Variable-to-fixed length codes provide better large deviations performance than fixed-to-variable length codes

It is proved that for finite-alphabet, finite-state unifilar sources, variable-to-fixed length codes provide better large deviations performance of the empirical compression ratio, than fixed-to-variable Manuscript received March 21, 1990; revised March 6, 1991. N. Merhav was with AT&T Bell Laboratories, Murray Hill, NJ. He is now with the Department of Electrical Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel. D. L. Neuhoff was with AT&T Bell Laboratories, Murray Hill, NJ. He is now with the Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI 48109. I ‘ . 1 IEEE Log Number 9102762. length codes. It is shown how to construct a universal variable-to-fixed length code that achieves the optimal performance.