1. doc.: IEEE 15-14-0197-00-0008 Submission Slide 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Reliable broadcast scheme for PAC networks] Date Submitted: [March 20th, 2014] Source: [Jeongseok Yu, Woongsoo Na, Hyoungchel Bae, Taejin Kim, Yunseong Lee, Juho Lee, Zeynep Vatandas, Sungrae Cho, and Junbeom Hur] Company [Chung-Ang University, Korea] E-Mail:[jsyu@uclab.re.kr, wsna@uclab.re.kr, hcbae@uclab.re.kr, tjkim@uclab.re.kr, yslee@uclab.re.kr, jhlee@uclab.re.kr, zvatandas@uclab.re.kr, srcho@cau.ac.kr, jbhur@cau.ac.kr] Re: [] Abstract:[] Purpose:[To provide materials for discussion in 802.15.8 TG] 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. Jeongseok Yu et al., Chung-Ang University

2. doc.: IEEE 15-14-0197-00-0008 Submission Reliable Broadcast Scheme for PAC networks Slide 2 Jeongseok Yu et al., Chung-Ang University

3. doc.: IEEE 15-14-0197-00-0008 Submission Introduction Why do we need reliable broadcast? –Before most of broadcast protocol don’t use ACK frame, because broadcast protocol don’t have to satisfy reliable. –In the PAC however, broadcast is necessary for disseminating data for various reasons, e.g., emergency alarm, etc. Reliability for broadcast might be guaranteed in some applications (e.g., public emergency, hazard notification). -> Reliable Broadcast. Slide 3 Jeongseok Yu et al., Chung-Ang University

4. doc.: IEEE 15-14-0197-00-0008 Submission Motivation (1/2) Suppose that every receiver node acknowledges (with ACK or NAK) for broadcast data, e.g., The broadcast node will be overwhelmed by acknowledge messages (a.k.a.) ACK/NAK implosion problem. Slide 4 Jeongseok Yu et al., Chung-Ang University

5. doc.: IEEE 15-14-0197-00-0008 Submission Motivation (2/2) This implosion problem also causes the problems of –Unnecessary Collision –Unnecessary Power Consumption Solution: limit the number of acknowledgements How?: –Use timers Timer-based Reliable Broadcast (TRB) Slide 5 Jeongseok Yu et al., Chung-Ang University

6. doc.: IEEE 15-14-0197-00-0008 Submission TRB (1/6) Transmitter Behavior (when it has broadcast data): –Upstream: If the data is from its child, it does the following in its appropriate schedule: It broadcasts the data (piggybacked by ACK/NAK) to its children (not siblings), and sets its timer D. It unicasts the data to its parent and associated neighbors, and sets its timer D. –Downstream: If the data is from its parent It broadcasts its data to its children (not siblings) and associated neighbors, and sets its timer D. Slide 6 Jeongseok Yu et al., Chung-Ang University

7. doc.: IEEE 15-14-0197-00-0008 Submission TRB (2/6) Transmitter Behavior (when it has broadcast data) –The other cases: If the transmitter is the originator of the data, it does the following in its appropriate schedule: It broadcasts the data to its children (not siblings), and sets its timer D. It unicasts the data to its parent and associated neighbors, and sets its timer D. –In all cases, a node that received a broadcast data from other node does not unicast back to that other node. –If timer D expires before receiving feedback (ACK/NAK), it retransmits the original data as above. Slide 7 Jeongseok Yu et al., Chung-Ang University

8. doc.: IEEE 15-14-0197-00-0008 Submission TRB (3/6) Receiver Behavior (after receiving broadcast data) –When a node receives a broadcast data, it delays its acknowledgement by a random timer described below: If the received data is erroneous, the node activates a NAK timer. If the received data is OK, the node activates an ACK timer. –If its timer expires, the node responds (with unicast) its feedback (NAK or ACK) to its transmitter. Slide 8 Jeongseok Yu et al., Chung-Ang University Error NAK timer ACK timer

9. doc.: IEEE 15-14-0197-00-0008 Submission TRB (4/6) Slide 9 Jeongseok Yu et al., Chung-Ang University Broadcast Data Received D αD (NAK Period)(1-α)D (ACK Period)

