Modulation-type discrimination in a wireless communication network

A modulation-type discriminator for a radio frequency receiver comprises:

• a log-likelihood ratio (LLR) module operable to receive a signal field of an encoded signal having a preamble training sequence associated with a frame, the LLR module operable to generate a first and a second LLR stream for each of a plurality of sub-symbols for a predetermined portion of the received encoded signal based on a two-bit wide modulation reference;
• a summing module disposed to receive the first and the second LLR streams and operable to cumulatively the first LLR stream to produce a first cumulative LLR and the second LLR stream to produce a second cumulative LLR;
• and
• a discriminator module operable to receive the first and the second cumulative LLR, and further operable to compare each of the first and the second cumulative LLR to provide a discriminated modulation type from a plurality of specified modulation types.

An integrated circuit radio transceiver comprises:

• transmit signal path circuitry operable to transmit radio-frequency signals;
• receive signal path circuitry operable to receive radio-frequency signals having a preamble associated with a frame, the preamble having a signal field, the receive signal path circuitry includes modulation-type discriminator circuitry coupled to discriminate a signal field modulation type from a predetermined portion of a received radio-frequency signal, the modulation-type discriminator circuitry includes logic circuitry that comprises:
• a digital receiver processing module;
• and
• memory coupled to the digital receiver processing module, wherein the memory stores operational instructions that prompts the digital receiver processing module to:
• generate at least a first log-likelihood ratio (LLR)stream and a second LLR stream for each of a plurality of sub-symbols for a predetermined portion of the received encoded signal based upon an m-bit wide modulation reference, wherein m represents the bit width of the modulation reference, the first LLR stream and the second LLR stream includes a plurality of LLR values;
• sum the plurality of LLR values of the first LLR stream to produce a first cumulative LLR;
• sum the plurality of LLR values of the second LLR stream to produce a second cumulative LLR;
• discriminate the first cumulative LLR with the second cumulative LLR to produce a discriminated modulation type output;
• and
• decode the signal field based upon the discriminated modulation type output.

A method of discriminating a modulation type for decoding a signal field of an encoded signal in a wireless communication system, the method comprises:

• receiving the encoded signal having a preamble training sequence associated with a frame, the preamble training sequence including the signal field;
• processing a plurality of sub-symbols of the received encoded signal associated with the signal field to produce a stream having a real portion and an imaginary portion for each of the sub-symbols, each of the portions having a magnitude;
• for each sub-symbol, discriminating the magnitude of the real portion with the magnitude of the imaginary portion to produce a discriminated modulation type output;
• and
• decoding the signal field based on the discriminated modulation type output.