A mathematical model is proposed for the operation of a cell in a mobile communication network with moving users. The cell is divided into several zones distinguished by the strength of the signal and, consequently, by the transmission rate. The process of users activation in various zones is defined by the marked Markovian arrival process. After activation, a user can move and transit to other zones or to another cell. The service rate of an arbitrary user depends on the zone where the user is currently located and the total number of active users in the cell. When the total bandwidth required by all active users exceeds the bandwidth of the base station, a proportional reduction of the bitrate provided to each user (bandwidth sharing) is applied. The key performance indicators of the system are computed, and illustrative numerical examples are presented.