Robust Detection of Packet Types
First Claim
1. A method for determining a modulation of an orthogonal frequency-division multiplexing (OFDM) symbol, the method comprising:
- receiving the symbol;
multiplying the received symbol by the conjugate transpose of an overall channel response for the symbol;
applying a decision function to the result of the multiplication for a set of sub-carriers;
determining the modulation of the symbol in accordance with the result of the decision function; and
processing a packet in accordance with the determination of the modulation.
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Accused Products
Abstract
Disclosed herein is a system and method for determining the presence of rotated-BPSK modulation. In addition, disclosed herein is a system and method for determining if a received packet is a Legacy, Mixed-Mode, or Green-Field packet in accordance with the determination of the presence of rotated-BPSK modulation. The presence of a Green-Field packet may be determined by detecting if additional tones are being excited in an LTF symbol of the received packet and/or if a SIG field symbol following the LTF symbol is modulated by rotated-BPSK. The presence of a Mixed-Mode packet may be determined by detecting if the first four bits of the SIG field symbol following the LTF symbol are [1 1 0 1] and/or detecting if a symbol following an L-SIG symbol is modulated by rotated-BPSK. The presence of a Legacy packet may be determined by detecting if the symbol following the L-SIG symbol is modulated by BPSK.
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Citations
20 Claims
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1. A method for determining a modulation of an orthogonal frequency-division multiplexing (OFDM) symbol, the method comprising:
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receiving the symbol; multiplying the received symbol by the conjugate transpose of an overall channel response for the symbol; applying a decision function to the result of the multiplication for a set of sub-carriers; determining the modulation of the symbol in accordance with the result of the decision function; and processing a packet in accordance with the determination of the modulation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus comprising:
at least one receiver configured to receive a packet of data and to determine whether the packet is a Legacy, Mixed-Mode, or Green-Field packet and to process the packet in accordance with the determined type of packet. - View Dependent Claims (12, 13, 14, 15)
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16. A system comprising:
a programmable processor configured to determine whether a received packet is a Legacy, Mixed-Mode, or Green-Field packet and further configured to process the packet in accordance with the determination, the determination comprising; applying a decision function to a SIG field symbol following an LTF symbol of the packet for a subset of all of the sub-carriers in a channel to determine a type of modulation for the SIG field symbol following the LTF symbol; determining that the packet is a Green-Field packet if the type of modulation for the SIG field symbol following the LTF symbol is rotated-BPSK; if the packet is not a Green-Field packet, applying a decision function to a symbol following an L-SIG symbol of the packet for a subset of all of the sub-carriers in a channel to determine a type of modulation for the symbol following the L-SIG symbol; determining that the packet is a Mixed-Mode packet if the type of modulation for the symbol following the L-SIG symbol is rotated-BPSK; and determining that the packet is a Legacy packet if the type of modulation for the symbol following the L-SIG symbol is BPSK. - View Dependent Claims (17, 18, 19, 20)
Specification