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: [02292r2P802-15_TG3-SPS-Issue-Resolution.ppt] Date Submitted: [05 July, 2002 Source: [Mark E. Schrader] Company [Eastman Kodak Co.] Address [1447 Saint Paul St., Rochester, NY 14653-7023, USA] Voice:[585-253-5241], FAX: [585-253-5658], E-Mail:[mark.e.schrader@kodak.com] Re: [Draft 10 Comment Resolution for Power Management and Stream Management.] Abstract: [This supplements 02/231 in discussing proposed changes to D10] Purpose: [Communciate changes to D10 proposed in 02/231 and use of changes by the network members.] 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. Mark Schrader, Eastman Kodak Co.

2. SPS Issue Resolution Channel Time Request and Stream Management Mark Schrader, Eastman Kodak Co.

3. Outline • In the context of the use of power management: • Proposed changes to CTRB and why. • Proposed adjustments for superframe loading control and documenting this capability. Mark Schrader, Eastman Kodak Co.

4. Changes to CTRB • Allow explicit choice of time base. • Time Base bit selects between “CTR Interval” field of CTRB and an “SPS Set” for either CTR Type. • PCTM setting in SPS. • Set PCTM bit allows the source DEV to tell the SPS DEV that it needs to listen to every beacon and change to ACTIVE mode. Mark Schrader, Eastman Kodak Co.

5. Mark Schrader, Eastman Kodak Co.

6. Inputs Outputs Mark Schrader, Eastman Kodak Co.

7. Advantages of Changes • There are 3 scenarios that need to be covered by our standard • 1. Active mode stream s1 created using “CTR Interval” time base: Suspend the stream s1 when switching to SPS mode. • A high-data-rate communication cannot be sourced by a DEV that has switched into SPS mode. • It will be begin again once the DEV has switched back to ACTIVE mode from SPS mode. Mark Schrader, Eastman Kodak Co.

8. Power Save Transitions Affect on Stream s1 (see previous slide) Mark Schrader, Eastman Kodak Co.

9. 2. ACTIVE mode DEV wants to talk to an SPS DEV using SPS timing. The ACTIVE DEV creates stream s2 using an “SPS Set” as the time base. Stream s2 will continue when ACTIVE DEV switches to SPS mode. • An example is a power sensitive recording device with wireless remote control. • Remote control stays in SPS mode, Recording device alternates between SPS and ACTIVE mode. • Alternating mode DEV must maintain link with the SPS mode DEV, preferably without any overhead communication to the PNC. Mark Schrader, Eastman Kodak Co.

10. Power Save Transitions Affect on Stream s2 (see previous slide) Mark Schrader, Eastman Kodak Co.

11. 3. A DEV is in ACTIVE mode. The DEV requests an SPS, CTR Type stream s3 using an “SPS Set” time base. s3 starts out suspended. When the DEV switches into SPS mode the stream s3 starts up. • Application space: A DEV wants to synchronously communicate with other SPS DEVs in a power sensitive application. • The application is exclusively for SPS mode. • When the DEV switches back to ACTIVE mode the stream s3 is suspended. Mark Schrader, Eastman Kodak Co.

12. Power Save Transition Affect on Stream s3 (see previous slide) Mark Schrader, Eastman Kodak Co.

13. 4. The same as 3 except that the DEV uses a “CTR Interval” time base rather than the “SPS Set” time base. • This is an example of a DEV that wants to save power without any data communication, and idle power save condition. • The “CTR Interval” is used as the time base to avoid wasting an SPS Set when no synchronization is required. • This “stream” only has awake beacons, no GTS slots. Mark Schrader, Eastman Kodak Co.

14. Power Save Transitions Affect on Stream s4 (see previous slide) Mark Schrader, Eastman Kodak Co.

15. Power Save Transitions Summary Affects on Streams s1, s2, s3 and s4 (see previous slides) Mark Schrader, Eastman Kodak Co.

16. Proposed Addition to Standard Mark Schrader, Eastman Kodak Co.

17. APS and SPS After Changes Convergence? Mark Schrader, Eastman Kodak Co.

18. SPS/APS Overlap With Proposed Changes • Combined SPS and APS major capabilities: • 1. PCTM traffic indication. • 2. Flexible listen-to-beacon schedule up to a maximum. • 3. Synchronous communication. • 4. Predictable listen-to-beacon times. • 5. Single DEV defines sleep duration. • The only APS-unique capability left will be number two in the list above. Is this close enough to eliminate APS? Mark Schrader, Eastman Kodak Co.

