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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Polling vs. Token Passing for bi-directional CTAs] Date Submitted: [16 August 2004] Source: [Bill Shvodian] Company [Freescale Semiconductor] - PowerPoint PPT Presentation
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August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 1
doc.: IEEE 802.15-<04-0436r1>
Submission
Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Polling vs. Token Passing for bi-directional CTAs]Date Submitted: [16 August 2004]Source: [Bill Shvodian] Company [Freescale Semiconductor]Address [8133 Leesburg Pike, Suite 700, Vienna, VA 22182, USA]Voice:[703-269-3047], FAX: [], E-Mail:[bill.shvodian @ freescale.com]
Re: [TG3b call for contributions]
Abstract: [This proposal describes token passing vs. Polling for bi-directional CTAs. An accompanying Excel spreadsheet compares performance.]
Purpose: [The author would like the IEEE to consider adoption of polling for TG3b.]
Notice: This document has been prepared to assist the IEEE P802.15. 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 P802.15.
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 2
doc.: IEEE 802.15-<04-0436r1>
Submission
Scenarios for comparison of polling and token passing for bi-directional CTAs
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 3
doc.: IEEE 802.15-<04-0436r1>
Submission
Background
• Token Passing has been proposed for bi-directional traffic in TG3b
• A comparison between polling and token passing throughput was created to compare the performance of the two
• The accompanying spreadsheet (doc 15-04-0437-01) shows the relative performance of the two approaches
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 4
doc.: IEEE 802.15-<04-0436r1>
Submission
Token Passing
• Owner of a CTA (srcID) always initiates transmission in a CTA. • Because it is the only DEV that all of the DEVs using the CTA
must hear, the token always comes back to the owner of the CTA before being sent to another DEV
• A new Token frame type is required • Token frames are not ACKed (per discussions in Portland)• Options for comparison purposes:
– Token single - token holder is only allowed to send one data frame when it receives the token (this scenario is not recommended but was included for comparison purposes)
– Token Multi – Token holder can send up to TBD frames or TBD duration
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 5
doc.: IEEE 802.15-<04-0436r1>
Submission
Polling
• The owner of a CTA sends a frame to a particular destination DEV. The header contains the srcID, destID and polleeID
• Polling options for comparison:– Polling single - Poller/pollee holder can only send
one frame per poll– Polling Multi – Poller/Pollee can send up to TBD
frames or TBD duration. (this scenario is not recommended but was included for comparison purposes.)
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 6
doc.: IEEE 802.15-<04-0436r1>
Submission
Implied ACK
• Thrown in to the throughput comparison for old times sake
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 7
doc.: IEEE 802.15-<04-0436r1>
Submission
Scenario overview
• 6 scenarios were used to represent different traffic scenarios in a piconet
• For each of these scenarios, the throughput was calculated for polling and token passing and delayed ACK
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 8
doc.: IEEE 802.15-<04-0436r1>
Submission
Scenarios
• Scenario 1: only CTA Owner has traffic• Scenario 2: only 1 CTA non-Owner has traffic• Scenario 3: all DEVs have traffic• Scenario 4: 2 DEVs have traffic (Owner has traffic to
all)• Scenario 5: only CTA Owner has traffic to one DEV• Scenario 6: only CTA Owner & 1 DEV have traffic
and only to each other
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 9
doc.: IEEE 802.15-<04-0436r1>
Submission
Scenario 1: only CTA Owner has traffic
Data/poll ACK Data/pollPACK ACK PACK Data/poll ACK PACKPolling single
Data ACKToken single Data ACKTKN TKN TKN
Data Data Data/poll PACKPolling
DataToken multi Data Data ACK TKN
ACK
Del ACK
Imm ACK
Data/poll Data/pollPACK PACK Data/poll PACKPolling single
DataToken multi Data Data TKN
No ACK
Data1->n ACKImplied ACK Data1->n ACK Data1-n ACK
Implied ACK
TKN
DataToken single DataTKN TKN TKN TKN TKN TKN
TKN
Data ACKToken multi Data ACK Data ACK TKN TKN TKN
TKN
Polling multi?
Polling multi? Data Data Data/poll PACK
Data ACK Data ACK Data/poll ACK PACK
TKN TKN
TKN TKN TKN
Data/poll PACK
1->2 2->1 1->3 3->1 1->4 4->1
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 10
doc.: IEEE 802.15-<04-0436r1>
Submission
Scenario 2: only 1 CTA non-Owner has traffic
Poll Data ACKPolling multi?
