Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1997-11-12
2001-02-06
Felber, Joseph L. (Department: 2732)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S463000
Reexamination Certificate
active
06185225
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to telecommunications equipment.
Systems for carrying data at increased rates are being developed, and offer the chance to extend the range of services which customers can enjoy using the terminal in their homes. Existing terminals can handle services according to the ISDN specification such as facsimile transmission or computer communication, in additional to analogue telephony, but higher data rates would offer the chance to transmit television signals into the user terminal as well as to permit interactive viewing. Typically, the terminal in the home is linked to the local exchange by means of copper wire pairs, but the increased bandwidth associated with the higher data rates prevents transmission over such distances eg. up to 9 km.
It has therefore been proposed to provide local sites eg. street cabinets for serving subscribers within a, say, 1 km radius, and to combine at that site services which are separately connected to the local exchange or other network eg. ISDN services linked to the local exchange by copper wire pairs and higher data rate services linked by optical fibre. The telecommunications network, it should be noted, already uses street cabinets in densely populated areas, but these are passive devices.
Because the proposed street cabinets would combine signals, it would be necessary to provide a power supply for them. A problem would then arise in the event that the power supply failed.
SUMMARY OF THE INVENTION
The invention provides network terminating equipment for connection by a link to a communication network to receive line signals, comprising processing means arranged to operate at a data rate appropriate to a line signal representing first services and to extract from the line signal the first services and also second services which are generated at a lower data rate than are the first services but which are incorporated within the line signal, the processing means being selectively capable of operating at the lower rate of the second services to extract the second services from a line signal of that lower data rate.
The invention also provides a multiplexer for connection by a link to network terminating equipment, comprising ports for reception from a communication network of data at one rate representing first services and of data at a lower rate representing second services, means for producing and transmitting along the link a line signal representing the first services and the second services, power supply means for the multiplexer, including means for connecting the port for reception of the data representing the second services directly to the link in the event of failure of the power supply means.
The link eg. a copper wire pair carries data at the first rate appropriate to the first service eg. a high data rate service such as TV, but incorporates the data generated at the lower rate eg. ISDN including analogue telephony, the two being combined by the multiplexer. In the event of power failure, the system drops back to the lower data rate service.
Among the suitable access methods being developed for the high speed data rate facility for terminal users are VDSL (Very High Speed Digital Asymmetrical Subscriber Line, HDSL (High Speed Digital Subscriber Line) and ADSL (Asymmetrical Digital Subscriber Line). ADSL is described in ANSI Reference T1.413. Typically, VDSL could operate with a data rate up to 25 Mbit/sec in one direction, and 3 Mbit/sec in the other direction. Typically HDSL has data rates up to 2 Mbit/sec in each direction, and ADSL has rates up to 6 Mbit/sec in one direction, and a few 100 kbit/sec in the other direction. Compared to this, basic rate ISDN is generated typically at 144 kbit/sec. The lower data rate associated with the second services may be incorporated with the higher data rate associated with the first services in the multiplexer by using the apparatus and method claimed in our co-pending patent application No. 08/970,260, filed Nov. 14, 1997.
REFERENCES:
patent: 4481621 (1984-11-01), Schmack et al.
patent: 5883941 (1999-03-01), Akers
Felber Joseph L.
Kirschstein et al.
Marconi Communications Limited
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