Method for detecting delayed data frames in a transport function

Abstract

A method for detecting delayed data frames in a transport function includes the steps of comparing a frame sequence counter with a predetermined threshold value, detecting a delayed frame if the sequence counter exceeds the threshold value, and processing the detected delayed frame accordingly. In an RLP data transport protocol, the delayed frame may be processed as a retransmitted frame. The threshold value may be proportional to the maximum number of frames sent in a given bundle times the maximum delay, in units of frame intervals, between frames sent simultaneously over the air in the same frame interval.

We claim:  
     
         1 . A method of detecting a delayed frame in a transport function wherein a plurality of frames are sent from a transmitter to a receiver, the method comprising the steps of: 
 determining a threshold value proportional to a product of a number of frames within a bundle of frames and a maximum delay time in frame-length time increments between frames sent in said bundle of frames;    comparing, for a received frame, a frame sequencing counter number with said threshold value, the frame sequencing counter number being derived from a header of the received frame; and    detecting the received frame as a delayed frame if the frame sequencing counter number exceeds said threshold value.    
     
     
         2 . The method as recited in  claim 1  wherein the plurality of frames is sent in bundles of frames, each bundle including an equal number of frames, the frames within any bundle being sent simultaneously.  
     
     
         3 . The method of  claim 1 , further comprising the step of processing a detected delayed frame as a retransmitted frame.  
     
     
         4 . The method of  claim 1 , wherein the transport function is a Radio Link Protocol interface.  
     
     
         5 . An apparatus for detecting a delayed frame in a transport function wherein a plurality of frames are sent from a transmitter to a receiver, the apparatus comprising: 
 means for determining a threshold value proportional to a product of a number of frames within a bundle of frames and a maximum delay time in frame-length time increments between frames sent in said bundle of frames;    means for comparing, for a received frame, a frame sequencing counter number with said threshold value, the frame sequencing counter number being derived from a header of the received frame; and    means for detecting the received frame as a delayed frame if the frame sequencing counter number exceeds the threshold value.    
     
     
         6 . The apparatus as recited in  claim 5  wherein the plurality of frames is sent in bundles of frames, each bundle including an equal number of frames, the frames within any bundle being sent simultaneously.  
     
     
         7 . The apparatus of  claim 5 , further comprising means for processing a detected delayed frame as a retransmitted frame.  
     
     
         8 . The apparatus of  claim 5 , wherein the transport function is a Radio Link Protocol interface.