Token single DataTKN
Polling
DataToken Data Data ACK TKN
Del ACK
Imm ACK
No ACK
Implied ACK
Implied ACK
Poll PACK
TKN TKN ACK
Data2->1
Poll Data PACKACK Poll
Poll PACK
TKN TKN TKN
Data Data
DataToken single TKN TKN TKNTKN TKN TKN
Polling single Poll Data Poll PACK Poll PACK
Data ACK
TKN TKN TKN
PACKPoll
TKN TKN
ACKNull NullACK ACKNull
Poll Data ACKPolling single Poll PACK Poll PACK
Token multi Data Data ACK TKN TKN TKN ACK TKN TKN TKN
Polling multi? Poll Data PACKPoll PACK Poll Data Data
DataToken multi Data Data TKNTKN TKN TKNTKN TKN
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 11
doc.: IEEE 802.15-<04-0436r1>
Submission
Scenario 3: all DEVs have traffic
Data ACKPolling multi
Token single Data
Polling
DataToken Data Data ACK TKN
Del ACK
Imm ACK
Polling multi?
DataToken multi Data Data TKN
No ACK
Implied ACK
Implied ACK
ACK
Data
Data2->x
ACK Data Data
Data Data/poll
DataACK
TKN TKN
ACK
Data/poll ACK
Data ACK
Data/poll Data/poll
Data
Data Data/poll
Data TKN
Data1->2 Data3->x ACK Data1->3
Data ACKPolling single Data/poll ACK
Token multi Data Data ACK ACK TKN
Polling single Data Data/poll Data Data/poll
DataToken single TKN Data TKN Data TKN
Data
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 12
doc.: IEEE 802.15-<04-0436r1>
Submission
Scenario 4: 2 DEVs have traffic
Polling multi
Polling
DataToken Data Data ACK TKN
Del ACK
Imm ACK
Polling multi?
DataToken multi Data TKN
No ACK
Implied ACK
Implied ACK
Data
ACK Data Data
Data Data/poll
Token multi Data Data ACK ACK TKN
Data/poll Data/poll
Data
Data/poll
Data
Data1->2 Data2->x ACK
PACK
Data ACKPolling single Data/poll ACK Data/poll ACK Data/poll
Token single Data ACK TKN TKN Data ACK
Polling single Data Data/poll Data/poll PACK
DataToken single TKN Data TKN TKN TKNTKN TKN
ACKNull ACKNull
Data ACK Data ACK Data/poll ACK Data
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 13
doc.: IEEE 802.15-<04-0436r1>
Submission
Scenario 5: only CTA Owner has traffic to one DEV
Data/poll ACK PACKPolling single
Data ACKToken single Data ACKTKN TKN TKN
Data Data Data/poll PACKPolling
DataToken multi Data Data ACK TKN
ACK
Del ACK
Imm ACK
Data/poll PACKPolling single
DataToken multi Data Data TKN
No ACK
Data1->n ACKImplied ACK Data1->n ACK Data1-n ACK
Implied ACK
TKN
DataToken single DataTKN TKN TKN TKN TKN TKN
TKN
Data ACKToken multi Data ACK Data ACK TKN TKN TKN
TKN
Polling multi?
Polling multi? Data Data Data/poll PACK
Data ACK Data ACK Data/poll ACK PACK
TKN TKN
TKN TKN TKN
Poll PACK
Data/poll ACK PACK Data/poll ACK PACK
Data/poll PACK Data/poll PACK
Data
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 14
doc.: IEEE 802.15-<04-0436r1>
Submission
Scenario 6: only CTA Owner & 1 DEV have traffic to each other
Data/poll ACKPolling single
Data ACKToken single Data ACKTKN TKN TKN
Data Data Data/poll PACKPolling
DataToken multi Data Data ACK TKN
ACK
Del ACK
Imm ACK
Data/poll PACKPolling single
DataToken multi Data Data TKN
No ACK
Data1->n ACKImplied ACK Data1->n ACK Data1-n ACK
Implied ACK
TKN
DataToken single DataTKN TKN TKN TKN TKN TKN
TKN
Data ACKToken multi Data ACK Data ACK TKN TKN TKN
TKN
Polling multi?
Polling multi? Data Data Data/poll PACK
Data ACK Data ACK Data/poll
TKN TKN
TKN TKN TKN
Poll PACK
Data/poll ACK PACK
Data/poll PACK Data/poll PACK
Data
Data
1->2 2->1 1->3 3->1 1->4 4->1
1->2 2->1
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 15
doc.: IEEE 802.15-<04-0436r1>
Submission
Conclusion
• The spreadsheets in document 15-04-0437-01compare the throughput for these scenarios
• Polling provides throughput as good as or better than token passing in every scenario
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 16
doc.: IEEE 802.15-<04-0436r1>
Submission
Recommended Action
• Adopt polling to provide bidirectional traffic in a CTA to support protocols like TCP
• Add an 8 bit pollee field and a new polling enable bit to the header
August 18, 2004
Bill Shvodian, Freescale SemiconductorSlide 17
doc.: IEEE 802.15-<04-0436r1>
Submission
Fallback Action
• Redefine the ACK policy to include Delayed ACK