Project: IEEE 802.15 Working Group for Wireless Personal Area Networks (WPANs)

1. Project: IEEE 802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: [Requirements for a UWB Common Signaling Protocol] Date Submitted:[12 March, 2004] Source: [Yasaman Bahreini, John Santhoff, Kai Siwiak], [Ismail Lakkis]: Company1 [Pulse~LINK] Company2 [ Wideband Access], Address1 [1969 Kellogg Ave. Carlsbad, CA 92008], Address 2 [12396 World Trade Ave. Suite 117, San Diego, CA 92128], Voice 1:[(760) 607-0844], FAX 1: [(760) 607-0861], E-Mails 1:[ybahreini@ieee.org, jsanthoff@pulselink.net, k.siwiak@ieee.org] Voice 2:[(858) 618-1930], FAX 2: [(858) 618-1980], E-Mail 2:[ilakkis@widebandaccess.com] Re: [Ad hoc Meeting Submission] Abstract: [At least one task group has chosen a UWB PHY, and another group in P802.15 is considering UWB PHY that will operate in common spectrum. This presentation focuses on potential coexistence issues of multiple UWB PHY layers in a common frequency band.] Purpose: [Focus and attention need to be directed to P802.15 and discussions started on issues effecting coexistence of multiple UWB PHY layers using common spectrum. It is early enough in the standards draft process to consider preemptive measures to ensure coexistence.] 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. Yasaman Bahreini, Pulse~LINK

2. Coexistence of Multiple UWB Physical Layers ? Allowing Many Flavors of UWB Signaling to Coexist Yasaman Bahreini, Pulse~LINK

3. Outline • Coexistence picture today • How do we address UWB Coexistence? • A Common Signaling Protocol (CSP) • Design goals for a CSP • Proposed options for CSP • Summary comparison of proposed CSP options Yasaman Bahreini, Pulse~LINK

4. Coexistence Picture Today • Currently: only one UWB standard in draft: P802.15.3a • Today the concern is coexistence of UWB with Narrow-Band technologies • Coexistence, however,is: “the ability of one system to perform a task in a given shared environment where other systems that may or may not be using the same set of rules”. [IEEE 802.15.2 definition of coexistence, http://grouper.ieee.org/groups/802/15/pub/2000/ Sep00/99134r2P802-15_TG2-CoexistenceInteroperabilityandOtherTerms.ppt] • In the works: • P802.15.4SG4a might consider a UWB solution • P802.11 are looking for solutions which might involve UWB • We need a pre-emptive action to ensure the orderly introduction of various UWB PHYs Yasaman Bahreini, Pulse~LINK

5. Why A Common Signaling Method? • We have a Once-in-a Lifetime opportunity to define an emerging wireless standard on a potentially global scale • Let’s use this opportunity to address interoperability and coexistence as a part of the standard instead of as an after thought • Today’s action set the path for UWB evolution for decades • Example of the recent past: • the unlicensed ISM bands have experienced explosive growth with multiple PHY layer interfaces defined • In the ISM 2.4 GHz band, there are no less than five different PHY standards competing for coexistence in the same spectrum. (802.11b, 802.15.3, 802.15.4, Bluetooth and Cordless Phones) • We need an “Etiquette” to manage peaceful coexistence of different UWB PHY layers • We need aframework that addresses guidelines on “what spectrum” is accessed “when” • A common signaling protocol can act as such an arbitrator Yasaman Bahreini, Pulse~LINK

6. What is a Common Signaling Protocol? • A UWB operational mode understandable to all UWB air interfaces • Methodology for allowing multiple different UWB PHY layers to coexist in • the same spectrum bands • same coverage areas • Uses cooperative management of allocated PHY resources of time and frequency Yasaman Bahreini, Pulse~LINK

7. High Level Design Philosophy • Common mechanism that is “pro-active” rather than “re-active” • Uses a pre-defined framework potentially allowing fair UWB PHY layer resource allocation • Collaborative: • Collaborated TDMA /FDMA techniques to allow for alternate transmissions among different UWB standards • Collaboratedtechniques for managing packet transmission based on channel monitoring • Non-Collaborative: • Adaptive packet (time/frequency) selection and scheduling Yasaman Bahreini, Pulse~LINK

8. Design Goals Primary: • Address coexistence - interoperability among differing UWB PHYs • Low cost so minimal PHY is not burdened • Provide discovery beacon • Provide coarse SYNCH and frequency acquisition, protocol selection Secondary: • Provide diversity, fine SYNCH and frequency acquisition, AGC, channel estimation • Basis for a low rate – long range PHY • Enable simpler geo-positioning capabilities • Provide mechanism for sleep mode, and wake up for power conservation Yasaman Bahreini, Pulse~LINK

