Cellular congestion reduction via intracell handover providing fixed and flexible service

The invention relates to a method at a cellular radio communications system which makes possible that the probability of congestion for multislot mobiles in said system is reduced. In the future, the GSM-system will offer high speed data services, at which one of these is HSCSD (High Speed Circuit Switched Data). The HSCSD-service includes two services called “fixed service” and “flexible service”. At the first mentioned service, the mobile is allocated a fixed number of time slots which shall be allocated during the whole call, whereas at the last mentioned service the number of allocated time slots can vary during the course of the call. The mobile stations of today with their simplex filters can perform only one thing at a time, i.e. either transmit, measure or receive signals. It therefore is important to have possibility to allocate consecutive time slots for multislot mobiles. By that demands are made for that the algorithm of the channel allocation in an efficient way shall be able to allocate the free time slots in order to increase the channel utilization and data speed. The invention solves this problem by utilizing intracell handover to meet the demands for consecutive time slots. This results in that the probability of congestion for mobiles which have requested “fixed service” will be reduced and approach the probability of congestion for one-slot mobiles. Another advantage with intracell handover is that the data speed for mobiles which have requested “flexible service” will increase.