In the telecommunication system, the devices directly used for communication between users are mostly full-utilization link systems with infinite load source loss, while the devices used to control the connection process of communication devices are mostly full-utilization systems with infinite load source waiting. When the number of load sources is not large relative to the capacity of the wire harness, a full utilization system or a partial utilization system with limited load sources is usually adopted.
According to the call behavior of the load source, that is, whether the user makes a new call attempt after the call fails, the wiring harness can be divided into repeated call system and non-repeated call system. There are repeated calls in actual communication systems, and the non-repeated call system is an approximation of the repeated call system.
1) Make full use of the wiring harness. If any service equipment (trunk or machine key) in the wiring harness can be used by any load source in the load source group it serves, it is called full utilization wiring harness.
Fig. 2 shows a fully utilized wire harness consisting of 100 first preselectors (load source groups) of a step switch, and the 10 outgoing wires of its wire arc are correspondingly multiplexed to 10 first selectors (the service equipment is a machine key). Any service device (first selector) in the circle can be used by any load source (first preselector) in the load source group (100 first preselector) it serves.
2) partial use of wiring harness. If any load source in the load source group can only use part of the service equipment in the wiring harness, such wiring harness is called partial utilization wiring harness. Partly, the load source group is divided into several subgroups by using the wiring harness, and the products are reconnected between the outgoing lines of the load group. This structure can be described by the example shown in the figure below.
In the above figure, the 100 load source (the first preselector in the stepping switch) is divided into two load source groups. The step 1 of the first group and the outgoing line of step 2 are correspondingly multiplexed to the first group of selectors 1 and 2, and the step 1 of the second group and the outgoing line of step 2 are correspondingly multiplexed to the first group of selectors 1655. As can be seen from the figure, the first group of selectors 1, 2 (service equipment 1, 2) can only be used by the first group of load sources, and the first group of selectors 1 1, 12 can only be used by the second group of load sources. 3 ~ 10 of the first selection group can be used for the whole load source group (100 first top selector).
Under the same utilization capacity, the partially utilized utilization capacity is lower than the fully utilized utilization capacity. Its traffic load capacity or call loss rate is related to utilization rate and reconnection mode of sub-products. With the same harness capacity and call loss rate, a good multi-connection structure can improve the load capacity of the harness. The higher the utilization rate, the closer the efficiency of the harness is to the full utilization of the harness.