Communication system in which data are transferred between terminal stations and satellite stations by infrared signals

Claim 2

A communication system in which data are transferred between terminal stations and satellite stations by infrared signals, characterized in that for covering an extended area, a plurality of satellite stations (S1-S8) each with infrared transmitting means (17, 19) operating at a common carrier frequency are provided, the radiation fields of said transmitting means at least partially overlapping, and that common electrical link means (13, 15) are provided for transferring to all said satellite stations data signals (13) which are to be distributed to all said terminal stations simultaneously, and for further transferring a common timing signal (15) to all said satellite stations for synchronizing the carrier signals in said transmitting means, and that each terminal station within said extended area is provided with means for selectively accepting only one set of the simultaneously distributed data signals in any time period even if said terminal receives the infrared signals radiated by two or more satellite stations during said time period.

Claim 3

A communication system in accordance with claim 1, characterized in that a common control station (CC) is provided for all said satellite stations (S1-S8), and that said common electrical link means (13, 15) is a multidrop bus connecting all said satellite stations to said common control station.

Claim 4

A communication system in accordance with claim 1, characterized in that said common electrical link comprises a data bus line (13) and a synchronizing signal bus line (15); that each said satellite station (S2-S8) comprises a buffer (33) for a message received over said data bus, and means (35, 44, 45, 46) connecting said transmitting means (17, 19) to said synchronizing signal bus line and to said buffer so that a message stored in said buffer is transmitted in response to a received synchronizing signal sequence.

Claim 5

Communication system in which data are transferred between terminal stations and satellite stations by infrared signals, characterized in that for covering an extended area, a plurality of satellite stations (S1-S8) each with infrared transmitting means (17, 19) operating at a common carrier frequency are provided, the radiation fields of said transmitting means at least partially overlapping, and that common electrical link means (13, 15) are provided for transferring to all said satellite stations data signals (13) which are to be distributed to all said terminal stations simultaneously, and for further transferring a common timing signal (15) to all said satellite stations for synchronizing the carrier signals in said transmitting means, whereby any terminal station within said extended area can correctly receive the distributed data signals even if it receives the infrared signals radiated by two or more satellite stations; and further characterized in that each said satellite station (S1-S8) includes a buffer (55) for uplink message received from any terminal station, that an access and transfer mechanism (21, 57, 83, 85) is provided to separately transfer a buffered message from any satellite station over said common electrical link means (13, 15); and that selecting means (41, 63, 77, 79) are provided for eliminating all identically received copies, except one, of any uplink message.

Claim 6

Communication system in which data are transferred between terminal stations and satellite stations by infrared signals, characterized in that for covering an extended area, a plurality of satellite stations (S1-S8) each with infrared transmitting means (17, 19) operating at a common carrier frequency are provided, the radiation fields of said transmitting means at least partially overlapping, and that common electrical link means (13, 15) are provided for transferring to all said satellite stations data signals (13) which are to be distributed to all said terminal stations simultaneously, and for further transferring a common timing signal (15) to all said satellite stations for synchronizing the carrier signals in said transmitting means, whereby any terminal station within said extended area can correctly receive the distributed data signals even if it receives the infrared signals radiated by two or more satellite stations; and further characterized in that each said satellite station (S1-S8) includes a buffer (55) for uplink message received from any terminal station, that an access and transfer mechanism (21, 57, 83, 85) is provided to separately transfer a buffered message from any satellite station over said common electrical link means (13, 15); and that selecting means (41, 63, 77, 79) are provided for eliminating all identically received copies, except one, of any uplink message.

Claim 7

A communication system in accordance with claim 4, characterized in that checking means (59, 61, 81) are provided in each said satellite station for checking error-free reception of any uplink message, and control means (23, 25) for enabling the transfer of a buffered uplink message only if it was received error free.

Claim 8

A communication system in accordance with claim 4, characterized in that an uplink message, when transmitted from a satellite station (S1-S8), is distributed over the common bus to said control station (CC) and all said satellite stations, and that said selecting means (63, 79) include comparing means (65, 67, 69) for comparing common parts of a buffered uplink message received from a terminal station, and a distributed uplink message received over the bus, for eliminating uplink messages received in duplicate.