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: [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

2. Beacon Collision Avoidance mechanism for TG4e MAC ChangSub Shin, Wun-Cheol Jeong Anseok Lee, Seong-Soon Joo ETRI This work has been supported by the Ministry of Knowledge Economy (MKE) of the Republic of Korea under Grants 2008-F-052. ChangSub Shin et al

3. Deferred beacon method for collision avoidance ChangSub Shin et al

4. Motivation • 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 ChangSub Shin et al

5. Deferred beacon method (1/3) • Basic algorithm • Sender node uses CCA or back-off algorithm before sending a beacon frame • Sender node notifies the offset value between the start time of superframe and actual beacon transmitting time • Receiver node adjusts the next beacon receiving time using the offset value ChangSub Shin et al

6. Deferred beacon method (2/3) • 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 ChangSub Shin et al

7. Deferred beacon method (3/3) • 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 ChangSub Shin et al

8. Proposals on Frame Format • 15.4 beacon frame • Deferred time fields : The number of aUnitBackoffPeriod ChangSub Shin et al

9. Bitmap assisted beacon scheduling method for collision avoidance ChangSub Shin et al

10. Motivation • 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 ChangSub Shin et al

11. Bitmap assisted beacon scheduling method (1/3) • 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 ChangSub Shin et al

12. Bitmap assisted beacon scheduling method (2/3) • 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 ChangSub Shin et al

13. Bitmap assisted beacon scheduling method (3/3) ChangSub Shin et al

14. Proposals on Frame Format • 15.4 beacon frame ChangSub Shin et al

15. Thank you very much for your attention Any Questions? ChangSub Shin et al