Link adaptation

Abstract

The present invention discloses an apparatus and method for adapting a transmission parameter in a transmitting node of a data communication system to the current link quality of a data communication channel. The adapted transmission parameter is selected by the transmitting node from a set of transmission parameters in dependence on a number of successful transmissions. The number of successful transmissions is compared in the transmitting node against one of a first threshold value corresponding to a first state of the transmitting node and a second threshold value corresponding to a second state of the transmitting node. The method comprises in the transmitting node the steps of (a) counting the number of successful transmissions; (b) selecting the adapted transmission parameter (b 1 ) in response to the number of successful transmissions equaling or exceeding the first threshold value when the transmitting node is in the first state, and (b 2 ) in response to the number of successful transmissions equaling or exceeding the second threshold value when the transmitting node is in the second state; and in dependence of the result of a following transmission, operating the transmitting node in one of the first state and the second state.

1 . A method for adapting a transmission parameter in a transmitting node of a data communication system to the current link quality of a data communication channel, the adapted transmission parameter being selected by the transmitting node from a set of transmission parameters in dependence on a number of successful transmissions the number of successful transmissions being compared in the transmitting node against one of a first value corresponding to a first state of the transmitting node and a second value corresponding to a second state of the transmitting node, the method comprising in the transmitting node the steps of: 
 counting the number of successful transmissions;    selecting the adapted transmission parameter 
 in response to the number of successful transmissions equaling or exceeding the first value when the transmitting node is in the first state, and  
 in response to the number of successful transmissions equaling or exceeding the second value when the transmitting node is in the second state; and  
   in dependence of the success or failure of a subsequent transmission, operating the transmitting node in one of the first state and the second state.    
   
   
       2 . Method according to  claim 1 , wherein the step of operating the transmitting node in the second state further comprises in the event of a faulty transmission transitioning to the first state.  
   
   
       3 . Method according to any preceding claim further comprising setting the first value to 3 and the second value to 10.  
   
   
       4 . Method according to  claim 1 , further comprising counting a number of faulty transmissions and selecting the adapted transmission parameter in dependence of a threshold of the number of faulty transmissions.  
   
   
       5 . Method according to  claim 4 , further comprising setting the threshold of the number of faulty transmissions to 1.  
   
   
       6 . Method according to  claim 1 , further comprising selecting the transmission parameter used by a responding receiver.  
   
   
       7 . Method according to  claim 1 , wherein the step of selecting the adapted transmission parameter further comprises selecting a different data rate.  
   
   
       8 . Method according to  claim 1 , wherein the step of selecting the adapted transmission parameter further comprises selecting a packet length different to the length used before.  
   
   
       9 . A computer program comprising program code means for performing the steps of the method of  claim 1 , when said program is run on a computer.  
   
   
       10 . A computer program product stored on a computer usable medium, comprising computer readable program means for causing a computer to perform the steps of the method of  claim 1 .  
   
   
       11 . An apparatus for adapting a transmission parameter to the current link quality of a data communication channel, the adapted transmission parameter being selected from a set of transmission parameters in dependence on a number of successful transmissions, the number of successful transmissions being compared against one of a first value corresponding to a first state of the apparatus and a second value corresponding to a second state of the apparatus, the apparatus comprising: 
 a success counter for counting the number of successful transmissions;    a selecting unit for selecting the adapted transmission parameter 
 in response to the number of successful transmissions equaling or exceeding the first value when the apparatus is in the first state, and  
 in response to the number of successful transmissions equaling or exceeding the second value when the apparatus is in the second state; and  
   a decision unit which in dependence of the success or failure of a subsequent transmission informs the selecting unit to operate in one of the first state and the second state.    
   
   
       12 . Apparatus according to  claim 11 , further comprising a failure counter for counting a number of faulty transmissions.  
   
   
       13 . An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein for causing adaptation of a transmission parameter in a transmitting node of a data communication system, the computer readable program code means in said article of manufacture comprising computer readable program code means for causing a computer to effect in the transmitting node the steps of: 
 counting the number of successful transmissions;    selecting the adapted transmission parameter 
 in response to the number of successful transmissions equaling or exceeding the first value when the transmitting node is in the first state, and  
 in response to the number of successful transmissions equaling or exceeding the second value when the transmitting node is in the second state; and  
   in dependence of the success or failure of a subsequent transmission, operating the transmitting node in one of the first state and the second state.    
   
   
       14 . A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform method steps for adapting a transmission parameter in a transmitting node of a data communication system, said method steps comprising the steps of  claim 1 .  
   
   
       15 . An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein for causing adaptation of a transmission parameter in a transmitting node of a data communication system, the computer readable program code means in said article of manufacture comprising computer readable program code means for causing a computer to effect in the transmitting node the steps of  claim 2 .  
   
   
       16 . An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein for causing adaptation of a transmission parameter in a transmitting node of a data communication system, the computer readable program code means in said article of manufacture comprising computer readable program code means for causing a computer to effect in the transmitting node the steps of  claim 3 .  
   
   
       17 . An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein for causing adaptation of a transmission parameter in a transmitting node of a data communication system, the computer readable program code means in said article of manufacture comprising computer readable program code means for causing a computer to effect in the transmitting node the steps of  claim 4 .  
   
   
       18 . An article of manufacture comprising a computer usable medium having computer readable program code means embodied therein for causing adaptation of a transmission parameter in a transmitting node of a data communication system, the computer readable program code means in said article of manufacture comprising computer readable program code means for causing a computer to effect in the transmitting node the steps of  claim 5 .  
   
   
       19 . A computer program product comprising a computer usable medium having computer readable program code means embodied therein for causing adaptation of a transmission parameter to the current link quality of a data communication channel, the computer readable program code means in said computer program product comprising computer readable program code means for causing a computer to effect the functions of  claim 11 .  
   
   
       20 . A computer program product comprising a computer usable medium having computer readable program code means embodied therein for causing adaptation of a transmission parameter to the current link quality of a data communication channel, the computer readable program code means in said computer program product comprising computer readable program code means for causing a computer to effect the functions of  claim 12.