Fast Resilient Jumbo Fast Resilient Jumbo Frames in Wireless LANs Frames in Wireless LANs Apurv Bhartia Apurv Bhartia University of Texas at Austin University of Texas at Austin [email protected][email protected]Joint work with Joint work with Anand Padmanabha Iyer, Gaurav Deshpande, Anand Padmanabha Iyer, Gaurav Deshpande, Eric Rozner and Lili Qiu Eric Rozner and Lili Qiu IWQoS 2009 IWQoS 2009 July 15, 2009 July 15, 2009
22
Embed
Fast Resilient Jumbo Frames in Wireless LANs Apurv Bhartia University of Texas at Austin [email protected] Joint work with Anand Padmanabha Iyer, Gaurav.
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Fast Resilient JumboFast Resilient JumboFrames in Wireless LANsFrames in Wireless LANs
Apurv Bhartia Apurv Bhartia University of Texas at AustinUniversity of Texas at Austin
– Combination of MAC-layer and 2.5-layer ACKs– MAC-layer ACKs
• Adjustment of back-off window in IEEE 802.11• Increased reliability and efficiency than 2.5 ACKs
– 2.5-layer ACKs• To support partial recovery• Unicast for improved reliability and cumulative
Frame Offset
Segment Bitmap 1
Frame CRC
HeaderFrame Offset N
Segment Bitmap N
Start FrameSeg No
Type RateFrameBitmap
9
ApproachApproach• Retransmission
– Disable MAC layer retransmissions• set MAC retry count = 0• Retransmit the frames at the 2.5-layer
– Triggered by • 2.5-layer ACKs
– If 1st Retx: frames with higher seq nos or some segments in this frame are ACKed [first data transmissions is in-order]
– If 2nd or higher: some new segments in this frame are ACKed• Retransmission Timeout
– Standard approach as in TCP
10
Partial Recovery Aware Rate AdaptationPartial Recovery Aware Rate Adaptation– Traditional schemes identify optimal rate using frame loss rate
• Overestimates the loss rate• Lower data transmissions rates are selected
– Challenges for the ‘new’ scheme• Accurate estimation of channel condition at various data rates• Selecting rate that maximizes throughput under partial recovery