Network-based location of mobile transmitters

摘要

In an overlay, network-based, wireless location system, LMUs typically co-located with BTSs are used to collect radio signaling both in the forward and reverse channels for use in TDOA and/or AOA positioning methods. Information broadcast from the radio network and by global satellite navigation system constellations can be received by the LMU and used to reduce the difficulty of initial system configuration and reconfiguration due to radio network changes.

主权项

1. A method for improving receiver resolution in a network-based wireless location system (WLS) associated with a single carrier frequency-division multiple access (SC-FDMA) based wireless communications network that relies on dynamic scheduling of physical resources in both a frequency domain and a time domain, wherein both downlink and uplink radio resources are under control of an eNodeB (eNB), wherein the eNB grants uplink time and frequency allocations for each user equipment device (UE) by assigning resource blocks (RB), comprising:
collecting an uplink signal from a UE using a location measuring unit (LMU) in the vicinity of the UE; correlating the collected uplink signal against a reference signal to produce a first correlation signal; identifying a first greatest correlation peak within the first correlation signal corresponding to a first particular time and frequency, wherein the first particular time is identified as a first time-difference-of-arrival (TDOA) value, and wherein the uplink signal from the UE is characterized by a first bandwidth (BW) that is less than or equal to the bandwidth of the RB assigned to the UE; forming a secondary time search window centered on the first TDOA value and having a width set to the reciprocal of the first bandwidth (1/BW) used by the UE; correlating a sounding reference signal (SRS) burst transmitted by the UE against the uplink signal collected by the LMU to produce a second correlation signal, wherein the SRS burst is transmitted by the UE in a single predefined orthogonal frequency division multiplexing (OFDM) symbol period of a subframe, and wherein the SRS burst is characterized by a bandwidth that is broader than the bandwidth of the RB assigned to the UE; identifying a second greatest correlation peak within the second correlation signal, wherein the second correlation peak is identified as a second TDOA value; and reporting the second TDOA value for the LMU.