Implementation of ofdm

Implementation of OFDM Transmitter
based on the IEEE 802.16d Standard
Presented by:
Altamash Janjua, Umar Chohan
Supervisors:
Dr. Brian L. Evans and Mr. Ian Wong
Technical TA:
Mr. Youngok Kim
Date: 2nd December, 2004
Why is it Important to You?
 Tremendous Growth of
Wireless
Communications
 Wireless Metropolitan
Area Networks (WMANs)
 Future Projects in the
Industry www.gettyimages.com
Presentation Organization
 Introduction
 Transmitter Block Diagram
 IEEE 802.16d Standards
 Transmitter Implementation
 Design Testing and Validation
 Budget Constraints and Safety Features
 Future Recommendations
 Conclusion
Signals and Modulation
x(t)
 Continuous-time and
Discrete-time signals t
 Modulation : Carrier
Amplitude and/or
Frequency
http://www.ece.utexas.edu/~bevans
What Is Orthogonal Frequency Division
Multiplexing (OFDM)?
 Multi-carrier Amplitude modulation
scheme
– Each Carrier’s amplitude is modulated
 Well-suited for Wireless Communication
Amplitude
Frequency
www.iec.org/online/ tutorials/ofdm/topic04.html
How OFDM works?
 Parallel Data Streams
 Data Encoding is based on
Amplitude Modulation
 Multiple Carriers are combined
through the Fourier Series
– Computed by Inverse Fast
Fourier transform
4-QAM modulation
Our Simple Transmitter Block Diagram
Serial Encoding IFFT Parallel Cyclic
Serial To Bank To Prefix Channel
Data Parallel Serial
Source
Transmitter based on the IEEE 802.16d
Standard
 Upcoming Standard
for Wireless
Metropolitan Area
Networks (WMANs)
 Specifications Used
– 256 FFT
– 56 guard carriers
– 16- QAM
– Pilots and Guards
Transmitter Implementation
 National Instruments Lab VIEW FPGA
 VHDL and Lab VIEW programming
 One Main Virtual Instrument (VI)
– 16-QAM Encoding Bank
– 256 point Complex IFFT core developed by
Xilinx Inc.
– Cyclic Prefix Module
Testing and Validation
 Individual Modules Tested through Software
Simulations
 Developing a Host PC VI for the Testing of
final Hardware
 Sample test results provided in the IEEE
802.16d Standard
Safety Precautions
 Fundamental Canon of
Engineering:
“Hold Paramount Public Health
and Safety”
 Repeated Design Testing for
Functional Verification and
Robustness
 Additional Indicators for Warnings
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Budget Constraints
 No Purchases Involved
 Hardware and Software
Provided by Supervisors
 Time-Consuming
 Currently testing the design
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