Access method for distributed dynamic channel allocation in microcells

Abstract

A method of providing local autonomous control of channel allocation of a cellular telecommunications network. In one prior art method, which can be identified as the timid method, a channel is selected for use by an incoming user if it is not being used by any of the cells which surround it. Otherwise, another channel is selected according to the same rule. The channels are tested in random order and a call is blocked if all of the channels are in use. For heavy loading, because of the vagaries of the way the demand for channels occurs, this method can result in inefficient channel deployment. In another method, which can be identified as the aggressive method, a channel is selected for use by an incoming user even if that channel is currently being used in the surrounding cells. If the channel is in use, the incoming user 'bumps' the current user off the channel in the timid mode. The 'bumped' user is then forced to find and use another channel. With this method, an unreasonable number of reconfigurations and an unreasonable number of dropped calls can result, especially when the system is heavily loaded. This invention integrates the aggressive and timid methods to obtain the best of both: the former's improved performance and the latter's stability. Initially, the timid mode is used to look for a channel with acceptable interference. However, if the timid mode fails to obtain a channel, the call is not necessarily blocked. Instead, the mode of operation becomes more aggressive and the first channel tested that has only modest interference is taken. The 'bumped' user on that channel then attempts to locate another channel. If the 'bumped' user is unsuccessful, the incoming user must then retreat and is blocked.