Future-Proofed OFDM Implementation for SUN Technology

1. Rishi Mohindra, MAXIM Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: FPP-SUN Implementation Considerations Date Submitted: July 5, 2009 Source: Rishi Mohindra, MAXIM Integrated Products Contact: Rishi Mohindra, MAXIM Integrated Products Voice: +1 408 331 4123 , E-Mail: Rishi.Mohindra@maxim-ic.com Re: TG4g Call for proposals Abstract: PHY proposal towards TG4g Purpose: PHY proposal for the TG4g PHY amendment 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. Slide 1

2. Future Proof Platform for SUN: Implementation Considerations Rishi Mohindra IEEE 802 Plenary Session San Francisco July 2009 Contributors: Rishi Mohindra [MAXIM], Partha Murali [Redpine], Emmanuel Monerie [Landis & Gyr], Steve Shearer [Independent], Shusaku Shimada [Yokogawa Electric Co.], Bob Fishette [Trilliant], Sangsung Choi, [ETRI], Roberto Aiello [Independent], Kendall Smith [Aclara], David Howard [On-Ramp]

3. Contents • OFDM as Future Proof Technology • Path loss • OFDM implementation considerations • Transceiver Architecture advantages • Phase Noise • Receiver dynamic range • Crystal Tolerance and Adjacent Channel Rejection • Spectral mask & PA backoff • Battery Life Calculations • Legacy Meter Reading example use cases • Gate count and relative cost • Conclusions

4. Legacy Meter Reading technology issues: Different frequency bands, modulations, network topologies, interference conditions, MACs, Network Layers etc. No single existing flavor can work in all situations Data rates & modulation techniques are “old” and there is lack of advantages that are offered by today’s modern VLSI digital technologies. Digital gate count and signal processing capabilities reflect 15 year old 0.35 um CMOS technology. No existing deployment technology offers the possibility of future proofing through improved data rates and range Poor spectral efficiency Misconception that “simple is cheap” without a broader vision of modern technology advantages relating to cost and performance The 802.15.4g FSK proposals do not fully resolve the above issues, and will largely provide a new face to old technology with “commonality” as the driver instead of “Future Proofing.” Slide 4

5. OFDM as Future Proof Technology Physical Layer feature requirements 40kb/s to 1Mb/s through put data rates at nodes 20 year battery life for all non-AC powered nodes Cost Requirements Solution cost to be comparable to legacy solutions while supporting significantly higher data rates 1Mb/s solution cost should only be a small increment to the 40kb/s BOM Special Network Requirements for Gas & Water meters Not depend on AC powered nodes for repeaters or Hops. Support max # nodes (e.g. 100000 nodes) per BS in a MESH or STAR network 140 dB desirable link budget for up to a few miles range Should not be limited in range due to multipath conditions i.e. work well in rms delay spreads in excess of 10 usec. Special Requirements for MESH networks with AC powered hops Support 10x increase in network throughput with 100 kb/s link data rates at battery operated nodes. Allow upgrade paths for up to 1 Mb/s link data rates between AC powered nodes or hops for improved network capacity in the future Only OFDM offers a common future-proof technology that is scalable according the above needs Slide 5

6. Path Loss Path Loss analysis set up: Freq = 900 MHz Transmitter height for STAR (base station) = 8.9m Transmitter height for MESH (hops) = 0.5m Receiver height (all nodes) = 0.5m Path Loss models: Free Space 2-ray LOS with loss-less ground reflection Hata urban for STAR and MESH Hata suburban Hata rural Slide 6

7. Path Loss Slide 7

8. Path Loss Freq = 1.8GHz, MS height = 2m, BS height = 1m Typical urban in Southern England X-axis: 3 = 1000m Slide 8

9. Path Loss Conclusions Conclusions for 1km range based on Hata model Urban MESH requires 154 dB nominal link budget Urban STAR requires 137 dB nominal link budget Suburban STAR requires 127 dB nominal link budget Rural STAR requires 108 dB nominal link budget Rural STAR based on Hata actually matches the 2-ray LOS model. Hata model uses narrow band measurements & is prone to more spatial fading fluctuations Using wider modulation bandwidths (up to 1MHz for OFDM) will drastically reduce the deep spatial fades and reduce link budget requirements Slide 9

