Abstract

Quadrature Amplitude Modulation (QAM) has been predominant in current wireless digital communications, such as satellite and microwave radio communications. Due to diverse wireless communication applications, a digital QAM modem with diverse bit rates (R) and intermediate carry frequency (IF) is of great interest. The main objective of this thesis is to design, analyze and implement a multi-level QAM modem with programmable bit rates and programmable IF, thus not only meeting different requirements, but also dramatically reducing the complexity of the following analog Radio Frequency (RF) block. In the thesis, the digital QAM modem is built based on the fundamentals of Digital Communication Systems (DCS) and Digital Signal Processing (DSP). The underlying relationship between signal resampling and its filter impulse response is studied and analyzed. A new signed-array structure for 2's complement multiplication is introduced in order to improve the regularity and flexibility of hardware design. The modem analysis and comparisons are shown in terms of performances and structures. Hardware design techniques are developed in-depth. The modem model is coded in VHDL (VHSIC Hardware Description Language) and synthesized using Synopsys tools, and its performance is evaluated. The regular structure and portable VHDL coding of the modem can satisfy diverse applications implemented in different FPGAs or ASICs.

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