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

Continuous-time and Discrete-time signals

Modulation : Carrier Amplitude and/or Frequency

t

x(t)

http://www.ece.utexas.edu/~bevans

What Is Orthogonal Frequency Division Multiplexing (OFDM)?

Multi-carrier Amplitude modulationscheme– Each Carrier’s amplitude is modulated

Well-suited for Wireless Communication

www.iec.org/online/ tutorials/ofdm/topic04.html

Am

plitu

de

Frequency

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 transform4-QAM modulation

Our Simple Transmitter Block Diagram

Channel

SerialTo

Parallel

Encoding Bank

IFFT Parallel To

Serial

CyclicPrefixSerial

Data 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 Warningswww.gettyimages.com

Budget Constraints

No Purchases Involved

Hardware and Software Provided by Supervisors

Time-Consuming

Currently testing the designwww.gettyimages.com

Future Transmitter Implementations

Conventional Field Programmable Gate Arrays

Digital Signal Processors

Application Specific Integrated Circuits

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Acknowledgements

Supervisors:– Dr. Brian L. Evans – Mr. Ian Wong

Technical Teacher Assistant:– Mr. Youngok Kim

Conclusion

Thank You!!

Questions??

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