10. doc.: IEEE 15-14-0197-00-0008 Submission TRB (5/6) Transmitter Behavior (after receiving feedback) –Once the transmitter receives a NAK, it retransmits its data as described in Slide 7 to fix the error, and sets its timer D. –When an ACK received, the transmitter transmits its next broadcast data if it has as described in Slide 7, and sets its timer D. Slide 10 Jeongseok Yu et al., Chung-Ang University

11. doc.: IEEE 15-14-0197-00-0008 Submission TRB (6/6) Receiver Behavior (after receiving rebroadcast data) –The receiver node cancels its timer (NAK or ACK). –This will reduce unnecessary feedbacks to the transmitter. –Based on the result of error detection/correction, the receiver uses NAK/ACK timer. This series of procedure will continue up to predefined number of times. Overall behavior will look like as the following for and example: Slide 11 Jeongseok Yu et al., Chung-Ang University Tx Rx’s NAKs Many of receivers will suppress their timer Broadcast Rebroadcast NAK ACK

12. doc.: IEEE 15-14-0197-00-0008 Submission Downstream Example (1/7) Slide 12 Jeongseok Yu et al., Chung-Ang University C A EF G DB HIJKL Level N Level N-1 Level N+1 Level N+2 OK

13. doc.: IEEE 15-14-0197-00-0008 Submission Downstream Example (2/7) Slide 13 Jeongseok Yu et al., Chung-Ang University C A EF G DB HIJKL Level N Level N-1 Level N+1 Level N+2 ACK

14. doc.: IEEE 15-14-0197-00-0008 Submission Downstream Example (3/7) Slide 14 Jeongseok Yu et al., Chung-Ang University C A EF G DB HIJKL Level N Level N-1 Level N+1 Level N+2 OKError

15. doc.: IEEE 15-14-0197-00-0008 Submission Downstream Example (4/7) Slide 15 Jeongseok Yu et al., Chung-Ang University C A EF G DB HIJKL Level N Level N-1 Level N+1 Level N+2 NAK OK

16. doc.: IEEE 15-14-0197-00-0008 Submission Downstream Example (5/7) Slide 16 Jeongseok Yu et al., Chung-Ang University C A EF G DB HIJKL Level N Level N-1 Level N+1 Level N+2 OK ACK

17. doc.: IEEE 15-14-0197-00-0008 Submission Downstream Example (6/7) Slide 17 Jeongseok Yu et al., Chung-Ang University C A EF G DB HIJKL Level N Level N-1 Level N+1 Level N+2 OK

18. doc.: IEEE 15-14-0197-00-0008 Submission Downstream Example (7/7) Slide 18 Jeongseok Yu et al., Chung-Ang University C A EF G DB HIJKL Level N Level N-1 Level N+1 Level N+2 ACK

19. doc.: IEEE 15-14-0197-00-0008 Submission Upstream Example (1/4) Slide 19 Jeongseok Yu et al., Chung-Ang University C A EF G DB HIJKL Level N Level N-1 Level N+1 Level N+2 Broadcast Originator OK

20. doc.: IEEE 15-14-0197-00-0008 Submission Upstream Example (2/4) Slide 20 Jeongseok Yu et al., Chung-Ang University C A EF G DB HIJKL Level N Level N-1 Level N+1 Level N+2 OK ACK

21. doc.: IEEE 15-14-0197-00-0008 Submission Upstream Example (3/4) Slide 21 Jeongseok Yu et al., Chung-Ang University C A EF G DB HIJKL Level N Level N-1 Level N+1 Level N+2 Data/ACK OK

22. doc.: IEEE 15-14-0197-00-0008 Submission Upstream Example (4/4) After receiving C’s unicast data, nodes A broadcasts the data piggybacked with ACK. Slide 22 Jeongseok Yu et al., Chung-Ang University C A EF G DB HIJKL Level N Level N-1 Level N+1 Level N+2 Data/ACK

23. doc.: IEEE 15-14-0197-00-0008 Submission Summary ACK/NAK in reliable broadcast in PAC may cause problems of –Feedback implosion, –Unnecessary collisions, and –Unnecessary power consumption, –Due to unnecessary feedback messages Timer-based Reliable Broadcast (TRB) algorithm effectively solves the above mentioned problems. Slide 23 Jeongseok Yu et al., Chung-Ang University