Patent ID: 9060281
Filing Date: 2015-06-16
Classification: G01S,H04W

Abstract:
1. A method for locating a first wireless device operating in an LTE wireless communications system, wherein, to initially request access to the LTE wireless communications system, the first wireless device is configured to employ a Random Access Channel (RACH) and a process in which the first wireless device transmits a RACH preamble signal representing one of a predetermined total number of RACH preambles available in the LTE wireless communications system, wherein the predetermined total number of RACH preambles are shared among a plurality of mobile devices for initial access, the method comprising: employing a plurality of location measuring units (LMU) to monitor an LTE uplink channel for uplink RACH transmissions, wherein each of the plurality of LMUs is configured to operate as a reference LMU or a cooperative LMU; upon detection, by at least one of said LMUs, of a RACH preamble matching one of the predetermined total number of RACH preambles available in the LTE wireless communications system, recording a preamble identifier (RA-RNTI) associated with the RACH preamble in a database and employing a reference LMU to monitor a downlink channel of the LTE communications system for a RACH Response signal (RAR) addressed to the first wireless device via a first temporary identifier (C-RNTI) for the first wireless device; employing the reference LMU to detect a connection request message (RCC Connection Request) transmitted by the first wireless device, the connection request message including a second temporary identifier (S-TMSI) and a reason code (Establishment Cause), wherein the second temporary identifier is an SAE Temporary Mobile Subscriber Identity (S-TMSI) previously assigned to the first wireless device; associating the first temporary identifier (C-RNTI), second temporary identifier (S-TMSI), and reason code (Establishment Cause) in the database such that the database provides an access record including the preamble identifier (RA-RNTI), first and second temporary identifiers (C-RNTI, S-TMSI), and reason code (Establishment Cause); and determining whether the reason code matches a first predefined trigger, and if so locating the first wireless device.