1. 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

2. 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

3. Introduction Objective Background
May 2003
Introduction
Objective
To achieve high throughput/efficient schemes to improve the current MAC/PHY
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
S. Choi, SNU and Youngsoo Kim, Samsung/SNU

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

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

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

7. 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

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

9. 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

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

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

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

13. 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

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

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

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