| 摘要 |
<p>It has not been possible to monitor the movements of the terminal device in an area smaller than a cell in systems in which part of the subscriber connection is formed by a radio connection between the terminal device and the base station. However, in some cases, it is preferable to restrict mobility of the terminal device to a limited area within a cell. This is possible by measuring a value comparable to the signal propagation time between the terminal device and at least one base station. The value can be the timing advance between the terminal device and the base station or it can consist of the differences in the signal propagation times between the terminal device and several base stations. The value is compared to the reference value and, on the basis of the comparison, it is deduced whether the terminal device is in the area allowed for it. The method can be used, in addition to monitoring the location of the terminal device, in such a way that the user creates one or several allowed areas, such as home and a summer cottage. A lower tariff can be applied for calls made from these areas than for calls made in other parts of the network. The invention is suitable for use in both a cellular network and in a so-called WLL network, which implement wireless subscriber connections.</p> |
