Mobile Location Services - always in touch on the move

With mobility, location becomes a critical attribute that can be exploited by all involved in the wireless value chain.

Location-relevant services are one of the key elements in the Mobile Internet. E-OTD is one of the advanced technologies that can be employed to determine the physical location of a mobile subscriber, thus enabling location-relevant services. Deployment of E-OTD positioning can be made with minimum additional network investment because the solution is fully integrated into GSM network architecture. There is virtually no extra costs for terminals, either.

Terminal- or network-based positioning methods provide a means to locate a subscriber and/or valid mobile equipment. Positioning may be initiated by the subscriber, the network or an external application. Mobile operators (e.g. home/office zone applications and network planning applications), third-party service providers and government agencies (e.g. locating emergency calls), (e.g. electronic yellow page for nearby services and 'where am I' applications) are just a few of the entities that will employ mobile services.

Positioning technologies can be divided to three categories: basic, enhanced and advanced. Basic positioning methods are based on the use of cell identification (cell id). Cell id can be used alone, or together with timing advance (TA) and network measurement reports (NMR). Enhanced Observed Time Difference (E-OTD) is usually referred to as an enhanced positioning method. Assisted GPS (A-GPS) is an advanced positioning method.

The division of the position technologies above is based on accuracy of the positioning method. Other important factors are, for example, complexity of the system and the investment needed on the network side and possibly in handsets.

Mobile Location Services are value-added services that utilize the user's position information. From the user's perspective these services provide:


• localized and up-to-date information.

• personalized information.

• increased efficiency and pertinence.

• increased safety.

Mobile Location Services are not in themselves to be identified as a set of killer applications but rather location information will be integrated as the value-adding element in a whole range of services. For example, tourist information services letting you know the price of fuel in a country do not deliver value but being directed to the cheapest petrol station near your location does. An attractive set of location-based killer applications will be based on life management services supported by a dynamic portal that uses end-users' personalization details to change the type of information and delivery method according to the end-user's changing time or context (home, office, morning, evening, etc.).

Mobile services benefit from three major factors that boost information value to the end-user: personality, time-criticality, and location-dependency.

From the operator's perspective, the location element allows information to be more precisely targeted for users. Also, location-based applications are facilitators of catchy user services, eg elements of M-commerce.

The location information has no value in itself; it is only a medium for provisioning valuable applications relevant to a user at a specific location and at a specific point in time. Although location information is a highly efficient feature for bringing added value to several applications, positioning should remain transparent to the end-user.

There are three major market drivers for Mobile Location Services. These can be identified as commercial, technological and regulatory drivers.

Commercial drivers
Mobile Internet itself is one of the biggest driving forces behind Mobile Location Services, giving the possibility to bundle location sensitive information into other applications, such as mobile commerce. End-users are in a position to steer the service market towards their own needs because in the end, they are the ones in a position to accept or reject new types of services.

Technological drivers
Development of standards and cost-efficient location technologies are key technology drivers. Also, implementation of 3G networks, as well as the introduction of terminal categories, such as Communicators and Media Phones, enables whole new service categories to be offered, on which location will be a key attribute.

Regulatory drivers
One should note that regulation is one of the strongest drivers of Mobile Location Services. The US FCC mandate for E-911 services, as well as the equivalent European Union requirements for E-112, has an impact on the positioning technology adopted by mobile network operators.

Location - based / location - dependent Services
When talking about Mobile Location Services, it is useful to make a distinction between location-based services and location-dependent services, both of which come under Mobile Location Services.

Location-based services are actual services that are visible to the user, e.g. find-a-friend, navigation, yellow pages, etc. Location-based services are provided either by the operator or a third-party service provider that utilizes the available location information of the terminal. Additionally, the location application offers the user interface for the service. Services that are available depending on the user's actual (x, y) position are called location-dependent services.

Such a service is provided either by the operator or a third-party service provider that is available (pull type) or is activated (push type) when the user enters a certain area. Location-based charging is a good example of this kind of service. Furthermore, when talking about one's position, it refers to exact information usually presented in terms of longitude and latitude. (The distinction between position and location is that position is accurate information on one's location, i.e. location can be seen as quite a wide area geographically.)

The Technology behind MLS
Positioning technologies can basically be divided into handset based and handset-assisted, similarly network-based and network-assisted, each of which offer different levels of accuracy according to a three-tiered service level structure of: basic, intermediate and high level accuracy.

