1. July 2004
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Two-way CTA for TCP Application]
Date Submitted: [July 9, 2004]
Source: [Jinwoo Hong, Inhwan Kim, Dae-kyu Bae, Hyunah Sung] Company [Samsung Electronics]
Address [416 Maetan-3Dong, Yeongtong-Gu, Suwon-City, Gyeonggi-Do, South Korea]
Voice:[ ], FAX: [ ],
[Bill Shvodian] Company [Freescale Semiconductor]
Address [8133 Leesburg Pike, Suite 700, Vienna, VA 22182, USA]
Voice:[ ], FAX: [ ], freescale.com]
Re: []
Abstract: [Two-way CTA for IEEE b WPAN]
Purpose: [For discussion to support Two-way CTA for IEEE b WPAN]
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
Jinwoo Hong et al, Samsung Electronics

2. July 2004
Two-way CTA
July 2004
Jinwoo Hong et al, Samsung Electronics

3. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
July 2004
Abstract
We propose the new type of CTA named ‘two-way CTA’.
In existing CTA, only src DEV can send data to the other devices.
In two-way CTA, even the dest DEV of the CTA can send data to src DEV of the CTA when the src DEV doesn’t have data to send anymore.
Two-way CTA is efficient for TCP streaming applications
Jinwoo Hong et al, Samsung Electronics
<author>, <company>

4. July 2004
Problem
Home network standard specifies TCP streaming as a basic service
TCP application
The sender can proceed its transmission after receiving ACK of TCP/IP from the receiver.
Superframe duration RTT will limit maximum throughput
TCP ACK Latency with one way CTAs will severely impact the speed of opening up the TCP window
TCP streaming application over
Using isochronous
Dest DEV cannot send TCP ACK in CTA
Src DEV cannot send more data before receiving TCP ACK even though the CTA is available
Using asynchronous
QoS for streaming application is not guaranteed.
Jinwoo Hong et al, Samsung Electronics

5. Maximum throughput with a 64KB max TCP window
July 2004
Maximum throughput with a 64KB max TCP window
Not all TCP applications support TCP window scaling (rfc 1323)
TCP baseline max window is 216 bytes
Max TCP throughput for non-rfc1323 TCP at the max superframe duration
with one 1-way CTA in each direction 65,536*8/.0655= 8.00 Mbps
with one 2-way CTAs is 65,536*8/.001= 524 Mbps
Jinwoo Hong et al, Samsung Electronics

6. July 2004
Jinwoo Hong et al, Samsung Electronics

7. July 2004
Jinwoo Hong et al, Samsung Electronics

8. Slow start comparison (TCP throughput) with TCP window scaling
July 2004
Slow start comparison (TCP throughput) with TCP window scaling
TCP window scaling (rfc1323) allows for TCP max window size of up to 230 bytes
With 2 way CTA:
TCP can ramp up to 1.5 Gbps in 8 ms (or 8 * TCP RTT)
192 KB TCP window required to support 1.5 Gbps
With 1 way CTAs:
TCP can ramp up to 1.5 Gbps in 917 ms (114 times as long)
12.3 MB TCP window (64 times as large) required to support 1.5 Gbps
Assumptions:
Assuming 1 ms TCP ACK latency RTT
1500 byte TCP segment
65.5 ms superframe
Jinwoo Hong et al, Samsung Electronics

9. Two-way CTA Definition
July 2004
Two-way CTA Definition
Two-way channel time allocation
Both src and dest DEVs of the CTA can send data
Collision of frames is controlled by using token
Only Src DEV can control token timeout
Operation
The src DEV initiates data transmission
The src DEV passes token to the dest DEV if no more data to send
The dest DEV can send data after receiving token.
The dest DEV passes token to the src DEV if no more data to send
Above behaviors are repeated in the CTA.
Jinwoo Hong et al, Samsung Electronics

10. Modification (1) July 2004 MLME-CREATE-STREAM.request ( TrgtID,
DSPSSetIndex,
StreamRequestID,
StreamIndex,
ACKPolicy,
Priority,
PMCTRqType,
CTAType,
CTARateType,
CTARateFactor,
DirectionType,
CTRqTU,
MinNumTUs,
DesiredNumTU,
RequestTimeout)
Name
Type
Valid Range
Description
DirectionType
Enumeration
ONE_WAY, TWO_WAY
During the allocated channel time, only one DEV can send data frames (ONE_WAY), or both DEVs can send data frames (TWO_WAY)
Jinwoo Hong et al, Samsung Electronics

11. Modification (2) Channel time request block field
July 2004
Modification (2)
Channel time request block field
Octets:1 1
1-127
Desired number of Tus
Minimum number of Tus
CTRq TU
Direction Type
CTA rate factor
CTRq control
Stream index
Stream request ID
DSPS set Index
Target ID list
Num targets
Channel time allocation block in CTAIE
Octets:2 2 1
CTA duration
CTA location
Stream Index
Direction Type
Src ID
Dest ID
Jinwoo Hong et al, Samsung Electronics

12. Token Frame Valid frame type values Token frame format July 2004
b5 b4 b3
Frame Type Description
000
Beacon frame
001
Immediate ACK (Imm-ACK) frame
010
Delayed ACK (Dly-ACK) frame
011
Command frame
100
Data frame
101
Token frame
Reserved
Header field
Setting on transmission
Frame type
Token frame value
SEC
ACK policy
No-ACK value
Retry
More data
DestID
SrcID of the received frame
SrcID
DestID of the received frame
Fragmentation control
0x000000
Stream index
0x00
Jinwoo Hong et al, Samsung Electronics

13. Example I: Common case … … July 2004 Src DEV Dest DEV Data No Data
Token
Data
No Data
Token
Data …
Jinwoo Hong et al, Samsung Electronics

14. Example II: Src Token lost
July 2004
Example II: Src Token lost
Src DEV
Dest DEV
Data …
No Data
Token
timeout
Token
Data
Jinwoo Hong et al, Samsung Electronics

15. Example III: Dest Token Lost & Src Token Timeout
July 2004
Example III: Dest Token Lost & Src Token Timeout
Src DEV
Dest DEV
Data …
No Data
Token
Token
timeout
Token
Jinwoo Hong et al, Samsung Electronics