10. OFDM Data Rates Slide 10

11. Receiver Sensitivity for 4 dB noise figure & implementation loss Slide 11

12. Link Budget for 30 dBm transmitter & 4 dB receiver loss Slide 12

13. OFDM Implementation considerations Zero-IF Transceiver Architecture advantages Phase Noise Receiver dynamic range Crystal Tolerance and Adjacent Channel Rejection Coarse & Fine frequency estimation All digital compensation without packet based crystal tuning Spectral mask & PA backoff Slide 13

14. Zero-IF Architecture advantages Discussion of Zero IF DC cancellation Channel filtering Disadvantage of FSK Low-IF architecture Slide 14

15. Zero-IF block Diagram Slide 15

16. Transceiver Architecture advantages DC cancellation Channel filtering Disadvantage of FSK Low-IF architecture Slide 16

17. Low-IF disadvantages Disadvantage of FSK Low-IF Image rejection calibration Complex filter Slide 17

18. Phase noise Discussion Slide 18

19. Phase noise OFDM 16-QAM r=3/4 works well with 10 dB relaxedphase noise specifications (relative to FSK transceivers) Slide 19

20. Receiver Dynamic range Discussion of Noise & Linearity specs of OFDM vs GFSK transceiver Slide 20

21. Receiver Dynamic range Diagram of OFDM SNR or EVM vs Input Power using FSK transceiver specs Slide 21

22. Crystal Tolerance and Adjacent Channel Rejection Coarse & Fine frequency estimation discussions All digital compensation without packet based crystal tuning Slide 22

23. Crystal Tolerance and Adjacent Channel Rejection Limitations due to adjacent channel rejection Slide 23

24. Crystal Tolerance and Adjacent Channel Rejection Diagram of Limitations due to adjacent channel rejection Slide 24

25. Spectral Mask and PA backoff Diagram of ETSI and ARIB masks and PA spectral regrowth Slide 25

26. Legacy Meter Reading example use cases for battery life calculation • STAR topology cases: • 50000 nodes per BS, 12.5 kHz channels in Licensed 470 MHz band, GFSK, 30 dBm Tx, expensive crystal with TBD ppm life time accuracy, slow real time frequency error calibration at nodes for sub-ppm timing accuracy, slotted time structure with no collision, 6 hour transmission gaps per node. • Light MESH topology cases: • 25000 nodes per network with one concentrator point, up to 3 hops from end-nodes to concentrator point, ISM band FHSS GFSK, hops over AC powered devices only (1 per sq mile). • IEEE802.11n WLAN at 2.4GHz with 20 year battery life, 2 mile network radius per concentration point, hops over AC powered devices. • MESH topology cases: • 50000 nodes per network including up to 20000 AC powered hop-nodes, FHSS GFSK or MSK. • 2000 nodes per concentrator, multiple hops. Multiple nodes per home. 2.4GHz ISM band, IEEE802.15.4 OQPSK DSSS, 250 kb/s, 30dBm Tx at BS, 24 dBm Tx at gas & water nodes. Rake receiver. 40 ppm crystal tolerance. 2 mile network radius.

27. Battery Life Calculations OFDM Star Network Slide 27

28. Battery Life Calculations OFDM Mesh Network Slide 28

29. Battery Life Calculations FSK Star Network Slide 29

30. Battery Life Calculations Conclusions Slide 30

31. Gate Count and Relative cost Phy, MAC and Software implementation Assumptions Slide 31

32. Gate Count and Relative cost Gate count and Silicon Die area Slide 32

33. OFDM vs GFSK Relative cost Relative BOM cost Slide 33

34. Conclusions Discussions Slide 34