# US 2021/0333352 A1 · Mobile-based positioning using assistance data provided by onboard micro-bsa

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- Number: US 2021/0333352 A1
- Document ID: US20210333352A1
- Status: Published application
- Kind: A1
- Application number: 17/227,212
- Filed: 2021-04-09
- Published: 2021-10-28
- Earliest claimed: 2020-04-09
- Assignees: PHY Wireless, LLC
- Applicants: PHY Wireless, LLC
- Inventors: Steven C. THOMPSON; Raphael MALL; Neal RIEDEL; Steven J. CALIGURI; Zane RAU
- Web page: https://patentgrep.com/patent/US20210333352A1

## CPC

- G01S 5/0236: {Assistance data, e.g. base station almanac}
- G01C 21/3815: {Road data}
- G01S 5/0205: {Details}
- G01S 5/021: {Calibration, monitoring or correction (G01S5/0252 takes precedence)}
- G01S 5/0244: {Accuracy or reliability of position solution or of measurements contributing thereto}
- G01S 5/0246: {involving frequency difference of arrival or Doppler measurements (G01S5/02685 takes precedence)}
- G01S 5/02524: {Creating or updating the radio-map}
- G01S 5/0257: {Hybrid positioning (by coordinating position lines of different shape G01S5/12)}
- G01S 5/0268: {by deriving positions from different combinations of signals or of estimated positions in a single positioning system}
- G01S 5/0284: {Relative positioning}
- G01S 5/06: Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements (G01S5/12 takes precedence)
- G01S 5/14: Determining absolute distances from a plurality of spaced points of known location
- G06F 18/21342: {using statistical independence, i.e. minimising mutual information or maximising non-gaussianity}
- G06F 18/2415: based on parametric or probabilistic models, e.g. based on likelihood ratio or false acceptance rate versus a false rejection rate
- H04B 17/327: Received signal code power [RSCP]
- H04W 4/029: Location-based management or tracking services
- H04W 64/00: Locating users or terminals {or network equipment} for network management purposes, e.g. mobility management
- H04W 64/003: {locating network equipment}
- G01S 5/10: Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements {, e.g. omega or decca systems}(G01S5/12 takes precedence {; beacons and receivers cooperating therewith G01S1/306, G01S1/308})
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H04B: TRANSMISSION
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

A method for estimating position of a mobile device which includes receiving, from a network server, observed time difference of arrival (OTDOA) assistance data for a first plurality of cells from a base station almanac (BSA) accessible to the network server. The OTDOA assistance data is stored, within a memory of the mobile device, as a first micro-BSA. A position estimate for the mobile device is determined based upon time difference of arrival (TDOA) measurements associated with an initial subset of the first plurality of cells and initial OTDOA assistance data corresponding to the initial subset of the first plurality of cells. The initial OTDOA assistance data may be generated by the micro-BSA based upon an initial seed estimate.

## Claims

### Claim 1

A method performed in a mobile device for estimating position of the mobile device, the method comprising:
receiving, from a network server, observed time difference of arrival (OTDOA) assistance data for a first plurality of cells from a base station almanac (BSA) accessible to the network server;
storing, within a memory of the mobile device, the OTDOA assistance data as a first micro-BSA; and
determining an initial position estimate for the mobile device based upon time difference of arrival (TDOA) measurements associated with an initial subset of the first plurality of cells and initial OTDOA assistance data corresponding to the initial subset of the first plurality of cells wherein the initial OTDOA assistance data is generated by the micro-BSA based upon an initial seed estimate.

### Claim 2 (depends on 1)

The method of claim 1 further including storing, within the memory of the mobile device, additional OTDOA assistance data for a second plurality of cells from the BSA as a second micro-BSA wherein the second plurality of cells includes at least one cell not included within the first plurality of cells.

### Claim 3 (depends on 1)

The method of claim 1 further including determining an improved position estimate for the mobile device based upon TDOA measurements associated with an additional subset of the first plurality of cells and improved OTDOA assistance data corresponding to the additional subset of the first plurality of cells wherein the improved OTDOA assistance data is generated by the micro-BSA based upon the initial position estimate.

