Method for signaling information by modifying modulation constellations

Abstract

Methods and systems for communicating in a wireless network may distinguish different types of packet structures by modifying the phase of a modulation constellation, such as a binary phase shift keying (BPSK) constellation, in a signal field. Receiving devices may identify the type of packet structure associated with a transmission or whether the signal field is present by the phase of the modulation constellation used for mapping for the signal field. In one embodiment, the phase of the modulation constellation may be determined by examining the energy of the I and Q components after Fast Fourier Transform. Various specific embodiments and variations are also disclosed.

The invention claimed is: 
     
       1. A method of decoding encoded information by a wireless communication device, comprising:
 receiving a data unit including encoded information comprising one or more variable length low density parity check (LDPC) codewords from a network device; 
 decoding a length of the encoded information from a header of the data unit; 
 determining, based at least in part on the decoded length, the length of each of the one or more LDPC codewords; and 
 decoding the one or more LDPC codewords. 
 
     
     
       2. The method of  claim 1 , wherein decoding the one or more LDPC codewords comprises, for each of the one or more LDPC codewords:
 determining a plurality of variable node values; and 
 determining a plurality of check node values, corresponding to parity check relationships, based on the variable node values and a parity check matrix. 
 
     
     
       3. The method of  claim 1 , wherein decoding the one or more LDPC codewords comprises using a Bahl, Cocke, Jelinek and Raviv (BCJR) algorithm. 
     
     
       4. The method of  claim 1 , wherein decoding the one or more LDPC codewords comprises using a min-sum algorithm. 
     
     
       5. The method of  claim 1 , wherein decoding the one or more LDPC codewords comprises using a plurality of decoding iterations. 
     
     
       6. The method of  claim 5 , wherein the plurality of decoding iterations consist of eight decoding iterations. 
     
     
       7. A wireless communication device, including a memory and one or more antennas, the device capable to:
 receive a data unit including encoded information comprising one or more variable length low density parity check (LDPC) codewords from a network device; 
 decode a length of the encoded information from a header of the data unit; 
 determine, based at least in part on the decoded length, the length of each of the one or more LDPC codewords; and 
 decode the one or more LDPC codewords. 
 
     
     
       8. The device of  claim 7 , wherein the device is further capable to decode the one or more LDPC codewords, for each of the one or more LDPC codewords, by being configured to:
 determine a plurality of variable node values; and 
 determine a plurality of check node values, corresponding to parity check relationships, based on the variable node values and a parity check matrix. 
 
     
     
       9. The device of  claim 7 , wherein the device is further capable to decode the one or more LDPC codewords via a Bahl, Cocke, Jelinek and Raviv (BCJR) algorithm. 
     
     
       10. The device of  claim 7 , wherein the device is further capable to decode one or more LDPC codewords via a min-sum algorithm. 
     
     
       11. The device of  claim 7 , wherein the device is further capable to decode the one or more LDPC codewords via a plurality of decoding iterations. 
     
     
       12. The device of  claim 11 , wherein the plurality of decoding iterations consists of eight decoding iterations.