Distributed synchronization mechanism for shared communications media based networks

A method of synchronizing a plurality of stations directly connected to each other in a shared communications media based network, said method comprising the steps of:

• attempting, on a given station, to detect other stations already active in said network;
• and if one or more synchronization signals are detected,
• updating the phase of an internal clock in said given station in response to an earliest received synchronization signal received before the expected next tick of said internal clock;
• updating the rate of said internal clock as a function of the time difference between time phase of said earliest received synchronization signal and the time phase of said given station;
• and
• said given station transmitting synchronization signals upon achieving phase and rate alignment with said earliest received synchronization signal.

An apparatus for synchronizing a plurality of stations directly connected to each other over a shared communications media based network, comprising:

• a detection mechanism adapted to detect synchronization signals transmitted by other stations already active in said network;
• a phase acquisition mechanism adapted to update the phase of an internal clock in a given station in response to an earliest detected synchronization signal received before the expected next tick of said internal clock;
• a rate acquisition mechanism adapted to update the rate of said internal clock as a function of the time difference between time phase of said earliest detected synchronization signal and the time phase of said given station;
• and
• a transmission mechanism adapted to transmit synchronization signals upon achieving phase and rate alignment with said earliest detected synchronization signal.

A communications station for transmitting and receiving signals to and from other directly connected stations over a shared communications media based network, comprising:

• a coupling circuit for generating a receive signal received over said network and for outputting a transmit signal onto said network;
• a transmitter adapted to modulate data to be transmitted in accordance with a modulation scheme so as to generate said transmit signal therefrom;
• a receiver adapted to demodulate said receive signal in accordance with said modulation scheme so as to generate synchronization signals and a receive data signal therefrom;
• a media access control (MAC) circuit adapted to interface an application processor to said shared communications media;
• a synchronization control circuit comprising means adapted to:
• detect one or more synchronization signals transmitted by said other directly connected stations;
• align the phase and rate of an internal clock in accordance with an earliest received synchronization signal having a time phase earlier to the time phase of said internal clock;
• and
• said processor adapted to control the operation of said transmitter, receiver and MAC and to provide an interface between said MAC and an external host.