1. doc.: IEEE 802.11-03/567r1 Submission July 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)

2. doc.: IEEE 802.11-03/567r1 Submission July 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

3. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 3 Introduction Objective –To achieve high throughput/efficient schemes to improve the current 802.11 MAC/PHY Background –802.11 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 802.11 WLAN

4. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 4 Throughput Performance Analysis Assumptions –There are a single transmitter and a single receiver –The 802.11 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

5. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 5 Theoretical Throughput for 54 Mbps Preferred Operation Range

6. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 6 Packet Size Statistics This statistics is from the measurement taken in this room in the morning of July 22 nd 2003

7. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 7 Frame Aggregation Aggregation of multiple frames in order to reduce the fixed overheads relatively! Our frame aggregation approach was originally presented at the May 2003 meeting –Ref. 11-03-376r0-HTSG-Throughput Enhancement via Frame Aggregation11-03-376r0-HTSG-Throughput Enhancement via Frame Aggregation Multiple frames are aggregated above the MAC SAP –The aggregated frame is transmitted via a data frame

8. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 8 Frame Formats (Example) Original With aggregation

9. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 9 Numerical Analysis with Channel Error Compare throughput performance vs. distance –Without aggregation One 1000 bytes frame (IP datagram size) –With aggregation Two 1000 bytes frames are aggregated Assumptions –Ideal rate-adaptation (maximizing throughput) Path loss exponent = 4 & Tx_power = 200 mW –Based on error performance analysis assuming Hard-decision Viterbi decoding with AWGN at the receiver

10. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 10 Numerical Analysis Result

11. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 11 Some Lessons from Error Performance Short distance (high Tx rate) Long distance (low Tx rate) Throughput gainHighLow Error performance loss LowHigh Frame aggregation seems always a good solution to improve throughput when the distance between sender and receiver is relatively short !

12. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 12 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

13. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 13 New Measurement Results - UDP Throughput performance of packet aggregation with fixed rate UDP

14. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 14 New Measurement Results - TCP Throughput performance of packet aggregation with TCP

15. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 15 Conclusion Shown via analysis that frame aggregation is a good way to improve 802.11 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

16. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 16 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)

17. doc.: IEEE 802.11-03/567r1 Submission July 2003 Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 17 Any Comments or Questions ?