1. doc.: IEEE 15-08-0618-01-004e SubmissionSlide 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [beacon collision avoidance mechanism for TG4e MAC] Date Submitted: [September, 2008] Source: [ChangSub Shin, Wun-Cheol Jeong, Soyoung Hwang, Anseok Lee, Seong-Soon Joo] Company [ETRI] Address [161 Gajeong-dong Yuseong-gu, Daejeon, Korea] Voice:[+82-42-860-1668], FAX: [+82-42-869-1712], E-Mail:[shincs@etri.re.kr] Re: [IEEE P802.15.4e call for proposal] Abstract:[This document proposes beacon collision avoidance solution for IEEE802.15.4e MAC] Purpose:[This document is a response to call for proposals] 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. ChangSub Shin et al September 2008

2. doc.: IEEE 15-08-0618-01-004e SubmissionChangSub Shin et alSlide 2 Beacon Collision Avoidance mechanism for TG4e MAC ChangSub Shin, Wun-Cheol Jeong Anseok Lee, Seong-Soon Joo ETRI September 2008 This work has been supported by the Ministry of Knowledge Economy (MKE) of the Republic of Korea under Grants 2008-F-052.

3. doc.: IEEE 15-08-0618-01-004e Submission Deferred beacon method for collision avoidance ChangSub Shin et alSlide 3 September 2008

4. doc.: IEEE 15-08-0618-01-004e Submission Beacon collision problem in IEEE802.15.4 MAC Beacon transmitted without back-off algorithm Possible interfered in mesh topology Unreliable wireless environment Without a beacon collision avoidance method Beacon-enabled PAN with mutli-hop mesh topology can not be operated with IEEE 802.15.4 MAC Motivation ChangSub Shin et alSlide 4 September 2008

5. doc.: IEEE 15-08-0618-01-004e Submission Basic algorithm 1.Sender node uses CCA or back-off algorithm before sending a beacon frame 2.Sender node notifies the offset value between the start time of superframe and actual beacon transmitting time 3.Receiver node adjusts the next beacon receiving time using the offset value Deferred beacon method (1/3) ChangSub Shin et alSlide 5 September 2008

6. doc.: IEEE 15-08-0618-01-004e Submission A node : proposed method installed defer beacon transmission for collision avoidance calculate offset value (CCA or CSMA-CA) B node : IEEE 802.15.4-2006 set the beacon receiving time to the start time of superframe next beacon time : T  + BI C node : proposed method installed adjust the start time of superframe with offset value next beacon time : T  -  + BI Deferred beacon method (2/3) ChangSub Shin et alSlide 6 September 2008

7. doc.: IEEE 15-08-0618-01-004e Submission Maximum delay and loss CCA approach max number of CCA detection for a deferred beacon : 5 max delay with CCA detection : 1,600 us CSMA-CA approach macMinBE : 3 macMaxBE : 5 macMaxCSMABackoffs : 2 macMaxFrameRetries : 0 max delay with CSMA-CA : 8,320 us Deferred beacon method (3/3) ChangSub Shin et alSlide 7 September 2008 SO051014 SD (us)15,360491,52015,728,640251,658,240 CSMA-CA delay / SD (%)54.1671.6930.0530.003 CCA delay / SD (%)10.4170.3260.0100.001

8. doc.: IEEE 15-08-0618-01-004e Submission 15.4 beacon frame Deferred time fields : The number of aUnitBackoffPeriod Proposals on Frame Format ChangSub Shin et al September 2008 Slide 8

9. doc.: IEEE 15-08-0618-01-004e Submission Bitmap assisted beacon scheduling method for collision avoidance ChangSub Shin et alSlide 9 September 2008

10. doc.: IEEE 15-08-0618-01-004e Submission Beacon contains information on superframe structure and is used for synchronizing all devices in beacon enabled network Beacon scheduling mechanism is indispensible for multi- hop mesh networks Current IEEE802.15.4 MAC supports beacon scheduling using StartTime Limitation : supported only for tree topology Beacon scheduling is not operated in MAC layer => Propose beacon scheduling method Motivation ChangSub Shin et alSlide 10 September 2008

11. doc.: IEEE 15-08-0618-01-004e Submission Bitmap assisted beacon scheduling Inform own neighbor’s allocated SD information with the bitmap in a beacon frame New joining node shall listen neighbor’s beacon during maximum ScanDuration and select unallocated SD Tracking only neighbor’s SD May use BLE for energy saving Distributed scheduling method, not centralized Need superframe structure for beacon scheduling Superframe is consisted of the number of slotted SDs Bitmap assisted beacon scheduling method (1/3) ChangSub Shin et alSlide 11 September 2008

12. doc.: IEEE 15-08-0618-01-004e Submission Bitmap assisted beacon scheduling method (2/3) ChangSub Shin et alSlide 12 September 2008 Initialization Scan : listen neighbor’s beacon Select blank SD from two-hop neighbor’s bitmap information Transmit beacon in the selected SD If beacon collision happen, notify collision notification to it’s neighbor nodes

13. doc.: IEEE 15-08-0618-01-004e Submission Bitmap assisted beacon scheduling method (3/3) ChangSub Shin et alSlide 13 September 2008

14. doc.: IEEE 15-08-0618-01-004e Submission 15.4 beacon frame Proposals on Frame Format ChangSub Shin et al September 2008 Slide 14 Bits: 0-12-67 The length of Bitmap (bytes) Allocated number of SD Reserved

15. doc.: IEEE 15-08-0618-01-004e Submission Thank you very much for your attention Any Questions? ChangSub Shin et alSlide 15 September 2008