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: [Revised Frequency Plan and PRF Proposal for TG4a] Date Submitted: [27 April 2005] Source: [Ismail Lakkis & Saeid Safavi, Wideband Access Inc.] Contact: Saeid Safavi. Voice:[+1 858 642 9114, E-Mail: ssafavi@widebandaccess.com] Abstract: [Ban Plan, PRF, Preamble & Modulation] Purpose: [Clarification of relationship between minimum PRF and maximum allowed voltage level in UWB IR] 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. Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

2. Agenda • Proposed system features • Frequency Plan / PRF • Preamble • Modulation Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

3. Frequency Plan / PRF Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

4. Proposed System Features • Meets requirements for TG4a baseline draft • Frequency plan with simple PLL structure and safe margins to 3.1GHz and 4.9 GHz • Support of a range of PRFs (low and high) • Impulse-radio system • Common preamble structure for different classes of nodes/receivers type ( coh./noncoh.) & ranging • Flexible adaptive data rate • Robustness against SOP interference through frequency and code division • Robustness against other in-band interference • Scalability to trade-off complexity/performance Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

5. Frequency Plan Requirements • Requirements • Sub-banding (Three bands) with mandatory center band of ~500MHz and an optional wider co-centric band of ~1.5GHz • Mandatory: FCC spectral mask @ 3.1GHz  at least 10 dB attenuation constraint on filtering • Desirable: co-existence with WLAN @ 4.9GHz • Implications • A safe margin to 3.1GHz to meet FCC requirement • For IR system using a pulser (no mixer), the BPF is responsible for the 3.1GHz corner filtering • A safe margin to 4.9GHz to coexist with WLAN • Different frequencies should be easily generated from the system PLL with first divisions in powers of 2 Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

6. PRF Requirements • Requirements • Support of multiple (at least 2) PRF in band • Limit on lowest possible PRF due to CMOS 90 nm technology • Limit on highest possible PRF due to inter-frame interference for a non-coherent receiver • Implications • Supported PRFs should be easily derived from the PLL through simple divisions • Low PRF as base PRF • High PRF as second PRF • PRF should be high enough to take advantage of FCC rules Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

7. PRI VPeak TC Relationship between PRF & Peak Power Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

8. Minimum PRF vs Peak Power (CMOS 90nm) Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

9. Low PRF vs High PRF • A low PRF system has a lower implementation cost when compared to high PRF system • RF radio overall gain is lower for a low PRF system. A 12 MHz PRF system , for example, would reduce the receiver dynamic range by 7 dB when compared to a 60 MHz PRF system • The ADC would run at 12 MHz instead of 60 MHz in the above example and the entire digital processor would run at a lower clock reducing the power by a factor of 5 in CMOS • Easier acquisition with lower PRF due to a smaller sync matched filter size • Since energy per pulse is higher (7 dB in the above example), a non-coherent receiver would perform better • Better acquisition and tracking performance since a 60 MHz PRF system needs to integrate perfectly 5 pulses to perform equivalently to a 12 MHz PRF system Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

10. Proposed Frequency Plan Band No. 4 111 MHz 207 MHz 1 2 3 3 4 5 GHz 3.25 3.5 3.75 4.25 4.5 4.75 Note: This plan has almost double margin to 4.9 GHz as compared to 3.1 GHz Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

11. Frequency Plan Details Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

12. Proposed PRFs • A wide range of PRFs (total of 3) are supported which are compliant with the harmonic chip rate requirements • The base recommended PRF is 15.4375 MHz: it has an 8 dB peak power margin for a 500MHz BW • PRFs of 30.875MHz and 61.75MHz are also supported (margin > 4.5 dB) • The proposed PRFs can be easily generated from the center frequencies of the supported bands (next slide) Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

13. PRF Generation • All High frequency divisions are in powers of 2, while the low frequency divisions are only by 3 and 7 Center Freq. (MHz) PRF1 (MHz) PRF2 (MHz) PRF3 (MHz) Harmonic Ratio 3952 61.75 30.875 15.4375 64 2 2 3458 61.75 30.875 15.4375 8x7 2 2 4446 61.75 30.875 15.4375 8x3x3 2 2 Prime Factors: 7, 3 Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

