LTE user equipment positioning system and method
A method of determining the location of a mobile device in a communications network having a plurality of nodes, one of the plural nodes serving the device. Observed positioning measurements for a mobile device may be received from the serving node and uplink enhanced cell identification (E-CID) positioning measurements received from the mobile device. One or more ranges between ones of the plural nodes and the mobile device may then be determined as a function of the received observed positioning measurements and the received uplink E-CID positioning measurements. A geographic location of the mobile device may then be estimated as a function the determined one or more ranges.
1. A method of determining the location of a mobile device in a communications network having a plurality of nodes comprising the steps of:
(a) receiving observed positioning information for a mobile device from one or more nodes;
(b) determining downlink transmission time of a signal from the one or more nodes as a function of the received observed positioning information;
(c) receiving uplink positioning information from the mobile device;
(d) determining a propagation delay between a node serving the mobile device and the mobile device as a function of the received uplink positioning information;
(e) determining downlink timing information from the serving node as a function of the determined downlink transmission time and the determined propagation delay;
(f) determining one or more ranges between additional nodes and the mobile device as a function of the determined downlink transmission time and the determined downlink timing information; and
(g) determining a location of the mobile device as a function the determined one or more ranges and the determined propagation delay.
2. The method of claim 1 wherein the received observed positioning information is received from a serving eNodeB and a reference eNodeB or a serving base station and a reference station.
3. The method of claim 1 wherein the additional nodes are eNodeBs or base stations not in active communication with the mobile device.
4. The method of claim 1 wherein the observed positioning information includes System Frame Number initialization time.
5. The method of claim 1 wherein the downlink transmission time is determined using the relationship: Tx_enb n =SFN n −δ n , where Tx_enb n represents transmission time of a downlink frame at a transceiver antenna port of an n th node, SFN n represents System Frame Number initialization time at the n th node, and δ n represents delay at the n th node.
6. The method of claim 1 wherein the uplink positioning information includes timing advance information of a signal transmitted from the mobile device.
7. The method of claim 6 wherein the timing advance information is timing advance type 1 or timing advance type 2.
8. The method of claim 1 further comprising the step of adjusting the determined downlink timing information as a function of an observed positioning reference signal between a reference and neighboring nodes.
9. The method of claim 1 wherein the step of determining a location of the mobile device further comprises adjusting each determined range and adjusting the determined propagation delay to determine the location of the mobile device.
10. The method of claim 9 wherein the adjustment of each range is approximately the same amount.
11. The method of claim 9 wherein the step of adjusting each determined range and adjusting the determined propagation delay includes adjusting each range and the propagation delay as a function of a value selected from the group consisting of: downlink signal strength, UE Rx−Tx time difference, distance values between nodes, topography of the network, terrain, reference received signal power, reference signal quality, presence of multipath, and combinations thereof.
12. The method of claim 9 wherein the adjustment of each determined range and the adjustment of the determined propagation delay are different.
13. The method of claim 1 wherein the mobile device and the one or more nodes are synchronized.
14. A method of determining the location of a mobile device in a communications network having a plurality of nodes, one of the plural nodes serving the device comprising the steps of:
(a) receiving observed positioning measurements for a mobile device from the serving node;
(b) receiving uplink enhanced cell identification (E-CID) positioning measurements from the mobile device;
(c) determining one or more ranges between ones of the plural nodes and the mobile device as a function of the received observed positioning measurements and the received uplink E-CID positioning measurements; and
(d) determining a geographic location of the mobile device as a function the determined one or more ranges.
15. The method of claim 14 wherein the step of receiving observed positioning measurements further comprises determining downlink transmission time of a signal from the serving node as a function of the received observed positioning measurements.
16. The method of claim 14 wherein the step of receiving uplink E-CID positioning measurements further comprises:
determining a propagation delay between the serving node and the mobile device as a function of the received uplink E-CID positioning measurements; and
determining downlink timing information from the serving node as a function of the determined propagation delay.
17. The method of claim 16 wherein the uplink E-CID positioning measurements includes timing advance information of a signal transmitted from the mobile device.
18. The method of claim 14 wherein the step of determining a geographic location of the mobile device further comprises adjusting each determined range to determine the geographic location of the mobile device.
19. The method of claim 18 wherein the adjustment of each range is approximately the same amount.
20. A method of determining the location of a mobile device in a communications network having a plurality of nodes comprising the steps of:
(a) receiving observed time difference of arrival (OTDOA) measurements for a mobile device from one or more of the plural nodes;
(b) receiving uplink enhanced cell identification (E-CID) positioning measurements from the mobile device;
(c) determining one or more ranges between the plural nodes and the mobile device as a function of the received OTDOA measurements and received uplink E-CID positioning measurements;
(d) adjusting each determined range as a function of a metric; and
(e) determining a geographic location of the mobile device as a function the adjusted ranges.
21. The method of claim 20 wherein the adjustment of each range is approximately the same amount.
22. The method of claim 20 wherein the metric is determined as a function of a value selected from the group consisting of: downlink signal strength, UE Rx-Tx time difference, distance values between nodes, topography of the network, terrain, signal power, signal quality, presence of multipath, and combinations thereof.
23. The method of claim 20 wherein the E-CID positioning measurements include timing advance information of a signal transmitted from the mobile device.