International Journal of Health Geographics 2007, 6:9
; the area of coverage can also be extended by elimi- nating the need for downloading the ephemeris data directly from the satellite, which requires a higher signal quality than tracking alone;
WiFi Positioning System (WPS): SiRF and Skyhook have recently announced a hybrid GPS/Wi-Fi (WPS) loca- tion solution ;
Rosum TV-GPS: a TV based positioning solution with potential enhanced support for dense urban areas and inside buildings (currently only available for the North American/NTSC market) ;
Cellular positioning: offers a very wide coverage even in indoor situations while lacking the precision of satellite based navigation systems; and
Galileo Positioning System: will not be fully rolled out until 2010. The Swiss company u-blox have recently announced the release of their first receiver for the Euro- pean Galileo Positioning System, which will also use the signals of the American GPS satellites . It is expected that Galileo will provide an enhanced coverage over the current GPS, higher positional accuracy, as well as better availability, making it possible to work in urban canyons and even in small buildings.
Privacy issues Location capability poses service providers with the chal- lenge of responsibly handling consumers' personal pri- vacy . This is particularly important with 'tracking services' that continuously monitor and log user's loca- tion, like Wherifone, an American location-tracking serv- ice for the elderly and children , and other live tracking services using technologies like the GpsGate Server . Such services raise many privacy concerns and questions; for example, "If a consumer service allows one party access to the location of a second party, should that second party be notified when this location information has been pro- vided?"
However, CAALYX's approach to location information privacy is different. CAALYX is an extensible user health monitoring platform that uses GPS as to support that function (health monitoring) and for emergency han- dling. Thus CAALYX is not continuously tracking older people, or continuously communicating their location in real-time with the central monitoring station. There are a number of reasons for this. Firstly, allowing the data log- ger (a mobile smartphone that users carry on them) to col- lect the data rather than continuously stream it to a remote server means that expensive bandwidth is saved. It is also far more power-efficient than a system that has to continuously transmit data and pick up real-time geo-
graphic information via GPS, a paramount feature in any handheld device. But most importantly, it means people will not feel as if their every move is being watched. Loca- tion information is only sent when required during an emergency or when an alarm is raised. As such CAALYX has the potential of setting the standards and providing a 'modus operandi' or 'best-practice' model for wireless location privacy in mobile, location-intelligent/enabled e- health services.
Conclusions and future directions Europe is about to face a significant social change, brought about by an unprecedented demographic change: the ratio of older people to the entire population is stead- ily growing, while the ratio of younger age groups, espe- cially the working population (including healthcare workers) is shrinking. This demographic trend makes it difficult to foresee how Europe will find enough people to take care of its older population, without a major change in traditional older people's care methods. The role of e- health in facing such challenges will be very significant. In fact, leading health informatics think tanks like Professor Enrico Coiera are anticipating a total "reinvention" of healthcare by the year 2020, as the already significantly strained national health systems face the increasing needs to treat proportionately more people, with more illness, using relatively less tax money and fewer healthcare work- ers .
In this context, CAALYX represents a unique and much needed mobile, location-based (geo-aware) e-health serv- ice. Older people's autonomy (duration of independent living) and self-confidence can be greatly increased by wearing a light device that can measure vital signs, detect falls and location, and automatically raise an alert to their care centre in case of an emergency. Other tele-monitoring projects either send location information without much or any details about the current medical status of the user, or send detailed information about user's medical status without any information about their location. However, to be able to offer users proper assistance during emergen- cies wherever they might be (including incidents in which patients are unconscious or unable to adequately describe their location for any reason), a service would ideally require both detailed information about user's current medical status and details of user's current location, and that is exactly what CAALYX is offering.
To further improve service safety and reliability, the CAA- LYX design team will be looking at a 'technical contin- gency plan' to deal with problematic situations and locations when/where, for example, geo-positioning/get- ting a GPS fix using standard GPS is not possible (perhaps consideration will be given to using some form of 'Assisted GPS' in such cases) and/or when communication
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