1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANS)
Submission Title: [General Atomics Call For Proposals Presentation]
Date Submitted: [3 March 2003; 7 March rev1]
Source: Naiel Askar, General Atomics- Photonics Division, Advanced Wireless Group, Flanders Ct, San Diego, CA , Voice +1 (858) ], Fax [+1 (858) ],
Re: [ a Call For Proposal, Spectral Keying™ UWB Multi-Band Technology]
Abstract: [This presentation outlines General Atomics’ PHY proposal to the IEEE a Task Group]
Purpose: [To communicate a proposal for consideration by the standards committee]
Notice: This document has been prepared to assist the IEEE P It is offered as a basis for discussion and is not binding on the contributing individual or organization. The material in this document is subject to change in form and content after further study. The contributor reserves 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 P

2. Overview of General Atomics PHY Proposal to IEEE 802.15.3a
Presented by: Naiel Askar

3. Outline of Presentation
Description of Spectral KeyingTM (SK)
SK parameters and operating frequencies
Channelization scheme
SK performance
Implementation issues
Interference and co-existence
Preamble definition
Self-evaluation
Conclusions

4. Summary of Proposal Scalable data rates from 15-1300 Mbps
Spectral KeyingTM modulation*
Compliant with FCC 02-48, UWB Report & Order
Multi-Band system, scalable from 4-12 bands, occupying GHz total bandwidth
Supports at least 4 co-located piconets
* Spectral KeyingTM is a registered trademark of General Atomics

5. Key Features
A new modulation scheme which has been optimized for UWB systems
Low symbol rate with guard time between symbols
Enhanced multipath immunity by limiting channel-induced inter symbol interference (ISI)
Low duty cycle allows power saving features
Minimizes collisions between colocated piconets
Set of allowable symbols increases with the factorial of the number of frequencies
Bit rate scalable with power consumption, cost and occupied frequency
Enhanced co-existence with IEEE a

6. UWB Multi-Band Technology
UWB spectrum divided into multiple bands
One symbol will be composed of subpulses from multiple bands
Excellent performance in multipath
Scalability
Bit rate
Power consumption
Range
Complexity / Cost
Coexistence
IEEE a
Regulatory
Compliant with US FCC
Flexibility for world-wide regulatory action

7. Spectral Keying™ Modulation
UWB Symbol in Time
Transmit 2 or more subpulses using different bands
Order of bands defines symbol
Voltage
Time (ns)

8. SK Definitions Data encoded with Sequence of bands in the pulse
Phase information on the subpulses

9. Spectral Keying™ General Case
An SK symbol X, where can be defined in terms of the location in a MxT matrix, B and P
where
0 means no transmission
±1 allows Binary Phase Shift Keying (BPSK)
± i allows Quadrature Phase Shift Keying (QPSK)
M is # of frequency bands
T is # of time slots
B is # of non-zero entries
P is # of polarity bits
N is # of available bits
where
For Optimum BER Performance in SK use M=T=B

10. SK Rate Scalability Examples
2 bands no polarity bands, with BPSK bands with QPSK
Sequence bits/sym ~ ~15
Phase bits /sym
Total bits/sym
For sequence bits, the set of allowable symbols increases with the factorial of the number of bands

11. Data Rate Examples

12. SK Parameters For Base Rates

13. Transmit Sub-pulse Shaping
A rectangular 2 ns pulse is low pass filtered (2nd order) to suppress out of band emissions
3 dB bandwidth 440 MHz
10 dB BW 700 MHz

14. Frequency Plan for 110/200 Mbps
Piconet 1
Piconet 2
Piconet 3
Piconet 4
Define 20 bands centered GHz
Bands are spaced 200 MHz apart
Piconets will have different bands
4 piconets will have 5 unique bands
Bands in each piconet will have 800 MHz separation
Other piconets will share some frequencies, less separation

15. 4 Piconets at 110/200 Mbps
Systems will be able to cancel or modify the frequency of one band to avoid interference
Reducing receive filter bandwidth can reduce interference from adjacent piconets

16. Piconet Isolation Performance improved by 3 factors
Frequency separation isolation
Low symbol rate reduces collision rate between piconets; random or passively synchronized
Coding gain of SK and channel coding

17. Passive Synchronization for Channels
Time interleaving may be used by channels 3, 4 to minimize interference
Passive scanning of bands will identify best time slots
Improved performance with lower symbol rate
Has reasonable margin for
channel delay spread
timing uncertainty due to near-far problem
Clock synchronization can be avoided by repeated scanning

18. Performance Bounds for SK
Case when M = T = B, P = 1
The Euclidian Distance (ED) when a frequency is in error has a value of 2
Similar to antipodal modulation BPSK
SK will require lower EbNo for the same performance compared to BPSK because of the higher order modulation
Where
M is # of frequencies
T is # of time slots
B is # of non-zero entries
P is # of polarity bits
Ps is the probability of subpulse error
Es is the energy per subpulse
No is the noise spectral density
EbNo is the ratio of bit energy to noise density

19. SK Error Rate Performance: Predictable Analysis vs. Simulation ResultsTM

20. BER Performance of 5 Band SK in AWGN Improvement Over BPSKTM

21. Channel Capacity in AWGN (Coherent Receiver)
M is # of frequency bands
T is # of time slots
Q is # of non-zero entries
P is # of polarity bits
Operating Point

22. Channel Capacity in AWGN (Non coherent receiver)
M is # of frequency bands
T is # of time slots
Q is # of non-zero entries
P is # of polarity bits
Operating Point

