Submission Title: [ Wireless Neighborhood Area Networks – WNAN ]

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [ Wireless Neighborhood Area Networks – WNAN ] Date Submitted: [ 16 July, 2008 ] Source: [ George Flammer ] Company/Organization [ Silver Spring Networks ] Address: [ 575 Broadway, Redwood City, CA ] Tel [ 650-298-4200] E-Mail: [ gflammer (at) SilverSpringNet.com ] Re: IEEE 802 Plenary IG-NAN Abstract: WNAN recap of definitions, market, detailed technical & performance requirements. Purpose: To brief IEEE 802 Membership on WNAN application area and need for standards 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. The WNAN application space • Geographically distributed process control network • With a very large number of • High value endpoints in • Nominally fixed locations with • Handfuls of kilobytes moving • Within handfuls of seconds • Not a ‘fat’ pipe, but a ‘diverse’ pipe

3. The WNAN application space For the Utility application, the WNAN logically extends ‘from the tower to the toaster’. For process control, the WNAN extends from the computer to the monitored and controlled devices. Topologically, this can be 802.15.4 devices and relays aggregated by 802.11/802.16 WAN to an 802.3 LAN.

4. Some detailed PHY Requirements 16 July, 2008

5. Statement of Purpose: “Anyone should be able to build a radio to the standard of 802.15.xxthen add softwareimplementing protocol layers from the‘upper MAC’ to the applicationwith a suitable HALand run compatibly.”

6. WNAN network application space Industrial process control needs to be robust – you can never have enough range. With enough range, you have ubiquitous coverage. When you have complete coverage, you must have a scalable technology Which will not be used if it is not robust. The PHY and MAC need to be tailored to meet the WNAN technical requirements.

7. Robustness 1/10 Goal: maximum communication robustness In order to receive certification under FCC regulations, as well as architect a robust, scalable, and mesh-able network, conformance to CFR 15.247 is suggested. If channel hopping is selected, then from FCC CFR 15.247: if the 20 dB bandwidth of the hopping channel is less than 250 kHz, the system shall use at least 50 hopping channels and the average time of occupancy on any frequency shall not be greater than 0.4 seconds within a 20 second period PR01: modulation which will fit into 250kHz -20dB BW PR02: system capable of at least 50 separate non-overlapping channels (900MHz)

8. Robustness 2/10 Goal: maximum communication robustness large scale deployments will often have hundreds or thousands of adjacent nodes. Successful operation will depend upon efficient spectral use and reuse. If channel hopping is selected, then from FCC CFR 15.247: if the 20 dB bandwidth of the hopping channel is less than 250 kHz, the system shall use at least 50 hopping frequencies and the average time of occupancy on any frequency shall not be greater than 0.4 seconds within a 20 second period PR03: PHY should enable a maximum number of channels within available spectrum; 902-928 = 26MHz, 2.4GHz = 83.5MHz PR04: channels available should be capable of being defined to be non-overlapping channels

9. Robustness 3/10 Goal: maximum communication robustness large scale deployments of autonomous collaborative nodes may generate bursty traffic in response to sensor input. Comment: When bursty traffic aggregates at various ‘choke points’ within process control networks, all available contention reduction techniques should be available; channel reservation, receiver hard limiting, spacious frequency allocations, etc. PR05: PHY modulation/demodulation technologies shall be robust in the presence of simultaneous channel occupancy – hard limiting receivers (FSK, BPSK, etc.) MR01: MAC shall support temporal channel reservation

10. Robustness 4/10 Goal: robust modulation/demodulation techniques demodulators should be robust over all data Comment: inexpensive modulation/demodulation techniques can suffer from pattern sensitivity – long strings of ones or zeros can drive averaging demodulators outside of their hysteresis regions. Scramblers are typically used, but, in a network moving billions of packets monthly, there *are* data patterns that ‘unscramble the scrambler’ – these ‘killer’ packets can be avoided by changing the scrambler when required. PR06: PHY modulation/demodulation technologies shall be robust with regard to data patterns and pattern lengths being communicated. The standard needs to support varying the scrambler as required.

11. Robustness 5/10 Goal: robust demodulation at the packet level The upper layers of software should only be alerted to process validated packets. Comment: CRC or other packet vetting algorithms need to be selected to detect errors over the entire packet size; the larger the packet, the larger the ‘check field’. Current 802.15.4 16 bit CRC is statistically insufficient for larger packet sizes. PR07: Only validated packets should be presented by the PHY to the higher layer calling routines.

