Decoding using walsh space information

Abstract

Methods and apparatus to improve the speed and reliability of decoders are presented herein. Namely, a priori knowledge of Walsh space information is used to increase the speed at which messages are decoded. In systems where control messages contain transmission parameters of concurrently transmitted packet data, a faster demodulation and decoding of control messages allows a receiver to demodulate the packet data sooner, so that a shorter buffer is needed to store the received packet data. The receiver uses the Walsh space from the previous successfully decoded message to first decode the current message. If the decoding attempt is unsuccessful, the receiver then uses a neighboring Walsh space to decode the current message.

1 . An apparatus for decoding an over-the-air transmission, comprising: 
 a memory element; and    a processing element configured to execute a set of instructions stored in the memory element, the set of instructions for:    setting a current set of transmission parameters equal to a previous set of transmission parameters;    decoding a received message first using the current set of transmission parameters;    if the current set of transmission parameters fails to decode the received message, then:    altering the previous set of transmission parameters by an increment to derive a new set of transmission parameters;    setting the current set of transmission parameters equal to the new set of transmission parameters; and    decoding the received message using the current set of transmission parameters.    
   
   
       2 . The apparatus of  claim 1 , wherein the previous set of transmission parameters comprises a Walsh space.  
   
   
       3 . The apparatus of  claim 2 , wherein altering the previous set of transmission parameters by an increment comprises adding a Walsh code sequence to the Walsh space.  
   
   
       4 . The apparatus of  claim 2 , wherein altering the previous set of transmission parameters by an increment comprises subtracting a Walsh code sequence from the Walsh space.  
   
   
       5 . The apparatus of  claim 2 , wherein altering the previous set of transmission parameters comprises replacing the Walsh space with a neighboring Walsh space.  
   
   
       6 . An apparatus for decoding a control message that contains a set of transmission parameters associated with a data packet, comprising: 
 a memory element; and    a processing element configured to execute a set of instructions stored in the memory element, the set of instructions for:    receiving a new control message;    attempting to first decode the new control message using an old Walsh space that was used to decode a previous control message; and    if the old Walsh space fails to decode the new control message, then attempting to decode the new control message using a new Walsh space, wherein the new Walsh space is generated by incrementing the old Walsh space.    
   
   
       7 . A method for decoding an over-the-air transmission, comprising: 
 receiving a new over-the-air transmission;    attempting to first decode the new over-the-air transmission using an old Walsh space that was used to decode a previous over-the-air transmission; and    if the old Walsh space fails to decode the new over-the-air transmission, then attempting to decode the new over-the-air transmission using a new Walsh space, wherein the new Walsh space is generated by incrementing the old Walsh space.    
   
   
       8 . A method for decoding a transmission received over-the-air, comprising: 
 setting a current set of transmission parameters equal to a previous set of transmission parameters;    decoding a received transmission first using the current set of transmission parameters;    if the current set of transmission parameters fails to decode the received transmission, then:    altering the previous set of transmission parameters by an increment to derive a new set of transmission parameters;    setting the current set of transmission parameters equal to the new set of transmission parameters; and    decoding the received transmission using the current set of transmission parameters.    
   
   
       9 . The method of  claim 8 , wherein the previous set of transmission parameters comprises a Walsh space.  
   
   
       10 . The method of  claim 9 , wherein altering the previous set of transmission parameters by an increment comprises adding a Walsh code sequence to the Walsh space.  
   
   
       11 . The method of  claim 9 , wherein altering the previous set of transmission parameters by an increment comprises subtracting a Walsh code sequence from the Walsh space.  
   
   
       12 . The method of  claim 9 , wherein altering the previous set of transmission parameters comprises replacing the Walsh space with a neighboring Walsh space.  
   
   
       13 . An apparatus for decoding a transmission received over-the-air, comprising: 
 means for storing a previous set of transmission parameters, wherein the previous set of transmission parameters was used to successfully decode a previously received transmission;    means for altering the previous set of transmission parameters to derive a new set of transmission parameters; and    means for decoding a current transmission using the previous set of transmission parameters and decoding the current transmission using the new set of transmission parameters if the previous set of transmission parameters fails to decode the current transmission.