Abstract: Collisions caused by simultaneous allocation of the same channel identifier (CID) to two AAL2 connections over an ATM virtual channel connection between first and second nodes in an asynchronous network are avoided by the use of status records. Each node maintains a record of currently assigned CIDs and compares the CIDs of incoming connection requests with that record. Where the CID of such an incoming request is found to have been assigned, a message is returned to the request originator refusing the connection request. Preferably a set of CIDs is assigned to one node so that, in the event of a potential collision, that node seizes the connection.

Abstract: A network arrangement for transporting service (Servco) traffic between terminals via an asynchronous path comprises a servco access layer incorporating multimedia gateways for access by said terminals, an asynchronous network layer, a service layer incorporating adaptation layer switches each coupled to the network layer, and a transport layer providing a connection medium between the adaptation layer switches. The Servco traffic is carried in ATM minicells over the network layer. Delineation of the minicells is effected by searching the received ATM stream for a valid code word indicating the start of a minicell, and, for that minicell and subsequent minicells, determining length information so as to determine the start of each next minicell.

Abstract: There is disclosed a method and a system for multiplexing data from a plurality of user data sources across an ATM adaption layer type-2 connection, in which a multiplexed trunk group extends across a plurality of common part sub-layer protocol data unit (CSU-PDU) mini-cells, and across a plurality of ATM cells. Large trunk groups are assembled by use of a single bit continuation indicator in the service specific convergence sub-layer header (SSCS) of successive CPS-PDU mini-cells. A packet payload type field (PPT) of the common part sub-layer (CPS)/service specific convergence sub-layer (SSCS) is used to indicate timing of changes in number of user data sources in a trunk group and provides for robust error recovery on loss of a single CPS-PDU mini-cell.

Abstract: An arrangement for interfacing between TDM and ATM networks consists of a family of devices that comprises two groups. The first group comprises devices that perform multiplexing, segregation and routing field translation for the respective traffic type. They may also remove or substitute an outermost layer of encapsulation. These first group devices are bi-directional and output buffered with respect to the network. The second device group comprises devices that perform format conversions between the service payload (voice, video or data) and an adaptation layer control format. These second group devices are also bi-directional and buffering depends on the particular function, e.g. real-time, segmentation.

Abstract: In an adaptation layer switching network, functional partitioning is provided by providing a separation between service specific sublayers (SSCS), common part sublayers (CPS) and transport convergence. This enables the support of a range of SSCS functions via common set of CPS blocks.

Abstract: In a distribution network system delivering services to customers, convergence of internet and asynchronous transfer mode (ATM) protocols provides common distribution of data and real time communications services in the network.

Abstract: A telecommunications system comprises an asynchronous transfer mode (ATM) network having uncommitted bandwidth, and a plurality of adaptive grooming routers (AGR) coupled to the network. The AGRs comprise a group adapted to function as a virtual transit exchange whose fabric and control are distributed over the group. The vitual comprising the AGRs incorporates independent connection control and call routing functions and has means for determining the current system status whereby to set up narrow band connections across the ATM network based on that status determination.

Abstract: An asynchronous transfer mode adaptation layer switching network has independent call routing and connection control for setting up connections across the system. A plurality of adaptation layer switches (ALS) coupled to the ATM network comprise a group adapted to function as an adaptation layer switching network whose fabric and control are distributed over the group. The network having means for determining its current system status whereby to set up multimedia calls across the network based on that status determination.

Abstract: A non-geostationary satellite connection-less network incorporates a plurality of satellite nodes and ground stations in communication with the nodes. The network is modeled by the corresponding virtual model network. In the virtual network, connections between users are available between virtual nodes and are made according to a restricted set of routing plans based on the modeled virtual paths between those nodes. The virtual model provides a means of determining admission of connection-orientated calls of different quality of service (QoS) traffic class requirements into the network with engineered grade of service (GoS) and QoS guarantees.

Abstract: In a broad band network comprising a plurality of edge switches interconnected by a plurality of tandem switches, IP packet data is routed by determining from each packet whether that packet forms part of a flow of packets. Where a packet is determined to be part of a flow, it is segmented into minicells for transmission over a permanent virtual channel established across the network for that flow. Where a packet is not determined to be part of a flow, a destination edge switch is identified for that packet which is then transported to that edge switch via a default permanent virtual channel. Permanent virtual channels for new flows are established at the network periphery by defining a succession of nodes and virtual channels (VCs) to be used to reach the destination of that flow.

Abstract: A non-geostationary satellite network incorporates a plurality of satellite nodes and ground stations in communication with the nodes. Routing and control are established from a virtual model of the network. Within the virtual model, a capacity of space segment band width for different traffic QoS classes can be determined. The relationship between the virtual model and the real network is used to transfer the capacity determination to the real network.

