1. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
May 10, 2003
Project: IEEE P Working Group for Wireless Personal Area Networks (WPANs)
Submission Title: [Multicarrier-UWB]
Date Submitted: [10 May 2003]
Source: [Ahmed H Tewfik] Company [University of Minnesota]
Address [Dept. of Electrical and Computer Engineering, Room EECS Bldg.,Minneapolis, MN 55455]
Voice:[ ], FAX: [ ],
Re: [03147r0P802-15_TG3a-University-of-Minnesota-CFP-Presentation.ppt]
Response to a Call for Contributions Task Group 3a Call For Intent and Proposals, November 2002, updated January 2003, 02371r0P802-15_SG3a-5_Criteria.doc
Abstract: [We propose a multi-carrier UWB system for WPAN communications. We describe system design issues and proposed transmitter and receiver structures. We also provide a self-evaluation of the proposed system.]
Purpose: [For consideration by a task group.]
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
Tewfik/Saberinia, U. of MN
<author>, <company>

2. Fast Frequency Hopping UWB-OFDM
May 10, 2003
Fast Frequency Hopping UWB-OFDM
H. Tewfik and E. Saberinia
University of Minnesota
Tewfik/Saberinia, U. of MN

3. Fast Frequency Hopping UWB-OFDM
May 10, 2003
Fast Frequency Hopping UWB-OFDM
Focus of this presentation : FFH UWB-OFDM as compromise between multiband or multicarrier UWB and wideband OFDM
Full simulation results and implementation details to be presented by July meeting (PPT + full Word report)
Tewfik/Saberinia, U. of MN

4. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
May 10, 2003
Overview
FFH-UWB-OFDM: compromise between multi-band UWB and pure OFDM UWB
System comparisons and design trade-offs
Proposed System Transmitter and Receiver Structures
Coexistence and Multiple piconets
Complexity and Power Consumption
Conclusion
Tewfik/Saberinia, U. of MN
<author>, <company>

5. Multi-Carrier UWB Multi-band UWB Pure OFDM UWB
May 10, 2003
Multi-Carrier UWB
Multi-band UWB
Can exploit Multipath diversity
Usually requires Rake type receiver to do so
Needs multiple band transmitter and receiver
Pure OFDM UWB
No need for Rake receiver
Suffers from frequency selective fading
Requires heavy coding and interleaving to achieve frequency diversity
Long FFT and IFFT
FFH-UWB-OFDM (some where between!)
Implemented with short IFFT and FFT
Provides multipath and frequency diversity
Unified framework and architecture for trading complexity for ability to gather part or all multipath diversity
Tewfik/Saberinia, U. of MN

6. May 10, 2003
An FFH-UWB-OFDM Block
Make an OFDM block with N-IFFT of QAM symbols (N=32)
Create a base band signal with bandwidth W> 500 MHz and Duration NTu ns
f(MHz) W 31 30 1
NTu t
Tewfik/Saberinia, U. of MN

7. May 10, 2003
An FFH-UWB-OFDM Block
Transmit digital samples using N=32 short coded pulses separated by T
Lower the Average PDS
Provide multipath diversity
f(MHz) W 1 30 31 1 30 31 1 30 31
Tu T T+Tu (N-1)T (N-1)T+ Tu t
Tewfik/Saberinia, U. of MN

8. May 10, 2003
An FFH-UWB-OFDM Block
Fast frequency hopping inside each pulse to provide:
multipath resolution
optimal frequency spreading
Two options that avoid UNII band
Use only GHz (Lower Band System)
Use whole band GHz and avoid GHz (Whole Band System)
Tewfik/Saberinia, U. of MN

9. Frequency Hopping for Lower Band System within Single Coded Pulse
May 10, 2003
Frequency Hopping for Lower Band System within Single Coded Pulse
f(GHz)
4.75
4.2
3.65
3.1 1 30 31 1 30 31 1 30 31
Tu/ Tu/ Tu t(ns)
Tewfik/Saberinia, U. of MN

10. Frequency Hopping for Lower Band System within Single Coded Pulse
May 10, 2003
Frequency Hopping for Lower Band System within Single Coded Pulse
f(GHz)
4.75
3.1 1 30 31 1 30 31 1 30 31 1 30 31
Tu/ Tu/ Tu/ Tu t(ns)
Tewfik/Saberinia, U. of MN