9. CSP PHY Requirements • Introduce a mandatory/standard preamble before different UWB-based standards are ratified: • With the simplest modulation that is recognizable by all UWB systems, and in the frequency band that most likely would be used by all UWB devices • Simple to detect and lock-to for both HDR or LDR systems • Provides a type indicator to identify UWB protocols • This CSP preamble would be used for AGC, Antenna Diversity, DC Offset Removal, Energy Detection, Signal Detection, Coarse Timing and Frequency Estimation. Different UWB standard-specific preamble fields (responsible for 2nd AGC, and Channel Estimation, and Fine Timing and Frequency Estimation) can be appended to this standard preamble. Yasaman Bahreini, Pulse~LINK

10. CSP MAC Requirements • Time-slot Allocation • Scheduling of different PHY packets • Provide some provisions for QoS ALL Min. Changes to MAC Yasaman Bahreini, Pulse~LINK

11. Background • Packet Synch Sequence should be sent as modulated sequence in time domain because: • A DS-UWB or LDR transmitter does not need DAC to generate such sequence • Allows easier reception/acquisition via time-domain correlation • Is less sensitive to AGC and symbol timing initial acquisition • Allows lower complexity acquisition methods • Since Channel Estimation preamble is technology dependent, no need for Packet Synch Seq. to be constant in freq. domain Yasaman Bahreini, Pulse~LINK

12. Option 1 • CSP Preamble sent as in original MB-OFDM proposal: • BPSK at Symbol Rate of 3.2 Msps • Time-frequency interleaved over 3-bands in freq. range: 3.17-4.75 GHz • Packet Synch Sequence: Hierarchical (enables simpler detection mechanism, desirable correlation properties) • Every PNC is assigned to one set of Hierarchical sequences and a time-freq. combination • A non-hopping LDR DEV sees a symbol rate of 1.066 Msps. Yasaman Bahreini, Pulse~LINK

13. Option 1: PNC to DEV Communications • PNC –- MB-OFDM DEV: • As currently specified • PNC –- DS-UWB DEV: • In order to operate need • Rate conversion unit (polyphase filtering) to interpolate/decimate from 1.368 GSps to 528 MSps OR a frequency synthesizer capable of generating 528 MHz. • Loss of received RF energy at a portion of f1, and f3 bands due to mismatch of proposed front end filter requirements and band(s) of operation. Increased probability of false alarm. • Need for adjusting front end gain settings when moving from the preamble to DATA mode. • PNC –- LDR UWB DEV: • Can be supported via non-coherent simple receiver (delay & multiply, integrate& dump). Data rate ~ 1 Mbps or less. • Needs longer preamble for robust acquisition (extend the preamble for LDR mode) Yasaman Bahreini, Pulse~LINK

14. Option 1: DEV to PNC Communications • MB-OFDM DEV --- PNC: • As currently specified • DS-UWB DEV --- PNC : • In order to operate need • Rate Conversion: • Rate conversion unit (poly-phase) to interpolate 528 MHz to 1.368 GHz OR a frequency synthesizer capable of generating 528 MHz. • Need DAC to generate MB-OFDM preamble in the three bands of operation • No Rate Conversion: • No need for rate conversion. Need to generate optimal Ternary Code set that resembles the closest to MB-OFDM Hierarchical SYNCH Sequences (will not be optimal) Loss of received RF energy at a portion of f1, and f3 bands due to mismatch of proposed front end filter requirements and band(s) of operation. Increased probability of false alarm. Need for adjusting front end gain settings when moving from the preamble to DATA mode. • LDR UWB DEV --- PNC : • Can not be supported. High-speed DAC is required. Yasaman Bahreini, Pulse~LINK

15. Option 2 • CSP Preamble sent as in Option 1 • BPSK at Symbol Rate of 3.2 Msps • Time-frequency interleaved over 3-bands in freq. range: 3.17-4.75 GHz • Packet Synch Sequence: Hierarchical AND • DS-UWB Chip Rate is changed to 1.584 Gcps and hence all the relevant parameters adjusted to match this rate • No change to DS-UWB filter requirements Yasaman Bahreini, Pulse~LINK

16. Option 2: PNC to DEV Communications • PNC –- MB-OFDM DEV: • As currently specified • PNC –- DS-UWB DEV: • In order to operate need • Loss of received RF energy at a portion of f1, and f3 bands due to mismatch of proposed front end filter requirements and band(s) of operation. Increased probability of false alarm. • Need for adjusting front end gain settings when moving from the preamble to DATA mode. • PNC –- LDR UWB DEV: • Can be supported via non-coherent simple receiver (delay & multiply, integrate& dump). Data rate ~ 1 Mbps or less. • Needs longer preamble for robust acquisition (extend the preamble for LDR mode) Yasaman Bahreini, Pulse~LINK