Abstract: Communicative services are transported over a TDMA or TDM access network by packetising the services into minicells which minicells are transported within minislots created by subdivision of the TDM time slots. For low bit rate communicative services only, mini-slots are allocated periodically rather than in the blocks that are allocated to high bit rate services. The packetisation delay inherent within the transport layer can be significantly reduced for these low bit rate services.

Abstract: A communication system typically comprises a number of interconnected broadband-narrowband interfaces (304, 402-404) that together interact to provide a communication resource (400) that can support a call across the system At a time when the communication resource (or a portion thereof) is apparently in place, a terminating node of a broadband-narrowband interface sends a verify-request message (452) backwards across the communication resource. A connection broker (322), coupled to both ends of the communication resource in a particular broadband-narrowband interface (404), is aware of the issuance of the verify-request message, and is therefore able to assess and report, principally, on path connectivity of the communication resource (either within the broadband-narrowband interface or between adjacent interfaces).

Abstract: In order to support both signalling processing on a per channel basis and multiple adaptation protocols, an interface (10) is modularised principally by function. Incident channels (60-62, Cho—Chn) are applied to a routing device (16) that consults a connection map (64) to determine an appropriate path, via an interface (90), for signal processing of each channel, as shown in FIG. 2. Modularised processing platforms (70-74) each contain a number of signal processors (80-86), with each processing platform providing an additional level of indirection with respect to channel handling. In this latter respect, one of the signal processors (86) on each platform is assigned to distribute channel processing to appropriately configured other ones of the signal processors and such that signal processing functions may be distributed between the other ones (80-84) of the signal processors.

Abstract: A data structure, such as a telecommunications connection map, comprises at least one list of data elements which are stored in a predetermined sequence of locations of a memory device. The structure is updated by moving a portion of the list through the sequence of memory locations so as to insert a new element into, or delete or change an existing element at, a particular position in the structure while maintaining the order of the list. Elements of the structure are accessed in the sequence in which they are stored and the structure is updated during the accessing of the structure by moving elements through the sequence of memory locations. A particular application of this invention is in maintaining a connection map for a telecommunications switch, the map storing connection instructions defining into which ATM cell payload received narrowband call data is assembled.

Abstract: A number of narrow band networks are interconnected via a broad band network having a signalling protocol different from that or those of the narrow band networks. Calls between terminals associated with first and second narrow band networks are set up by the selection by a call server of a phantom trunk between the networks. This phantom trunk is used to relay the addresses of the two terminals to be connected. By recognizing that two connection requests have been received at opposite ends of the same phantom trunk, a processor in the second network determines that a connection between the terminals via the broad band network is required. Selection of the phantom trunk and sending of address messages is effected via a selected one of a number of identical connection brokers coupled to the call server. The workload of the call server is shared among the connection brokers coupled thereto.

Abstract: A non-blocking broad band asynchronous transfer mode (ATM) switch having a plurality of ports is adapted to provide a switching function for narrow band traffic by means of adaptive virtual junctors attached to the switch ports to provide ingress to and egress from the switch and each having means for assembly and disassembly of ATM payloads. Each adaptive virtual junctor has a virtual connection with every other adaptive virtual junctor, each said virtual connection comprising a number of virtual circuits. Control means associated with each said adaptive virtual junctor determine on a call by call basis the number of virtual circuits on each virtual connection associated with that adaptive virtual junctor. A semi-permanent pool of capacity may be provided by transmission adaptation devices associated with the adaptive virtual junctors.

Abstract: Interworking between narrow band and broad band traffic in an ATM network is provided by a narrow band switch having a point to multipoint capability. Narrow band channels are mapped to time slots in broad band virtual circuits by providing a mapping between channel addresses and virtual circuit payloads. The narrow band traffic is interfaced to the broad band ATM network via a network of adaptive virtual junctors each of which comprises an n.times.64 kbit/s connection so that the cell assembly delay is reduced by a factor of 1/n. this overcomes the assembly delay problem without the need to resort to unproductive padding. Further, by providing dynamic capacity adjustment of the virtual circuits between the junctors, maximum use is made of the available capacity without the need for the permanent reservation of capacity which may be unused for much of the time.

Abstract: Random bit errors in a digital transmission system in which data is scrambled and subsequently descrambled are detected by parsing the descrambled data into words, determining a syndrome error word for each data word, and determining a parity error word for each data word. A data word is left uncorrected when its corresponding syndrome error and parity error words are both zero. Single bit error correction of a data word is effected when its corresponding syndrome error and parity error words are both non-zero. Double or multiple bit error correction of a data word is effected when its corresponding parity error word is zero and its corresponding syndrome error word is non-zero.

Abstract: An ATM communications system incorporates both broadband and narrowband services. A plurality of channels are adapted into groups, each group comprising a virtual circuit for transmission purposes. Each group is subsequently readapted back to individual channels. Any channel can be connected with any virtual circuit and each group of channels comprising a virtual circuit maintains time slot integrity throughout the adaptation and transmission process.