Broadband communication networks provide high-speed data communication to many residential neighborhoods and commercial locations. To achieve efficient and reliable data transmission over a broadband communication link, sampling clocks used to sample and receive data must acquire synchronization with the transmitted data stream. In many broadband communication systems, downstream data is broadcast from a central office to all network units served by the central office. A particular network unit will decode only those portions of the downstream data which are addressed to it. As such, the downstream data link is relatively long-lived and the time to initially acquire sampling clock synchronization will have negligible effect on the performance of the downstream data link.
However, many broadband communication systems do not provide a similar long-lived data link for upstream data. Instead, the upstream data link is shared such that each network unit served by the central office is assigned a particular window during which the network unit may transmit its upstream data. The sampling clocks used to sample and receive data sample on the upstream data link must, therefore, resynchronize with each network unit each time the network unit's transmission window begins. Because the transmission windows are usually not long-lived, the time to acquire resynchronization may have a significant impact on the performance of the upstream data link.