### Claim 4 (depends on 1)

The method of claim 1 wherein the initial seed estimate is based upon a cell ID.

### Claim 5 (depends on 3)

The method of claim 3 further including determining additional position estimates for the mobile device based upon further improved OTDOA assistance data generated by the micro-BSA based upon a prior one of the additional position estimates.

### Claim 6 (depends on 5)

The method of claim 5 further including assessing a quality of the additional position estimates by at least one of: (i) evaluating contours in a position estimation cost function, and (ii) calculating a time difference of arrival (TDOA) residual error vector.

### Claim 7 (depends on 6)

The method of claim 6 further including requesting updated OTDOA assistance data from at least one of the micro-BSA and the network server when the quality is below a defined quality threshold.

### Claim 8 (depends on 6)

The method of claim 6 wherein elements of the TDOA residual error vector correspond to selected cells of the first plurality of cells, the method further comprising excluding at least one element of the TDOA residual error vector having a high error value exceeding one or more low error values associated with other of the elements.

### Claim 9 (depends on 6)

The method of claim 6 wherein elements of the TDOA residual error vector correspond to selected cells of the first plurality of cells, the TDOA residual error vector being denoted by e and having the form of:
e=r−h({circumflex over (x)})
where r is a TDOA measurement vector for one of the additional position estimates and wherein each element of r includes a TDOA measurement associated with one of the selected cells, and where h({circumflex over (x)}) is a TDOA vector for a position estimate {circumflex over (x)} and is given by:
h
m
⁡
(
x
^
)
=
1
c
⁢
(


x
^
-
x
m

-

x
^
-
x
1

)
where xm is the location of the mth cell and x1 is the location of a TDOA reference cell which is included in the improved OTDOA assistance data.

### Claim 10 (depends on 9)

The method of claim 9 further including requesting updated OTDOA assistance data from at least one of the micro-BSA and the network server when the quality is below a defined quality threshold.

### Claim 11 (depends on 9)

The method of claim 9 further comprising excluding at least one of the cells associated with one of the elements of e having a high error value wherein the high error value exceeds one or more low error values associated with other of the elements of e.

### Claim 12 (depends on 5)

The method of claim 5 further including removing, from the first micro-BSA, a portion of the OTDOA assistance data corresponding to at least one of the first plurality of cells based upon one or more of the additional position estimates.

### Claim 13 (depends on 1)

The method of claim 1 further including requesting additional OTDOA assistance data from the BSA wherein the additional OTDOA assistance data is associated with cells other than the first plurality of cells, the requesting being based upon one or more of: cell statistics associated with the first plurality of cells, results of scanning the first plurality of cells, and mobility of the mobile device.

### Claim 14 (depends on 13)

The method of claim 13 wherein the cell statistics include one or more of power received and timing measurements.

### Claim 15 (depends on 1)

The method of claim 1 wherein the additional subset of the first plurality of cells includes N cells, the method further including selecting the N cells at least in part to minimize a geometric dilution of precision.

### Claim 16 (depends on 15)

The method of claim 15 wherein the selecting is further based upon a method of Circular Sector Assistance Data Generation.

### Claim 17 (depends on 15)

The method of claim 15 further including:
detecting the geometric dilution of precision associated with the N cells exceeds a defined threshold;
refraining, based upon the detecting, from using either the initial position estimate or the improved position estimate in positioning of the mobile device.

### Claim 18 (depends on 15)

The method of claim 15 further including:
detecting the geometric dilution of precision associated the N cells exceeds a defined threshold;
returning, based upon the detecting, an error result relating to positioning of the mobile device.

### Claim 19 (depends on 15)

The method of claim 15 further including:
detecting the geometric dilution of precision associated with the N cells exceeds a defined threshold;
estimating, in response to the detecting, a position of the mobile device using an alternate positioning method not involving TDOA measurements.

