1. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 1 Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Enhancement to IEEE 802.15.4-2006 for Industrial Markets] Date Submitted: [11 January, 2008] Source: [K. Pister and C. Kang] Company [Dust Networks] Address [30695 Huntwood Avenue, Hayward, CA 94544, USA] Voice:[+1 510 400 2900], FAX: [+1 510 489 3799], E-Mail:[kpister@dustnetworks.com and ckang@dustnetworks.com] Re: [n/a] Abstract:[This document proposes an enhancement to IEEE 802.15.4-2006 MAC Layer for Industrial Markets] Purpose:[This document is a response to Item a) better support the industrial markets in IEEE P802.15.SG4e Call for Application on 14 November, 2007] 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. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 2 Time Synchronized Channel Hopping K. Pister C. Kang Dust Networks 11 January, 2008

3. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 3 GOALS Increase reliability and robustness required for Industrial Markets Multi-channel hopping Provide efficient multi-channel hopping and enable longer operational life for battery powered devices –Time Synchronized Time Division Multiplexing Simple to co-exist with current 802.15.4 MAC devices Simultaneous operation in 802.15.4-2006 and Time Synchronized Channel Hopping modes. Flexible and scale-able

4. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 4 802.15.4 Slot and Superframe timing Slot length –When SO = 0  60 symbols  0.96ms Active superframe duration –16 slots  15.36ms when SO=0 Superframe duration –15.36ms * 2 BO ; BO = 0..14 –Up to 4 minutes (> 250,000 msec) Semi-active Channel-hopping

5. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 5 Timeslots and Superframes Each mote-to-mote communication happens within a scheduled timeslot All timeslots are contained within a superframe Superframes repeat in time Multiple superframes can operate simultaneously within a network Superframe Unallocated SlotAllocated Slot

6. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 6 Time Synchronization Timing – perfect synchronization A B RX startup Transmit Packet: Preamble, SS, Headers, Payload, CRC RX packetVerify CRC Calculate ACK CRC Transmit ACK RX startup or TX->RX RX ACK RX/TX turnaround CCA: RX startup, listen, RX->TX

7. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 7 Time Synchronization (Cont’d) Tg Transmit Packet: Preamble, SS, Headers, Payload, CRC T ACK T C CA T crc Early Late Perfect Transmit Packet: Preamble, SS, Headers, Payload, CRC T ACK T C CA T crc Transmit Packet: Preamble, SS, Headers, Payload, CRC T ACK T C CA T crc Transmit Packet: Preamble, SS, Headers, Payload, CRC T ACK T C CA T crc Transmit Packet: Preamble, SS, Headers, Payload, CRC T ACK T C CA T crc Transmit Packet: Preamble, SS, Headers, Payload, CRC T ACK T C CA T crc Tg T slot = 2T g +T comm +T CCA T comm = T packet +T crc +T ACK T crc includes T gACK and all CRC and radio turnaround times. It’s the time from the last bit of the packet to the first bit of the preamble of the ACK.

8. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 8 Time Synchronization Acknowledgement-based Synchronization 1.Transmitter node sends a packet, timing at the start symbol. 2.Receiver timestamps the actual timing of the reception of start symbol 3.Receiver calculates TimeAdj = Expected Timing – Actual measured Timing 4.Receiver informs the sender TimeAdj 5.Transmitter adjusts its clock by TimeAdj

9. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 9 Time Synchronization (Cont’d) Received Packet-based Synchronization 1.Receiver timestamps the actual timing of the reception of start symbol 2.Receiver calculates TimeAdj = TimeExpected (expected arrival time) – Actual timing 3.Receiver adjusts its own clock by TimeAdj

10. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 10 CADACADA B C Link = (Time Slot, Channel Offset) A Time Chan. offset BABA BABA One Slot D The two links from B to A are dedicated D and C share a link for transmitting to A The shared link does not collide with the dedicated links BCBC FE BEBFBEBF

11. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 11 Timeslot and Channel Mapping CADACADA B C A Slot links for devices Time Chan. 2.405 GHz 2.470 GHz … 2.480 GHz BABA BABA One Slot 2.445 GHz 2.425 GHz 2.475 GHz 2.440 GHz D The two links from B to A are dedicated D and C share a link for transmitting to A The shared link does not collide with the dedicated links

12. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 12 Frequency Hopping CADACADA CADACADA Each link rotates through k available channels over k cycles. Blacklisting can be defined globally and locally. BABA CADACADA BABA Time Channel BABA BABA BABA BABA Cycle N Cycle N+1 Cycle N+2

13. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 13 Channel Hopping Need to map (slot, offset) into an 802.15.4 channel –For blacklisting, assume Num_channels LookUp() defines pseudo-random hop sequence over num_channels ASN = absolute slot number Chan = (ASN + offset) % num_channels 15.4Channel = LookUp(Chan)

14. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 14 Non-conflicting Timeslot assignment Devices can be given one or more offsets. OR Devices can be given one or more slots in a particular superframe. OR Devices can be given a block of (slot,offset)s Chan. offset slot

15. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 15 Non-conflicting timeslot assignment Devices can be given one or more offsets. OR Devices can be given one or more slots in a particular superframe. OR Devices can be given a block of (slot,offset)s SD=aBaseSuperframeDuration * 2 SO symbols BI=aBaseSuperframeDuration * 2 BO symbols

16. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 16 Non-conflicting timeslot assignment Multiple superframes with different lengths can operate without conflict as well. 4 cycles of the 250ms superframe are shown, along with a 1s superframe There are never collisions if the 1 second frame uses only the empty slots 250ms 1,000ms

17. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 17 Example of HART Capability Data collection –100 pkt/s per access point channel –16*100 pkt/s with no spatial reuse of frequency –105 MPDU bytes per packet assuming 22 bytes of MAC header, MIC, CRC Throughput –84kbps MPDU bits per second per access point –15 * 84k = 1.26Mbps combined payload throughput w/ no spatial reuse of frequency Latency –10ms / PDR (Packet Delivery Rate) per hop –Statistical, but well modeled

18. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 18 Built-In Flexibility Trade performance and power –Sample & reporting rate –Latency –High bandwidth connections Tradeoffs can vary with –Time –Location –Events Use power intelligently if you’ve got it –Highest performance with powered infrastructure

19. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 19 Added MAC PAN Service Primitives PrimitiveDescriptionRe- quest Con- firm Res- ponse Indica- tion SET-SUPERFRAME Add, delete, or modify a superframe XX ADD-LINK Add a new link XX DELETE-LINK Delete a new link XX TDMA-MODE Operate in TDMA mode using superframes and links XX

20. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 20 Added MAC MIB AttributeTypeDescription SuperframeTableSizeIntegerNumber of entries in the Superframe Table LInkTableSizeIntegerNumber of entries in the Link Table RxStartOfPacketTstampTimestampTimestamp of receiving the first bit of the packet’s SFD on the PHY RxEndOfPacketTstampTimestampTimestamp of receiving the last bit of the packet from the PHY AbsoluteSlotNumberlong IntegerAbsolute slot number of current superframe

21. doc.: IEEE 802.15-08-0024-01-004e Submission 11 January, 2008 K. Pister and C. Kang, Dust NetworksSlide 21 Added SMIB (Structured MIB) Link Table: contains all links configured on the device. Superframe Table: contains all superframes configured on the device.