Type of Document Master's Thesis Author Qu, Xin URN etd-12212000-222112 Title Automated Testbench Generation for Communication Systems Degree Master of Engineering Department Computer Engineering Advisory Committee
Advisor Name Title Gray, Festus Gail Committee Chair Armstrong, James R. Committee Member Midkiff, Scott F. Committee Member Keywords
Date of Defense 2000-11-28 Availability unrestricted AbstractThis thesis develops semi-automated methods to generate testbenches for VHDL models
of communication systems. To illustrate the methods, a VHDL model was constructed for
the speech-coding channel of the Global System for Mobile Communication (GSM).
GSM is the Pan-European digital mobile telephony standard specified by the European
Telecommunication Standards Institute (ETSI). This thesis emphasizes the error detection
and error correction procedures that form an important part of the standard.
First, a test bench template was generated using “Testbench Pro”, a waveform generation
tool developed by SynaptiCAD. The template includes a random sequence of speech
data. A C program was then developed as a user interface to control the simulation
procedure. Using the C program, the user can select a test bench template and specify the
input test vectors. The C program adds the user’s test vectors to the test bench template to
create a final VHDL test bench that is ready for simulation. The testing data is then
encoded by the GSM encoder models, passed through the noisy channel model that
introduces errors into the data stream and, finally, passed through the GSM decoder models which attempt to correct the channel errors. Sophisticated error detection and
error correction algorithms are used in the encoder/decoder models to increase the
reliability of data transmission over the noisy channel. Finally, the original speech data is
compared to the decoder output to detect any remaining bit errors and to evaluate the
The simulation system is semi-automated. The user selects a set of parameters using the
C program interface. A testbench is then automatically created and simulated. Two final
report files are automatically generated. No user interaction is needed after the initial
Several experiments were performed to illustrate the various features of the automated
testbench generation system.
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