doc.: ieee 802.11-03/567r1 submission july 2003 youngsoo kim, samsung/snu and s. choi, snu slide 1...
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![Page 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](https://reader035.vdocuments.us/reader035/viewer/2022062417/5514ab43550346f06e8b5f0a/html5/thumbnails/1.jpg)
July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 1
doc.: IEEE 802.11-03/567r1
Submission
Throughput Enhancement Throughput Enhancement via Frame Aggregation – A Sequelvia Frame Aggregation – A Sequel
Youngsoo Kim*+, Sunghyun Choi*,
Hyosun Hwang+, and Kyunghun Jang+
+Samsung Advance Institute of Technology (SAIT) and *Seoul National University (SNU)
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 2
doc.: IEEE 802.11-03/567r1
Submission
ContentsContents
• Introduction
• Frame aggregation
• New Results– Numerical throughput analysis with channel
error
– Performance measurement using TCP and UDP traffic
• Conclusion
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 3
doc.: IEEE 802.11-03/567r1
Submission
IntroductionIntroduction
• 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
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 4
doc.: IEEE 802.11-03/567r1
Submission
Throughput Performance AnalysisThroughput Performance Analysis
• Assumptions– There are a single transmitter and a single rec
eiver– The 802.11 DCF is used– All the datagrams have a fixed size– The transmitter has infinite number of datagra
ms– Channel error is not considered– Throughput is determined at the LLC SAP betw
een LLC and IP
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 5
doc.: IEEE 802.11-03/567r1
Submission
0
5
10
15
20
25
30
35
40
Datagram Size (octets)
Thro
ughp
ut (
Mbp
s)
Theoretical Throughput for 54 MbpsTheoretical Throughput for 54 Mbps
Preferred
Operation Range
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 6
doc.: IEEE 802.11-03/567r1
Submission
Packet Size StatisticsPacket Size Statistics
This statistics is from the measurement taken in this room in the morning of July 22nd 2003
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 7
doc.: IEEE 802.11-03/567r1
Submission
Frame AggregationFrame 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 Aggregation
• Multiple frames are aggregated above the MAC SAP– The aggregated frame is transmitted via a data frame
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 8
doc.: IEEE 802.11-03/567r1
Submission
Frame Formats (Example)Frame Formats (Example)
octets: 2 2 6 6 6 2 variable 4
octets: 3 5 variable IP
datagramSNAP
HeaderLLC
Header
Frame Control
Duration / ID Addr 1 Addr 2 Addr 3
Seq. Control Data FCS
802.2 LLC
802.11 MAC
octets: 2 2 6 6 6 2 variable 4
octets: 1 1 1 1 2 2 2 variable variable
Frame Control
Duration / ID
Addr 1
Addr 2
Addr 3
Seq. Control Data FCS
802.2 LLC with aggregation
802.11 MAC
Control(0x03)
Count(n)
Size 1 ... Size nEtherframe
1Etherframe
n...
octets: 6 6 2 variableSource
Addr.Type IP datagram
DestinationAddr.
SSAP(0xdd)
DSAP(0xdd)
Reserved
Original
With aggregation
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 9
doc.: IEEE 802.11-03/567r1
Submission
Numerical Analysis with Channel ErrorNumerical 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
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 10
doc.: IEEE 802.11-03/567r1
Submission
Numerical Analysis ResultNumerical Analysis Result
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 11
doc.: IEEE 802.11-03/567r1
Submission
Some Lessons from Error PerformanceSome Lessons from Error Performance
Short distance (high Tx rate)
Long distance(low Tx rate)
Throughput gain
High Low
Error performance loss
Low High
• Frame aggregation seems always a good solution to improve throughput when the distance between sender and receiver is relatively short !
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 12
doc.: IEEE 802.11-03/567r1
Submission
Performance MeasurementPerformance 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
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 13
doc.: IEEE 802.11-03/567r1
Submission
New Measurement Results - UDPNew Measurement Results - UDP
Packet aggregation, RTP, 10Mbps
0
1
2
3
4
5
6
7
8
0 200 400 600 800 1000 1200 1400 1600Packet Size (bytes, application-level)
Thr
ough
put (
Mbp
s)
original
aggregation
Theoretical
• Throughput performance of packet aggregation with fixed rate UDP
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 14
doc.: IEEE 802.11-03/567r1
Submission
New Measurement Results - TCPNew Measurement Results - TCP• Throughput performance of packet aggregation with
TCP
Packet Aggregation, TCP
0
1
2
3
4
5
6
7
0 200 400 600 800 1000 1200 1400 1600Packet Size (bytes, application-level)
Thr
ough
put (
Mbp
s)
original
aggregation
Theoretical
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 15
doc.: IEEE 802.11-03/567r1
Submission
ConclusionConclusion
• 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
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 16
doc.: IEEE 802.11-03/567r1
Submission
Future WorkFuture 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)
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July 2003
Youngsoo Kim, Samsung/SNU and S. Choi, SNU Slide 17
doc.: IEEE 802.11-03/567r1
Submission
Any Comments or Questions ?Any Comments or Questions ?