A Multi-Bit-Rate Substitute-Communication System with High Call-Carrying Capacity

A multi-bit-rate substitute-communication system (MSCS) is an efficient means to achieve higher call-carrying capacity in a congested network. When a trunk line is congested with a large amount of traffic, MSCS makes subscribers communicate by a lowerbit-rate medium, even though they request higher-bit-rate forms. This limitation is made when the number of idle basic channels is less than or equal to the predetermined system constant. This paper describes the control method, traffic characteristics, and concrete traffic design method, using a dual-bit-rate class (64 kbits/s, 8 kbits/s) model. It is found that the MSCS carries about five times as many calls as a conventional network without the MSCS.