Improvement of loop network availability under failure conditions by directed transmissions

For service integrated digital TDM telecommunication systems with different loop structures the dependency of the network availability from the network structure and the operation principle is investigated. Single and double loop networks with an undirected and directed transmission of the messages are compared in undisturbed and disturbed network operation states. It is shown that the application of a directed transmission not only keeps the network operational in a failure state but likewise improves the network availability by decreasing the total traffic load on the transmission lines. The availability is estimated either by the traffic loss or the degradation of the traffic distribution between the subscribers if no failure or one or more interrupts of the message flow arise. For the message exchange, principles of multiple access and decentralized switching are used.