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Flexible Wireless Systems for Rapid Network Evolution

Data Processing. Pilot Insertion. Serial to Parallel. IFFT. Cyclic Extension. DAC. RF TX. Input Bits. Data Extraction. Channel Correction. FFT . Remove cyclic extension. Synchronization. RF RX. ADC. Parallel to Serial. Output Bits.

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Flexible Wireless Systems for Rapid Network Evolution

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  1. Data Processing Pilot Insertion Serial to Parallel IFFT Cyclic Extension DAC RF TX Input Bits Data Extraction Channel Correction FFT Remove cyclic extension Synchronization RF RX ADC Parallel to Serial Output Bits MODEL 1: Block diagram of OFDM transceiver (FFT based) Data Processing Σ Cyclic extension RF TX Bank of Modulators (time domain) Serial to Parallel Pilot Insertion Input Bits Parallel to Serial Channel Correction Sampling & Decision (Parallel) Matched Filter Detection Data Extraction Synchronization RF RX Remove Cyclic Extension Output Bits Interleaving Coding QAM Mapping Decoding De-interleaving QAM De-mapping Data Processing Data Extraction Flexible Wireless Systems for Rapid Network Evolution Orthogonal Frequency Division Multiplexing (OFDM) For Flexible Wireless Radios OFDM Transceiver Models PROJECT CONCEPT • Develop flexible and wideband OFDM modulation techniques for wireless radios. • Evaluate different approaches through analysis, simulation and implementation. • Develop techniques to manage OFDM radio networks. MODEL 2: Block diagram of OFDM transceiver (Time Domain based) Research Plan Constellations for 64-QAM OFDM (AWGN Channel) • Design and analyze an initial OFDM system which • Locates a 60 MHz Frequency band between 5.2GHz and 5.8GHz. • Receives and transmits 16 bits of I and Q values. • Achieves Bit Error Rate below 10-6. • Uses XILINX Virtex II Pro FPGA. • Integrate the above OFDM system into the KU Flexible Radios system. • Extend the system to work in mobile and dynamic wireless environments. • These are the results from the basic simulations on OFDM over AWGN channel. • Figure 1: Perfect symbol constellation at the transmitter. • Figure 2: Constellation at receiver when signal to noise ratio (SNR) is low which shows high distortion. • Figure 3: Constellation at receiver when SNR is high which is close to the perfect constellation. • Figure 4: The plot comparing theoretical values and the simulated results for bit error probability vs. SNR per bit. Figure 2: With Eb/N0 = 0 dB Figure 1: Noiseless constellation Figure 3: With Eb/N0 = 30 Figure 4: BER versus Eb/N0 051804 G. Minden, <gminden@ittc.ku.edu> A40113

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