OFDM cognitive radio with zero overhead signalling of deleted subcarriers frequencies
AssigneeNXP B.V.
InventorCharles Razzell
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Abstract
A system, device and method are described for suppressing certain sub-carrier frequencies within a multi-path transmission system and efficiently notifying a receiver (400) of the suppressed sub-carriers. In various embodiments of the invention, an OFDM system uses the preamble (210) of an OFDM burst for indicating which sub-carrier frequencies are being suppressed by a transmitter (300).
Claims20
A method for suppressing at least one sub-carrier frequency within a channel frequency profile, the method comprising:
- identifying the at least one sub-carrier frequency, within the wireless channel frequency profile, having an interference level above a first threshold;
- notching the at least one sub-carrier frequency in a preamble of a burst to generate a notched preamble;
- transmitting the burst, comprising the notched preamble and a payload, into a wireless channel;
- receiving the burst from the wireless channel and analyzing the notched preamble to identify the at least one sub-carrier frequency;
- inserting at least one erasure in the payload of the burst at the at least one sub-carrier frequency identified by analyzing the notched preamble;
- and
- decoding the payload of the burst.
A transmitter module apparatus located within a multi-frequency wireless transmitter, the module comprising:
- an interference detector, coupled to an antenna, that analyzes frequency characteristics within a frequency spectrum and identifies undesirable sub-carrier frequencies within the frequency spectrum;
- a preamble generator, communicatively coupled to the interference detector, that generates a notched preamble having at least one sub-carrier frequency notch corresponding to the identified undesirable frequencies, wherein the notched preamble is configured to instruct a receiver to insert at least one erasure in a payload of a burst at least one of the undesirable sub-carrier frequencies;
- and
- an active interference cancellation module, communicatively coupled to the interference detector, that generates sub-carrier guards that are adjacent to the at least one sub-carrier frequency notch to reduce energy from spilling into the at least one sub-carrier frequency notch.
A receiver module apparatus located within a multi-frequency wireless transmitter, the module comprising:
- a channel estimation module, coupled to receive a burst from a wireless channel, that analyzes a notched preamble to identify at least one notched sub-carrier frequency within the notched preamble of the burst;
- a nulled sub-carrier identification and list module, coupled to the channel estimation module, that stores the at least one notched sub-carrier frequency identified by the channel estimation module;
- and
- a channel decoder, coupled to the channel estimation module and the nulled sub-carrier identification and list module, that associates at least one suppressed sub-carrier frequency within a payload of the burst with the at least one notched sub-carrier frequency in the notched preamble, and decodes the notched preamble.
Dependencies are inferred from the claim text.