| 摘要 |
<p>A method and apparatus are described for determining whether a mobile terminal 105 of a communications system has moved outside a locale 107. The terminal is able to measure the relative time offsets of the signals, received by the terminal from transmitters of the network, relative to each other or to a reference. The method includes measuring, at a first time when the terminal is within a given locale, the time of receipt of the signals received by the terminal from a plurality of the transmitters 101-103 relative to a reference or to each other, to create a first set of one or more receive time offsets and storing the first set. At a second time when it is desired to determine whether the mobile terminal has moved outside said locale, the time of receipt of one or more signals received by the terminal 105 from one or more transmitters 101-103 of the plurality of transmitters relative to a reference or to each other is measured, to create a second set of one or more receive time offsets. Using receive time offsets from corresponding transmitters in the first and second sets, the change or changes in receive time offsets is calculated. The change or changes, between the first and second times, in transmission time offsets of the signals transmitted by at least one transmitter of the network relative to a reference or to another transmitter of the network is obtained. One or more movement indicators are calculated by subtracting said change or changes in obtained transmission time offsets from the corresponding change or changes in receive time offsets, and the movement indicators are compared with one or more threshold values in order to determine whether the mobile terminal has moved outside the locale.</p> |
