Ismail Lakkis

1
Project IEEE P802.15 Working Group for Wireless
Personal Area Networks (WPANs) Submission
Title Modulation for TG4a Date Submitted 19
July 2005 Source Ismail Lakkis Saeid
Safavi, Wideband Access Inc. Contact Saeid
Safavi. Voice1 858 642 9114, E-Mail
ssafavi_at_widebandaccess.com Abstract
Modulation proposal Purpose To assist the
group in the selection of a modulation
scheme 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.
2
Agenda

• PRF Peak Power
• BER in AWGN
• Proposed Modulation Scheme
• Proposed System Parameters
• Simulation Results

3
Relationship between PRF Peak Power
4
Minimum PRF vs Peak Power (CMOS 90nm)
BW 500 MHz
BW 1500 MHz
5
BER In AWGN

• The requirement of PER lt 1 for a 32 octets
  packet translates into a BER lt 3.926e-5
• EbN0 requirements for uncoded BPSK and ON-OFF
  keying systems
• g (BPSK) 8.9 dB
• g (ON-OFF) 15.45 dB
• EbN0 requirements for coded BPSK and ON-OFF
  keying systems
• g (BPSK) 4 dB
• g (ON-OFF) 10 dB

6
Modulation

• Spreading via scrambling
• Scrambling time varying spreading
• Use a single (set) scrambler of length (ex
  32768) and assign a different offset (of 16 or
  32) to different nodes
• Number of users supported is 1024
• Perfect co-channel interference rejection
• Support virtually any data rate from 8Mbps to 64
  Kbps for a PRF of 16MHz
• Spectrum is virtually flat (no back-off)

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Ternary Modulator I

• Orthogonal time varying spreading
• Supports coherent, differentially
• coherent non-coherent

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Ternary Modulator I

• Binary time varying spreader
• In one symbol either the code or code is sent
• Option for coherent detectors

9
Ternary Modulator II
If a guard of 2 pulses is used
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Ternary Receiver Non-Coherent
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Collaboration

• Options I, II, III are the result of
  collaboration with
• Ismail Lakkis Wideband Access Inc.
• Saeid Safavi Wideband Access Inc.
• Matt Welborn Freescale Semiconductor
• Shahriar Emami Freescale Semiconductor
• Francois Shin I2R
• Michael Mc Laughlin decaWave
• Andy Molisch Mitsubishi Electric
• Philip Orlik Mitsubishi Electric
• Zafer Sahinoglu Mitsubishi Electric
• Ryuji Khono NICT
• Vern Berthour Time Domain Corp.

12
Bipolar Burst Burst PMM

• Average PRF 15.4375 MHz ? Average PRI 64.77
  ns
• Target data rate (before FEC) 1.93 Mbps
• Target data rate (after FEC) 0.965 Mbps
• bit duration 518.2 ns
• number of pulses per bit for a 1.93 MHz data rate
  8 ON pulses
• Option I
• Bipolar burst for coherent
• Burst PPM for non-coherent
• Option II
• Burst PPM polarity for Coherent (2 bits/Symbol)
• Burst PPM for non-coherent

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Option I

• Higher PRF allow guard intervals
• Guard intervals ? less interference between
  adjacent bits
• Non-coherent SOP is still high because of ON burst

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Option II

• Coherent can support 2 bits/symbol however the
  bits are not equally protected

15
Option III

• Preferred Option
• Use Low PRF for coherent
• Use high PRF with ternary spreading for
  non-coherent
• Ternary codes improve SOP for non-coherent

16
Receiver Structure
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Proposed System Parameters
Bandwidth 10dB-BW 500 MHz
Base Peak PRF 15.4375 MHz
Additional PRFs 30.875, 61.75, 123.5
Data rates 7.7Mbps, 3.8Mbps, 1.9Mbps, 0.96Mbps, 480Kbps, 240Kbps, 120Kbps
Channel coding Convolutional code K 5, Rate 1/2
modulation Ternary via scrambler spreader
SOPs 6 per FDM band
Multiple access FDM/Scrambler CDM
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Simulation Assumptions

• PRF 15.4375 MHz
• Effective Data Rate 1 MHz
• Channel Coding Rate ½ Conv. (K 5)
• Frame/Frequency Assume perfect sync
• Channel estimation not perfect
• Uncoded Packet Length 32 octets
• Option I with Peak PRF of 7.7 MHz

19
Simulation Results (Coherent)
EbN0 Required for 1PER
AWGN 4 dB

CM1
8 Fingers -
7 Fingers -
6 Fingers -
5 Fingers 5.5 dB
4 Fingers 6.5 dB
3 Fingers 6.5 dB
2 Fingers 8.5 dB
1 Finger 11 dB
20
Simulation Results (Coherent)
CM8 EbN0 Required for 1PER
8 Fingers 10.0
7 Fingers 11.0
6 Fingers 11.5
5 Fingers 12.0
4 Fingers -
3 Fingers -
2 Fingers -
1 Finger -
21
Simulation Results (Non-Coherent)
EbN0 Required for 1PER
AWGN 10 dB

CM1
8 Fingers -
7 Fingers -
6 Fingers -
5 Fingers -
4 Fingers -
3 Fingers 15 dB
2 Fingers 16 dB
1 Finger -