WiFi Positioning Bench Test Method and Instrument

• US 20110257923A1
• Filed: 12/22/2010
• Published: 10/20/2011
• Est. Priority Date: 04/16/2010
• Status: Active Grant

• Current Assignee: Spirent Communications Incorporated
• Original Assignee: Spirent Communications Incorporated
• Inventors: Boulton, Peter George
• Granted Patent: US 8,938,201 B2
• Time in Patent Office: Days
• US Class Current: 702/117
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 5/02213 Receivers arranged in a network for determining the position of a transmitter
• CPC Class Codes: H04L 41/22 comprising specially adapted graphical user interfaces [GUI]
• CPC Class Codes: H04L 43/50 Testing arrangements
• CPC Class Codes: H04W 24/06 Testing, supervising or monitoring using simulated traffic
• CPC Class Codes: H04W 24/08 Testing, supervising or monitoring using real traffic
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

The present invention relates to simulation on a lab workbench of conditions that would be encountered by a mobile device during a so-called drive test, which involves transporting the mobile device along a course so that it encounters fading and changing wireless access points used normally to connect the mobile device to a wireless network but in this case used to locate the device. The instrument and method also support parametric testing of transceivers used for WiFi positioning and, optionally, GNSS positioning by the same mobile device used for WiFi positioning.

Claims

1. A method of testing WiFi location circuitry and software of a mobile device under test (abbreviated DUT), the method including:

coupling a test device in communication with a DUT;

generating and mixing signals that emulate at least ten WiFi access points (abbreviated APs) visible from the simulated DUT location at test times during a test;

wherein the emulated signal from each AP is characterized by at least a MAC address, SSID, wireless protocol, channel number, and signal strength that are reproducible by a test time reference;

wherein at least one emulated open access point provides two-way communication access for the DUT to a network;

sending the mixed signals from the test device to the DUT.

2. The method of claim 1, further including systematically varying the number of APs and the signal strengths of the APs emulated for test times during the test.

3. The method of claim 1, further including:

selecting a simulated location sequence for a simulated location of the DUT during a test;

generating the emulated signals based on emulated AP locations proximate to the simulated DUT locations, including for the test times during the test

accessing an AP location database;

selecting a plurality of AP locations proximate to the simulated DUT location;

for each selected AP location,

calculating signal strength to emulate using at least the selected AP location and the simulated DUT location; and

using at least MAC address, SSID and channel number information from the database to generate the emulated signals.

4. The method of claim 1, further including:

generating the emulated signals based on received signals at the simulated DUT location, including retrieving from a test drive replay data set, for the simulated DUT locations, characteristics of the received signals to be replayed by the emulated APs;

wherein the characteristics of the emulated APs include at least signal strength, MAC address, SSID, and channel number.

5. The method of claim 1, wherein the replay data set includes AP characteristics derived from war-driving and recording real world APs observed during the war-driving.

6. The method of claim 1, further including:

coupling the emulated open access point to a network that provides access to a live AP location database that correlates DUT location information with reported locations of APs and characteristics of the APs including at least SSID, MAC address and channel number and regularly updates the reported locations and characteristics of real world APs; and

forwarding messages between the DUT and the live AP location database.

7. The method of claim 1, further including:

coupling the emulated open access point to a synthetic AP location database that correlates DUT location information with locations of APs and characteristics of the APs including at least SSID, MAC address and channel number;

wherein synthetic AP location database is maintained for test purposes without any necessary correlation to particular real world APs and the synthetic AP location database emulates a protocol used to connect with a live AP location database.

8. The method of claim 1, further including applying sectored attenuation of power received from the AP, wherein the obstructions or antenna arrangements are accounted for by directionally sectored attenuation parameters.

9. The method of claim 6, further including emulating synthetic APs for APs moving in vehicles, for which location data is not available in an AP location database.

10. The method of claim 6, further including emulating APs at locations that are different from location data posted in an AP location database.

11. The method of claim 1, further including emulating attenuation due to characteristics of a local environment within 20 feet or less of DUT.

12. The method of claim 1, applied to co-testing of WiFi and GNSS capabilities, the method further including generating, mixing and feeding to the DUT emulated GNSS signals for the simulated DUT location at the test times during the test.

13. A test device that tests WiFi location circuitry and software of a mobile device under test (abbreviated DUT), the device including:

one or more signal generators and attenuators adapted to emulate at least ten WiFi access points (abbreviated APs) visible from the simulated DUT location at times during the test;

means for determining characteristics of emulated APs at specific times during the test, including determining a MAC address, SSID, wireless protocol, channel number and signal strength for a particular AP, wherein the means for determining is coupled to the signal generators;

a mixer that mixes the emulated APs for transmission to the DUT, coupled to the signal generators; and

a wired or wireless channel coupled to the mixer and adapted to couple to the DUT.

14. The device of claim 13, wherein the means for determining includes:

an interface that accepts user entry of AP characteristics and of one or more test ranges of the characteristics to be emulated at times during the test;

and an emulation controller that varies AP characteristics during the test according to the test ranges.

15. The device of claim 14, wherein the emulation controller systematical varies the number of APs, the channel numbers used, and the signal strengths of the APs emulated through the test ranges.

16. The device of claim 13, wherein the means for determining includes:

a database that stores data for replay to the DUT at a plurality of simulated locations in a simulated location sequence, the data for replay including a plurality of APs visible at the particular location and, for each AP, at least MAC address, SSID, wireless protocol, channel number, and received signal strength; and

a replay controller that feeds at least some of the data for replay to the signal generators at the times during the test.

17. The device of claim 13, further including:

a test controller, running on a processor and coupled to the means for determining characteristics of emulated APs, that supplies a simulated location sequence that represents one or more simulated locations of a DUT during a test;

wherein the means for determining includes;

a database that stores AP locations and AP characteristics, the characteristics including at least a MAC address, SSID, wireless protocol, channel number and broadcast signal strength;

an AP selector that selects particular APs to emulate from APs visible to the DUT at a plurality of simulated locations in the simulated location sequence;

a received signal strength calculator that calculates received signal strength for signals from the selected APs based on at least the AP location, distance to the simulated location of the DUT, and the broadcast signal strength; and

an emulation controller that feeds the calculated received signal strength and the AP characteristics for the selected APs to the signal generators at times during the test.

18. The device of claim 13, further including:

at least one open AP among the emulated APs; and

means for supplying location database services to the DUT via the open AP.

19. The device of claim 18, wherein the means for supplying location database services includes:

access to a network that via which the DUT can access to a live AP location database that correlates DUT location information with reported locations of APs and characteristics of the APs including at least SSID, MAC address and channel number and regularly updates the reported locations and characteristics of real world APs; and

message forwarding between the DUT and the live AP location database.

20. The device of claim 18, wherein the means for supplying location database services includes:

a synthetic AP location database that correlates DUT location information with locations of APs and characteristics of the APs including at least SSID, MAC address and channel number;

wherein synthetic AP location database is maintained for test purposes without any necessary correlation to particular real world APs and the synthetic AP location database emulates a protocol used to connect with a live AP location database.

21. The device of claim 13, further including:

at least one attenuator;

directional AP signal strength attenuation data in memory accessible to the means for determining;

wherein the attenuator attenuates the generated signal corresponding to at least a direction from a particular AP to the simulated DUT location and the directional AP signal strength attenuation data.