11. An FFH-UWB-OFDM Block Repeat this block every T=12.8ns N=32 times
May 10, 2003
An FFH-UWB-OFDM Block
Repeat this block every T=12.8ns N=32 times
f(GHz)
4.75
4.2
3.65
3.1 1 22 23 1 22 23
Tu T t(ns)
Tewfik/Saberinia, U. of MN

12. Frequency Hopping for Whole Band System
May 10, 2003
Frequency Hopping for Whole Band System
f(GHz)
9.75
5.9
4.8
3.15 1 30 31 1 30 31 1 30 31 1 30 31 1 30 31 1 30 31 1 30 31 1 30 31 1 30 31 1 30 31
Tu t(ns)
Tewfik/Saberinia, U. of MN

13. Spectrum Bandwidth=1.65GHz Multipath resolution=0.6ns Bandwidth=7.5GHz
May 10, 2003
Spectrum
Bandwidth=1.65GHz
Multipath resolution=0.6ns
Bandwidth=7.5GHz
Multipath resolution=0.13ns
Tewfik/Saberinia, U. of MN

14. Single-Channel To Multi-Channel
May 10, 2003
Single-Channel To Multi-Channel
A FFH-UWB-OFDM over a channel with L tap
Pure-OFDM over K independent channel with L/K tap K=T/Tr
Tewfik/Saberinia, U. of MN

15. Single-Channel To Multi-Channel
May 10, 2003
Single-Channel To Multi-Channel
Provides K multipath diversity
Captures all the channel energy
K=1 is pure OFDM
K=channel length is Multi-band system
Tewfik/Saberinia, U. of MN

16. Proposed System N=32 Subcarrier C=10 Cyclic Prefix
May 10, 2003
Proposed System
N=32 Subcarrier
C=10 Cyclic Prefix
¾ Convolutional Channel Coding
QPSK Constellation:
T=10.3ns: 110 Mbits/s (Collect K=17 multipath)
T=5.45ns: 210 Mbits/s (Collect K=9 multipath)
16-QAM for 480 Mbits/s
Tewfik/Saberinia, U. of MN

17. doc.: IEEE 802.15-<doc#>
<month year>
doc.: IEEE <doc#>
May 10, 2003
Transmitter I
FFT
¾ Convolution Code
QAM
Mapping
Interleaving
D/A X
Frequency Hopping
Input rate= 1/T M samples/s (100 or 200 M samples/s)
Tewfik/Saberinia, U. of MN
<author>, <company>

18. Receiver 1.65 G samples/s  capture 17 paths
May 10, 2003
Receiver
1.65 G samples/s  capture 17 paths
825 M samples/s  capture 8 paths
Combine Channels K
1-tap
Equalizers
Matched
Filter X
FFT
Frequency Hopping De
Interleaving
Decoding
De-mapping
Tewfik/Saberinia, U. of MN

19. Tradeoff between Complexity and Performance
May 10, 2003
Tradeoff between Complexity and Performance
Transmitter provides full multipath and frequency diversity
Flexible receiver structures that trade complexity for degree of diversity exploitation, e.g. :
Sampling rate=1.65 GHZ multipath diversity
Sampling rate=825 MHZ 8 multipath diversity
Sampling rate=550 MHZ 6 multipath diversity
Always capture the whole channel energy
Tewfik/Saberinia, U. of MN

20. Transmitter Complexity
May 10, 2003
Transmitter Complexity
¾ Convolution Coder
IFFT
32-point
QPSK only
D/A operating at 100 to 200 MHz
Tewfik/Saberinia, U. of MN

21. Receiver Complexity Possible to choose different A/D sampling rates
May 10, 2003
Receiver Complexity
Possible to choose different A/D sampling rates
multibit vs 1 bit
Simple equalization and channel estimation using cyclic prefix and FFT:
32-Point QPSK FFT
K 1-tap equalizer (K=17 or K=9)
Can capture more diversity or use larger bands as technology improves
Tewfik/Saberinia, U. of MN

22. May 10, 2003
Coexistence
Tewfik/Saberinia, U. of MN

23. May 10, 2003
Multiple Piconets
Simultaneous operation achieved by proper selection of:
FH code
Use of pilots
Add pseudo-random codes on top of modulation
Combination
Tewfik/Saberinia, U. of MN

24. May 10, 2003
Conclusion
FFH-UWB-OFDM provides a compromise between pure OFDM and Multi-band UWB
Provides full frequency diversity
Provides multipath diversity while capturing all channel energy
Avoids Rake type receiver with reasonable size FFT-IFFT
Unified structures and architectures that offer trade-offs between complexity and extent of multipath diversity exploitation
Tewfik/Saberinia, U. of MN