Danai Skournetou

Establishing a common service platform for smart living: challenges and a research agenda

The vision of smart living promises innovative services from providers in energy, healthcare, entertainment and surveillance sectors. While smart homes used to equal home automation, evolving ICT technologies now enable truly adaptive and intelligent services that are integrated in several industries. Sector-specific service platforms are emerging that provide basic intelligence for services. However, smart living services should not be constrained to a specific industry sector, and hence the service platforms should be easily accessible for service providers regardless of their industry. In addition, smart living services should not be constrained to residents within the home, but should take advantage of outdoors position information to open up a range of novel service concepts. Establishing such a vision of smart living involves various technological and organizational challenges. This paper gives an overview of the current service platforms for smart homes and positioning information. Based on this overview, we propose a research agenda for enabling smart living services. The two major issues are how to achieve collective action between players from multiple sectors in order to set up a common service platform, and how to design business models that allow adding GNSS-based positioning information to the service platform.

Pulse shaping investigation for the applicability of future GNSS signals in indoor environments

It has been commonly recognized that the use of Global Navigation Satellite System (GNSS) signals for indoor positioning is extremely challenging due to the significantly attenuated signal power and the presence of strong multipath components. However, with the advent of new GNSS signals the position accuracy is expected to be improved in outdoor environments and their applicability indoors shall be re-examined. In indoor environments, it is likely that the pure GNSS solution will not be sufficient; assisted-GNSS or any solutions where combined communication and navigation receivers are employed are very promising candidates to solve this problem. One issue in this case is the bandwidth limitation, introduced via the pulse shaping at the transmitter side and/or the bandwidth limiting filters at the receiver side. This is the problem addressed here. More precisely, in this paper we investigate the impact of different pulse shape filters on the tracking accuracy of the future Global Positioning System (GPS) and Galileo signals. The simulation results indicate that Chebyshev and Butterowrth filters are good candidates compared to the infinite bandwidth rectangular pulses and in terms of error variance degradation.

Impact of Galileo commercial service on location-based service providers: business model analysis and policy implications

Todays mobile location-based services (LBSs) largely depend on a free-of-charge, best-effort positioning technology, called global positioning system, which is controlled by the US military. The European alternative Galileo will not only offer a similar best-effort system by 2020, but also a premium-rate service known as Galileo commercial service (CS). Galileo CS is planned to provide higher positioning accuracy, improved security due to signal authentication and service guarantee. While the technology behind Galileo is often studied, the impact of Galileo CS on the LBS marketplace is rarely discussed. In this article, we fill this gap by analysing how improved accuracy, authentication and service guarantee may impact the business models of LBS providers. We do so by interviewing service providers, policy makers and industry experts on what new services would be enabled; technological alternatives that may emerge in the coming years; and organisational and financial issues that service providers face when adopting such a premium-priced positioning signal. We find that a more accurate, secure and reliable global navigation satellite system signal enables a range of new LBSs, although several alternative technologies are emerging that may make Galileo CS obsolete before it is even launched. To convince the LBS providers to adopt Galileo CS, the institution operating Galileo should get governments on board early on for building trust and should consider progressive pricing schemes. Still, service providers are sceptical about adopting Galileo CS, and the hope to recoup any investments in Galileo may thus be in vain.

Performance analysis of dual-frequency range estimation methods in the presence of ionospheric and multipath propagation effects

In the global navigation satellite systems (GNSS), the performance of GNSS is subject to various errors, such as ionosphere delay, receiver noise and multipath. Among all these errors, the ionosphere delay error and multipath error are commonly regarded as the most limiting factors. In theory, a dual-frequency receiver can eliminate the ionospheric effect. However, in reality, the tracking error has effects on the ionospheric delay correction. This effect has not been studied, especially in realistic channel scenarios. In this paper, the authors investigate the effect of tracking error, obtained from Galileo signal Simulink-based simulators with realistic channel models on the range estimation in dual frequency receivers and compare the performance of three dual frequency ionosphere delay correction methods, namely the least square (LS), constrained LS (CLS) and Bruce Force Constraint (BFC). The results showed that the BFC performed the best below a fairly high ionosphere delay error. The LS method was only affected by multipath error, but the effect was small. CLS performance was better than or equal to LS at the expense of increased complexity.

