A pyramid vector quantizer

The geometric properties of a memoryless Laplacian source are presented and used to establish a source coding theorem. Motivated by this geometric structure, a pyramid vector quantizer (PVQ) is developed for arbitrary vector dimension. The PVQ is based on the cubic lattice points that lie on the surface of an
L
-dimensional pyramid and has simple encoding and decoding algorithms. A product code version of the PVQ is developed and generalized to apply to a variety of sources. Analytical expressions are derived for the PVQ mean square error (mse), and simulation results are presented for PVQ encoding of several memoryless sources. For large rate and dimension, PVQ encoding of memoryless Laplacian, gamma, and Gaussian sources provides rose improvements of
5.64, 8.40
, and
2.39
dB, respectively, over the corresponding optimum scalar quantizer. Although suboptimum in a rate-distortion sense, because the PVQ can encode large-dimensional vectors, it offers significant reduction in rose distortion compared with the optimum Lloyd-Max scalar quantizer, and provides an attractive alternative to currently available vector quantizers.