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: [Narrow Band Frequency Hopping PHY Proposal for 802.15.4g] Date Submitted: [July 2009] Source (in no particular order): [Michael Schmidt, Dietmar Eggert] Company [Atmel] [Jeritt Kent] Company [Analog Devices] [Cristina Seibert, George Flammer] Company [Silver Spring Networks] Address [] Voice [] E-Mail: [cseibert @ silverspringnet.com] Re: [] Abstract: Detailed Proposal for a Narrow Band Frequency Hopping PHY for 802.15.4g Purpose: Technical Proposal 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. Atmel, ADI, Silver Spring Networks

2. Overview of NBFH PHY Proposal • SUN Characteristics • PHY Proposal Highlights • Normative PHY Specification • MAC Support • Conclusions Atmel, ADI, Silver Spring Networks

3. Key Characteristics of SUN • Low data rate: over the air data rates of 40 kbps up to 1 Mbps • Robust, proven techniques critical • Spectral efficiency desirable but not critical • Dynamic scaling to very large aggregate networks • Networks with millions of arbitrarily co-located nodes • Requirement for cost effective deployments • Interference mitigation capability • Peer to Peer, minimal infrastructure-dependent operation • PHY techniques suitable for packet forwarding and with minimal added interference • Enhanced IP support (> 1500 octet payload) Atmel, ADI, Silver Spring Networks

4. PHY Proposal Highlights Atmel, ADI, Silver Spring Networks

5. PHY Proposal Highlights (Cont’d) Atmel, ADI, Silver Spring Networks

6. Benefit of Channel Diversity Atmel, ADI, Silver Spring Networks

7. NBFH with FSK Modulation • Advantages: • Many channels => good interference mitigation • Constant envelope signal => inexpensive and low power PAs, receive/transmit chains • Does not rely on high precision clocks and sharp filters => low cost • Low to moderate SUN data rates => long symbol time => low ISI, low processing requirements • Proven actual deployments on the scale of millions of units • SSN, Coronis/France Telecom, Elster, CellNet/Hunt, GE, Eka • Disadvantages • Spectrally less efficient than other techniques Atmel, ADI, Silver Spring Networks

8. Parameter Details • Narrow band channels • Good channel diversity while also supportive of PAR rates • Ability to use maximum transmit power as may be allowed by regulations (for example under US FCC part 15.247, the criteria for 1W FHSS), and adjust transmit power to fit the local regulations • Robust performance in the presence of multiple interference sources • Various channel spacings may be useful, and can be accommodated via method described in 15-09-0453 • Support for efficient frequency hopping • Primarily band agnostic and seamless inter-band hopping • Support for channel “black-listing” and “white-listing”, whereby access to specific channels can be restricted or encouraged Atmel, ADI, Silver Spring Networks

9. Parameter Details (Cont’d) • Data “whitening” (scrambling) • Whitens payload data (PSDU/MPDU) to avoid long series of 1’s and 0’s. • 8-bit scrambler (255 bit sequence), taps at bits [8,4,3,2] • Scrambler re-seeded periodically for added reliability • A nominal data rate of 100 kbps consistent with the PAR, others optional • TPC for adapting to regulator domain and to support adaptation to observed link conditions • Monotonic RSSI Atmel, ADI, Silver Spring Networks

10. PHY Frame (PPDU) • Support for 2047 octet payload (802.1 MTU) • IEEE CRC-32 on PHY frame • Extension bit for “future proofing” • Flexible preamble, further investigation pending Structure of PPDU Atmel, ADI, Silver Spring Networks

11. PIB table Atmel, ADI, Silver Spring Networks

12. PIB Table (Cont’d) Atmel, ADI, Silver Spring Networks

13. Data Transfer Atmel, ADI, Silver Spring Networks

14. Data whitening • Whitens payload data (PSDU/MPDU) to avoid long series of 1’s and 0’s. • 8-bit scrambler (255 bit sequence) • taps at bits [8,4,3,2] • Ability to reset the scrambling seed across packets and retransmissions Atmel, ADI, Silver Spring Networks

15. A PHY Parameter Set Atmel, ADI, Silver Spring Networks

16. Free Running Clock (FRC) • It is required that a free running clock be available, accessible by both the PHY and MAC and used to time stamp packet receptions and schedule packet transmissions. • The PHY captures the time of PPDU arrival upon receipt. A snapshot of the FRC is taken at the receipt of the last bit of the scrambler seed. If available, the FRC value captured will be reported with the PSDU in the PD_DATA.indication. • The FRC may also be used by the MAC layer for scheduling packet transmissions to occur at a specific FRC value. Atmel, ADI, Silver Spring Networks

17. General Radio Specification • The TX-to-RX turnaround time refers to the shortest time possible at the air interface from the trailing edge of the last symbol of a transmitted PPDU to the leading edge of the first symbol of the next received PPDU. • The RX-to-TX turnaround time refers to the shortest time possible at the air interface from the trailing edge of the last symbol of the received PPDU to the leading edge of the first symbol of the next transmitted PPDU. • The RX-to-TX turnaround time shall be less than or equal to 1 ms and shall be greater than or equal to the TX-to-RX turnaround time. Atmel, ADI, Silver Spring Networks

18. MAC Support • MAC controls frequency hopping and programs PHY accordingly. • In the proposed design, nodes can communicate by knowing: • The receiver frequency hopping sequence and • Relative time at that receiver • MAC also responsible for enforcing regulatory requirements for channel occupancy • Reliability support • Packet acknowledgment • Packet retransmission Atmel, ADI, Silver Spring Networks

19. Conclusions • Proposal consistent with scope of approved SUN PAR • Support millions of users at low data rates • Robust and available • Low cost and ubiquitous • Operation in unlicensed spectrum • Applications supported by this proposal are consistent with those proposed by utilities and manufacturers during PAR approval process and in tutorials • Some references: • 15-08-0199-00-wng0-the-smart-grid.ppt • 15-08-0455-00-0000-utility-view-of-nan-drivers-and-requirements.pdf • 15-08-0639-02-0nan-strawman-5c-input-for-wnan.doc Atmel, ADI, Silver Spring Networks