May 2013 doc IEEE 802 15 13 0269

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Contents • •

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Benefits of synchronized

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Consideration of PAC

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Definition of time

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Timestamp method for

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Reference design of

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Distributed time synchronization

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Deferred beacon Back-off(α)

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Beacon transmission for

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Superframe structure •

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Multi-hop time synchronization

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May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Project: IEEE P 802. 15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Superframe Structure and Deferred Beacon in Distributed PAC Environments] Date Submitted: [May 2013] Source: [Chang Sub Shin, Wun-Cheol Jeong, Tae-Joon Park, Hoyong Kang, Cheol Sig Pyo] Company: [ETRI] E-Mail: [shincs@etri. re. kr] Re: [] Abstract: Notice: This document has been prepared to assist the IEEE P 802. 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 P 802. 15. Submission Slide 1 Chang. Sub Shin et al.

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Superframe Structure and Deferred Beacon in Distributed PAC Environments Chang Sub Shin, Wun-Cheol Jeong, Tae-Joon Park, Hoyong Kang, Cheol Sig Pyo ETRI Submission Slide 2 Chang. Sub Shin et al.

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Contents • • Benefits of synchronized approach for PAC Consideration of PAC environments Distributed time synchronization method Superframe structure Submission Slide 3 Chang. Sub Shin et al.

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Benefits of synchronized approach for PAC • Utilization of resource • Less contention • Low power consumption • Duty cycling • Low latency • Time slot reservation • Multi-channel support • Multi-channel management based TDMA => Need to time synchronization function Submission Slide 4 Chang. Sub Shin et al.

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Consideration of PAC environments • Unlicensed band • Bad channel condition • Noise for PAC • Infrastructureless topology • Ad-hoc topology • Difficulty in control and management • High density of PDs • Scalable problem • Overhead of resource management => Need to reliable and distributed time synchronization function Submission Slide 5 Chang. Sub Shin et al.

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Definition of time synchronization • C(t) = a * t + b • C(t) : Computer clock • a is clock drift (rate or skew) • b is an offset of the clock • Perfect clock • Rate = 1 • Offset = 0 • Time Synchronization • Requires Knowing both offset and drift Submission Slide 6 Chang. Sub Shin et al.

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Timestamp method for synchronization in MAC Insert Timestamp value Interface delay Sender MAC Modulation and Tx Interface PHY Rx and Demodulation Receiver Detection of receiving frame Sync error Submission Slide 7 PHY Chang. Sub Shin et al.

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Reference design of time slot (from IEEE 802. 15. 4) RF turnaround Tx data sender Rx ack SO 0. 192 4. 256 0. 352+α Guard time Rx data receiver 1 1 4. 256 RF turnaro und Tx ack 0. 192 0. 352 S-Slot(us) S-Slot(ms) 0 960 0. 96 1 1920 1. 92 2 3840 3. 84 3 7680 7. 68 4 15360 15. 36 5 30720 30. 72 6 61440 61. 44 7 122880 122. 88 8 245760 245. 76 Minimum time slot duration : 6. 8 ms Submission Slide 8 Chang. Sub Shin et al.

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Distributed time synchronization method • Beacon based time synchronization in MAC layer • Time information in beacon frame • Reliable beacon transmission • Interference avoidance using deferred beacon • Distributed manner • Candidate PDs which try to transmit beacon with contention • Prioritized back-off algorithm to resolve beacon frame delay • Using minimized contention window value or CCA only • Multi-hop time synchronization • A PD which received beacon frame can transmit beacon frame Submission Slide 9 Chang. Sub Shin et al.

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Deferred beacon Back-off(α) BIn+1 Timestamp value : (Bin, α) Beacon B Beacon A Beacon Interval PD(B) adjust time synchronization with Bin, α, receiving time Submission Slide 10 Chang. Sub Shin et al.

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Beacon transmission for fault recovery D A BIn-1 BIn B BIn+1 Beacon Collapsed PD Beacon BIn-2 C C Candidate PDs D Beacon Interval Submission Slide 11 Chang. Sub Shin et al.

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Superframe structure • PAC PAN can be operated either in synchronous or asynchronous manner − Mode flag : Asynchronous and Synchronous mode selection in beacon frame • Flexible and Extensible Superframe structure in synchronous PAN mode: − The duration of Contention Period and Contention Free Period are set by the number of slot in beacon frame − Control Period starts after receiving beacon frame − Beacon Period and Contention Free Period can use multi-channel Submission Slide 12 Chang. Sub Shin et al.

May 2013 doc. : IEEE 802. 15 -13 -0269 -01 -0008 Multi-hop time synchronization and multi-channel usage based on superframe Submission Slide 13 Chang. Sub Shin et al.