In handset-based technology, the terminal performs the position calculation autonomously, e.g. stand-alone GPS. However, in handset-assisted technology the mobile terminal provides some assistance for positioning, while the network performs the actual position calculation, e.g. terminal assisted E-OTD (Enhanced Observed Time Difference). Further, in network-based positioning technology, the network performs the position calculation by itself, e.g. Cell-ID. Finally, in network-assisted technology, the network provides some assistance in positioning, while the terminal itself performs the position calculation, e.g. A-GPS, and mobile terminal-based E-OTD. The three major emerging technologies for wide-area positioning are:


• Cell Identification with variations, e.g. Service Area Identity (SAI) for 3G, LocWAP and enhanced Cell-ID, and enhancements with propagation time measurements, such as Timing Advance (TA) and Round Trip Time (RTT) and measured signal levels (RX levels).


• Cellular signal timing based methods, like E-OTD for GSM and its variations AF-LT (Advanced Forward Link Triangulation) and IP-DL (Idle Period Downlink), for CDMA and WCDMA, respectively,

and


• GPS (Global Positioning System), stand-alone or network assisted (A-GPS). In addition to wide area positioning technologies, user self-locating and, for example, complementary local area technologies, such as Bluetooth Local Positioning may be used to improve coverage.

Short-range wireless technologies, such as PHS (Personal Handyphone System), Bluetooth IEEE 802.11, Ultra Wideband (UWB) and other proprietary technologies, can be used to provide position determination, where they provide coverage.

In multi-mode devices, this can be used to complement other positioning technologies, to enhance accuracy, coverage and/or acquisition time. The Bluetooth 'Local Positioning' profile is being developed to provide GPS-like accuracy, especially in places where GPS does not work very well or not at all, such as indoors.

Accuracy
The basic positioning accuracy category is focused on penetration and should be available for all phones enabling fast time to market. The intermediate accuracy level will have a software impact on handsets and the high accuracy category will have a hardware impact on handsets. All three levels of accuracy will exist in parallel in the future.

The accuracy of Cell-ID is primarily dependent on cell radius significantly improves as cell size gets smaller. Likewise, the accuracy of measurement analysis techniques, such as TA and methods that employ network measurements from neighbouring cells in certain situations, can reach 100-200 m. E-OTD and TOA (Time of Arrival) in GSM networks have slightly better accuracy profiles (even 50-100 m) but E-OTD is dependent on the visibility of base stations for its performance whereas TOA is dependent on the visibility of terminal transmissions at LMU (Location Measurement Unit) sites. A-GPS is the most accurate method but this is subject to degradation in certain environments, such as inside buildings and 'urban canyons', where the line of sight to satellites is established with difficulty if at all. Indeed any geographical impediment that degrades the signal will result in reduced accuracy. Unfortunately, GPS fails to work in many indoor environments, where people typically spend significant proportions of their time.

Position accuracy and the degree of coverage dictate what type of application can be deployed. Currently most commercial applications use information-based services over Cell-ID due to its broad coverage and cost implications. In cases where accurate but costly positioning solutions are not viable, solutions requiring no modification to user equipment can be offered to all terminal users, thereby making the technology compatible with all cellular telephones currently in use. Whilst Cell-ID accuracy is very low this can be enhanced by a self-location method, whereby the end-users use landmarks and addresses to improve their positioning precision. This in turn makes it possible to deliver more tailored and relevant content.

The role of mid-accuracy technologies such as E-OTD is found in the services needing the next level of accuracy, capacity and availability. While E-OTD's accuracy might not be enough to deliver services such as turn-by-turn navigation and whilst it is important to base any decisions on consumer research, the likelihood is that it is accurate enough for services such as E911, tracking and permission marketing. With A-GPS, it is possible to provide rich applications that users are willing to pay for, such as zonal billing, pinpoint services, self navigation and emergency services.

It is essential to choose the optimal technological business solution. Several factors influence the decision making:


• Standards compliant

• Open interfaces

• Optimized network loading

• Interoperability between networks and equipment

• Upgradeability

• Scalability

• Support of as many positioning technologies as possible

As a summary, cell-based techniques are subject to the characteristics and behaviour of the radio network. Currently, it cannot be guaranteed that the mobile terminal chooses the same network cell every time it is in the same position, due to the fact that the cell ranges overlap.

In general, Mobile Location Services and wireless communication devices form a good combination.

The location information adds a new dimension to mobile applications and brings more value to customers by improving their safety, their productivity and/or the quality of information needed.

In order to allow for a smooth market introduction for Mobile Location Services, the freedom must be given to the subscriber to choose how much he/she will pay for the terminals supporting those services as well as accuracy levels required from the services.

A clear prerequisite is that it is the customer and not the operator or service provider who has control over the use of his/her location information.