Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. 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. Bill Shvodian, Freescale Semiconductor

2. Scenarios for comparison of polling and token passing for bi-directional CTAs Bill Shvodian, Freescale Semiconductor

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 15-04-0437-01) shows the relative performance of the two approaches Bill Shvodian, Freescale Semiconductor

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 Bill Shvodian, Freescale Semiconductor

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.) Bill Shvodian, Freescale Semiconductor

6. Implied ACK • Thrown in to the throughput comparison for old times sake Bill Shvodian, Freescale Semiconductor

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 Bill Shvodian, Freescale Semiconductor

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 Bill Shvodian, Freescale Semiconductor

9. Scenario 1: only CTA Owner has traffic Imm ACK Polling single Data/poll ACK PACK Data/poll ACK PACK Data/poll ACK PACK Polling multi? Data ACK Data ACK Data/poll ACK PACK 1->2 2->1 1->3 3->1 1->4 4->1 Token single Data ACK TKN TKN TKN TKN TKN TKN Data ACK Token multi Data ACK Data ACK Data ACK TKN TKN TKN Del ACK Polling Data Data Data/poll ACK PACK Token multi Data Data Data ACK TKN No ACK Polling single Data/poll PACK Data/poll PACK Data/poll PACK Polling multi? Data Data Data/poll PACK Data/poll PACK Token multi Data Data Data TKN TKN TKN TKN TKN TKN Token single Data TKN TKN TKN TKN TKN TKN Data Implied ACK Implied ACK Data1->n ACK Data1->n ACK Data1-n ACK Bill Shvodian, Freescale Semiconductor

10. Scenario 2: only 1 CTA non-Owner has traffic Imm ACK Polling single Poll Data ACK Poll PACK Poll PACK Polling multi? Poll Data ACK Data ACK Poll PACK Poll PACK Token single TKN Data ACK TKN TKN TKN TKN TKN Token multi TKN Data ACK Data ACK TKN TKN TKN TKN TKN Del ACK Polling Poll Data Data Data ACK Poll PACK Poll PACK Token TKN Data Data Data ACK TKN TKN TKN TKN TKN No ACK Polling single Poll Data Poll PACK Poll PACK Polling multi? Poll Data Data Data Poll PACK Poll PACK Token single TKN Data TKN TKN TKN TKN TKN Token multi TKN Data Data Data TKN TKN TKN TKN TKN Implied ACK Implied ACK Null Data2->1 ACK Null ACK Null ACK Bill Shvodian, Freescale Semiconductor

11. Scenario 3: all DEVs have traffic Imm ACK Polling single Data/poll ACK Data ACK Polling multi Data ACK Data/poll ACK Data ACK Data Token single Data ACK TKN Data ACK TKN Token multi Data ACK Data ACK TKN Del ACK Polling Data/poll Data Data ACK Data/poll Token Data Data Data ACK TKN Data No ACK Polling single Data/poll Data Data/poll Data Polling multi? Data Data/poll Data Data Data/poll Token single Data TKN Data TKN Data TKN Token multi Data Data Data TKN Data TKN Implied ACK Implied ACK Data1->2 Data2->x ACK Data1->3 Data3->x ACK Bill Shvodian, Freescale Semiconductor

12. Scenario 4: 2 DEVs have traffic Imm ACK Polling single Data/poll ACK Data ACK Data/poll ACK Data/poll Polling multi Data Data/poll ACK Data ACK Data ACK Token single Data ACK TKN Data ACK TKN Token multi Data ACK Data ACK TKN Del ACK Polling Data/poll Data Data ACK Data/poll Token Data Data Data ACK TKN Data No ACK Data/poll Data Data/poll PACK Polling single Polling multi? Data/poll Data Data Data/poll PACK Token single Data TKN Data TKN TKN TKN TKN TKN Token multi Data Data TKN Data Implied ACK Implied ACK Data1->2 Data2->x ACK Null ACK Null ACK Bill Shvodian, Freescale Semiconductor

13. Scenario 5: only CTA Owner has traffic to one DEV Imm ACK Polling single Data/poll ACK PACK Data/poll ACK PACK Data/poll ACK PACK Polling multi? Poll PACK Data ACK Data ACK Data/poll ACK PACK Token single Data ACK TKN TKN TKN TKN TKN TKN Data ACK Token multi Data ACK Data ACK Data ACK TKN TKN TKN Del ACK Polling Data Data Data/poll ACK PACK Token multi Data Data Data ACK TKN No ACK Polling single Data/poll PACK Data/poll PACK Data/poll PACK Polling multi? Data Data Data/poll PACK Data Token multi Data Data Data TKN TKN TKN TKN TKN TKN Token single Data TKN TKN TKN TKN TKN TKN Data Implied ACK Implied ACK Data1->n ACK Data1->n ACK Data1-n ACK Bill Shvodian, Freescale Semiconductor

14. Scenario 6: only CTA Owner & 1 DEV have traffic to each other Imm ACK Polling single Data/poll ACK Data Data/poll ACK PACK Polling multi? Data ACK Poll PACK Data ACK Data/poll 1->2 2->1 1->3 3->1 1->4 4->1 Token single Data ACK TKN TKN TKN TKN TKN TKN Data ACK 2->1 1->2 Token multi Data ACK Data ACK Data ACK TKN TKN TKN Del ACK Polling Data Data Data/poll ACK PACK Token multi Data Data Data ACK TKN No ACK Polling single Data/poll PACK Data/poll PACK Data/poll PACK Polling multi? Data Data Data/poll PACK Data Token multi Data Data Data TKN TKN TKN TKN TKN TKN Token single Data TKN TKN TKN TKN TKN TKN Data Implied ACK Implied ACK Data1->n ACK Data1->n ACK Data1-n ACK Bill Shvodian, Freescale Semiconductor

15. 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 Bill Shvodian, Freescale Semiconductor

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 Bill Shvodian, Freescale Semiconductor

17. Fallback Action • Redefine the ACK policy to include Delayed ACK Bill Shvodian, Freescale Semiconductor