17. Option 2: DEV to PNC Communications • MB-OFDM DEV --- PNC: • As currently specified • DS-UWB DEV --- PNC : • In order to operate need • Need DAC to generate MB-OFDM preamble in bands f1, and f3 (due to rotation wrt f2) • Loss of received RF energy at a portion of f1, and f3 bands due to mismatch of proposed front end filter requirements and band(s) of operation. Increased probability of false alarm. • Need for adjusting front end gain settings when moving from the preamble to DATA mode. • LDR UWB DEV --- PNC : • Can not be supported. High-speed DAC is required. Yasaman Bahreini, Pulse~LINK

18. Option 3 • CSP Preamble sent only in the middle band of MB-OFDM: • There is no FH, and hence no time-freq. combination per PNC • Center band (f2: 3.696 – 4.224 GHz) is used for all PNC’s • Hence different PNC’s use different set of Hierarchical sequences • Cyclic prefix, and guard interval can be removed; hence a better TX/RX power efficiency and better probability of detection AND • DS-UWB Chip Rate is changed to 1.584 Gcps and hence all the relevant parameters adjusted to match this rate • No change to DS-UWB filter requirements Yasaman Bahreini, Pulse~LINK

19. Option 3: PNC to DEV Communications • PNC –- MB-OFDM DEV: • As currently specified BUT frequency diversity is taken away • Better probability of detection • Need for adjusting front end gain settings when moving from the preamble to DATA mode. • PNC –- DS-UWB DEV: • In order to operate need only to adjust front end gain settings when moving from the preamble to DATA mode • PNC –- LDR UWB DEV: • Can be supported via non-coherent simple receiver (delay & multiply, integrate& dump). Data rate ~ 1 Mbps or less via. • Needs longer preamble for robust acquisition (extend the preamble for LDR mode) Yasaman Bahreini, Pulse~LINK

20. Option 3: DEV to PNC Communications • MB-OFDM DEV --- PNC: • As currently specified BUT frequency diversity is taken away • Better probability of detection • Need for adjusting front end gain settings when moving from the preamble to DATA mode. • DS-UWB DEV --- PNC : • In order to operate • Need for adjusting front end gain settings when moving from the preamble to DATA mode. • LDR UWB DEV --- PNC : • May be supported. Yasaman Bahreini, Pulse~LINK

21. Option 4 Design Goals • A LDR beacon that broadcasts around every 10ms • The HDR modes are not bugged down since this is not so frequent • HDR preambles would be categorized as “Initial Mode Preamble = CSP Preamble” and “Streaming Mode Preambles” • Power save mode (sleep mode) • Additional hardware. Needs to be low cost. • Very simple LDR TX/RX architecture Yasaman Bahreini, Pulse~LINK

22. Option 4 Specifics • Modulation: as simple as DBPSK • Synch Sequence: longer than Option 3 to assure adequate probability of detect for LDR • Allows simple transceiver architecture. (coherent or non-coherent analog correlator receiver) • Frequency band: at least 984 MHz band centered around 4.0 GHz • The base rate needs to be an integer sub-multiple of 24 Mbps • Different PNC’s use different codes Yasaman Bahreini, Pulse~LINK

23. Option 4: PNC to DEV Communications • PNC –- MB-OFDM DEV: • Minimum Added circuitry • Coexistence achieved • PNC –- DS-UWB DEV: • Min Added circuitry • Coexistence achieved • PNC –- LDR UWB DEV: • Can be supported • Coexistence achieved Yasaman Bahreini, Pulse~LINK

24. Option 4: DEV to PNC Communications • MB-OFDM DEV --- PNC: • Minimum Added circuitry • Coexistence achieved • DS-UWB DEV --- PNC : • Minimum Added circuitry • Coexistence achieved • LDR UWB DEV --- PNC : • Can be supported • Coexistence achieved Yasaman Bahreini, Pulse~LINK

25. Summary • Coexistence among multiple UWB PHYs is feasible • We proposed 4 different methods that achieve different degrees of coexistence • Option 3 and Option 4 seem to be the most attractive compromise points • Proposed “Option 3“ does not enable coexistence of LDR and HDR. Packet Synch Sequence demonstrates unacceptable (lower than %90-%10) Probability of Detection- False Alarm for LDR UWB Yasaman Bahreini, Pulse~LINK