Abstract-This paper presents a highly energy efficient alternative algorithm to the conventional workload averaging technique for voltage quantized dynamic voltage scaling. This algorithm incorporates the strengths of the conventional workload averaging technique and our previously proposed Rate Selection Algorithm, resulting in higher energy savings while minimizing the buffer size requirement and improving the overall system stability by minimizing the number of voltage transitions. Our experimental work using the Forward Mapped Inverse Discrete Cosine Transform computation (FMIDCT) as the variable workload computation, nine 300-frame MPEG-2 video sequences as the test data, and a 4-level voltage quantization shows that our algorithm produces better energy savings in all test cases when compared to the workload averaging technique, and the maximum energy saving for the test cases was 23%.

LDPC codes of column weight of two are constructed from minimal distance graphs or cages. Distance graphs are used to represent LDPC code matrices such that graph vertices that represent rows and edges are columns. The conversion of a distance graph into matrix form produces an adjacency matrix with column weight of two and girth double that of the graph. The number of 1's in each row (row weight) is equal to the degree of the corresponding vertex. By constructing graphs with different vertex degrees, we can vary the rate of corresponding LDPC code matrices. Cage graphs are used as examples of distance graphs to design codes with different girths and rates. Performance of obtained codes depends on girth and structure of the corresponding distance graphs.

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