Throughput Enhancement via Frame Aggregation May 2003 Throughput Enhancement via Frame Aggregation Sunghyun Choi*, Youngsoo Kim*+, Hyosun Hwang+, and Kyunghoon Jang+ *Seoul National University (SNU) and +Samsung Advance Institute of Technology (SAIT) S. Choi, SNU and Youngsoo Kim, Samsung/SNU

Contents Introduction Throughput performance analysis by packet size May 2003 Contents Introduction Throughput performance analysis by packet size Frame aggregation Result Throughput analysis Performance evaluation by real platform Conclusion S. Choi, SNU and Youngsoo Kim, Samsung/SNU

Introduction Objective Background May 2003 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 S. Choi, SNU and Youngsoo Kim, Samsung/SNU

Frame Size Affects Throughput May 2003 Frame Size Affects Throughput 802.11 MAC/PHY have big fixed overheads MAC header, IFSs, ACK, and Backoff PLCP preamble & header S. Choi, SNU and Youngsoo Kim, Samsung/SNU

Throughput Performance Analysis May 2003 Throughput Performance Analysis Assumptions There is 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 Throughput is determined at the LLC SAP between LLC and IP S. Choi, SNU and Youngsoo Kim, Samsung/SNU

Theoretical Throughput for 54 Mbps May 2003 Theoretical Throughput for 54 Mbps Preferred Operation Range However, … S. Choi, SNU and Youngsoo Kim, Samsung/SNU

Internet Packet Size Distribution May 2003 Internet Packet Size Distribution Reference: by Agere in Hot Chips ’01 There are too many small packets !!! S. Choi, SNU and Youngsoo Kim, Samsung/SNU

May 2003 Frame Aggregation Aggregation of multiple frames in order to reduce the fixed overheads relatively! Aggregation was once part of 802.11e in 802.11e/D1.0 It defined a new management frame for this aggregation mechanism Multiple MSDUs are aggregated into a single management frame S. Choi, SNU and Youngsoo Kim, Samsung/SNU

Frame Aggregation Made Easy! May 2003 Frame Aggregation Made Easy! Our proposal is defining the frame aggregation above the MAP SAP !!! We don’t need a new frame type for this purpose A normal MPDU can be used as the aggregated frame arrives at the MAC SAP as an MSDU This can be added into any existing MAC implementation with minor SW modification !!! S. Choi, SNU and Youngsoo Kim, Samsung/SNU

Frame Formats (Example) May 2003 Frame Formats (Example) Original With aggregation S. Choi, SNU and Youngsoo Kim, Samsung/SNU

Modified 802.11 Reference Model May 2003 Modified 802.11 Reference Model Adding a proxy sublayer called Aggregation Sublayer S. Choi, SNU and Youngsoo Kim, Samsung/SNU

Theoretical Throughput w/ Aggregation May 2003 Theoretical Throughput w/ Aggregation S. Choi, SNU and Youngsoo Kim, Samsung/SNU

Performance Measurement May 2003 Performance Measurement Implement frame aggregation in real platform Linux & Intersil-based platform Traffic source 1 AP STA Traffic source 2 Traffic source 3 S. Choi, SNU and Youngsoo Kim, Samsung/SNU

Measurement Results May 2003 S. Choi, SNU and Youngsoo Kim, Samsung/SNU

May 2003 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 S. Choi, SNU and Youngsoo Kim, Samsung/SNU

Any Comments or Questions ? May 2003 Any Comments or Questions ? S. Choi, SNU and Youngsoo Kim, Samsung/SNU