Implementation of OFDM Transmitter based on the IEEE d Standard Presented by: Altamash Janjua Group Partner: Umar Chohan Supervisors: Dr. Brian L. Evans and Mr. Ian Wong Date: September 23 rd, 2004

Why should you listen? Tremendous Growth of Wireless Communications Wireless Metropolitan Area Networks (WMANs)

Presentation Organization Introduction What is Orthogonal Frequency Division Multiplexing? IEEE d Wireless Communications Standards Project Flow Diagram Transmitter Block Diagram Design Options and Trade-offs Conclusion

Introduction Continuous-time and Discrete-time signals Modulation : Carrier Amplitude and Frequency t x(t)x(t)

What is OFDM? Orthogonal Frequency Division Multiplexing Multi-carrier modulation scheme – Each Carrier’s amplitude is modulated tutorials/ofdm/topic04.html Amplitude Frequency

IEEE d Standard Upcoming Standard for Wireless Metropolitan Area Networks (WMANs) Specifications – Unlicensed bands below 11 GHz – 256 length IFFT – 56 guard carriers not used to carry data – Amplitude Modulation on each sub carrier to carry 1, 2, 4 or 6 bits images/wp_802.asp

Project Flow Diagram

Simplified Transmitter Block Diagram Serial to Parallel Conversion Amplitude Modulation Mapping Bank 256-Length Inverse Fast Fourier Tranform Parallel to Serial Conversion Cyclic Prefix Parallel Data Streams Data Encoding is based on Amplitude Modulation Multiple Carriers are combined through the Fourier Series - Computed by Inverse Fast Fourier transform Serial Data In

Design Options and Trade-offs Transmitter – Design 1: LabVIEW floating-point desktop simulation – Design 2: LabVIEW fixed-point FPGA realization Design Trade-Offs – Bit error vs. Signal to Noise ratio – Implementation Complexity

Final Setup Transmitter: Implemented on the LabVIEW FPGA Channel: LabVIEW floating-point desktop simulation Receiver: LabVIEW floating-point desktop simulation

Conclusion Thank You! Questions?