E911 overlay solution for GSM, for use in a wireless location system
First Claim
1. A wireless location system overlaid on a GSM or UMTS wireless communications system, comprising:
- first and second location measuring units (LMUs) for collection of a mobile transmitter'"'"'s radio emissions, wherein each of said first and second LMUs is co-located and shares an RF antenna with a base transceiver station (BTS) of said wireless communications system;
a sensor, operatively coupled to said first LMU, for monitoring of control channel messages for emergency call detection and channel allocation; and
a central processor, operatively coupled to said first and second LMUs, for the tasking of LMUs and computation of the mobile transmitter'"'"'s position.
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Accused Products
Abstract
In a network overlay Location Services solution for a GSM communications network, the LMU monitors the uplink and/or downlink control channels and determines which call originations are for E911 emergencies and which call setup (Stand-alone Dedicated Control Channel, or SDCCH), assigned traffic (TCH) and associated (Slow Associated Control Channel, or SACCH) channels are subsequently assigned. Capturing the energy on the call setup channel, SDCCH, and its associated SACCH will typically provide a sub-100 meter level of accuracy. If not, the SMLC can redirect the LMU to the assigned traffic channel, TCH, to capture additional RF energy and improve the location accuracy as required. This approach takes advantage of the fact that Channel Request messages on the RACH include an information element that indicates the purpose for the access request. One of the values of this information element identifies that the Channel Request is for an emergency call. By monitoring the Access Grant channels (downlink), e.g., the AGCH, the primary (serving) LMU (LMU 200A in FIG. 1) can capture the Immediate Assignment Message (IMM ASS) for emergency calls. The Immediate Assignment Message contains the Channel Request message (with the emergency call indication) and the SDCCH channel to be used by the MS for subsequent call setup messaging. The primary LMU will forward the Immediate Assignment Message to the SMLC, which will task the cooperating LMUs to collect the RF energy from the associated SDCCH, SACCH and TCH channels and provide TDOA, AoA, and FDOA determinations.
169 Citations
74 Claims
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1. A wireless location system overlaid on a GSM or UMTS wireless communications system, comprising:
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first and second location measuring units (LMUs) for collection of a mobile transmitter'"'"'s radio emissions, wherein each of said first and second LMUs is co-located and shares an RF antenna with a base transceiver station (BTS) of said wireless communications system; a sensor, operatively coupled to said first LMU, for monitoring of control channel messages for emergency call detection and channel allocation; and a central processor, operatively coupled to said first and second LMUs, for the tasking of LMUs and computation of the mobile transmitter'"'"'s position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A method for use in a wireless location system comprising a plurality of location measuring units (LMUs) that are co-located and share an RF antenna with a corresponding base transceiver station (BTS) of a GSM or UMTS wireless communications system, comprising:
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monitoring uplink and downlink control channel messages for emergency call detection and channel allocation, said monitoring including the detection of at least one pre-defined control channel message indicative of an emergency call being initiated by a mobile transmitter, and the detection of at least one additional message indicative of channel assignment information for said emergency call; employing said channel assignment information to tune a plurality of LMUs to the assigned channel for the reception of signals transmitted by said mobile transmitter; and computing the mobile transmitter'"'"'s position using the signals received by the plurality of LMUs in conjunction with time difference of arrival (TDOA) and/or angle of arrival (AOA) algorithms. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51)
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52. A wireless location system (WLS) overlaid on a GSM or UMTS wireless communications system, comprising:
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a first Location Measuring Unit (LMU), which in use is operable as a primary LMU for monitoring a downlink control channel carrying signals from a Base Transceiver Station (BTS) to a first Mobile Station (MS), and from said downlink control channel identifying an E911 call origination from the first MS and identifying call setup (SDCCH), assigned traffic (TCH) and associated channels subsequently assigned to said first MS; at least one additional LMU, which in use is operable as a cooperating LMU; and a Serving Mobile Location Center (SMLC) for receiving data from the primary and cooperating LMUs and calculating the geographic location of the first MS; wherein the primary and cooperating LMUs are operable to capture energy on the uplink call setup channel, SDCCH, and its associated channels, and provide information to the SMLC sufficient to enable the SMLS to calculate the geographic location of the first MS. - View Dependent Claims (53, 54, 55, 56, 57, 58, 59, 60)
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61. A wireless location system (WLS) overlaid on a GSM or UMTS wireless communications system, comprising:
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a first Location Measuring Unit (LMU), which in use is operable as a primary LMU for monitoring a downlink control channel carrying signals from a Base Transceiver Station (BTS) to a first Mobile Station (MS), and from said downlink control channel identifying an E911 call origination from the first MS and identifying call setup (SDCCH), assigned traffic (TCH) and associated channels subsequently assigned to said first MS; at least one additional LMU, which in use is operable as a cooperating LMU; and a Serving Mobile Location Center (SMLC) for receiving data from the primary and cooperating LMUs and calculating the geographic location of the first MS; wherein the primary and cooperating LMUs are operable to capture energy on an uplink call setup channel and its associated channels, and provide information to the SMLC sufficient to enable the SMLS to calculate the geographic location of the first MS; and
wherein the WLS is overlaid on the wireless communications system in that each of said first and at least one cooperating LMUs is co-located with a Base Transceiver Station (BTS) and shares an RF antenna of the BTS. - View Dependent Claims (62, 63)
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64. A wireless location system (WLS) overlaid on a GSM or UMTS wireless communications system, comprising:
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a first Location Measuring Unit (LMU), which in use is operable as a primary LMU for monitoring a control channel carrying signals from or to a Base Transceiver Station (BTS) to or from a first Mobile Station (MS), and from said control channel identifying an E911 call origination from the first MS and identifying call setup (SDCCH), assigned traffic (TCH) and associated channels subsequently assigned to said first MS; at least one additional LMU, which in use is operable as a cooperating LMU; and a Serving Mobile Location Center (SMLC) for receiving data from the primary and cooperating LMUs and calculating the geographic location of the first MS; wherein the primary and cooperating LMUs are operable to capture energy on an uplink call setup channel and its associated channels, and provide information to the SMLC sufficient to enable the SMLS to calculate the geographic location of the first MS; and
wherein the WLS is overlaid on the wireless communications system such that each of said first and at least one cooperating LMUs is co-located with a Base Transceiver Station (BTS) and shares an RF antenna of the BTS. - View Dependent Claims (65, 66, 67, 68, 69, 70, 71, 72, 73, 74)
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Specification