Aggregation mechanism for moving vehicles

Abstract

In one embodiment, a method implemented on an access point of a wireless communication system includes: determining an estimate for a relative velocity between a mobile wireless client device and the access point, the mobile wireless client device communicating wirelessly with the access point over a channel; determining a channel coherence time for the channel using said estimated relative velocity; and determining a maximum aggregated frame size based on the determined channel coherence time.

What is claimed is: 
     
         1 . A method implemented on an access point of a wireless communication system, said method comprising:
 determining an estimate for a relative velocity between a mobile wireless client device and said access point, said mobile wireless client device communicating wirelessly with said access point over a channel;   determining a channel coherence time for said channel using said estimated relative velocity; and   determining a maximum aggregated frame size based on said determined channel coherence time.   
     
     
         2 . The method of  claim 1 , further comprising adjusting a packet aggregation process according to said determined maximum aggregated frame size for a next transmission between said mobile wireless client device and said access point. 
     
     
         3 . The method of  claim 1 , wherein said determining an estimate for a relative velocity is based at least on a signal strength indication received from said mobile wireless client device. 
     
     
         4 . The method of  claim 3 , further comprising:
 providing estimates of parameters relevant to said mobile wireless client device using said received signal strength indication, said parameters comprising: an instant velocity of said mobile wireless client device; an angle between said mobile wireless client device and said access point; a distance between said mobile wireless device and said access point; and a position of said mobile wireless client device relative to said access point; and   determining an estimate of a relative velocity between said mobile wireless client device and said access point using said estimates.   
     
     
         5 . The method of  claim 1 , wherein said determining a maximum aggregated frame size comprises determining a maximum aggregated frame size based on said determined channel coherence time for a particular modulation and coding scheme, channel bandwidth and number of spatial streams used by said mobile wireless client device to communicate wirelessly with said access point. 
     
     
         6 . The method of  claim 5 , wherein said determining a maximum aggregated frame size comprises determining a maximum aggregate medium access control protocol data unit for a short guard interval using said determined channel coherence time. 
     
     
         7 . The method of  claim 5 , wherein said determining a maximum aggregated frame size comprises determining a maximum aggregate medium access control protocol data unit for a long guard interval using said determined channel coherence time. 
     
     
         8 . The method of  claim 5 , further comprising:
 determining a maximum physical layer conversion protocol data unit frame size using said determined channel coherence time; and   determining a maximum aggregate medium access control protocol data unit for a short guard interval using said determined maximum physical layer conversion protocol data unit frame size.   
     
     
         9 . The method of  claim 5 , further comprising:
 determining a maximum physical layer conversion protocol data unit frame size using said determined channel coherence time; and   determining a maximum aggregate medium access control protocol data unit for a long guard interval using said determined maximum physical layer conversion protocol data unit frame size.   
     
     
         10 . The method of  claim 1 , further comprising:
 computing a plurality of channel coherence times, each of said computed channel coherence times corresponding to a particular relative velocity between a mobile wireless client device and said access point;   storing said plurality of computed channel coherence times at said access point; and   wherein said determining a channel coherence time for said channel comprises retrieving a stored channel coherence time corresponding to said estimated relative velocity.   
     
     
         11 . The method of  claim 10 , wherein said determining a maximum aggregated frame size comprises determining a maximum aggregated frame size based on said retrieved channel coherence time for a particular modulation and coding scheme, channel bandwidth and number of spatial streams used by said mobile wireless client device to communicate wirelessly with said access point. 
     
     
         12 . The method of  claim 11 , wherein said determining a maximum aggregated frame size comprises determining a maximum aggregate medium access control protocol data unit for a short guard interval using said retrieved channel coherence time. 
     
     
         13 . The method of  claim 11 , wherein said determining a maximum aggregated frame size comprises determining a maximum aggregate medium access control protocol data unit for a long guard interval using said retrieved channel coherence time. 
     
     
         14 . The method of  claim 11 , wherein:
 said computing further comprises computing a plurality of maximum physical layer conversion protocol data unit frame sizes, each of said maximum physical layer conversion protocol data unit frame sizes being computed using a corresponding computed channel coherence time;   said storing further comprises storing said plurality of computed maximum physical layer conversion protocol data unit frame sizes; and   wherein said determining a channel coherence time for said channel further comprises retrieving a stored maximum physical layer conversion protocol data unit frame size corresponding to said estimated relative velocity.   
     
     
         15 . The method of  claim 14 , wherein said determining a maximum aggregate medium access control protocol data unit comprises determining a maximum aggregate medium access control protocol data unit for a short guard interval using said retrieved maximum physical layer conversion protocol data unit frame size. 
     
     
         16 . The method of  claim 14 , wherein said determining a maximum aggregate medium access control protocol data unit comprises determining a maximum aggregate medium access control protocol data unit for a long guard interval using said retrieved maximum physical layer conversion protocol data unit frame size. 
     
     
         17 . An access point controller comprising a processor, said processor being operable to:
 determine an estimate for a relative velocity between a mobile wireless client device and said access point, said mobile wireless client device communicating wirelessly with said access point over a channel;   determine a channel coherence time for said channel using said estimated relative velocity; and   determine a maximum aggregated frame size based on said determined channel coherence time.   
     
     
         18 . The apparatus of  claim 17 , wherein said access point controller further comprises a Kalman filler configured to provide estimates of parameters relevant to said mobile wireless client device using said received signal strength indication, said parameters comprising: an instant velocity of said mobile wireless client device; a distance between said mobile wireless device and said access point; an angle between said mobile wireless client device and said access point; and a position of said mobile wireless client device relative to said access point. 
     
     
         19 . The apparatus of  claim 17 , wherein said mobile wireless client device is a workgroup bridge located in a moving vehicle, said workgroup bridge being operable to serve one or more mobile client devices without wireless network connectivity located in said moving vehicle. 
     
     
         20 . One or more computer readable tangible storage media encoded with software comprising computer executable instructions and when the software is executed operable to:
 determine an estimate for a relative velocity between a mobile wireless client device and an access point, said mobile wireless client device communicating wirelessly with said access point over a channel;   determine a channel coherence time for said channel using said estimated relative velocity; and   determine a maximum aggregated frame size based on said determined channel coherence time.