Abstract: Method for wireless optical communication between a transmitting station and a receiving station, whereby the transmitting station provides a Request-to-Send (RTS) frame to the receiving station to announce the transmission of a data frame, the receiving station provides a Clear-to-Send (CTS) frame to the transmitting station in case of correct reception of the RTS frame, and the transmitting station subsequently sends the data frame to the receiving station. The RTS frame comprises Preamble (PA), Synchronization (SYNC), and Robust Header (RH) fields. The RTS frame further comprises a Source Address/Destination Address field (SA/DA) and a Cyclic Redundancy Check field (CRC). Adjusting the power level of the RTS frame to be different from the nominal transmission power level at which the data frame is sent, and by variable repetition coding within the Robust Header (RH) field of the RTS frame, allows a larger dynamic range of link quality estimation and improved collision avoidance properties.

Abstract: 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; 50) is employed which can be understood by all participating stations. This robust header (50) at least comprises a preamble (52) 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 (52) serves for relative synchronization and carrier detection of the receiving stations. The robust header (50) further comprises a unique synchronization word (53) used for absolute synchronization of the receiving stations. This synchronization word (53) is followed by a control field (59) of fixed length and known structure. By means of this control field (59) the receiving stations are informed which modulation method will be used for the transmission of data.

Abstract: In an infrared communication system in which many units of different requirements can communicate with each other, transceivers are assigned to different categories, each with its own transmitting power and receiving sensitivity depending on the required distance range. This allows simultaneous independent infrared communications in different local areas between low power/sensitivity devices but enables also transmission over larger distances or over the whole system between larger power/sensitivity devices. Depending on the power/sensitivity relation and distance, a potential receiver may either be able to decode data signals correctly, or it may be only able to detect the presence of a carrier. To allow a clear access protocol in all cases, a unit gets two chances to reenter access competition after having sensed the carrier: Either upon decoding a data end delimiter, or upon a timeout equal to the longest possible packet transmission time.

Abstract: An optical bus arrangement is disclosed for interconnecting a plurality of circuit modules (15, 17 . . . ). It comprises a plurality of optical busses (25) each including a feeder waveguide (41) and a signal waveguide (43). Junctions (45) for controllably switching light from feeder to signal waveguide, and leaky regions (47) for detecting the status of the signal waveguide, are provided at regular intervals. Arrays of lasers/LEDs (33) at both ends constantly furnish light to the feeder waveguides.Each module has a plurality of input ports (27) each comprising a photodetector for detecting light from one leaky region, and a plurality of output ports (45) each comprising an electrode grating for controlling switching of light in one junction. Input ports and output ports are integrated portions of the chips. Thus, the optical waveguide switches disclosed have the specific feature of being partially incorporated as waveguide junction in a substrate (23), and partially as control electrodes integrated on a chip.