14. PLL Reference Diagram FX FComp Oscillator Reference Divider (R) XTAL Phase Det. F123,c LPF VCO Divider, M ÷8 ÷ 7,8 or 9 PRF Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

15. Band Plan / PRF Summary • Enough margin to 3.1GHz (111 MHz) and 4.9GHz (207 MHz) to meet FCC requirements and to coexist with WLAN ( avoids expensive sharp roll-off filtering) • Support of a wide range of XTALs (9.6,19.2,13,26,12,24) • Center frequencies and PRFs can be generated from a single PLL with first divisions in power of 2 and low frequency division by 3 or 7 • Support of a wide range of PRFs. The proposed PRFs have a peak power margin of 4.5-8 dB to accommodate implementation losses and take advantage of FCC rules Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

16. Acquisition Preamble Structure Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

17. BER of BPSK & ON-OFF Keying Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

18. BER Requirements • The requirement of PER < 1% for a 32 octets packet translates into a BER < 3.926e-5 • EbN0 requirements for uncoded BPSK and ON-OFF keying systems: • g (BPSK) = 8.9dB • g (ON-OFF) = 15.45dB • EbN0 requirements for coded BPSK and ON-OFF keying systems (assuming a coding gain of 4dB and receiver implementation losses of 1.5 dB): • g (BPSK) = 6.4 dB • g (ON-OFF) = 13 dB Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

19. SNR Loss in Square Law Detectors Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

20. BPSK: Detection & False Alarm Probabilities • PRF = 16 MHz • AWGN Channel • 2 dB margin to account for timing/frequency errors & other factors • PD = 95% & PF = 5% Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

21. BPSK: Detection & False Alarm Probabilities • PRF = 16 MHz • Multipath Channel assuming we capture 25% of the energy • 2 dB margin to account for timing/frequency errors & other factors • PD = 95% & PF = 5% Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

22. BPSK: Detection & False Alarm Probabilities Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

23. BPSK: Detection & False Alarm Probabilities Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

24. ON-OFF Detection & False Alarm Probabilities • PRF = 16 MHz • AWGN Channel • 2 dB margin to account for timing/frequency errors & other factors • PD = 95% & PF = 5% Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

25. Spreading Codes: Objectives • Design a set of sequences with good autocorrelation (ACF) and cross correlation (CCF) properties that support • Coherent receivers • Differentially coherent receivers • Noncoherent receivers • The sequence set should be as large as possible to support multiple piconets per frequency band and to mitigate co-channel interference (in-band interference) Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

26. Spreading Codes Desirable Characteristics • The autocorrelation function of a sequence can be characterized by the following parameters: • PAR of the PSD (back-off factor): a b PAR is desirable otherwise reduction in Tx power is required • Zero correlation zone (ZCZ) : for improved ranging, synchronization, channel estimation, and Pd vs Pf • Merit Factor (MF) of a binary sequence of length N: The MF measures the interference due to the sidelobe energies in the zone under interest (say 1μs) • Sequence length: this determines the coherent processing gain during acquisition ( a short spreading sequence  system is acquisition limited rather than PER limited) Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

27. Barker code 11 & m-sequence 31 Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

28. Freescale & ZCZ sequences Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

29. Single Spreading Code System ? • A single spreading code common to the preamble and frame body is not recommended as all good sequences have bad PSD which results in a large Tx power reduction (Back-off) Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

30. Hierarchical Preamble code structure • Let Z be the ZCZ sequence of length 3 • Create hierarchical code using zero-correlation Walsh sequences 1,2,3 and 5 • For ternary –Z corresponds to an inverted sequence • There are at least 32 ZCZ, this gives 128 SOPs Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

31. modulation Ismail Lakkis & Saeid Safavi Wideband Access, Inc.

32. Modulation • Spreading via random scrambling • Use a single scrambler of length (ex: 32768) and assign a different offset (of 16 or 32) to different nodes • For ternary modulation invert sequence when transmitting a 0 • Number of users supported is 1024 • Perfect co-channel interference rejection • Support virtually any data rate from 16MHz to 32 Kbps for a PRF of 16MHz • Spectrum is virtually flat (no back-off) Ismail Lakkis & Saeid Safavi Wideband Access, Inc.