Scalable Direct Sequence Waveform for BAN Standards

1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: Combined Preliminary Proposal Date Submitted: 9 March 2009 Source: Frederick Martin, Paul Gorday, Ed Callaway, Monique Brown, Motorola, Inc. Address: 8000 W. Sunrise Blvd., Plantation, FL, 33322, USA Voice: +1-954-723-6395, FAX: +1-954-723-3712, E-Mail: f.martin@motorola.com Re: TG6 Call For Proposals, IEEE P802.15-08-0829-01-0006, 3 December 2008. Abstract: Key requirements of the BAN standards effort, including power, cost and throughput scalability, can be addressed using a scalable direct sequence waveform. In addition, this approach facilitates receiver novel ultra-low cost receiver implementations. Purpose: This document is intended as a preliminary proposal for addressing the requirements of the TG6 standard. 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. Martin, Motorola

2. Contributors Martin et al

3. Presentation Summary Partial Proposal – PHY Only – compatible with many MAC proposals Focus – cost, power, form factor Leverage the current 802.15.4 2006 Physical Layer Martin, Motorola

4. The BAN Challenge: Scalability Standard must meet many applications with a single solution Must span 10 kbit/s to 10 Mbit/s Must scale power with throughput (Low bit rate solutions must be competitive with low throughput point solutions) Must be size and cost competitive with non-scalable solutions Must promote BAN size power and form factor constraints Martin, Motorola

5. Proposal direct sequence (chip) waveform -- similar in structure to 802.15.4 Moderate sequence length (length 16, 32, 64 ??) Orthogonal cyclical shift coding for increased throughput -- chip rate scaled with throughput Low chip rate, narrow transmission band for low throughput Higher chip rate, wider transmission bandwidth for higher throughput -- eliminate coding for narrow (1 MHz or less) channels Martin, Motorola

6. Frequency Bands 2400 – 2485 MHz -- worldwide band -- flexible bandwidth requirements 2360-2400 MHz -- proposed medical band in US -- 1 MHz channels ?? 902-928 MHz -- ISM band in North America Martin, Motorola

7. Why DSSS? Simplicity: lends itself to low-power, low cost Scalability: Same structure can be used for low or high throughput Compatibility: Can be made compatible with existing 802.15.4 hardware Extendibility: Creates opportunities for ultra-low cost receiver implementations Martin, Motorola

8. PHY Scalability IEEE 802.15.4-2003 uses a fixed DSSS approach at 2.4 GHz … add scalability using chip rate and coding options: * OC = Orthogonal Coding. Martin, Motorola

9. PN Sequence Selection O-QPSK Modulation s0 I Serial To Parallel Bits s1 . . . Q z-1 s15 4-Bit Index 32-Chip Sequence 802.15.4 PHY ReviewModulation • 4 bits per symbol • 16-ary symbol alphabet (nearly-orthogonal PN sequences) • 32 chips per symbol • Chip modulation is O-QPSK with half-sine pulse shape (similar to MSK) Martin, Motorola

10. PN Sequence Matched Filters 4-bit Symbol Value Magnitude s0  Chip Matched Filters Choose Largest I s1 Parallel to Serial  Bits . . . Q s15  802.15.4 PHY ReviewMatched Filter Detection • Textbook detection: Sequence matched filters (non-coherent) • Advantage: Low Eb/No, low C/I • Disadvantage: Requires good frequency control Martin, Motorola

11. Baseband Chip Filtering O-QPSK Modulation I FM or Differential Phase Detection Bits I Bits Q Q z-1 Detection Modulation High Efficiency BAN OptionUncoded • No coding → Modulate bits directly using O-QPSK (or MSK) • Recover bits with FM detection or differential phase detection • Advantage: Higher spectral efficiency • Disadvantage: No coding/processing gain Martin, Motorola

12. 0 10 -1 10 PER -2 10 Orthogonal Coding (MFD) Orthogonal Coding (DD) Uncoded (DD) -3 10 0 2 4 6 8 10 12 14 16 Eb/No (dB) Simulated AWGN Performance Basic AWGN results • Simulated in Matlab with 8 samples/chip • Symbol sync modeled • Otherwise ideal • 256-byte payload Measured at 10% PER: *Assumes BW = 0.625Rc Martin, Motorola

