doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 1 Project: IEEE P 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:[ ], FAX: [], 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 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

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 2 Scenarios for comparison of polling and token passing for bi-directional CTAs

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 3 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 ) shows the relative performance of the two approaches

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 4 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

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 5 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.)

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 6 Implied ACK Thrown in to the throughput comparison for old times sake

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 7 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

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 8 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

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 9 Scenario 1: only CTA Owner has traffic Data/poll ACK Data/poll PACKACKPACK Data/poll ACKPACK Polling single Data ACK Token single Data ACKTKN Data Data/poll PACK Polling Data Token multi Data ACKTKN ACK Del ACK Imm ACK Data/poll PACK Data/poll PACK Polling single Data Token multi Data TKN No ACK Data1->n ACK Implied ACK Data1->n ACK Data1-n ACK Implied ACK TKN Data Token single Data TKN Data ACK Token multi Data ACK Data ACKTKN Polling multi? Data Data/poll PACK Data ACK Data ACK Data/poll ACKPACK TKN Data/poll PACK 1->22->11->33->11->44->1

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 10 Scenario 2: only 1 CTA non-Owner has traffic Poll Data ACK Polling multi? Token single Data TKN Polling Data Token Data ACKTKN Del ACK Imm ACK No ACK Implied ACK PollPACK TKN ACK Data2->1 Poll Data PACKACKPoll PACK TKN Data Token single TKN Polling single Poll Data PollPACKPollPACK Data ACK TKN PACKPoll TKN ACKNull ACK Null Poll Data ACK Polling single PollPACKPollPACK Token multi Data ACKTKN ACKTKN Polling multi? Poll Data PACKPollPACKPoll Data Token multi Data TKN

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 11 Scenario 3: all DEVs have traffic Data ACK Polling multi Token single Data Polling Data Token Data ACKTKN Del ACK Imm ACK Polling multi? Data Token multi Data TKN No ACK Implied ACK ACK Data Data2->x ACK Data Data/poll Data ACK TKN ACK Data/poll ACK Data ACK Data/poll Data Data/poll Data TKN Data1->2 Data3->x ACK Data1->3 Data ACK Polling single Data/poll ACK Token multi Data ACK TKN Polling single Data Data/poll Data Data/poll Data Token single TKN Data TKN Data TKN Data

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 12 Scenario 4: 2 DEVs have traffic Polling multi Polling Data Token Data ACKTKN Del ACK Imm ACK Polling multi? Data Token multi Data TKN No ACK Implied ACK Data ACK Data Data/poll Token multi Data ACK TKN Data/poll Data Data/poll Data Data1->2 Data2->x ACK PACK Data ACK Polling single Data/poll ACK Data/poll ACK Data/poll Token single Data ACKTKN Data ACK Polling single Data Data/poll PACK Data Token single TKN Data TKN ACKNullACKNull Data ACK Data ACK Data/poll ACK Data

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 13 Scenario 5: only CTA Owner has traffic to one DEV Data/poll ACKPACK Polling single Data ACK Token single Data ACKTKN Data Data/poll PACK Polling Data Token multi Data ACKTKN ACK Del ACK Imm ACK Data/poll PACK Polling single Data Token multi Data TKN No ACK Data1->n ACK Implied ACK Data1->n ACK Data1-n ACK Implied ACK TKN Data Token single Data TKN Data ACK Token multi Data ACK Data ACKTKN Polling multi? Data Data/poll PACK Data ACK Data ACK Data/poll ACKPACK TKN PollPACK Data/poll ACKPACK Data/poll ACKPACK Data/poll PACK Data/poll PACK Data

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 14 Scenario 6: only CTA Owner & 1 DEV have traffic to each other Data/poll ACK Polling single Data ACK Token single Data ACKTKN Data Data/poll PACK Polling Data Token multi Data ACKTKN ACK Del ACK Imm ACK Data/poll PACK Polling single Data Token multi Data TKN No ACK Data1->n ACK Implied ACK Data1->n ACK Data1-n ACK Implied ACK TKN Data Token single Data TKN Data ACK Token multi Data ACK Data ACKTKN Polling multi? Data Data/poll PACK Data ACK Data ACK Data/poll TKN PollPACK Data/poll ACKPACK Data/poll PACK Data/poll PACK Data 1->22->11->33->11->44->1 1->2 2->1

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 15 Conclusion The spreadsheets in document compare the throughput for these scenarios Polling provides throughput as good as or better than token passing in every scenario

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 16 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

doc.: IEEE Submission August 18, 2004 Bill Shvodian, Freescale SemiconductorSlide 17 Fallback Action Redefine the ACK policy to include Delayed ACK