1. May 5, 2005
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: TG4a PRF (Pulse Repetition Frequency) Selection Guidelines
Date Submitted: May 2005
Source: Gian Mario Maggio (STMicroelectronics), Philippe Rouzet (STMicroelectronics)
Contact: Gian Mario Maggio
Voice: ,
Abstract: PRF value(s) selection guidelines for TG4a PHY standard (UWB-IR part)
Purpose: To provide information for further investigation and selection of the PRF value(s) for UWB Impulse Radio (low bit-rate plus ranging)
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(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 P
Gian Mario Maggio & Philippe Rouzet (STM)

2. PRF (Pulse Repetition Frequency) Selection Guidelines
May 5, 2005
PRF (Pulse Repetition Frequency) Selection Guidelines
Gian Mario Maggio
&
Philippe Rouzet
(STMicroelectronics)
Gian Mario Maggio & Philippe Rouzet (STM)

3. PRF Selection Strategy
May 5, 2005
PRF Selection Strategy
For each sub-band (mandatory + optionals), based on physical parameters, derive PRF range:
Min PRF (technology, regulation, ranging, etc.)
Max PRF (channel delay spread, etc.)
Optimize PRF value(s) based upon design parameters:
Modulation/demodulation
Acquisition
Implementation …
Gian Mario Maggio & Philippe Rouzet (STM)

4. PRF: Physical Parameters (1/2)
May 5, 2005
PRF: Physical Parameters (1/2)
UWB Radio
PRF 
PRF 
Comments
Bandwidth
B  
The higher the bandwidth, B, the higher minimum required constant
 Scalable PRF (mandatory + optional)
Technology
Peak-to-Peak Voltage
Vpp 
Baseline: CMOS 90nm, max Vpp = 1 V (conservative)
Channel
Delay Spread 
Typical (indoor) channel delay spread in the range ~ ns
Regulations
Peak-to-Average Power Ratio 
Any “hidden” regulation limit?
Ranging
Ranging Accuracy 
Higher PRF  Better ranging accuracy
Gian Mario Maggio & Philippe Rouzet (STM)

5. PRF: Design Parameters (2/2)
May 5, 2005
PRF: Design Parameters (2/2)
UWB Radio
PRF 
PRF 
Comments
Mod/Demod
BPPM + BPSK
Energy/Pulse  
Low PRF  high energy/pulse: challenging to generate, easier to detect (non-coherent)
Coherent Integration
Higher SNR  Relax minimum energy/pulse
Acquisition
Acquisition Time 
For higher PRF, in general, it takes less time to acquire code synchronization
Complexity 
For lower PRF, the synch matched filter is smaller than for higher PRF
Implementation
Cost 
Generally speaking, low PRF may result in lower cost (lower frequency) components
RX Dynamic Range 
Ex: 12 MHz PRF reduces the RX dynamic range by 7 dB, compared to 60 MHz PRF
ADC frequency 
Note: ADC frequency may be dictated by ranging requirements
Gian Mario Maggio & Philippe Rouzet (STM)

6. May 5, 2005
Supporting Material
I2R - Francois Chin ( a): PRF definition, Minimum PRF
Wideband Access - Ismail Lakkis/Saeid Safavi ( a): Minimum PRF
Wisair - Gadi Shor ( a): PRF proposals
CEA-LETI/STM: PRP vs. pulse amplitude and peak power
Gian Mario Maggio & Philippe Rouzet (STM)

7. May 5, 2005
(a) PRF: Definition
Pulse repetition frequency (PRF): Number of pulses occurring in 1 s.
Pulse repetition interval (PRI): Time from the beginning of one pulse to the beginning of the next.
VPeak TC
PRI
Gian Mario Maggio & Philippe Rouzet (STM)

8. (a) PRF Definition: Example
May 5, 2005
(a) PRF Definition: Example
Pulse Repetition Interval 1 2 3 4 5 6 7 8
N-1 N
…………………………
Non-inverted pulses are blue,
Inverted pulses are green.
…………………………
Active time
Quiet time
Symbol Interval
Gian Mario Maggio & Philippe Rouzet (STM)

9. (a) Minimum PRF Requirements
May 5, 2005
(a) Minimum PRF Requirements
BW = 528 MHz
Technology
CMOS 90nm 0.7 Vpp
TChip (nsec)
1.9
Sequence
Bipolar
Ternary (equal ±1 & 0)
VPeak (v)
0.35
PAve (dBm)
-14
PPeak (dBm) 1 -2
PRF VPeak
16.5 33
BW = 1584 MHz
Technology
CMOS 90nm 0.7 Vpp
TChip (nsec)
0.54
BW (MHz)
Bipolar
Ternary (equal ±1 & 0)
VPeak (v)
0.35
PAve (dBm)
-9.3
PPeak (dBm)
1.5
-1.5
PRF VPeak
132
264
Gian Mario Maggio & Philippe Rouzet (STM)

10. (b) Minimum PRF Requirements
May 5, 2005
(b) Minimum PRF Requirements
BW = 520 MHz
Technology
CMOS 90nm 2.5 Vpp
CMOS 90nm 1.0 Vpp
TChip (nsec)
1.9
BW (MHz)
520
VPeak (v)
1.25
0.5
PAve (dBm)
-14
-9.4
PPeak (dBm) 12 4
PRF VPeak
1.3 8
BW = 1560
Technology
CMOS 90nm 2.5 Vpp
CMOS 90nm 1.0 Vpp
TChip (nsec)
1.9
BW (MHz)
1560
VPeak (v)
1.25
0.5
PAve (dBm)
-14
-9.4
PPeak (dBm) 12 4
PRF VPeak
11.5 72
Gian Mario Maggio & Philippe Rouzet (STM)

11. May 5, 2005
(c) PRF Proposals
The PRF represents the rate of transmission of the basic pattern. The PRF is an integer division of all center frequencies. The basic PRF is 66 MHz. A PRF of 33 MHz is also supported for environments with long delay spread.
Justification: PRF can be generated from a PLL by dividing the center frequency down to the PRF. The first divisions can be based on the divisions implemented as part of the PLL. The center frequencies and PRF are selected such that the first two divisions for off the shelf XOs are divisions by 2. This simplifies the implementation of the high frequency division elements.
Gian Mario Maggio & Philippe Rouzet (STM)

12. (d) PRP vs. Pulse Amplitude and Peak Power
May 5, 2005
(d) PRP vs. Pulse Amplitude and Peak Power
Fcc limit : 0 dBm
(upper band only)
Gian Mario Maggio & Philippe Rouzet (STM)

13. Conclusions (Preliminary)
May 5, 2005
Conclusions (Preliminary)
Scalable PRF:
Bands supported: 500MHz (mandatory), 1.5 GHz
No. of supported PRF values: 2 (or more)
For CMOS 90nm, PRF lower MHz seems to be ~10 MHz
Proposed PRF values (so far):
Basic: 13/33 MHz
Optional: 26/66 MHz
PRI value to be dictated by sequence design
Note: PRF requirements may be mitigated by the adoption of multi-pulse chips
Gian Mario Maggio & Philippe Rouzet (STM)