Overload control in a communications network

Abstract

An adaptive overload system for controlling the amount of traffic processed by a network access controller is described for a network access controller arranged to control a plurality of network access points. Each network access point provides traffic with access to the communications network and the system comprises determining at the network access controller if an overload condition exists, and if so, generating at least one global constraint to restrict the rate at which a network access point admits said traffic to the communications network. The controller then multicasts at least one global traffic constraint to one or more of said plurality of network access points. Each network access point receiving the global constraint then processes the global traffic constraint to determine a plurality of local constraint conditions. The receiving network access point performs the following steps to determine said local constraint conditions: determining a local predetermined gap interval to be imposed on said traffic; and determining an initial gap interval which differs from the subsequent local predetermined gap intervals, the initial gap intervals differing between each of said plurality of network access points. The initial gap intervals are determined in either a random or pseudo-random manner to ensure synchronization effects at the network access controller which would otherwise occur in high call rate scenarios are removed.