Nortel Networks Corporation

Northern Telecom Limited

Peter John Dyke

Michael Philip Dyer

Mark James Parry

Brian Michael Unitt

Duncan John Forbes

Peter John Etter

Andrew Paul Lewis

Michael Phillip Dyer

A communications network having two complementary optical networks each connectable to a headend, each optical network comprising a plurality of periodic interleaving filters serially connected by optical waveguides such that an output port of one periodic interleaving filter is couple to an input port of another periodic interleaving filter, and wherein an input or output node of the network is formed by a non-serially connected input or output port of a periodic interleaving filter.

Optical network architecture

A system () to enable the transfer of Internet protocol (IP) format data () over a point-to-multipoint passive optical network (PON,) is illustrated in FIG.. An exchange () is connected to a plurality of outstations () via an optical communication resource () including a passive optical splitter () providing isolation to individual outstations. Media access control of the plurality of outstations is administered by the exchange (), with collision detection logic () in the exchange determining collision () of Internet protocol (IP) encoded data communicated thereto through the PON (). The IP encoded data realises a transport mechanism through the PON. Each of the plurality of outstations () and the exchange () is adapted to pass data in an IP format to and from the optical communication resource such that IP encoded data is transported, in use, directly between the outstation and the exchange.

System and method for transfer of IP data in an optical communication networks

Optical fibre ducting system

A local telecommunications network system IS arranged to provide a first asymmetric digital subscriber line (ADSL) service in a first frequency band to a first set of subscribers and a second very high bit rate digital subscriber line (VDSL) service in a second frequency band higher than the first frequency band to a second set of subscribers. Interference between the two types of digital traffic within the multi-pair feeder cables leading to the exchange is suppressed by low pass filtering the ADSL traffic and high pass filtering the VDSL traffic. The filtering may be applied to the line cards to which each subscriber line is connected.

Providing digital services to telephone subscribers

A passive optical network having a plurality of optical splitters/combiners each comprising first and second through ports and at least one drop port. The through ports of the plurality of splitters/combiners are concatenated to form a linear arrangement having two end through ports. Optical signals may be transmitted between the end through ports by means of the linear arrangement; and signals may be transmitted between at least one of the end through ports and one of the drop ports by means of the linear arrangement. The splitter/combiners can be inserted to form drop points in a ring or dual-homed passive optical network to provide flexibility in provision of protection and network reconfiguration.

Passive optical network arrangement

An infrastructure exchange (,) has a cross-point switch that is arranged to couple data transmission between subscriber terminals (,), each having a dedicated modem (,), and at least one assignable modem (,) located in the infrastructure exchange (,). The infrastructure exchange (,) comprises fewer assignable modems than a combined number of dedicated modems within the subscriber terminals (,) and, since the cross-point switch (,) is responsive to the data transmission sent via the modems of the subscriber terminals, the cross-point switch (,) thereby acts to concentrate a ratio of dedicated modems to assignable modems.

Communication system architecture, infrastructure exchange and method of operation

To reduce the complexity, size and power dissipation associated with the deployment of xDSL-type modems in distribution points (140-142) of a telecommunications network, a transparent concentrating optical transmission scheme is interposed between an exchange (100) and a subscriber terminal (210). Specifically, xDSL-type modems (102-104 and 220-224) are employed both within the exchange (100) and, nominally each subscriber terminal (210) of the telecommunication system, while an optical fiber supports the transmission of frequency division multiplexed broadband signals sent between the exchange (100) and the distribution points (140-142). Twisted-pairs then couple respective broadband signals received and demultiplexed at the distribution points (140-142) to appropriately addressed subscriber terminals (210), while upstream transmissions are subjected to a complementary process from the xDSL modems (220-224) in the subscriber terminals (210) to the xDSL modems (220-224) in the exchange (100).

Communication system architecture, exchange having a plurality of

A cabinet for outdoor use for enclosing a rack of electronics equipment has a double skin protective outer casing comprising a lower air intake into a cavity between the skins of the double skin and an upper air output from the cavity to the outside, for unforced cooling air to flow, to extract heat from the equipment by convection. The inner of the skins is formed in part at least by a heat sink of the rack. This unites the thermal management of the rack and that of the enclosure to provide an improved thermal path from the cards in the rack to the cold wall. This means the temperature difference between the inner skin and the air in the cavity can be increased for a given card temperature, so more heat can be extracted. The heat sink may share the back wall of the rack with the motherboard.

Cabinet with enhanced convection cooling

To accommodate the overlay of broadband information over narrowband bearers while reducing cross-talk in upstream and downstream directions, different baseband line codes are used to modulate respective upstream and downstream transmissions on a common wireline communication resource, such as a twisted copper-pair. In this way, filtering components located at each end of a connection can reject cross-talk based upon dissimilar signal characteristics that arise between wanted broadband signals having a first baseband line code and spectrally-shifted cross-talk emanating from interfering broadband signals having a different baseband line code.

Method and apparatus for reducing cross-talk in broadband systems using

To decode an attenuated multi-level signal (42) in a receive interface (120) of communication apparatus, first (134) and second (150) diode pumps co-operate with a biasing chain to ensure that threshold reference levels used by respective positive (52) and negative (54) data comparators are dynamically adjusted to a level dependent upon the attenuated multi-level signal (42) applied to the diode pumps. Particularly, a voltage divider (138-144) acts dynamically to bias differential inputs to the respective positive (52) and negative (54) data comparators, with a ratio between a biasing chain of resistors (138-144) and a common input resistor 128 determining the threshold reference levels used to assign logical levels for the reconstruction of symbols encoded within the multi-level signal (42).

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Widdington, United Kingdom

Peter John Dyke