1. Yun-Ting Chiang Advisor: Prof Dr. Ho-Ting Wu 2013.6.10
The Design of power saving mechanisms in Ethernet Passive Optical Networks
Yun-Ting Chiang
Advisor: Prof Dr. Ho-Ting Wu

2. Outline Introduction Conclusion Optical-Fiber Network
Passive Optical Network (PON)
EPON
Interleaved Polling with Adaptive Cycle Time (IPACT)
Power Saving Issue
Research purpose
The Design of Power Saving mechanisms in Ethernet Passive Optical Networks
Conclusion

3. Passive Optical Network (PON)

4. Passive Optical Network (PON)
Optical line terminal (OLT)
Optical network units (ONUs) or
Optical network terminals (ONTs)
Use broadcast on Downstream
Use TDMA on Upstream
All ONUs register to OLT with LLID

5. EPON GATE REPORT and GATE message REPORT
ONU to report its bandwidth requirements
OLT passes REPORT to the DBA algorithm
GATE
After executing DBA algorithm, OLT transmits GATE down-stream to issue up to four transmission grants to ONU
Transmission start time
Transmission length
Timestamp (used by ONU for synchronization)

6. Interleaved Polling with Adaptive Cycle Time (IPACT)
OLT maintain a Table with Byte and RTT
First grant, G(1), is set to some arbitrary value
In polling cycle n, ONU measures its backlog in bytes at end of current upstream data transmission & piggybacks the reported queue size, Q(n), at end of G(n)
Q(n) used by OLT to determine next grant G(n+1) => adaptive cycle time & dynamic bandwidth allocation
If Q(n)=0, OLT issues zero-byte grant to let ONU report its backlog for next grant

8. Power Saving Issue How long can ONU sleep ?
How to reduce switch times (overhead)?
How to balance between energy consumption and packet delay?

9. Lei Shi, Biswanath Mukherjee and Sang-Soo Lee’s research
Early wake up
Toverhead = 2.125ms
Poverhead
Extra guard time

10. Research Purpose
Reducing both downstream and upstream real-time data delay for Power saving in EPON.

11. The Design of Power Saving mechanisms in Ethernet Passive Optical Networks
Sleep mode
Early wake up ( for upstream high priority data)
Doze mode ( for downstream high priority data)
Power Level
Upstream scheduling
Downstream scheduling

12. Sleep mode ONU Tx: off Rx: off
Upstream high priority data will trigger sleep ONU wake up.

13. Early wake up
Because of Toverhead , ONU have wait 2.125ms to receive GATE msg. from OLT

14. Doze mode ONU Tx: off Rx:on
Downstream high priority data won’t trigger sleep ONU wake up so it need doze mode.
Doze mode can make OLT send downstream data earlier.
Doze mode will extend when downstream time interval longer then default doze mode interval.

15. Doze mode

16. Power Level

17. S A D Early wake up <S> Early wake up <D>
No upstream data in ONU[x]
OLT scheduling doze-mode in sleep mode interval
No high priority downstream data to ONU[x] or Doze-mode time out

18. Upstream scheduling Using fixed service.
REPORT msg. increase sleep request in protocol.
OLT upstream slot increase sleep mode tags.
OLT upstream slot increase doze mode tags.

19. Downstream scheduling
Although downstream slot and upstream slot are difference but there have some relationship.
Different from general EPON, because ONU[x] in sleep mode, OLT can’t send downstream data. Downstream scheduling need to be considered.
ONUs’ doze mode maybe overlap so OLT need to select one of ONUs to send high priority downstream data.

20. Downstream scheduling

21. Downstream scheduling

22. Downstream scheduling

23. Conclusion
In this study, power saving mechanisms focus on reduce high priority downstream data delay in power saving EPON.
Doze mode has power overhead when switching. If ONU switch to doze mode but there are no downstream data, power will be wasted but it can reduce high priority downstream data delay, it’s trade-off in this design. For this reason, downstream scheduling in power saving mechanisms is important for performance.

24. Reference
[1] Glen Kramer and Biswanath Mukherjee “IPACT: A Dynamic Protocol for an Ethernet PON (EPON),” IEEE Communications Magazine, February [2] Lei Shi, Biswanath Mukherjee and Sang-Soo Lee “Energy-Efficient PON with Sleep-Mode ONU: Progress, Challenges, and Solutions,” IEEE Network March/April 2012 pp [3] Jingjing Zhang and Nirwan Ansari “Toward Energy-Efficient 1G-EPON and 10G-EPON with Sleep-Aware MAC Control and Scheduling,” IEEE Communications Magazine February 2011 pp. s34-38.

25. Thanks for your listening