13. Channel Simulations(900 MHz, 2.4 GHz) • BAN channel delay spread is relatively low (doc.# 780r4) • Body surface to body surface (CM3) • <15 ns at 900 MHz • < 22 ns at 2.45 GHz • Body surface to external (CM4) • Delay spread not specified • Power delay profiles not specified for 900 MHz or 2.4 GHz • Use diffuse exponential model [1-4] to benchmark proposed PHY Martin, Motorola

14. Channel Simulations(32-chip Orthogonal Code, Matched Filter Det.) Simple receiver synchronizes to the largest correlation peak. Performs well for RMS delay spreads as high as the chip duration, Tc. >> More than sufficient for BAN applications. *Rayleigh Fading, all channels used in averaging results Martin, Motorola

15. Channel Simulations(Uncoded, Diff. Det.) Simple receiver with differential phase detection. No equalization. Equalization or additional coding needed for delay spreads > 0.2Tb. (8 Mbps and 16 Mbit/s modes) *Rayleigh Fading, all channels used in averaging results Martin, Motorola

16. Power Spectrum(32-chip Orthogonal Code) • IEEE 802.15.4 • 250 kbit/s • 2 Mchip/s • 5 MHz channels • Notes • Spectrum similar to MSK. • Effects of 32-chip code • are visible. 2.6 MHz Martin, Motorola

17. Power Spectrum(32-chip Orthogonal Code) • Wideband example: • 2 Mbit/s • 16 Mchip/s • 22 MHz channels • Notes • Spectrum similar to MSK. • Effects of 32-chip code • more visible due to low • ratio of RBW to signal BW. 20.8 MHz Martin, Motorola

18. Power Spectrum(Uncoded) • Narrowband example: • 500 kbit/s • 1 MHz channels • Notes • Spectrum of MSK. 0.65 MHz Martin, Motorola

19. Link Budget – 500 kbit/s uncoded mode Martin, Motorola

20. Multi-Piconet Coexistence 2400-2483.5 MHz Band 16 non-overlapping channels (5 MHz spacing) with up to 2 Mbit/s uncoded, 250 kbit/s coded* 8 non-overlapping channels (10 MHz spacing) with up to 4 Mbit/s uncoded, 500 kbit/s coded* 2 non-overlapping channels (20 MHz spacing) with up to 16 Mbit/s uncoded, 2 Mbit/s coded* * (30 dB adjacent channel) Proposed 2360-2400 MHz Band 19 non-overlapping channels (2 MHz spacing) with up to 500 kbit/s uncoded, 62.5 kbit/s coded 902-928 MHz Band 13 non-overlapping channels (2 MHz spacing) with up to 500 kbit/s uncoded, 62.5 kbit/s coded Martin, Motorola

21. Crystal-less operation Additional benefit which can be realized with this proposal when using high chip rates (2 Mchip/s or higher) By combining differential detection of coded a coded waveform with frequency-differentiated packet header, crystal-less transceiver operation can be achieved. See IEEE 802.15-09-0006-01-0006. Crystal-less operation facilitates low cost, small form factor for minimal on-body devices. Martin, Motorola

22. Summary Preliminary proposal – scalable direct sequence waveform -- meets requirements of BAN -- Leverages technology and manufacturing base of 802.15.4 -- low cost implementation features PHY-layer partial proposal – we welcome collaboration with other proposers Martin, Motorola

23. References • [1] B. O’Hara and A. Petrick, IEEE 802.11 Handbook – A Designer’s Companion, IEEE Press, 1999. • [2] J. Foester, “Channel Modeling Sub-committee Report (Final),” IEEE P802.15-02/490r1-SG3a, Feb. 2003. • [3] J. Medbo and P. Schramm, “Channel Models for HIPERLAN/2,” ETSI/BRAN doc. No. 3ERI085B, 1998. • [4] K. Pahlavan and A. Levesque, Wireless Information Networks, John Wiley & Sons, 1995. Martin, Motorola