

  using the level of interference · CPC title

• H04B7/0639

  Using selective indices, e.g. of a codebook, e.g. pre-distortion matrix index [PMI] or for beam selection · CPC title

• H04W4/027

  using movement velocity, acceleration information · CPC title

• H04W72/12

  Wireless traffic scheduling · CPC title

• G01N29/36 Primary

  Detecting the response signal {, e.g. electronic circuits specially adapted therefor} · CPC title