| 摘要 |
<p>The invention relates to assistance in locating a mobile communication terminal (2) in a closed environment on the basis of signals C/A from a satellite location system. The signals C/A are encoded and broadcasted by a set of pseudolite base stations (PS1-PS4) set up within the closed environment over a unidirectional radio frequency communication link (10) enabling a satellite receiver, equipping said mobile communication terminal (2), to receive the signals broadcasted by each of the pseudolite base stations of said set. The encryption key is selected such that the signals encoded by the pseudolite base stations correspond to the uncorrupted signals C/A that are shifted according to a time distribution or frequency hopping rule. The terminal (2) is then authenticated on the basis of identification signals transmitted by the latter over a wireless transmission link (11) that is separate from said unidirectional communication link (10), said link (11) being a short link, maintained between the mobile communication terminal (2) and at least one station (WF1-WF3) set up inside the environment, or a data link of a radio cellular system. The decryption key is transmitted over the wireless transmission link to the mobile terminal if authentication is positive.</p> |