### Claim 20 (depends on 3)

The method of claim 3 wherein the additional subset of the first plurality of cells includes N cells, the method further including verifying that N exceeds a minimum number.

### Claim 21 (depends on 3)

The method of claim 3 wherein the determining the improved position estimate further includes:
calculating a first position estimate for the mobile device based upon TDOA measurements associated with a first configuration of cells within the first plurality of cells and first improved OTDOA assistance data corresponding to the first configuration of cells wherein the first configuration of cells is characterized by a first geometric dilution of precision (GDOP);
calculating a second position estimate for the mobile device based upon TDOA measurements associated with a second configuration of cells within the first plurality of cells and second improved OTDOA assistance data corresponding to the second configuration of cells wherein the second configuration of cells is characterized by a second GDOP;
calculating a third position estimate for the mobile device using an alternate positioning method not involving TDOA measurements; and
selecting among the first position estimate, the second position estimate and the third position estimate.

### Claim 22 (depends on 21)

The method of claim 21 wherein the alternate positioning method is enhanced cell ID.

### Claim 23 (depends on 1)

The method of claim 1 wherein the mobile device transitions, after determining the initial position estimate, into a low power sleep mode, the further including:
determining, upon the mobile device temporarily transitioning out of the low power sleep mode, an updated position estimate for the mobile device based upon additional time difference of arrival (TDOA) measurements associated with the initial subset of the first plurality of cells and additional OTDOA assistance data corresponding to the initial subset of the first plurality of cells wherein the additional OTDOA assistance data is generated by the micro-BSA based upon the initial position estimate;
wherein the mobile device transitions, after determining the updated position estimate, into the low power sleep mode.

### Claim 24

A mobile device, comprising:
a processor;
a receiver in communication with the processor; and
a memory including program code executable by the processor for estimating position of the mobile device, the program code including:
code receiving, from a network server, observed time difference of arrival (OTDOA) assistance data for a first plurality of cells, the OTDOA assistance data included within a base station almanac (BSA) accessible to the network server;
code for storing, within the memory, the OTDOA assistance data as a first micro-BSA;
code for determining an initial position estimate for the mobile device based upon time difference of arrival (TDOA) measurements associated with an initial subset of the first plurality of cells and initial OTDOA assistance data corresponding to the initial subset of the first plurality of cells wherein the initial OTDOA assistance data is generated by the micro-BSA based upon an initial seed estimate; and
code for determining an improved position estimate for the mobile device based upon TDOA measurements associated with an additional subset of the first plurality of cells and improved OTDOA assistance data corresponding to the additional subset of the first plurality of cells wherein the improved OTDOA assistance data is generated by the micro-BSA based upon the initial position estimate.

### Claim 25

A method performed in a mobile device for estimating position of the mobile device, the method comprising:
receiving, from a network server, first observed time difference of arrival (OTDOA) assistance data for a first plurality of cells and second OTDOA assistance data for a second plurality of cells from a base station almanac (BSA) accessible to the network server, the first plurality of cells corresponding to a first geographic area and the second plurality of cells corresponding to a second geographic area different from the first geographic area wherein the second plurality of cells includes at least one cell not included within the first plurality of cells;
storing, within a memory of the mobile device, the first OTDOA assistance data as a first micro-BSA and the second OTDOA assistance data as a second micro-BSA;
determining, without receiving additional OTDOA assistance data from the network server, a first position estimate for the mobile device based upon first time difference of arrival (TDOA) measurements associated with a subset of the first plurality of cells and first OTDOA assistance data corresponding to the subset of the first plurality of cells, the first OTDOA assistance data being generated by the first micro-BSA based upon a prior position estimate; and
determining, without receiving additional OTDOA assistance data from the network server, a second position estimate for the mobile device based upon second time difference of arrival (TDOA) measurements associated with a subset of the second plurality of cells and second OTDOA assistance data corresponding to the subset of the second plurality of cells, the second OTDOA assistance data being generated by the second micro-BSA based upon the first position estimate.

### Claim at position 26

26-43. (canceled)