Comparison of Single and Dual Frequency GNSS Receivers in the Presence of Ionospheric and Multipath Errors

In this paper, we test the performance of single and dual frequency GPS and Galileo GNSS receivers in terms of satellite-receiver range estimation. In particular, we focus on the effects caused by ionosphere and multipath propagation. Therefore, the available pseudoranges are assumed to be contaminated with first-order ionospheric delay and measurement errors produced in the code tracking stage. We used three dual-frequency methods, two ionospheric models (Klobuchar and NeQuick for GPS and Galileo receivers, respectively) and compared their ionosphere-corrected ranges on a Root Mean Square Error basis. The simulation results showed that a dual-frequency receiver is superior to a single-frequency one, only when the standard deviation of the measurement error is small and when the correlation factor between the two available pseudoranges is higher than − 0.4.

Ionospheric delay corrections in multi-frequency receivers: Are three frequencies better than two?

The amount of mobile applications that utilize positioning information is ever increasing. Together with the demand for more location-aware applications, there is a growing demand for a higher positioning accuracy. In order to increase the accuracy level and to improve the perceived quality of positioning, the different error sources have to be mitigated. Among those, ionosphere delay accounts for the largest delay of the satellite signal and therefore it has to be effectively corrected. Dual-frequency receivers can effectively remove the first-order ionospheric delay, provided that there are no other errors present in the pseudorange measurements. However, recent work in this field showed that, when the measurements are contaminated also by multipath tracking errors, the performance of dual-frequency receivers degrades significantly. In this paper, we compare the range estimation performance of three algorithms and test the best dual-frequency pair, El-E5a, together with all possible triple-frequency combinations in terms of ionospheric correction. The results indicate that the availability of a third measurement brings little benefit if any, and only when there is a very high positive correlation between the pseudorange measurements on the three frequencies.

Performance of Deconvolution Methods in Estimating CBOC-Modulated Signals

Multipath propagation is one of the most difficult error sources to compensate in global navigation satellite systems due to its environment-specific nature. In order to gain a better understanding of its impact on the received signal, the establishment of a theoretical performance limit can be of great assistance. In this paper, we derive the Cramer Rao lower bounds (CRLBs), where in one case, the unknown parameter vector corresponds to any of the three multipath signal parameters of carrier phase, code delay, and amplitude, and in the second case, all possible combinations of joint parameter estimation are considered. Furthermore, we study how various channel parameters affect the computed CRLBs, and we use these bounds to compare the performance of three deconvolution methods: least squares, minimum mean square error, and projection onto convex space. In all our simulations, we employ CBOC modulation, which is the one selected for future Galileo E1 signals.

Designing roadmaps for the Galileo Commercial Service platform

Unlike existing Global Navigation Satellite Systems, future Galileo is envisioned to provide a Commercial Service (CS) with improved as well as new characteristics. However, as yet, it is still highly unclear whether Location Based Service (LBS) providers are in fact interested to pay for accessing CS signals. The purpose of this paper is two-fold: First, to show how business model roadmapping can be used for analyzing the impact of a new service offering on customer and second, to demonstrate the steps and activities that have to be done in order to create a business model for Galileo CS. The roadmap-based study identified three crucial points that the European Commission and the future Galileo operating company should take into account in their planning for the future: First, the creation of awareness on Galileo CS platform at an early stage, second, getting LBS providers on board by applying progressive pricing schemes or choosing non-discriminatory pricing schemes and third, getting governments on board to create trust and reputation for the platform or focusing attention on LBS providers directly.

Has the time to commercialize satellite navigation signals come

While mobile location based service providers today still depend on the US military controlled GPS system, the European Union is looking to reduce this dependency by launching its own global navigation satellite system, Galileo, which will be fully operational around 2020. Besides the free-of-charge basic signal, a Commercial Service (CS) will be offered at a premium-rate to service providers to provide higher positioning accuracy, signal authentication and service guarantee. However, it is still highly uncertain whether location-based service providers are willing to pay for accessing CS signals. Motivated by the lack of research in this area, this paper analyzes the viability of CS by conducting various interviews with key stakeholders, complemented by desk research. The results indicate that the willingness to adopt CS platform is questionable. It depends greatly on the type of applications of interest, as well as on the existing and future alternative solutions.