Method and apparatus for maintaining synchronization in a communication system

A cable modem configured to receive downstream transmissions from a cable modem termination system (CMTS), comprising:

• a clock generation element configured determine a first clock using first timing information from a first downstream signal to provide a symbol clock and, when the first downstream signal is lost, to determine second timing information from a second downstream signal using the symbol clock to provide a second clock, and to provide a forward-predicted version of the first clock;
• an offset determination element configured to determine an offset between the first and second clocks when the first downstream signal is lost;
• an upstream timing element configured to adjust the forward-predicted version of the first clock based on the offset;
• and
• an upstream transmitter configured to synchronize upstream transmissions to the CMTS using the forward-predicted version of the first clock.

A method in a cable modem, the method comprising:

• determining a first clock using first timing information from a first downstream signal to provide a symbol clock;
• maintaining the symbol clock in accordance with the first timing information when the first downstream signal is lost;
• determining second timing information from a second downstream signal using the symbol clock to provide a second clock when the first downstream signal is lost;
• and
• adjusting the symbol dock based upon an offset between the first and second clocks.