doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 1 Throughput Enhancement via Frame Aggregation – A Sequel Youngsoo Kim *+, Sunghyun Choi *, Hyosun Hwang +, and Kyunghun Jang + + Samsung Advance Institute of Technology (SAIT) and * Seoul National University (SNU)

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 2 Contents Introduction Frame aggregation New Results –Numerical throughput analysis with channel error –Performance measurement using TCP and UDP traffic Conclusion

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 3 Introduction Objective –To achieve high throughput/efficient schemes to improve the current MAC Background – MAC/PHY has fixed overheads irrespective of packet size –The small-size packet can cause more throughput degradation –To reduce the overheads is the one of main concerns to enhance current WLAN

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 4 Throughput Performance Analysis Assumptions –There is a single transmitter and a single receiver –The DCF is used –All the datagrams have a fixed size –The transmitter has infinite number of datagrams –Channel error is not considered –Throughput is determined at the LLC SAP between LLC and IP

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 5 Theoretical Throughput for 54 Mbps Preferred Operation Range

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 6 Frame Aggregation Aggregation of multiple frames in order to reduce the fixed overheads relatively! Aggregation was once part of e in e/D1.0 –It defined a new management frame for this aggregation mechanism –Multiple MSDUs are aggregated into a single management frame Frame aggregation was presented at the May 2003 meeting ( r0-HTSG-Throughput_Enhancement_via_Frame_Aggregation.ppt)

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 7 Frame Formats (Example) Original With aggregation

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 8 Numerical Analysis with Channel Error Compare the throughput performance by distance of two scenarios –Without aggregation One 1000 bytes frame (IP datagram size) –With aggregation Two 1000 bytes frames are aggregated Assumption –Ideal rate-adaptation (maximizing throughput) Path loss exponent = 4 & Tx_power = 200 mW –Based on error performance analysis assuming Binary convolutional coding Hard-decision Viterbi decoding with AWGN at the input

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 9 Numerical Analysis Result

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 10 Some Lessons from Error Performance Short distance (high Tx rate) Long distance (low Tx rate) Throughput gainHighLow Error performance loss LowHigh Frame aggregation seems a good solution to improve throughput when the distance between sender and receiver is relatively short !

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 11 Performance Measurement Implement frame aggregation in real platform Linux & Intersil-based platform (11b) Measure the throughput performance of UDP and TCP traffic Note: Frame aggregation is only applied when there are multiple frames in the queue Traffic generator AP STA

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 12 New Measurement Results - UDP Throughput performance of packet aggregation with fixed rate UDP

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 13 New Measurement Results - TCP Throughput performance of packet aggregation with TCP

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 14 Conclusion Shown via analysis that frame aggregation is a good way to improve MAC efficiency Measurements from real implementation also show the performance enhancement Frame aggregation can be done above the MAC SAP very easily Frame aggregation can be considered an enhanced mechanism

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 15 Future Work Measurement/simulations with more realistic traffic scenarios –Considering usage scenarios developed in this group Incorporating the PHY channel error performance –Based on a more realistic simulation, not an analysis (given here)

doc.: IEEE /567r0 Submission May 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 16 Any Comments or Questions ?