# US 8,542,610 B2 · Adaptive power saving for a mobile subscriber unit in a wireless communication network

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- Number: US 8,542,610 B2
- Document ID: US8542610B2
- Status: Granted
- Kind: B2
- Application number: 13/077,258
- Filed: 2011-03-31
- Published: 2012-10-04
- Granted: 2013-09-24
- Earliest claimed: 2011-03-31
- Assignees: Motorola Solutions, Inc.
- Applicants: Ohad Shatil; Yungang Wang; Win NuNu Win
- Inventors: Ohad Shatil; Yungang Wang; Win NuNu Win
- Web page: https://patentgrep.com/patent/US8542610B2

## CPC

- H04W 52/0216: {using a pre-established activity schedule, e.g. traffic indication frame}
- H04W 52/0229: {where the received signal is a wanted signal}
- Y02D 30/70: in wireless communication networks
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)
- Y02D: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN INFORMATION AND COMMUNICATION TECHNOLOGIES [ICT], I.E. INFORMATION AND COMMUNICATION TECHNOLOGIES AIMING AT THE REDUCTION OF THEIR OWN ENERGY USE

## Abstract

A method and apparatus for adaptive power saving for a mobile subscriber unit in a wireless communication network includes receiving beacons from an access point, measuring timing periods between received beacons, determining a delay in timing periods, and associating the delay in timing periods to a change in a quality of a communication link. The link quality can be quantified and used for reconfiguring power-save parameters in response to a change in link quality.

## Claims

### Claim 1

A method for classifying Radio Frequency communication link quality by a mobile subscriber unit in a wireless local area communication network, the method comprising the steps of:
sampling a portion of beacons transmitted from an access point;
measuring a change in timing periods between received beacons by determining a difference between an actual reception time of a beacon and a scheduled reception time from a previous beacon as TBTTcurrent beacon=MODULUS(number=TSFprevious beacon, divisor=BIprevious beacon), where TBTT is Target Beacon Transmission Time, TSF is Time Synchronization Function field in the sampled beacon, and BI is the configured Beacon Interval;
determining a measurement accuracy classification of the communication link quality based on the change in timing periods TBTTcurrent beacon; and
reconfiguring sampling based on the accuracy classification.

### Claim 2 (depends on 1)

The method of claim 1, wherein reconfiguring includes accommodates bi-directional drifts involving both adding and subtracting positive and negative timing drifts in sampling a portion of the beacons.

### Claim 3 (depends on 1)

The method of claim 1, wherein the accuracy classification in determining includes specific categories of accuracy classifications for TBTTcurrent beacon values with respect to particular ranges of multiples of a standard ±0.01% range.

### Claim 4 (depends on 1)

The method of claim 1, wherein determining includes determining that link quality changes in a random manner in specific regions of the network indicating over-the-air issues, whereupon reconfiguring in performed in a way responsive to the over-the-air issues.

### Claim 5 (depends on 4)

The method of claim 4, wherein determining includes determining that link quality changes indicate that the access point is systematically underperforming with regards to IEEE 802.11 standard runtime operation irrespective of geographical area, whereupon reconfiguring in performed in a way responsive to the underperforming.

### Claim 6 (depends on 1)

The method of claim 1, further comprising the step of normalizing link quality relative to an initialized link quality reference value to provide a percentage representing an amount of link quality change on a link quality scale.

### Claim 7 (depends on 1)

The method of claim 1, further comprising the step of quantifying link quality.

### Claim 8 (depends on 7)

The method of claim 7, further comprising the step of reconfiguring power-save parameters in response to a change in link quality.

### Claim 9 (depends on 8)

The method of claim 8, wherein reconfiguring power-save parameters includes changing a dwell time of at least one awake period.

### Claim 10

A mobile subscriber unit adapted for classifying Radio Frequency communication link quality in a wireless communication network, the mobile subscriber unit comprising:
a memory operable to be configured a classification of the communication link quality based on beacon timing period changes;
a transceiver operable to sample portions of beacons transmitted from an access point; and
a processor coupled to the memory and transceiver, the processor operable to measure a change in timing periods between received beacons by determining a difference between an actual reception time of a beacon and a scheduled reception time from a previous beacon as TBTTcurrent beacon=MODULUS(number=TSFprevious beacon, divisor=BIprevious beacon), where TBTT is Target Beacon Transmission Time, TSF is Time Synchronization Function field in the sampled beacon, and BI is the configured Beacon Interval, determine a measurement accuracy classification of the communication link quality based on the change in timing periods TBTTcurrent beacon, and reconfiguring sampling based on the accuracy classification.

### Claim 11 (depends on 10)

The mobile subscriber unit of claim 10, wherein the transceiver is operable to accommodate bi-directional drifts involving both adding and subtracting positive and negative timing drifts to sample a portion of the beacons.

### Claim 12 (depends on 10)

The mobile subscriber unit of claim 10, wherein the accuracy classification determined by the processor includes specific categories of accuracy classifications for TBTTcurrent beacon values with respect to particular ranges of multiples of a standard ±0.01% range.

### Claim 13 (depends on 10)

The mobile subscriber unit of claim 10, wherein the processor is further operable to determine that link quality changes in a random manner in specific regions of the network, which indicates over-the-air issues, whereupon sampling is reconfigured in a way responsive to the over-the-air issues.

### Claim 14 (depends on 10)

The mobile subscriber unit of claim 10, where the processor is further operable to quantify link quality.

### Claim 15 (depends on 14)

The mobile subscriber unit of claim 14, wherein the processor is further operable to reconfigure power-save parameters in response to a change in link quality.

### Claim 16 (depends on 15)

The mobile subscriber unit of claim 15, wherein reconfiguring power-save parameters includes changing a dwell time of at least one awake period.