Method and wireless device employing a preamble to initiate communications
First Claim
1. A method in a wireless receiver to detect a message identifier comprising:
- scanning, asynchronously and sequentially during a wakeup time, a plurality of predetermined frequencies for the message identifier;
collecting a plurality of received sample sequences, one received sample sequence collected at each of the plurality of predetermined frequencies;
performing a correlation between data corresponding to the message identifier and data corresponding to a first received sample sequence to provide a correlation result; and
comparing the correlation result to a threshold value to determine when the message identifier has been detected.
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Accused Products
Abstract
A wireless receiver 300 and corresponding method to detect a message identifier or preamble that has been generated and provided by a transmitter 200 uses FFTs to estimate frequency and time offset. The wireless receiver 300 scans, asynchronously and sequentially during a wakeup time, a plurality of predetermined frequencies for the message identifier or specialized preamble. A plurality of received sample sequences are collected, one received sample sequence collected at each of the plurality of predetermined frequencies. A correlation between data corresponding to the preamble and data corresponding to a received sample sequence is compared to a threshold value to determine when the preamble has been detected. The wireless receiver 300 is wakened from a low power mode when the preamble is detected.
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Citations
26 Claims
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1. A method in a wireless receiver to detect a message identifier comprising:
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scanning, asynchronously and sequentially during a wakeup time, a plurality of predetermined frequencies for the message identifier;
collecting a plurality of received sample sequences, one received sample sequence collected at each of the plurality of predetermined frequencies;
performing a correlation between data corresponding to the message identifier and data corresponding to a first received sample sequence to provide a correlation result; and
comparing the correlation result to a threshold value to determine when the message identifier has been detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A transmitter arranged to transmit a preamble signal to wake up target receivers, the wireless transmitter comprising:
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a signal generator for creating the preamble signal, the preamble signal comprising a data sequence that is periodic over,a preamble period, the preamble signal repeated during a plurality of time slots;
a signal source that provides a signal having a unique and predetermined frequency during each of the plurality of time slots; and
a transmitter apparatus coupled and responsive to the signal source, to transmit the signal modulated by the preamble signal during the plurality of time slots. - View Dependent Claims (13, 14, 15, 16)
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18. A wireless receiver arranged to detect a preamble signal to exit a standby low power mode, the wireless receiver comprising:
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a receiver for scanning, asynchronously and sequentially during a wakeup time, a plurality of predetermined frequencies for the preamble signal;
a sampler, coupled to the receiver, for collecting a plurality of received sample sequences, one received sample sequence collected at each of the plurality of predetermined frequencies; and
a controller coupled to the receiver and sampler;
for performing a correlation between data corresponding to the preamble signal and data corresponding to a first received sample sequence to provide a correlation result; and
for comparing the correlation result to a threshold value to determine when the preamble signal has been detected. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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Specification