On pair relationships in time‐division switching network

Abstract

Since a PCM transmission path can carry voice signals in one direction, the time‐division switching network at any PCM telephone exchanges employs a four‐wire configuration. Therefore, a pair of paths is required to form one connection. A general way of preparing such pairs is to establish the pair relationships between switches or links in the switching networks and to create paths automatically based upon those relationships. Having implemented these pair relationships, the blocking probability, the amount of path hunting and the required amount of control hardware for switching networks can be reduced considerably. Pair relationships are quite important in the efficient composition of time‐division switching networks. However, no general theory exists yet for the pair relationships. This report presents an overall study on the pair relationships in time‐division switching networks. First, we define the pair relationships and classify them into several forms and then present practical examples. We then describe how to compose the more important pair relationships and briefly review the connection patterns that are produced by forming the pair relationships and modifying link connection patterns. Finally, we explain how to compose favorable pair relationships based on the above study conclusions.