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Projecte llegit

Títol: Towards the Implementation of the Passive-TDOA algorithm on COTS WiFi devices

Estudiants que han llegit aquest projecte:

Director/a: ZOLA, ENRICA VALERIA

Departament: ENTEL

Títol: Towards the Implementation of the Passive-TDOA algorithm on COTS WiFi devices

Data inici oferta: 21-12-2021     Data finalització oferta: 21-07-2022


Estudis d'assignació del projecte:
    GR ENG SIS TELECOMUN
    GR ENG TELEMÀTICA
Tipus: Individual
 
Lloc de realització:
UPC
    Departament: Ing. telemática
 
Segon director/a (UPC): MARTIN ESCALONA, ISRAEL
 
Paraules clau:
Implementation, assembler, passive-TDOA localization algorithm
 
Descripció del contingut i pla d'activitats:
Nowadays, indoor positioning is a still an open issue. The
main reason, though not the only one, is that location indoors
require accurate measurements, i.e. positioning errors of 1 to
2 meters in average. There are technologies, such as those
based in ultra wideband (UWB) that are able to provide
positions with only centimeters of uncertainty. However, those
technologies require custom network and user equipment to
work, which often make them costly and hard to deploy.

Lots of efforts have been addressed to use communication
networks for location purposes. However, the problem then is
that positioning errors rise (noticeably) over the 2 meters.

In the recent past, a new location technique for WiFi networks
have been presented: passive TDOA. This technique uses the
concept of 2-way TOA to compute the time of flight of WiFi
signals, but in a passive way (i.e. without injecting location
traffic).

This technique has been assessed under simulation, reporting
good performance.
Then it has been implemented in the top of the WiFi Linux
protocol stack (i.e. in the SoftMAC module). Although the
results are good enough for indoor positioning under dark
areas, they are far from what it's expected from simulation
results. This is due to the latency generated on traversing
the WiFi protocol stack. This project tries to overcome that
limitation.

Objectives: The goal of this project is to implement the
passive TDOA technique embedded in the firmware a Commercial
Off-The-Shelf (COTS) devices based on Broadcom hardware.

The second objective would be providing a set of tools to
control and retrieve the measurements captured by the
firmware, so that they can be used by any third piece of
software interested in.

Finally an assessment of the quality of the reported
measurements will be done.
 
Overview (resum en anglès):
Localisation and positioning of devices in indoor scenarios is one of the major research lines in the scientific community. While outdoor position solutions have already converged into an integration of GNSS networks, and scenarios with no GNSS connectivity still represent a challenge.

A novel technique has been recently presented in , which allows the positioning of devices by overhearing network operations. Nevertheless, implementations of the time difference computations done at an operating system kernel level concluded that the results obtained were affected by non-linear latency. The operating system attempt finished by proposing to implement the same mechanism at firmware level, thus reducing the impact of the system latency.

This bachelor thesis focuses on a first implementation of a passive positioning algorithm on a commercial off-the-shelf device through the use of time differences of arrival (TDOA) computed by exploiting the nature of the wireless shared medium access in Wi-Fi networks. The raw TDOA algorithm is integrated within a commercial wireless network card (WNIC) firmware. Since manufacturers keep the firmware integrated on the WNIC devices closed-software, the implementation is done on top of the open code project, OpenFWWF, released in 2018. The implemented algorithm exploits the request-response operations of the IEEE 802.11 medium access control (MAC), as the request to send (RTS) and clear to send(CTS) mechanism, to compute the time difference of arrival between the two frames.

Additionally a platform to retrieve and control the access of the TDOA measures is designed and integrated as a kernel module. The platform is designed with scalability in mind, allowing for multiple user-level applications to leverage the TDOA measurements to provide localisation services.

Lastly, a first behavioral analysis of the platform and algorithm versus the distance between network elements is done,
in order to validate the implementation and its ability in capturing the time differences over increased distances.

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