Traffic congestion control based on call density control
Hiroshi Tokunaga, Hiromichi Kawano · Electronics and Communications in Japan (Part I Communications) · 1989
Abstract As a means to control traffic congestion in the communication system, it is most effective to control the traffic directed toward the congested switch, at the input of the network. From such a viewpoint, a method is employed in which a constant rate of traffic is controlled at the originating switch, according to the state of the switch congestion. However, the congestion recently observed frequently in ticket reservation and in other cases is difficult to be controlled completely by this method. From such a viewpoint, this paper proposes a control method based on the combination of the following two schemes: (1) the call number distribution, where the number of calls which can be processed in the congested switch is allocated individually to the originating switches; and (2) the call density control, where the number of connected calls (output call attempts) per unit time is controlled to within the specified value at the originating switch. The characteristics of the output call attempts at the originating switch are analyzed for the call density control. It is shown that the mean number of output call attempts is close to the ideal, but the variation coefficient of the output call attempts is somewhat large compared with the traditional call gap control. An extended call density control is proposed, where the number of output call attempts is adjusted in each time interval according to the state of connection, and it is shown that the mean number of output call attempts is close to the ideal. By employing the proposed scheme, the normal traffic can be secured, even if the control is started before the congestion arises, and the peak can be reduced when there is a sudden increase in originating calls.