TÍTULO V: NORMAS GENERALES DE EDIFICACIÓN Y USOS
Artículo 5.03.64 Condiciones particulares del uso de aparcamientos públicos y
Outdoor localisation solutions have become a huge success mainly because it provides an ideal environment for innovation. Currently it has the advantage of reliable positioning via GNSS and a defined business model for the delivery of content to the LBS users.
However, the same cannot be said for indoor LBS. Probably because both pre-knowledge of location-reference database and infrastructure have to be provided by the owner of the building, indoor positioning and context-sensitive services have mostly stayed away from each other. Thus, this means that current solutions still suffer from the lack continuity due to loss of GNSS signals when SPs go indoors, unless pre-installed localisation sensor networks, such as those offered by BLE-iBeaconing and WiFi fingerprinting, are specifically implemented to provide the SPs location while indoors in that particular vicinity. GNSS signals suffer from strong attenuation caused by building materials when the SPs enter indoors. I.e. the provision of semi-accurate indoors-SPs location, on-the-go anywhere anytime, has proven somewhat problematic to deliver thus far.
After having reviewed the available localisation techniques, technologies and solutions on SPs, we have established the following investigation:
1. Achieving accuracy of SPs location in localisation solutions is varying according to: environmental complexity, using localisation techniques as a standalone or as a combined approach, limitations/capabilities onboard technologies, hardware or
60
software designed of the solutions, and mathematical/statistical calculation ‘SPs position method.
2. Existing localisation techniques, such as RSS-based techniques, do provide good performance (despite signal propagation problem) but at the expense of pre-installing dedicated infrastructure and therefore limited in LBS applications.
Other distance-based techniques are sufficient on its own, but it suffers from jitters, instability, coverage and dilution of precision issues. Finally, DR technique, especially when using low-cost inertial sensors such as accelerometer and gyroscope onboard SPs, are highly smooth and stable, but their performance degrades quickly over time due to the accumulated measurement noise of sensors causing cumulative positioning error. Therefore, a combination of these techniques is necessary to exploit the advantages of each of these techniques while compensating for their limitations.
3. Cellular, WiFi, BT or inertial-sensors based positioning solutions on SPs can be used to define SPs location as an alternative solution in environments where GNSS-signals are not available. However, limited coverage of WAPs/BT-anchors, no information of BSs/WAPs/BT-anchors physical positions within a building, no access to API functions of important device data onboard SPs, no localisation protocol extensions, no synchronisation between SPs and reference stations are some of the main challenges to design a spontaneous autonomous positioning solution with reliable accuracy at reasonable cost.
Due to these limitations, currently technologies and/or localisation solutions on SPs do not provide seamless positioning solution from outdoors to indoors, accurately, on-the-go, anywhere, anytime. To achieve this, this research study developed a hybridisation solution of GNSS with other onboard wireless and sensors technologies. The developed solution is a good candidate for seamless LBS localisation applications on SPs. This is because:
61
1. The developed solution, to calculate accurate indoors-SPs position (e.g. within 2 or 3 meters accuracy), uses BT signals between SPs to construct an aiding network and then to: a) synchronise all reachable WAPs with GNSS time from outdoors SPs (see section 3.4), b) define synched WAPs position (see section 4.4), c) exchange and establish SP location and time-offsets based on available/reliable GNSS location from outdoors SPs (see section 5.4), d) Hop-counting synchronisation to estimate pseudoranges between connected SPs (see section 5.4.1.1), e) SMSR to enhance the estimated pseudoranges (see section 5.4.1.2), f) PRP to mitigate DOP issue (see section 5.4.1.3), g) and to then calculate location of indoors-SPs based on the proposed SILS (see section 5.4.1).
2. The developed solution is also fusing inertial sensors measurements with the measurements from SILS so to improve localisation accuracy when deep indoors, as we called UNILS, (see section 5.5.1). This means that, in deep indoors, UNILS utilises only available devices/sensors on SPs, when communication with WAPs or BT-anchors is deemed unreliable or unavailable. In another vain, this fusion of measurements provides a combination of localisation techniques, (see section 5.5.1.3). For example, when the UNILS introduces pseudorange-measurements (via TOA technique) into the DR technique, it leads to mitigate or even to avoid the accumulated drift issue. Also, using enhanced DR measurements at the same time is to keep stability of pseudorange estimation and reducing the number of reference positions which are constrained in TOA technique.
3. The developed solution doesn’t need any dedicated hardware as all the SPs are equipped with a Wi-Fi transceiver as well as there is no need to deploy an extra dedicated network as radio signals from at least a few WAPs can be detected in the majority of areas of interest, due to the proliferation of WLAN. Furthermore, the developed solution doesn’t require radio mapping and calibration which are typically associated with current indoor solutions including Skyhook and Ekahau.
Also, the solution doesn’t need to use Internet service to connect with host servers or location-databases which is associated with the current solutions (WiFi-SLAM
62
and Sensewhere). Therefore, the solution shall reduce the required memory and traffic on SPs thus saving battery consumption, connection/interaction traffic and reduce processing time.
4. The developed hybridisation solution is compatible with all SPs interfaces.
Because the solution will work regardless of how the user holds the SP, it is not restricted to a direction to the WAPs or other SPs in the vicinity such as in the case of RSS-Fingerprinting technique.
To the best of my knowledge, my proposed hybridisation technologies and combined techniques solution to offer seamless, accurate, low-cost and on-the-go localisation solution for LBS application on SPs has not been attempted in other work, and thus represents a novel direction of research.
63