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: [Power Saving Algorithms for IEEE 802.15.5] Date Submitted: [July, 2007] Source: [Tae Rim Park*, Myung Lee*, Jaehong Ryu**] Company [*CUNY, **ETRI] Address [Electrical Engineering, Steinman Hall, 140th St & Convent Ave, New York, NY 10031, USA] Voice:[+1-212-650-7260], FAX: [+1-212-650-8249], E-Mail:[taerim@ee.ccny.cuny.edu] Re: [] Abstract: [This proposal discusses power saving issue arising inIEEE 802.15.5 WPAN Mesh] Purpose: [This proposal is provided for the discussion for IEEE 802.15.5 WPAN Mesh] 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. Tae Rim Park

2. Power Saving Algorithms Tae Rim Park, Myung Lee, Jaehong Ryu CUNY, ETRI Tae Rim Park

3. Objectives • Providing background information to discuss power saving algorithms • To propose a power saving solution for the current IEEE 802.15.5 draft. Tae Rim Park

4. Proposal Outline • Design consideration • Possible power saving algorithms • Algorithm comparison • Discussion • Summary Tae Rim Park

5. Design Consideration • Mesh layer solution based on IEEE 802.15.4-2006 • Supporting long battery life • Two AA batteries, 1year • Flexible active time • End-to-end latency constraint • Synchronous usually has longer latency • Considering receiver energy consumption • Tree relation • Easy implementation Tae Rim Park

6. Long Battery Life • Two AA batteries • 2000 mA-hr • Energy consumption of cc2420 • Tx; 17.4 mA • Rx; 19.7 mA • When a device turns on the transceiver • 4.2 days • When the device keeps 5% active time • 84 days (under 3 months)  Minimizing active ratio is the key! Tae Rim Park

7. Mesh Layer Solution • Two reasons • Fine control • Minimize active time • Currently on the beacon mode the minimum value is 15.36 ms • Reliable communication • Overcome possible problems of IEEE 802.15.4 • Control methods • Standard primitive • MCPS-DATA/PURGE • MLME-SET/GET • Can not use information inside MAC • Can not add MAC control frames • Timing problem • Can not guarantee response time • Ex. The time from calling MCPS-DATA.request to starting backoff Tae Rim Park

8. Possible Algorithms • On beacon mode • Non-beacon Tracking (NBT) • Beacon Tracking (BT) • On non-beacon mode • Long Preamble Emulation (LPE); BMAC • Long Preamble Emulation with Ack (LPEA); XMAC • Non-beacon Tracking Emulation (NTE) • Global Synchronization (GS); SMAC Tae Rim Park

9. Algorithms on Beacon Mode • Reliability, Beacon collision • Upper control also required Tae Rim Park

10. Synchronous Algorithm on Non-Beacon • SMAC • Time control precision • Difficult to synchronize all devices Tae Rim Park

11. Asynchronous on Non-beacon Mode • LPE • LPEA • NTE Tae Rim Park

12. Beacon vs. Non-beacon Mode • Beacon mode • Suitable for the networks • Long beacon interval & small number of neighbors • Hard time beacon transmission  beacon collision • Unreliable • NBT; beacon collision • BT; Sync tree problem • Upper layer support for • Active time scheduling, minimizing active time, broadcasting frames • Non-beacon mode • Requires all operation at the mesh layer • Difficulty in timing control • Flexible !, can make better solutions for large scale networks Tae Rim Park

13. Synchronous vs. Asynchronous • Synchronous • Ideal for broadcasting (RREQ in AODV) • Requires overhead to synchronize devices • Relatively long active duration • Control packet overhead • Requires tight frame control • Usually longer latency • Asynchronous • Easy to implement • Ethernet vs. Token ring, TCP vs. ATM, DCF vs. PCF • Can have minimum active duration (BMAC emulation); longest battery life • Loose frame control Tae Rim Park

14. Discussion • Rebroadcasting in 15.5 • Two hop broadcasting with n neighbor • n+1 for transmission • n(n+1) for reception • n=316, n=536 • Protocol issues (out of scope?) • Association procedure and time • Mesh layer backoff • Active duration adjustment • Distributed wakeup interval selection • Local synchronization Tae Rim Park

15. Summary • To get long battery life • Minimizing active time • Accepting trade off relation • Mesh layer solution • With only standard primitives • Asynchronous algorithms is better to implement • Asynchronous algorithms have similar behaviors • Non-beacon Tracking Emulation (NTE) • Can have flexible active duration Tae Rim Park