Data transmission system

Claim 2

An electrical intelligence transmission system, in which both circuit-switched connections and packet-switched connections can be set up, circuit-switched connections having priority over packet-switched connections, in which a said circuit-switched connection is set up using a free one of a number of time slots in a time division multiplex transmission system, in which at any time at which one or more circuit switched connections are in existence the remainder of the system bandwidth is available for the establishment of packet-switched connections, in which if all time slots are in use for circuit-switched connections any packets awaiting transmission are stored in buffer storage means, being released via the transmission medium as and when time slots become available, and in which the sharing of the transmission medium between the circuit-switched connections and the packet-switched connections is adjusted dynamically in accordance with the traffic offered to the system and without interference with connections which have already been set up.

Claim 3

An electrical intelligence transmission system according to claim 1, in which clocks are generated at each end of the transmission system in order to control the shared proportion of transmission.bandwidth and in which the control information is derived from common channel signalling for the establishment and clearing of circuit switched connections.

Claim 4

An electrical intelligence transmission system according to claim 2 in which synchronism of the clocks is maintained by means of a signal multiplexed with frame' alignment signals.

Claim 5

An electrical intelligence transmission system, in which both circuit-switched voice connections and packet-switched non-voice connections can be set up, circuit-switched connections having priority over packet-switched connections, which includes a time division multiplex (TDM) transmission system, means whereby circuit-switched connections are set up such that each such connection uses a free one of a number of time slots in the TDM system frame, means to monitor the system to detect a condition in which less than the full number of time slots are in use for circuit-switched connections, means responsive to the detection of such a condition to allocate the system bandwidth corresponding to the time slots not in use for circuit-switched connections to the establishment of packet-switched connections, the arrangement being such that the bandwidth represented by two or more such available time slots may be used for the same packet-switched connection, buffer storage means in which if all time slots are in use for circuit-switched connections any packets awaiting transmission are stored and means under control of said monitoring means for releasing packets from the buffer store to the transmission medium over which both types of connections are conveyed as and when the bandwidth corresponding to free time slots becomes available, the arrangement being such that the sharing of the transmission medium's bandwidth between the circuit-switched and the packet-switched connections is adjusted dynamically in accordance with the traffic offered to the system and without interference with circuit-switched connections which have already been set up.

Claim 6

An electrical intelligence transmission system, in which both circuit-switched voice connections and packet-switched non-voice connections can be set up, circuit-switched connections having priority over packet-switched connections, which includes a time division multiplex (TDM) transmission system, means whereby circuit-switched connections are set up such that each such connection uses a free one of a number of time slots in the TDM system frame, means to monitor the system to detect a condition in which less than the full number of time slots are in use for circuit-switched connections, means responsive to the detection of such a condition to allocate the system bandwidth corresponding to the time slots not in use for circuit-switched connections to the establishment of packet-switched connections, the arrangement being such that the bandwidth represented by two or more such available time slots may be used for the same packet-switched connection, buffer storage means in which if all time slots are in use for circuit-switched connections any packets awaiting transmission are stored and means under control of said monitoring means for releasing packets from the buffer store to the transmission medium over which both types of connections are conveyed as and when the bandwidth corresponding to free time slots becomes available, the arrangement being such that the sharing of the transmission medium's bandwidth between the circuit-switched and the packet-switched connections is adjusted dynamically in accordance with the traffic offered to the system and without interference with circuit-switched connections which have already been set up.