19. Superframe Loading Mark Schrader, Eastman Kodak Co.

20. Concern: Superframe Loading • Superframe loading is the number of GTS slots allocated to a superframe • Differential superframe loading is the ratio of the largest number of GTS slots allocated to a superframe to the smallest number of SF’s allocated to a superframe. This can be caused by a large number of DEVs using the same SPS Set. Mark Schrader, Eastman Kodak Co.

21. Can there be some control over SF loading? • Yes by noting that the maximum power save always occurs if the SPS mode DEV’s awake superframes only occur when a GTS slot is needed. • In this case any SPS DEV using the same SPS Set to achieve the same GTS slot allocation rate must have a slot in the exact same super frame. • For this case the CTR Interval is always “1”, meaning “one awake beacon per Slot”. Mark Schrader, Eastman Kodak Co.

22. SF Loading Control Continued • What if the SPS Set is specified with a an SPS interval that makes the SPS DEV wake up 4 times as often as it needs a slot, then the power saved is less and the possible loading is less also. • The next two charts show how the PNC may allocate slots to distribute the loading. • It is up to the SPS DEV to trade off superframe loading for power. Mark Schrader, Eastman Kodak Co.

23. Mark Schrader, Eastman Kodak Co.

24. Mark Schrader, Eastman Kodak Co.

25. Changes Required to the Draft • Include the two diagrams shown here to show possible slot distribution by the PNC. • Make the minimum number SPS Sets 2 in order to facilitate an SPS DEV transitioning from one SPS Set to another, when a large number of DEVs have joined. • Add an indication of “Superframe Overloading” as a return code for a DEV trying to allocate channel time and have the PNC tell the SPS Set creator DEV if necessary. Mark Schrader, Eastman Kodak Co.

26. SPS Information Element Use and Format Issues Mark Schrader, Eastman Kodak Co.

27. Power Save Mode Issues • A DEV 1 may need to change its PS mode without being able to communicate to all DEVs that might be effected by the change. • When should a DEV 2 inquire about the PS mode of a DEV 1? There is no way to know. • There is no guaranteed performance for inquiring about the PS mode of a DEV 1. • The St Louis compromise demanded that ready access to the PS mode and SPS information be available in the beacon. Mark Schrader, Eastman Kodak Co.

28. What is the Minimum Information Required? • The current format requires one IE for each SPS Set that is “in use”, meaning that at least one set member is currently in SPS mode. • Both PS mode and SPS Set information is required for DEV 2 to make the correct CTR to the PNC. • The structure of the SPS IE, should be changed to be like that of the PCTM, but otherwise not changed. Mark Schrader, Eastman Kodak Co.

29. Proposed Change • The SPS IE should be in the same format as the PCTM to limit its size. • The SPS IE is necessary to allow DEVs to make superframe by superframe decisions on what CTRB parameters to use for effective channel specification and changes that could effect current CTRs in effect. Mark Schrader, Eastman Kodak Co.

30. 02263r0 Alternative Power Save Proposal Mark Schrader, Eastman Kodak Co.

31. Acronym for This Document: PSCI • Power Save CTR Interval, PSCI, is defined as a the CTR Interval associated with a CTRB made with the new field defined in 02163r0: “Use a single bit to indicate if the Channel time request is a power save request or not.” Mark Schrader, Eastman Kodak Co.

32. Creating and Managing Unique PSCIs • The PNC creates a unique (indexed) PSCI-1, PSCI-2, etc. for each PSCI in a CTRB that:: • 1. Has a CTR Interval that no other PSCI has or • 2. (for an identical CTR Interval) does not have at least one DEVID in common with existing PSCIs with the same CTR Interval. • For each PSCI-n, the PNC must keep a list of both the CTR Interval and PNIDs of streams that the PNC has assigned to it. • This is equivalent to PNC generated and managed SPS Sets with no limits to the number of sets. Mark Schrader, Eastman Kodak Co.

33. Differences • One slot per wake beacon is the only possibility. • The DEVIDs are used by the PNC to determine which existing PSCI-n will be used or if a new PSCI-k will be created. • PNC controls Mark Schrader, Eastman Kodak Co.

34. The order of stream creation matters Mark Schrader, Eastman Kodak Co.

35. Notes on the Previous Figure • D0, D1, D2, D3 uses PSCI-1 and D4, D5, D6, D7 uses PSCI-2 • Devices D0, D1, D2, D3 and D4, D5, D6, D7 cannot have sychronized timing because of the sequence of stream creation. • Result: D0 and D7 do not achieve their power save goals. If PSCI-1 and PSCI-2 are very different, the power saving of one of these devices could be impacted significantly. • A DEV must create its first stream with a set in the PSCI-k that it ultimately wants to use. Mark Schrader, Eastman Kodak Co.

36. Appendix Mark Schrader, Eastman Kodak Co.

37. A More Detailed Version of Slide 6 Mark Schrader, Eastman Kodak Co.