Dynamic wireless link adaptation

Abstract

A system method that adapts wireless link parameters for a wireless communication link. A measure is determined of errors signal quality occurring in communication over a wireless link. In a case that the measure of errors signal quality corresponds to more errors than a first predetermined threshold, communication changes from a first set of wireless link parameters to a second set of wireless link parameters. The second set of wireless link parameters corresponds to higher error tolerance than the first set of wireless link parameters. In a case that the measure of errors signal quality corresponds to fewer errors than a second predetermined threshold, communication changes from the first set of wireless link parameters to a third set of wireless link parameters. The third set of wireless link parameters corresponds to lower error tolerance than the first set of wireless link parameters. Preferably, the measure of errors signal quality is determined by monitoring a number of NACK messages and a number of ACK messages that occur. It is determined that the measure of errors signal quality corresponds to more errors than the first predetermined threshold when more than a predetermined number of NACK messages occur in succession. It is determined that the measure of errors signal quality corresponds to fewer errors than the second predetermined threshold when more than a predetermined number of ACK messages occur in succession.

What is claimed is: 
     
       1. A method of dynamically adapting wireless link parameters, comprising:
 determining a plurality of states, each state corresponding to a plurality of wireless link parameters;   determining a plurality of thresholds for transitioning from a current state to a next state of said plurality of states, said thresholds comprising a number of NACK messages or a number of ACK messages received using said wireless link parameters for said current state; and   transitioning among said plurality of states based on said thresholds, thereby dynamically adapting said wireless link parameters for a wireless link.   
     
     
       2. A method as in  claim 1 , wherein said wireless link parameters comprise a modulation scheme, a symbol rate, and an error correction scheme. 
     
     
       3. A method as in  claim 1 , wherein each of said plurality of states can only transition to and from one or two adjacent states. 
     
     
       4. A method as in  claim 1 , wherein said plurality of states are stored in a memory. 
     
     
       5. An apparatus that dynamically adapts wireless link parameters, comprising:
 a wireless link interface to a wireless link;   a processor; and   a memory storing instructions executable by the processor to control communication over the wireless link interface, the instructions including the steps of:   determining a plurality of states, each state corresponding to a plurality of wireless link parameters;   determining a plurality of thresholds for transitioning from a current state to a next state of said plurality of states, said thresholds comprising a number of NACK messages or a number of ACK messages received using said wireless link parameters for said current state; and   transitioning among said plurality of states based on said thresholds, thereby dynamically adapting said wireless link parameters for the wireless link.   
     
     
       6. A method of dynamically adapting wireless link parameters for communicating data messages over a wireless link, comprising:
 selecting one or more wireless link parameters for transmission of the data messages over the wireless link;   establishing a first state and a second state of operation for the wireless link, the first state associated with a first set of wireless link parameters and the second state associated with a second set of wireless link parameters;   measuring the signal quality of the wireless link, wherein measuring the signal quality of the wireless link comprises counting a number of NACK messages and a number of ACK messages received during a period of time;   transitioning from the first state to the second state when the signal quality of the wireless link is worse than a first predetermined threshold; and   transitioning from the second state to the first state when the signal quality of the wireless link exceeds a second predetermined threshold.    
     
     
       7. A method as claimed in claim 6, wherein the second set of wireless link parameters enables transmission of the data messages with a higher error tolerance than the first set of wireless link parameters.  
     
     
       8. A method as claimed in claim 6, wherein the first set of wireless link parameters enables transmission of the data messages with a lower error tolerance than the second set of wireless link parameters.  
     
     
       9. A method as claimed in claim 8, further comprising:
 establishing a third state of operation for the wireless link associated with a third set of wireless link parameters; and   establishing a third predetermined threshold and a fourth predetermined threshold based on the signal quality of the wireless link, the third set of wireless link parameters enabling transmission of the data messages with a higher error tolerance than the second set of wireless link parameters.    
     
     
       10. A method as claimed in claim 9, further comprising:
 transitioning from the second state to the third state when the signal quality of the wireless link is less than the third predetermined threshold; and   transitioning from the third state to the second state when the signal quality of the wireless link exceeds the fourth predetermined threshold.    
     
     
       11. A method as claimed in claim 10, wherein the operation of the wireless link can transition from the second state to one of the first state and the third state based on the second and third predetermined thresholds.  
     
     
       12. A method as claimed in claim 10, wherein transitioning from the second state to the third state occurs when the number of NACK messages exceeds the third predetermined threshold.  
     
     
       13. A method as claimed in claim 10, wherein transitioning from the third state to the second state occurs when the number of ACK messages exceeds the fourth predetermined threshold.  
     
     
       14. A method as claimed in claim 9, wherein the third predetermined threshold comprises a second number of NACK messages and the fourth predetermined threshold comprises a second number of ACK messages.  
     
     
       15. A method as claimed in claim 6, wherein said first set of wireless link parameters and said second set of wireless link parameters each comprise a modulation scheme, a symbol rate, and an error correction scheme.  
     
     
       16. A method as claimed in claim 6, wherein one of the first predetermined threshold and the second predetermined threshold is determined by measuring throughput efficiency versus signal to interference and noise ratio (SINR) for the wireless link parameters.  
     
     
       17. A method as claimed in claim 6, wherein one of the first and second states is established based on a highest throughput efficiency for a current measurement of the signal quality of the wireless link.  
     
     
       18. A method as claimed in claim 6, wherein the first predetermined threshold is determined using throughput efficiency versus signal to interference and noise ratio.  
     
     
       19. A method as claimed in claim 6, wherein the first predetermined threshold comprises a first number of NACK messages and the second predetermined threshold comprises a second number of ACK messages.  
     
     
       20. A method as claimed in claim 6, wherein transitioning from the first state to the second state occurs when the number of NACK messages exceeds the first predetermined threshold.  
     
     
       21. A method as claimed in claim 6, wherein transitioning from the second state to the first state occurs when the number of ACK messages exceeds the second predetermined threshold.