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: [Distributed Channel Hopping (DCH) over EGTS Structure] Date Submitted: [May 12, 2009] Source: [Wun-Cheol Jeong, Seong-Soon Joo, Chang-Sub Shin, Anseok Lee] Address [] Voice:[+82-42-860-5104], FAX: [], E-Mail:[wjeong@etri.re.kr] Re: [IEEE P802.15.4e] Abstract: [This document describes operational description of DCH over EGTS structure.] Purpose: [Discussion in 802.15.4e Task Group] 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.

2. Distributed Channel Hopping (DCH) over EGTS structure Wun-Cheol Jeong, Seong-Soon Joo, Chang-Sub Shin, Anseok Lee ETRI

3. Table of Contents • Channel Diversity Subgroup Report • Merging DCH over EGTS structure • Initialization • Channel Hopping Sequence & Hopping Sequence Offset Selection • EGTS Slot allocation • Required Changes

4. Channel Diversity Subgroup Contributors • ETRI: Wun-Cheol Jeong, Changsub Shin, Anseok Lee, Seong-Soon Joo • Dust Networks: Chol Su Kang, Kris Pister (UC Berkeley) • Freescale: Kuor-Hsin Chang, Clinton Powell • Emerson: José A. Gutierrez • Siemens: Ludwig Winkel • Rick Enns: Consultant • CUNY • Huawei • Arch Rock • SIMIT • Vino • USTB • SIA

5. Channel DiversitySubgroup Report • Description of Channel Diversity • Channel hopping • Channel adaptation • Proposals for Channel Diversity • Distributed Channel Hopping (DCH) • Time Slotted Channel Hopping (TSCH) • Enhanced GTS (EGTS) Channel Adaptation

6. Channel DiversitySubgroup Report ISA, HCF Contention-Free Contention-Free TSCH E-GTS • Two different structures • EGTS • TSCH • Merging Activity • DCH over EGTS ZigBee, 802.15.5 Contention Access Contention Access nonbeacon-enabled PAN beacon-enabled PAN Overhead Reduction/Security Low Energy Channel Diversity 802.15.4

7. Initiation of DCH Operation • During association process, a node device scans channel to locate beacon frames. • If a beacon frame is found and ‘EGTS Flag’ is True, a device shall operate in a EGTS mode. Otherwise, the PAN is not in EGTS mode. • If ‘Channel Diversity Mode’ is ‘1’, a device shall operate in a EGTS-DCH mode. Otherwise, the PAN is in EGTS-CA mode. • By listening beacon frames, a node device shall update channel hopping information. • A node shall send a Association frame to join the network.

8. Channel Hopping Sequence & Hopping Sequence Offset Management • If a PAN is found to be operating in EGTS-DCH mode, a node device shall update channel hopping offset information by listening ‘Channel Diversity Specification’ field in the received beacon frame. • ‘Channel Offset Bitmap’ sub field in ‘Channel Diversity Specification’ field shall inform which offset values used among 2 hop-distance nodes at the perspective of the reference node. • Updates macChannelOffset attribute in PIB. • NHL shall select channel offset value and inform MAC sub layer using primitive. MAC entity send a Association request frame with the selected channel offset value and channel hopping sequence request using ‘Channel Sequence Request’. • Upon the reception of a Association request frame, the corresponding node informs channel hopping sequence using ‘Channel Hopping Sequence’ field in a Association response frame.

9. Channel Hopping Sequence & Hopping Sequence Offset Management CAP CFP Channel Time Illustration of Channel Hopping over EGTS multi-superframe structure

10. Channel Hopping Sequence & Hopping Sequence Offset Management • Hopping Sequences are manages in tables in MAC PIBs which have following properties: • One or more hopping sequences can be stored as parameters for PIBs. • Hopping sequences in PIBs can be modified by higher layer. • Newly joined node may request for the transmission of hopping sequences if those are not in PIBs. • NHL monitors channel status. That is, channels with bad quality can be blacked out, and channels with good quality can be marked as white channels. Channels in poor quality can be excluded during the EGTS slot allocation process.

11. EGTS Slot Allocation • EGTS slots are scheduled by exchanging EGTS handshake command frames. • However, nodes exchange Timeslot Allocation Bitmaps (TABs) only. Note that the size of TAB simply represents the availability of corresponding EGTS slots. Thus, it is much smaller than EGTS ABT sub-block which represents the availability of corresponding EGTS slots and channels as well. • Since there may be links using the same channel offset value within interfering distances, there would be collision if same slots are used among the links using same channel offset value. • To avoid collision, three-way handshaking is used.

12. EGTS Slot Allocation Node 1 assigns slots (3), (4) for node 3 Note: Timeslot Allocation Bitmap is exchanged, not ABT! Every node that hears the broadcasts updates its allocation bitmap table (ABT) • 2. DCH reply, broadcast • Payload : • Dstaddr (3) • Timeslots Allocation Bitmap(TAB) • 0011000 • DCH slot request, unicast • Payload : • Dstaddr (1) • Number of request slots: 2 • Timeslots Allocation Bitmap(TAB) • 0100100 • 3. DCH notify, broadcast • Payload : • Dst addr (1) • Timeslots Allocation Bitmap(TAB) • 0011000 Assuming slots (2), (5) are already Assigned from node 4 for transmitting Frames to node 3.

13. Required Changes • Primitives • MLME-START.request • MLME-GTS.request • MLME-GTS.confirm • MAC command frames • Beacon frame • Association request • Association respond • MAC PIBs

14. Required Changes • MLME-START.request ( …. • EGTSFlag, • ChannelDiversityMode, • DCHDescriptor • )

15. Required Changes • MLME-START.request ( …. • EGTSFlag, • ChannelDiversityMode, • DCHDescriptor • ) Elements of DCHDescriptor

16. Required Changes • MLME-GTS.request ( …. • EGTSFlag, • EGTSCharacteristics • )

17. Required Changes • MLME-GTS.confirm ( …. • EGTSFlag, • EGTSCharacteristics • )

18. Required Changes • Beacon Frame Beacon Frame Format Channel Diversity Specification Field

19. Required Changes • Association Request Command Association Request Command Frame Capability Information Field Formant

20. Required Changes • Association Respond Command Association Respond Command Frame

21. Required Changes • New MAC PIBs • macEGTSFlag : will use the definition of EGTS Characteristics • macChannelDiversityMode : indicate the type of channel diversity mode • macTAB : timeslot allocation bitmap for channel hopping mode