International Business Machines Corporation

Martin De Lange

Fritz R Gfeller

Walter Hirt

Disclosed is an optical communication system enabling communication between several co-existing transmitting and receiving stations. In order to allow communication between the co-existing stations, a robust physical layer header (RPLH; ) is employed which can be understood by all participating stations. This robust header ( ) at least comprises a preamble ( ) consisting of frames forming a periodic sequence of pulses, the number of slots per frame and the frame content being known to all participating stations. The preamble ( ) serves for relative synchronization and carrier detection of the receiving stations. The robust header ( ) further comprises a unique synchronization word ( ) used for absolute synchronization of the receiving stations. This synchronization word ( ) is followed by a control field ( ) of fixed length and known structure. By means of this control field ( ) the receiving stations are informed which modulation method will be used for the transmission of data. Under certain circumstances it is also useful to provide other control information in said control field ( ) for communication link and network control. Furthermore, information may be exchanged to allow negotiation and/or adaptation of the data rate used for transmission. This allows to optimize the throughput depending on the conditions (quality) on the channel.

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Zurich, Switzerland

Martin De Lange