Embedded wake-up signaling

Patent metadata

Field	Value
Publication number	US-9525540-B1
Application number	US-201615017500-A
Country	US
Kind code	B1
Filing date	Feb 5, 2016
Priority date	Jun 18, 2015
Publication date	Dec 20, 2016
Grant date	Dec 20, 2016

Abstract

When embedding a signal into a selected subcarrier of a multicarrier downlink waveform of regular data/control signaling, a base station modulates the embedded signal with a different modulation scheme than the other data in the downlink waveform. The base station nulls adjacent subcarriers to minimize interference at a low-power wake-up receiver of an IOE device(s). The IOE device wakes up the low-power wake-up receiver at scheduled times to listen for the signal. For synchronization signals, the IOE device corrects a local clock based on a correlation value of the signal to a predetermined sequence. For wake-up signals, the IOE device correlates whatever is detected at the antenna to a predetermined sequence and compares the correlation value to a predetermined threshold. If the threshold is met, the IOE device registers a wake-up signal and wakes the primary transceiver of the device. If not, the receiver goes back to sleep.

First claim

What is claimed is:

1. A method for wireless communication, comprising:
identifying, by a first communications device, at least one subcarrier within an orthogonal frequency division multiplexing (OFDM) downlink signal for use in communicating with a wake-up receiver of a second communications device with a primary receiver of the second communications device in deep sleep;
inserting, by the first communications device, an embedded signal into the identified at least one subcarrier at one or more pre-specified times for transmission to the wake-up receiver of the second communications device; and
transmitting, from the first communications device, the embedded signal for reception at the wake-up receiver of the second communications device with a first modulation using the identified at least one subcarrier, the first modulation being different from a second modulation used in transmitting data with one or more remaining subcarriers in the OFDM downlink signal.

2. The method of claim 1 , further comprising:
modulating one or more adjacent subcarriers to the identified one or more subcarriers with zero amplitude; and
boosting a power of the embedded signal an amount based on an amount of power freed up from the one or more adjacent subcarriers modulated with zero amplitude.

3. The method of claim 1 , wherein:
the embedded signal comprises a synchronization signal assigned to a first time from among the one or more pre-specified times, the synchronization signal including data to enable the second communications device to synchronize a clock local to the second communications device to a clock local to the first communications device, and
the embedded signal comprises a wake-up signal assigned to a second time from among the one or more pre-specified times, the first and second times being different from each other, the wake-up signal indicating to the second communications device to wake up the primary receiver for a pre-determined operation.

4. The method of claim 3 , wherein the first communications device communicates with a plurality of second communications devices, each second communications device comprising a wake-up receiver, the method further comprising:
broadcasting the synchronization signal to the plurality of second communications devices in the first time, the synchronization signal comprising a first pseudo-random noise sequence.

5. The method of claim 4 , wherein the second time comprises a plurality of times, each different from the first time and from each other, the method further comprising:
assigning, to each second communications device, a different time from among the plurality of different times at which each second communications device is to wake up its wake-up receiver to listen for the wake-up signal,
wherein the wake-up signal comprises the first pseudo-random noise sequence.

6. The method of claim 4 , wherein the at least one subcarrier comprises a plurality of subcarriers, the method further comprising:
assigning, to a first device from among the plurality of second communications devices, a first subcarrier that is used to transmit the wake-up signal to the first device during the second time; and
assigning, to a second device from among the plurality of second communications devices, a second subcarrier that is used to transmit the wake-up signal to the second device during the second time, the first and second subcarriers being different from each other in frequency,
wherein the wake-up signal transmitted on the first and second subcarriers each comprises the first pseudo-random noise sequence.

7. The method of claim 4 , wherein the second time comprises a plurality of times, each different from the first time and from each other, the method further comprising:
assigning a first group of communications devices from among the plurality of second communications devices to a first different time from among the plurality of different times and a second group of communications devices from among the plurality of second communications devices to a second different time from among the plurality of different times,
wherein the first group of communications devices is to wake up their wake-up receivers to listen for the wake-up signal during the first different time and the second group of communications devices is to wake up their wake-up receivers to listen for the wake-up signal during the second different time, and
wherein the wake-up signal for the first group of communications devices comprises a second pseudo-random noise sequence and the wake-up signal for the second group of communications devices comprises a third pseudo-random noise sequence.

8. The method of claim 1 , wherein:
the first modulation comprises on-off keying;
the first communications device comprises a base station; and
the second communications device comprises an internet of everything (IOE) device.

9. A method for wireless communication, comprising:
waking up a wake-up receiver of a first communications device, while a primary receiver of the first communications device is in deep sleep, at a pre-determined time to listen for an embedded signal within at least one selected subcarrier in an orthogonal frequency multiplexing (OFDM) downlink signal from a second communications device;
detecting a signal at the wake-up receiver at the at least one selected subcarrier during the pre-determined time; and
determining whether the detected signal is the embedded signal having a first modulation from the second communications device and intended for the first communications device, the first modulation being different from a second modulation used in transmitting data with one or more remaining subcarriers in the OFDM downlink signal.

10. The method of claim 9 , further comprising:
waking up the primary receiver in response to determining that the detected signal is the embedded signal intended for the first communications device, wherein:
the first modulation comprises on-off keying;
the first communications device comprises an internet of everything (IOE) device; and
the second communications device comprises a base station.

11. The method of claim 9 , wherein:
the pre-determined time comprises a plurality of specified times,
the embedded signal comprises a synchronization signal that is assigned to a first time from among the plurality of specified times, the synchronization signal comprising a first pseudo-random noise sequence previously shared with the first communications device, and
the embedded signal comprises a wake-up signal assigned to a second time from among the plurality of specified times, the first and second times being different from each other, the wake-up signal indicating to the first communications device to wake up the primary receiver for a pre-determined operation.

12. The method of claim 11 , wherein the detected signal is received during the first time, the method further comprising:
determining, by the first communications device, a correlation of the detected signal to the first pseudo-random noise sequence of the synchronization signal; and
correcting, by the first communications device, a clock offset of a clock local to the first communications device to be time aligned with a clock local to the second communications device based on a resulting magnitude of the correlation.

13. The method of claim 11 , wherein the detected signal is received during the second time, the wake-up signal comprises the first pseudo-random noise sequence, and the second time is uniquely assigned to the first communications device, the method further comprising:
determining, by the first communications device, a

Assignees

• Qualcomm Inc

Inventors

• Shellhammer Stephen Jay
• Ang Peter Pui Lok
• Burke Joseph Patrick
• Ji Tingfang
• Nguyen Cong
• Soriaga Joseph Binamira

Classifications

• H04L5/0053 Primary

  Allocation of signalling, i.e. of overhead other than pilot signals · CPC title

• H04L27/0008

  arrangements for allowing a transmitter or receiver to use more than one type of modulation (negotiating modulation type for two-way transmission paths H04L5/1453) · CPC title

• H04L27/04

  Modulator circuits; Transmitter circuits · CPC title

• H04W52/0229

  where the received signal is a wanted signal · CPC title

• H04W52/0283

  with sequential power up or power down of successive circuit blocks, e.g. switching on the local oscillator before RF or mixer stages · CPC title