Fec in cognitive multi-user ofdma

Abstract

A multiuser scheme allowing for a number of users, sets of user, or carriers to share one or more channels is provided. In the invention, the available channel bandwidth is subdivided into a number of equal-bandwidth subchannels according to standard OFDM practice. A transmitter transmits data on a set of OFDM subchannels that need not be contiguous in the spectrum or belong to the same OFDM channel. A receiver receives and decodes the data and detects errors on subchannels. The receiver then broadcasts the identity of those subchannels on which the error rate exceeds a specific threshold, and the transmitter may select different subchannels for transmission based on this information.

What is claimed is: 
     
         1 . A method performed on a computing device, the method comprising: selecting an OFDM subchannel for use based on performing error correction. 
     
     
         2 . The method of  claim 1  where the selecting comprises identifying, based on the performed error correction, a subchannel causing an error. 
     
     
         3 . The method of  claim 2  where the identifying is further based on signal strength. 
     
     
         4 . The method of  claim 2  further comprising broadcasting information identifying the subchannel causing the error. 
     
     
         5 . The method of  claim 4  where the broadcasting further includes information identifying another subchannel that is considered good. 
     
     
         6 . The method of  claim 5  further comprising repeating the broadcasting. 
     
     
         7 . The method of  claim 1  where the selecting is further based on receiving, from another device, a broadcast that includes information identifying a subchannel identified by the other device as causing an error and another subchannel identified by the other device as good. 
     
     
         8 . A system comprising a computing device and at least one program module that are together configured for performing actions comprising: selecting an OFDM subchannel for use based on performing error correction. 
     
     
         9 . The system of  claim 8  where the selecting comprises identifying, based on the performed error correction, a subchannel causing an error. 
     
     
         10 . The system of  claim 9  where the identifying is further based on signal strength. 
     
     
         11 . The system of  claim 9 , the actions further comprising broadcasting information identifying the subchannel causing the error. 
     
     
         12 . The system of  claim 11  where the broadcasting further includes information identifying another subchannel that is considered good. 
     
     
         13 . The system of  claim 12 , the actions further comprising repeating the broadcasting. 
     
     
         14 . The system of  claim 8  where the selecting is further based on receiving, from another device, a broadcast that includes information identifying a subchannel identified by the other device as causing an error and another subchannel identified by the other device as good. 
     
     
         15 . At least one computer-readable storage medium storing computer-executable instructions that, when executed on a computing device, cause the computing device to perform actions: selecting an OFDM subchannel for use based on performing error correction. 
     
     
         16 . The at least one computer-readable storage medium of  claim 15  where the selecting comprises identifying, based on the performed error correction, a subchannel causing an error. 
     
     
         17 . The at least one computer-readable storage medium of  claim 16  where the identifying is further based on signal strength. 
     
     
         18 . The at least one computer-readable storage medium of  claim 16 , the actions further comprising broadcasting information identifying the subchannel causing the error and another subchannel that is considered good. 
     
     
         19 . The at least one computer-readable storage medium of  claim 18 , the actions further comprising repeat rig the broadcasting. 
     
     
         20 . The at least one computer-readable storage medium of  claim 15  where the selecting is further based on receiving, from another device, a broadcast that includes information identifying a subchannel identified by the other device as causing an error and another subchannel identified by the other device as good.