1. <month year>
doc.: IEEE e
doc.: IEEE < e >
<Sep 2008>
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [The embedded CAP for GTS transmission for IEEE e]
Date Submitted: [7 July, 2008]
Source: [Rui Zhang, Tae Rim Park, Myung J. Lee and Jong-suk Chae] Company [CUNY and ETRI]
Address [140th St. and Convent Ave, New York, NY, USA]
Voice:[ ], FAX: [],
Re: [IEEE P e Call For proposal]
Abstract: [This document proposes an enhancement to IEEE MAC Layer with
modified superframe structure named embedded CAP]
Purpose: [This document is a response to call for preliminary proposals. ]
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
<Rui Zhang>, <CUNY>
<Tae Rim Park>, <CUNY>

2. The embedded CAP for GTS transmission for IEEE 802.15.4e
<month year>
doc.: IEEE e
doc.: IEEE < e >
<Sep 2008>
The embedded CAP for GTS transmission for IEEE e
Rui Zhang*, Tae Rim Park*, Myung J Lee*, Jong-suk Chae **,
* CUNY, ** ETRI
<Rui Zhang>, <CUNY>

3. Time Guaranteed Services
<month year>
doc.: IEEE e
doc.: IEEE < e >
<Sep 2008>
Time Guaranteed Services
Required Time Guaranteed Services for IEEE e
For industrial applications
Two approaches
Enhancing GTS structure in 15.4b
A New TDMA Architectures may be necessary for certain applications
<Rui Zhang>, <CUNY>

4. Time Guaranteed Services
<month year>
doc.: IEEE e
doc.: IEEE < e >
<Sep 2008>
Time Guaranteed Services
Can current GTS solution provide guaranteed and reliable service?
Strictly Time Slot Assignment: Positive
Avoid Random back-off:
Hidden/Exposed terminal: Positive
Well designed time slot assignment to avoid hidden/exposed terminal problem.
Lossy wireless link:
Packet loss due to lossy wireless link: still need enhancement
<Rui Zhang>, <CUNY>

5. Current GTS structure Issues for current GTS solution
<month year>
doc.: IEEE e
doc.: IEEE < e >
<Sep 2008>
Current GTS structure
Issues for current GTS solution
In lossy wireless links, retransmission is inevitable
If the retransmission can not be accomplished in its assigned GTS slot.
Long retransmission delay for non-delay sensitive traffic
Packet dropped for delay sensitive case.
<Rui Zhang>, <CUNY>

6. Proposed Ideas Proposed idea: Embedded CAP
<month year>
doc.: IEEE e
doc.: IEEE < e >
<Sep 2008>
Proposed Ideas
In 15.4b, a CFP slot for one node’s transmission
Proposed idea: Embedded CAP
To allow remaining time in GTS for other nodes to (re)transmit frames via CSMA/CA
<Rui Zhang>, <CUNY>

7. An Example Timeline Still 600 symbols = 9.6 ms is left
doc.: IEEE < e >
<Sep 2008>
An Example Timeline
Successful Longest frame transmission = 360 symbols
Still 600 symbols = 9.6 ms is left
Longest Frame + tACK + ACK + LIFS = 360 symbols PHY rate: 250kb/s = 62.5k symbols/s (QPSK)
One symbol = 16 us
<Rui Zhang>, <CUNY>

8. Operation of Embedded CAP
doc.: IEEE < e >
<Sep 2008>
Operation of Embedded CAP
No change for each node’s GTS slot.
During other GTSs
Nodes wait for ACK
CSMA/CA to compete the channel for (re)transmission
Some special cases
Multiple packets: ACK should notify the existence of subsequent frames until the final ACK
No packet: the assigned GTS device send a short probe frame and the ACK(broadcast type) will be sent back by PC to release the channel for other nodes
<Rui Zhang>, <CUNY>

9. Multiple packets case: burst data solution
<Sep 2008>
Multiple packets case: burst data solution
<Rui Zhang>, <CUNY>

10. No packet case: free the channel for others to compete
<Sep 2008>
No packet case: free the channel for others to compete
<Rui Zhang>, <CUNY>

11. An Example for Latency Improvement
doc.: IEEE < e >
<Sep 2008>
An Example for Latency Improvement
Star topology
Node 1-7 have periodical data to report to PC(PAN Coordinator)
Node 1-7 have been assigned GTS slots respectively. PC 1 2 4 3 7 6 5 8 9 10 11 12
<Rui Zhang>, <CUNY>

12. doc.: IEEE 802.15-< 15-08-0597-01-004e >
<Sep 2008>
For15.4b case: the node 1 needs to wait a whole beacon interval to retransmit. Latency = 491ms
<Rui Zhang>, <CUNY>

13. doc.: IEEE 802.15-< 15-08-0597-01-004e >
<Sep 2008>
Proposed Embedded CAP: the node 1 can access node 2’s CFP using CSMA/CA .Latency = 15.36ms
<Rui Zhang>, <CUNY>

14. Summary for Embedded CAP
doc.: IEEE < e >
<Sep 2008>
Summary for Embedded CAP
Enlarged Effective GTS slots
A node can use others’ GTS slots to retransmit its GTS frame
Potential latency reduction of GTS frame
Enlarged Effective CAP Period
Residual time for each GTS slot is available for other nodes via CSMA/CA
Enhanced packet delivery
More “reliable and guaranteed” than current solution
Little modification
<Rui Zhang>, <CUNY>