ece4305_lab4

ece4305_lab4 - ECE4305: Software-Defined Radio Systems and...

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Unformatted text preview: ECE4305: Software-Defined Radio Systems and Analysis Lab 4: Multi-Carrier Modulation D-Term 2010 Objective This laboratory will introduce fundamental principles of multicarrier modulation (MCM) and show why it is an integral part of modern communications systems. Contents 1 Theoretical Preparation 2 1.1 Single Carrier Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1.1 Modulation and Demodulation of QAM symbols . . . . . . . . . . . . . . . . . . 2 1.2 Multi Carrier Transmission . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.3 Dispersive Channel Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 1.4 OFDM with Cyclic Prefix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.5 Frequency Domain Equalization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 1.6 Bit and Power Allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1.6.1 Bit Allocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 1.6.2 Power Distribution of the Transmitted Signal . . . . . . . . . . . . . . . . . . . . 11 1.7 Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2 Software Implementation 13 2.1 MATLAB Design of Multicarrier Transmission . . . . . . . . . . . . . . . . . . . . . . . 13 2.2 Simulink Design of Multicarrier Transmission . . . . . . . . . . . . . . . . . . . . . . . . 14 2.2.1 Orthogonally Multiplexed QAM . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.2.2 OFDM Transmitter and Receiver . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3 GNU Radio Experiments 16 3.1 Audio FDM Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.2 Creating Hierarchical Blocks in GRC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 4 Analysis and Synthesis 22 5 Lab Report Instructions 22 1 1 Theoretical Preparation Instead of having one center frequency, f c , Multi-Carrier Modulation (MCM) multiplexes serial input data into several parallel streams and transmits them over independent sub-carriers. These sub-carriers can be individually modulated and manipulated allowing for optimization with respect to the channel. This is especially true for a wireline communications system where the channel is well defined. Why MCM? What are the disadvantages of transmitting at a high data rate over a single carrier? What happens if part of your channel is severely attenuated? MCM offers a different approach to these prob- lems. By sub-dividing the transmission over many carriers and tuning the modulation schemes and power levels of each carrier, a multi-carrier transmission scheme becomes quite robust to fast-fading channels and narrowband interference....
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ece4305_lab4 - ECE4305: Software-Defined Radio Systems and...

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