Communications: electrical – Continuously variable indicating – With meter reading
Patent
1991-05-06
1994-07-19
Horabik, Michael
Communications: electrical
Continuously variable indicating
With meter reading
34082504, 3408255, 370 951, 370 953, 370 856, 370 857, 370 859, H04L 1228, H04L 1240
Patent
active
053313160
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a communication system with a plurality of substations intercoupled by first and second paths on which recurrent first and second cells each including a signalling channel and a data field, are conveyed in opposite directions, each substation including a transmitter to write information in first cells each including a plurality of signalling channels and a receiver to read information from second cells.
BACKGROUND ART
Such a communication system is already known from the article "The QPSX Man" by R. M. Newman et al, published in IEEE Communications Magazine. April 1988, Vol. 26, No. 4, pp. 20-28. In this known system the signalling channels of each first cell are allocated to respective ones of a like number of priorities and each substation having data of a certain priority to be transmitted is able to write a data transmission request signal in the signalling channel allocated to this priority of a first cell. But since there is only a single such signalling channel per cell conflicts could occur and to avoid this each substation includes an additional receiver to assess the busy/free state of the concerned signalling channel of a received first cell before possibly writing a transmission request signal therein. Further, each substation is provided with means including an additional transmitter to monitor the use of the data channels of the second cells as a function of the request signals received in the signalling channels of the first cells. Both the additional receiver and the additional transmitter and the circuitry associated therewith have for effect that each substation is of relatively complex structure and therefore relatively expensive.
It should be noted that if the above known system processes data of a same priority the first cells only include a single signalling channel for transmitting request signals so that also in this case conflicts between the stations can occur and additional transmitters and receivers have to be provided.
DISCLOSURE OF THE INVENTION
Accordingly, an object of the present invention is to provide a less complex communication system of the above type, particularly by the avoidance of such additional receiver and transmitter in each substation.
According to the invention this object is achieved due to the fact that it includes a main station with another receiver to read information from said first cells and with another transmitter to write information into said second cells, each of said first and second cells including a plurality of signalling channels smaller than the number of substations, means in said main station and substations to allocate to each substation having to transmit data any free one of said plurality of channels, means in each substation having a signalling channel allocated to it to transmit to said main station a request signal for data transmission in this signalling channel of a first cell, and means in said main station which in response to the receipt of said transmission request signal, transmit to the requesting substation a data transmission grant signal in a signalling channel of a second cell.
Because a signalling channel of a first cell is allocated to a substation having to transmit data no conflicts for the use of this channel can occur so that no additional receiver is required in the substation. On the other hand, the data channel monitoring function is now performed in the main station only so that also no additional receiver is required in the substations.
One could have provided a number of signalling channels equal to the number of substations but this would have led to the use of too much signalling bandwidth per cell. By using a number of signalling channels in function of the traffic, i.e. in function of the number of substations which have to transmit data simultaneously, the signalling bandwidth may be maintained within acceptable limits.
It should be noted that the article "System 12. Configuration for ISDN Subscriber Equipment Network Termination Digital Telephones,
REFERENCES:
patent: 3639904 (1972-02-01), Arvlpragasam
patent: 4554656 (1985-11-01), Budrikis et al.
patent: 4718061 (1988-01-01), Turner
patent: 4891804 (1990-01-01), Lake
R. M. Newman, et al., IEEE Communications Magazine, "The QPSX Man", Apr. 1988, vol. 26, No. 4, pp. 20-28.
T. Israel, et al., Electrical Communication, "System 12. Configuration for ISDN Subscriber Equipment Network Termination Digital Telephones, and Terminal Adapters", vol. 59, No. 1/2, 1985, pp. 120-126.
Bell System Technical Journal, vol. XLIII, Sep. 1964, No. 5, Part 1, pp. 1869-1870.
W. M. Hubbard, "Fiberguide Integrated Services Multiple Access Network", ISSLS 1984, Nice, Oct. 1-5, 1984, pp. 153-156.
Mestdagh Denis J. G.
Pauwels Bart J. G.
Van Engelshoven Robertus J.
ALCATEL N.V.
Horabik Michael
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