Universal Wyner–Ziv Coding for Distortion Constrained General Side Information

We investigate the Wyner-Ziv coding in which the statistics of the principal source is known but the statistics of the channel generating the side information is unknown except that it is in a certain class. The class consists of channels such that the distortion between the principal source and side information is smaller than a threshold, but channels may be neither stationary nor ergodic. In this situation, we define a new rate-distortion function as the minimum rate such that there exists a Wyner-Ziv code that is universal for every channel in the class. Then, we show an upper bound and a lower bound on the rate-distortion function, and derive a matching condition such that the upper and lower bounds coincide. The relation between the new rate-distortion function and rate-distortion function of the Heegard-Berger problem is also discussed.