Transmission system for data cells in a local network

Abstract

In a transmission system for the transmission of data cells between local stations and a central station, cell arrivals are registered in a local register (CAR). Those registrations are periodically transmitted to the central station. The central station thereafter transmits the permit codes to the various local stations, in order to transmit the data cells which are most ready. In each local station the data cell which is most ready for transmission is transferred from a cell arrival buffer (CAB) to a cell departure buffer (CDB) as long as the permit code expected for the station, on the basis of the number of time slots since the cell arrival, remains forthcoming. The data cell remains in the buffer as long as no permit code addressed to the station is received. The data cell is transmitted as yet after the reception of a permit code addressed to the station. The data cell is discarded, however, as soon as an empty (unaddressed) permit code is received while the data cell still resides in the buffer. All this has the effect that transmission errors do not permanently frustrate the system.