  In IEEE 802.11, the retry limit is set the same value for all packets. In
this paper, we dynamically classify video teleconferencing packets based on the
type of the video frame that a packet carries and the packet loss events that
have happened in the network, and assign them different retry limits. We
consider the IPPP video encoding structure with instantaneous decoder refresh
(IDR) frame insertion based on packet loss feedback. The loss of a single frame
causes error propagation for a period of time equal to the packet loss feedback
delay. To optimize the video quality, we propose a method to concentrate the
packet losses to small segments of the entire video sequence, and study the
performance by an analytic model. Our proposed method is implemented only on
the stations interested in enhanced video quality, and is compatible with
unmodified IEEE 802.11 stations and access points in terms of performance.
Simulation results show that the performance gain can be significant compared
to the IEEE 802.11 standard without negatively affecting cross traffic.
