Reliable Packet Detection In A Wireless Receiver When Packets Contain A Known Repetitive Sequence
First Claim
1. A method of detecting reception of packets in a wireless receiver, a preamble portion of each packet comprising a set of elements repeated to form a repetitive sequence, said method being implemented in said wireless receiver, said method comprising:
- receiving a signal on a wireless medium;
cross-correlating said signal with a copy of said set of elements at a plurality of time instances to generate a corresponding plurality of values;
computing a measure of variation in said plurality of values; and
determining that said signal represents said packet only if said measure is greater than a threshold value.
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Accused Products
Abstract
A wireless receiver operating in a wireless communication environment in which a beginning of a packet contains a repetitive sequence. The wireless receiver may compute a variance (example of a measure of variations in the cross correlation values) of cross-correlation values obtained by cross correlating a received signal and a copy of the preamble sequence starting at different time instances. When a valid packet is received, the variance of the values resulting from the cross correlation is high, otherwise the variance is low. As a result packet detection is made robust, and false packet detection due to interference signals is reduced. In an embodiment, the wireless receiver is implemented in the context of WLAN 802.11 a/g network.
21 Citations
20 Claims
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1. A method of detecting reception of packets in a wireless receiver, a preamble portion of each packet comprising a set of elements repeated to form a repetitive sequence, said method being implemented in said wireless receiver, said method comprising:
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receiving a signal on a wireless medium; cross-correlating said signal with a copy of said set of elements at a plurality of time instances to generate a corresponding plurality of values; computing a measure of variation in said plurality of values; and determining that said signal represents said packet only if said measure is greater than a threshold value. - View Dependent Claims (2, 3, 4, 5)
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6. A wireless receiver designed to detect reception of packets in a wireless receiver, a preamble portion of each packet comprising a set of elements repeated to form a repetitive sequence, said wireless receiver comprising:
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means for receiving a signal on a wireless medium; means for cross-correlating said signal with a copy of said set of elements at a plurality of time instances to generate a corresponding plurality of values; means for computing a measure of variation in said plurality of values; and means for determining that said signal represents said packet only if said measure is greater than a threshold value. - View Dependent Claims (7, 8, 9, 10)
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11. A wireless receiver designed to detect reception of packets in a wireless receiver, a preamble portion of each packet comprising a set of elements repeated to form a repetitive sequence, said wireless receiver comprising:
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an antenna to receive a signal on a wireless medium; an analog front end to generate a plurality of digital codes representing the strength of said signal at corresponding time instances; and a processor to cross-correlate said signal with a copy of said set of elements at a plurality of time instances to generate a corresponding plurality of values and to compute a measure of variation in said plurality of values, said processor determining that said signal represents said packet only if said measure is greater than a threshold value. - View Dependent Claims (12, 13, 14, 15)
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16. A wireless device comprising:
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an analog front end to generate a plurality of digital codes representing the strength of a signal received on a wireless path at corresponding time instances; a processor to cross-correlate said signal with a copy of said set of elements at a plurality of time instances to generate a corresponding plurality of values and to compute a measure of variation in said plurality of values, said processor determining that said signal represents said packet only if said measure is greater than a threshold value, said processor generating a plurality of payload values from a payload portion of said packet; and a host unit processing said plurality of payload values. - View Dependent Claims (17, 18, 19, 20)
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Specification