Hierarchical distributed infrared communication system
First Claim
1. System for interconnecting a plurality of data handling units by infrared signals over a common infrared communication channel, said units including a plurality of stations and associated I/O devices, each said unit comprising at least one infrared transceiver and accessing the common infrared communication channel only in dependence of carrier sense function, characterized in thateach said transceiver is assigned to one of a plurality of hierarchical categories according to its required distance range of coverage within said system, and each transceiver includes means for establishing its infrared transmitting power and/or receiving sensitivity at magnitude(s) uniquely corresponding to its hierarchical category.
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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. A mixed-media network is obtained by attaching, via respective interface units, subnetworks in which units are interconnected by cables but use the same access protocol as the IR interconnected units.
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Citations
17 Claims
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1. System for interconnecting a plurality of data handling units by infrared signals over a common infrared communication channel, said units including a plurality of stations and associated I/O devices, each said unit comprising at least one infrared transceiver and accessing the common infrared communication channel only in dependence of carrier sense function, characterized in that
each said transceiver is assigned to one of a plurality of hierarchical categories according to its required distance range of coverage within said system, and each transceiver includes means for establishing its infrared transmitting power and/or receiving sensitivity at magnitude(s) uniquely corresponding to its hierarchical category.
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10. A system for interconnecting data transmitting and receiving units including a plurality of stations and associated I/O devices and at least one repeater unit, by infrared signals, information being transmitted in the form of packet frames comprising at least one address field and a control information field, characterized in that
said control information field comprises plural mode control bits each having a state for identifying one of said units individually or for identifying a group of said units having the same function in the system, and that activating means are provided in each said unit for activating an identified unit to accept or to retransmit a received packet frame upon detecting the mode control bit state corresponding to such unit only if that unit is selected by an assigned mode control bit in the respective frame.
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12. A method of transmitting data signals in a system comprising units which include stations and devices assigned to said stations, in which any individual such unit accesses a common transmission medium only in dependence of a carrier sense function for transmitting data in the form of packets, comprising the steps of:
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sensing a signal transmission by said unit; driving said unit to a non-transmit state; starting a time-out cycle of a duration (To) at least equal to the longest packet transmission time (Tpmax) in said unit; detecting either and end-of-transmission delimiter (EOP) or the end of a time-out cycle (EOPTO) by said unit; starting a data transmission in a time slot assigned to said unit in the event no signal transmission is detected by said unit prior to initiation of data transmission by said unit.
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13. A method of transmitting data by infrared signals in a system comprising a plurality of units including transmitters, receivers and stations, and devices assigned to said stations, in which system any unit accesses a common infrared transmission channel only in dependence of a carrier sense function for transmitting data in the form of packets, comprising the steps of:
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operating said transmitters and receivers with different transmitting powers and receiving sensitivities, respectively, depending on the required distance range to be covered; sensing an infrared signal transmission by each said unit; driving each said unit to a non-transmit state; starting a time-out cycle of a duration (To) at least equal to the longest possible packet transmission time (Tpmax) in each said unit; detecting either an end-of-transmission delimiter (EOP) or the end of said time-out cycle (EOPTO) whichever comes first, in each said unit; transmitting data in a time slot assigned to a corresponding unit in the event no infrared signal transmission is detected by said correspondence unit prior to initiation of data transmission by said corresponding unit. - View Dependent Claims (14, 15, 16, 17)
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Specification