Abstract: A transmitting unit for use in sending data in packets in timeslots within time frames, each packet being sent in a timeslot, the unit comprising means to reserve for uplink transmission in the next uplink time frame a number of timeslots (X), the number of timeslots (X) being determined dependent upon a value which is the number of timeslots (Y) used for uplink transmission in the previous uplink time frame plus the number of packets (Z) remaining for uplink transmission during the last time frame minus the number of time slots (Q) to be used in the present uplink time frame.

Abstract: A transmitting unit for use in sending data in packets in timeslots within time frames, each packet being sent in a timeslot, the unit comprising means to reserve for uplink transmission in the next uplink time frame a number of timeslots (X), the number of timeslots (X) being determined dependent upon a value which is the number of timeslots (Y) used for uplink transmission in the previous uplink time frame plus the number of packets (Z) remaining for uplink transmission during the last time frame minus the number of time slots (Q) to be used in the present uplink time frame.

Abstract: A method of providing redundancy in a LAN Emulation network in the event an LES fails. The method is light in that it does not require complicated database synchronizations between LECSs and their associated complex message protocol exchanges. The method comprises defining a plurality of LESs per ELAN, but permitting only one of the LESs to be active at any one moment in time. All the LECSs are configured with the same Topology Database which include the all the potential LESs for each ELAN. The LECSs try to connect to each LES and the results are logged. The operative LESs having the highest priority is chosen as the active LES whereby all LECs get assigned to the active LES. When the active LES fails the LECs attempt a new connection to LECs. The LECs assigns the LECs to another operative LES in the database list. All the LECs previously connected to the failed LES, are attached to the new LES assigned by the LECs and communications are reestablished with the new LES.

Abstract: This invention relates to a supervisory control and data acquisition (SCADA) system in which a central station (10) sends control information to, and acquires information from remote stations (11, 12) over a wire, radio or other link. Each station comprises a tabular memory (15-18) comprising storage locations in an `x` direction for storing data relating to different elements of the second system and storage locations in a `y` direction for storing data relating to different parameters of those elements. Transmitting means are provided for transmitting a message from one unit to the other unit, said message comprising an `x` part, a `y` part and a qualifier, for reading from and writing to storage locations in the tabular memory of the other unit depending on the result of a logical operation defined by the qualifier. The tabular memory can equally be considered to have a tree-like structure.