12. WNAN networks: support for IP packet sizes Average round trip time (RTT) of ~450 byte meter reads for 48,000 meters.

13. Robustness 6/10 Goal: Consistent (and good) receiver sensitivity such that interoperating nodes will not have asymmetric links (heard in one direction only). Comment: The current 802.15.4 specifies receiver sensitivity on a per-band basis. State of the art has improved somewhat from -85dBm packet sensitivity. PR09: Minimum receiver sensitivities shall be specified

14. WNAN networks: very high connectivity High WNAN connectivity can be used to develop optimal routes as well as to provide connectivity for hard-to-reach nodes.These data are typical for suburban or urban deployments.

15. Robustness 7/10 Goal: Consistent (and good) receiver adjacent channel rejection performance such that interoperating nodes will not have asymmetric links (heard in one direction only). Comment: The current 802.15.4 specifies receiver adjacent and alternate channel rejection on a per-band basis. You can never have *too good* filtering, and adjacent channel performance is a dominant determiner of the ultimate throughput and survivability of the mesh – especially in anomalous operating conditions. PR10: Minimum receiver adjacent and alternate channel rejection should be specified.

16. WNAN networks: highly variable density WNAN endpoint density for 100’ hexagonal cells in a deployment area 20 km by 8km.

17. Robustness 8/10 Goal: Be able to realize system benefits accruing to the use of timing and frequency sources of a minimum stability. Comment: System performance benefits in several ways from increased frequency stability: channels may be ‘tighter’, filter skirts may be steeper, bit synchronization will persist longer. At a system level, frequency stability translates to fewer synchronization transmissions and thus to a lower transmit duty cycle/ power consumption. Stability, while not cheap, is not expensive and provides broad based performance improvements. Current specifications specify stability on a per band basis. PR11: Appropriate minimum frequency stability shall be specified.

18. Robustness 9/10 Goal: Transmitter compatibility Comment: Incompatible transmitter power ramps can cause otherwise compatible system to be unable to communicate. Specification of maximum tx rise and fall times guarantees compatibility. PR11: Maximum transmitter and/or amplifier rise and fall times shall be specified.

19. Robustness 10/10 Goal: Node to node compatibility for frequency agile systems. Comment: If channel hopping is selected, channel-to-channel slew time is an important specification. Though systems can be created to ‘negotiate’ slew, variable slew rates within the same network is an avoidable complexity. PR12: Maximum channel to channel (band edge to band edge) times shall be specified on a per band basis.

20. Support 1/4 Goal: Received Signal Strength indication Comment: Received signal strength can vary widely (several dB) on a packet to packet basis, over the same path - even line-of-sight paths. Thus, very high resolution (better than 1 dB) is not generally useful. PR08: Received Signal Strength Indication (RSSI) should be monotonic.

21. Support 2/4 Goal: Variable transmit power Comment: As a corollary to the RSSI requirement. The received strength of packet can will often vary several dB without obvious change in conditions. This relaxes constraints on the resolution of the transmit power steps. Transmitter power need not have great resolution; e.g., 6 to 10dB steps may be quite adequate and need not be highly accurate. PR08: transmit power should be variable in a few multiple steps.

22. Support 3/4 Goal: highly accurate and useful timing of packet arrival Comment: The first instant in the arrival of a packet that is unambiguously known is at byte synchronization. This often is when the start flag has been received. This arrival time should be made available to the upper layers - timed to low micro-seconds/symbol times.Alternately (or in addition) a free running counter can be latched into a register for later, more leisurely retrieval. PR13: There shall be a high resolution indication of packet arrival.

23. Support 4/4 Goal: ability to transport large packets without fragmentation Comment: Many of the anticipated applications request data of many hundreds of bytes at a time. Internet Protocols (IP) are being carried over these networks without compression. Standard routing hardware (e.g. Ethernet) processes 1.5k octets without fragmentation and can be considered a necessary goal. PR14: Support should exist for large unfragmented packets of at least 1.5k octets in size.

24. Standards – the simpler the better The power plug has been an ‘open standard’ for 100 years Leverages trillion dollar utility capital Millions of devices have been independently developed Plug it in and it ‘just works’ • IP provides and open standard for the Wireless NAN • Leverages trillion dollar collective R&D budget • Enables vendor community to develop products independently • Plug it in and it ‘just works’

25. Thank You