International Business Machines Corporation

Harold G Markey

Lynn P West

Donald C Flemming

Joseph M Bensadon

Robert P Barner

Jacques A Besseyre

Ralph J Metz

A self-switched in-band signaling communication apparatus is disclosed which enables the switching of the signaling mode to the data mode on a single transmission line between a data terminal equipment or data communication equipment and the data port of a satellite communications controller, and the opposite switching from the data mode to the signaling mode under a single control bit. Signaling to and from the data port of the satellite communications controller is carried out using conventional dialing pulses at a signaling rate which is independent of the line data rate. The apparatus provides for the multipoint communication between a plurality of data terminal equipments using a unique multipoint turn-around process which provides a mobile bandwidth capability for the communications system.

Self-switched data port in-band signaling protocol

Digital exchange terminals are linked by earth satellite and terrestrial point-to-point time division trunks in a privately coordinatable time division switching and communication network serving to connectively link multiple ports attachable to separate voice telephone and data communication 'subscriber' trunk lines. The terminals operate relative to the satellite in a time division multiple access (TDMA) system with a portion of the system capacity (traffic burst channels) variably allocated to the terminals by demand assignment. The demand assignment is autonomously controlled by the terminals through supervisory communications carried over dedicated satellite channels (Order Wires) also utilized for synchronization. Internally the terminals employ modular multiplex switching between ports and 'virtual' channels (buffer stores) and voice activity compression (mapping of groups of up to n virtual channels into groups of up to m, m less than n, actual time division channels on the time division trunks). The activity compression serves to make the terrestrial and satellite channel resources of the system virtually available to more lines than can actually be served in one TDMA frame. External management (data processing) apparatus attached to a terminal line port supplies information stored by the terminals and used by the terminals to restrict options in selecting connection path segments between respective ports and virtual channels. Thus, the network system may be adapted on various levels to balance its traffic loads (demand assignment 'short term', network management/reconfiguration 'longer term', and physical relocation of terminal modules/ports 'longest term').

External management of satellite linked exchange network

Modular digital exchanges linked by earth satellite provide coordinated time division switching and time compressed communication services relative to externally attached telephone and data (user) trunks. Branch exchange modules (NCU's) perform call switching, buffer storage, time compression and activity selective channel assignment handling between individual external user trunks and multi-bit channels of external time division highways (digital links). The latter are linked pyramidally to time division multiple access nodes of the satellite through Network (Nodal) Access Unit modules (NAU's) which perform further time compression handling and adaptive assignment of satellite channels based upon nodal distribution of demand. The NCU modules also provide 'local' switching between user trunks and 'tandem' linkage directly between NCU's (without NAU and satellite handling). The modules have individual common control processors which inter-communicate via reserved signaling channels on the digital links and satellite. The modularity is in increments suitable for adaptive deployment of connection equipment relative to satellite access nodes (e.g. to adapt to shifts in user populations and/or plant facilities).

Modular branch exchange and nodal access units for multiple access

Digital exchange stations linked by earth satellite operate in a coordinately controllable time division switching and communication network system relative to externally attached telephone and data trunks. Modular switching equipment operating in coordination with satellite frames establishes and releases connection paths to trunk stores which interface with time and space domain channels of the system. Circuits through the system utilizing these paths are termed virtual connections because in different frames a circuit may be completed through different channels or even blocked under certain conditions. Telephone speech is converted between analog and digital forms relative to modular groups of 96 ports. Digital switching (slot interchange) equipment serving up to four groups (and cycling in coordination with satellite time division frames) cyclically completes local (intra-station) connections between ports and segments of toll (inter-station) connections between ports and locations in the trunk stores. The trunk stores comprise separate sections for system traffic bound to and from ports of the respective station. A duplicate arrangement of subsections in each section is alternately filled and emptied in successive frames; enabling the station to maintain continuity of communication relative to the system in successive frames. The 192 bit spaces of each location are filled in one frame and emptied in the next frame. Groups of 96 outbound locations are 'virtually' associated for transmission with groups of 48 time division transmission channels of said facilities. The association operates by a process of selection termed voice activity compression (abbreviated VAC) based upon activity information developed at the port interface and carried through the switching equipment in positional association with trunk locations. The VAC process assigns only locations (virtual channels) containing activity to up to 46 of the 48 time channels, eliminating any excess of active virtual channels (over 46) in a selective order of priority. VAC mask information transmitted in a separate one of the 48 time channels indicates the virtual-to-real (96-to-46) assignment for the respective group in the respective frame. A bit in the mask for each virtual channel of the group indicates the assignment or elimination of the respective virtual channel. Assigned channels are transmitted in the time order of respective mask bits. Establishment of virtual connections is restricted system-wide by tables stored in the stations. These tables are subject to external modification and may contain path exclusion information enabling the system to remain effectively operational with inoperative elements.

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Raleigh, NC, United States of America

Harold G Markey