Implementation of OFDM Transmitter based on the IEEE d Standard Presented by: Altamash Janjua, Umar Chohan Supervisors: Dr. Brian L. Evans and Mr. Ian Wong Technical TA: Mr. Youngok Kim Date: 2 nd December, 2004

Why is it Important to You? Tremendous Growth of Wireless Communications Wireless Metropolitan Area Networks (WMANs) Future Projects in the Industry

Presentation Organization Introduction Transmitter Block Diagram IEEE d 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)x(t)

What Is Orthogonal Frequency Division Multiplexing (OFDM)? Multi-carrier Amplitude modulation scheme – Each Carrier’s amplitude is modulated Well-suited for Wireless Communication tutorials/ofdm/topic04.html Amplitude 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 transform 4-QAM modulation

Our Simple Transmitter Block Diagram Channel Serial To Parallel Encoding Bank IFFTParallel To Serial Cyclic Prefix Serial Data Source

Transmitter based on the IEEE d 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 d 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

Budget Constraints No Purchases Involved Hardware and Software Provided by Supervisors Time-Consuming Currently testing the design

Future Transmitter Implementations Conventional Field Programmable Gate Arrays Digital Signal Processors Application Specific Integrated Circuits

Future Designs d OFDM Receiver Channel Coding – Reed-Solomon encoder, Convolution coder Real-Time Channel Models Code Division Multiple Access (CDMA) and Orthogonal Frequency Division Multiple Access (OFDMA) Systems

Acknowledgements Supervisors: – Dr. Brian L. Evans – Mr. Ian Wong Technical Teacher Assistant: – Mr. Youngok Kim

Conclusion Thank You!! Questions??