CELL-BASED CLOCK RECOVERY DEVICE

摘要

A clock recovery unit provides a clock recovery function in the receiving entity of a system to implement adaptation of constant bit-rate (CBR) services over an asynchronous transfer mode (ATM) or ATM-like network. Incoming cells are periodically sampled for buffer fill level Li. The maximum fill level of undelayed cells Lxj is extracted from successive series of a predetermined whole number M of buffer-fill samples Li. A frequency adjustment logic unit provides at its output a bit stream at a given clock frequency fj. The frequency adjustment logic unit makes incremental adjustments to the clock frequency fj tending to cause the steady state mean of the fill level Lxj, or its derivative, to move toward zero.