23. Error Correction Coding Approach
Coding algorithm: Turbo Convolutional Code (TCC)
Best performance
Manageable cost and power consumption
Best in flexibility in selection of code rate, on the fly code change
Already selected for 3GPP, DVB, etc.
Cost:
Estimated power consumption = 35 mW.
Estimated chip area = 3 mm2 in 0.13 mm CMOS
Parameters
Overall code rate 4/5
Memory size (4k bits), larger packets will be concatenated
Number of iterations = 4, 3 bits of quantization
EbNo = 3.6 dB for BER = 1e-5
Turbo code simulation (DLL) and performance supplied by iCODING Technologies

24. Turbo Code Scalability
Range of Performance
1 iteration matches performance of K=7 convolutional code
1.5 or more iterations exceeds performance of K=7 convolutional code
3 or more iterations substantial performance gains (2-4 dB)
Code rate is adjustable for longer range mode(s)
Power consumption can be reduced by early stopping
Larger frame size (up to 8K) can further increase performance
Extreme low cost, low power & low latency option
K=4 constituent code can be used as stand alone FEC option.
Uses same encoder components as full Turbo Code
Area less than 0.25 mm^2 in 0.18u process
1/8th the complexity of a K=7 CC with upwards scalability built in
Very high coding gains in frequency selective fading channel
2-4 dB gain in AWGN can translate to 4-7 dB gain in frequency selective fading channels over non-iterative techniques.

25. Bit to Symbol Mapping
Maximum # of frequency bits in SK symbol (M=T=B=5, P=0) = log2 120 = 6.9 (excluding polarity bits)
Simple mapping will produce 6.5 bits,13 bits from 2 symbols
The 3rd frequency of 2 symbols are combined to produce 3 bits
Reserved symbols for preambles are available
Time slot number
No of choices
Available bits
Used bits T1 5
2.3 2 T2 4 T3 3
1.6
1.5 T4 1 T5

26. SK Simulation in AWGN with Channel Decoder
8% PER
1e-5 BER

27. Link Budget

28. Transceiver Block Diagram

29. Example of a Spectral Keying™ Transmitter

30. Example of a 5-Band SK Receiver

31. Unit Manufacturing Complexity*
Preliminary area estimates
~3 mm2 for RF
~7.0 mm2 for digital
The target is to have a one chip solution
First implementation may have separate RF and digital chips
The receiver has one signal chain per band (5 total)
Allows implementing Rake receiver without extra hardware
Having multiple receive chains increases area ~0.5 mm, but has little impact on overall complexity
Allows tracking signal peak on each band individually giving improved performance
Low risk
* Estimates based on collaboration with Philips Semiconductors

32. Power Consumption* Power consumption will be dominated by
Oscillators: trade performance for low current
ADCs: limit number of bits to 3
Front end receiver: dominated by NF/11a interference requirements
Minimize by designing with adaptive linearity/power tradeoff
Low symbol rate gives low duty cycle allowing power saving techniques to be applied
* Estimates based on collaboration with Philips Semiconductors

33. Manufacturability & Technical Feasibility
Use of proven technology and processes
No high risk components or technology
Immune from distortion or ringing from antennas or filters owing to relatively long subpulse time
Relaxed antenna characteristics
Modules already tested in the lab
TRDA / Taiyo Yuden
Antenna Size 10 x 8 mm
General Atomics
Spectral Keying™ Transceiver Module

34. Experimental Results of SK Validate Simulations

35. Scalability Power consumption
Scalable from 127 to 425 mW based on rate (55-200Mbps)
Data rate
Scalable from 23 – 1300 Mbps
Range:
Scalable with more rakes, more coding, lower symbol rate
Complexity
Lower complexity, lower performance system possible

36. Interference from a
Flexibility in choice of bands is key to performance
Bands centered at 5.0, 5.2, 5.4 GHz will be avoided
Table below based on selection criteria parameters
Bands centered on 4.8, 5.6 will be marginal at 1m
Bands centered on 4.6, 5.8 will be OK at 1m separation between interferer and victim, marginal at 0.3m separation
All other bands are OK

37. 802.11a Co-existence
Flexibility in removing bands from or moving to adjacent bands improves co-existence
Interference from UWB is much lower than an a device at same distance
SIR levels are based on a minimum sensitivity of -82 dBm for 6 Mbps rate

38. PHY Preamble
Utilize the same preamble as the 15.3 PHY for each band separately
Composed of 16 Constant Zero Autocorrelation (CAZAC) symbols
The pattern is repeated 10 times
Last symbol will have inverted polarity
Total 160 symbols lasting 12.3 µsec.
Detection miss probability and false alarm rate < 10-3 in multipath are achievable
Detection is declared when a threshold is exceeded in 2 out of the 5 bands

39. General Solution Criteria (1/2)

40. General Solution Criteria (2/2)

41. Conclusions
A UWB system based on Spectral KeyingTM will meet or exceed all selection criteria
Spectral KeyingTM is a Multi-Band scheme
Good multipath performance
Flexibility in assigning bands for regulatory and interference avoidance
Unique high order modulation allows low symbol rate with long guard time between symbols
Minimizes ISI - At maximum data rate no equalizer needed
Off period is 75% at 13 MHz symbol rate - Allows power conservation
Efficient spectrum utilization allows frequency based channels
Provides scalability for power consumption, rate, range and complexity
Technology proven with demonstrations
Letter of assurance for essential patents submitted to the IEEE a leadership
The May 2003 presentation will focus on analysis and simulation

42. General Atomics will be cooperating with:
a Early Merge Work
General Atomics will be cooperating with:
Discrete Time
Focus Enhancements
Intel
Philips
Samsung
Time Domain
Wisair
Objectives:
“Best” Technical Solution
ONE Solution
Excellent Business Terms
Fast Time To Market
We encourage participation by any party who can help us reach our goals.