Time-division switching networks with partial-access pulse shifters performing serial-parallel conversion

Some means of time-slot interchanging is required in a pulse-code-modulation (PCM) transit switching system to satisfy the blocking requirements due to the fact that average trunk loading is high and that the time slots of incoming calls are preassigned at the remote office. This paper presents the use of serial-to-parallel conversion and parallel-to-serial conversion pulse shifters, both having limited time-slot interchange capability at the input and the output of the switching networks, respectively. The features of the system are that the required memory capacity is much smaller than the conventional systems and that serial transmission and parallel switching are possible. The results of optimization through blocking probability evaluation and network cost estimation are also described for networks with one, two, and three gate stages, and with an additional parallel pulse-shifter stage.