1. < Sungrae Cho >, <Chung-Ang UNIV>
<September 2008>
doc.: IEEE
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Impact of Frame Length on Latency and Throughput]
Date Submitted: [September, 2008]
Source: [Sungrae Cho, Wonsuk Choi, Xiangbo Zhang, Laihyuk Park and Dong Dong]
[School of Computer Science and Engineering, Chung-Ang University ]
Address [221 Heukseok, Dongjak, Seoul , Republic of Korea]
Voice:[ ], FAX: [ ],
Re: [Contribution to IEEE Meeting, September 2008]
Abstract: [This document describes an impact of frame length on latency and throughput for WBAN networks.]
Purpose: [Contribution]
Notice: This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release: The contributor acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P
<September, 2008>
< Sungrae Cho >, <Chung-Ang UNIV>

2. Impact of Frame Length on Latency and Throughput
<September 2008>
doc.: IEEE
Impact of Frame Length on Latency and Throughput
Sungrae Cho, Wonsuk Choi, Xiangbo Zhang, Laihyuk Park, and Dong Dong
UC LAB
Chung-Ang University
<September, 2008>
< Sungrae Cho >, <Chung-Ang UNIV>
Slide 2

3. < Sungrae Cho >, <Chung-Ang UNIV>
<September 2008>
doc.: IEEE
Introduction
The QoS management and reliability should be provided for high priority alarm message and real time vital information
Differentiation (or Prioritization) is necessary based on
Timeliness (Urgency)
Reliability
Etc.
<September, 2008>
< Sungrae Cho >, <Chung-Ang UNIV>
Slide 3

4. < Sungrae Cho >, <Chung-Ang UNIV>
<September 2008>
doc.: IEEE
Assumptions
Considers CSMA/CA.
Single channel.
Two types of priority groups: Hi and Lo
Different priority sources use different access mechanisms.
High priority sources randomly choose backoff interval in range of [0, α-1], and low priority sources choose in range of [α, β-1] where β > α+1.
Different priority sources use different exponential increase factors.
<September, 2008>
< Sungrae Cho >, <Chung-Ang UNIV>
Slide 4

5. Low Priority Source Data is Long
doc.: IEEE
Low Priority Source Data is Long
Low
Priority Flow
RTS
CTS
DATA
ACK
But still needs to wait for
this long time
A very urgent packet needs
to be transmitted
<September, 2008>
< Sungrae Cho >, <Chung-Ang UNIV>
Slide 5

6. Low Priority Source Data is Short
doc.: IEEE
Low Priority Source Data is Short
To limit max Data Length
Low
Priority Flow
RTS
CTS
DATA
ACK
High
Priority Flow
Carrier Sense/Backoff
RTS
CTS
DATA
ACK
High
Priority Flow gets
the channel
faster than previous
slide
A very urgent packet needs
to be transmitted
<September, 2008>
< Sungrae Cho >, <Chung-Ang UNIV>
Slide 6

7. < Sungrae Cho >, <Chung-Ang UNIV>
<September 2008>
doc.: IEEE
Simple Comparison
C++ event-driven simulation
2Mb/s link without noise or inference
Poisson packet arrivals
Frame header 50B
Cwmin = 16 (Hi CW: 0~7, Lo CW: 8~15)
Exponential Backoff
Measured
Latency: average waiting time for hi-priority source to gain the channel
Throughput: average throughput for lo-priority source
<September, 2008>
< Sungrae Cho >, <Chung-Ang UNIV>
Slide 7

8. Latency for Hi-Priority Source
doc.: IEEE
Latency for Hi-Priority Source
<September, 2008>
< Sungrae Cho >, <Chung-Ang UNIV>
Slide 8

9. Throughput for Lo-Priority Source
doc.: IEEE
Throughput for Lo-Priority Source
<September, 2008>
< Sungrae Cho >, <Chung-Ang UNIV>
Slide 9

10. < Sungrae Cho >, <Chung-Ang UNIV>
<September 2008>
doc.: IEEE
Summary
Prioritization is necessary with respect to Timeliness (Urgency) and Reliability, etc.
Using shorter frame allows hi-priority source to access the channel earlier at the expenses of decreased throughput of lo-priority source.
Is a restriction of lo-priority data frame necessary for hi-priority sources?
Or is there any way to stop long data frame of lower priority source in order to send higher priority source’s urgent data.
<September, 2008>
< Sungrae Cho >, <Chung-Ang UNIV>
Slide 10

11. This work has been supported by HNRC of IITA.
<September 2008>
doc.: IEEE
This work has been supported by HNRC of IITA.
<September, 2008>
< Sungrae Cho >, <Chung-Ang UNIV>
Slide 11

12. < Sungrae Cho >, <Chung-Ang UNIV>
<September 2008>
doc.: IEEE
Thank You!
<September, 2008>
< Sungrae Cho >, <Chung-Ang UNIV>
Slide 12