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POSITIONING WITH LTE • GREATER ACCURACY EVERYWHERE
A decade ago wireless technology was dominated by mobile telephony. More recently, a 4G-capable
mobile broadband platform is offered by LTE radio-access technology [1] developed by 3GPP. Today,
there are around 5.8 billion mobile subscriptions. In the US market, for example, LTE networks
cover more than 50 percent of the population and this figure is rapidly increasing. LTE enables an
ever-widening range of services, enhanced QoS, efficient use of resources and flexible spectrum
utilization. All of this in turn creates a wealth of new business opportunities, leading to tougher
competition among service providers and application builders. Applications using highly accurate
wireless-device positioning are constantly being developed and enhanced. This increases user
expectations, which consequently creates demand for smarter services.
Positioning is the process of determining the geographical location of a device – such as a
mobile phone, laptop or tablet computer, a personal digital assistant (PDA), or navigation or tracking
equipment. Once the coordinates of a device have been established, they can be mapped to a
location – such as a road, a building, a park or an object – and then delivered back to the requesting
service. The mapping function and the delivery of location information are part of location services
(LCS) – which, for example, emergency services depend on. Services that use location data are
referred to as being location-aware, and customer services that offer added value by being location-
aware are known as location-based services (LBSs). Services based on positioning benefit users,
and LBSs can be used to optimize network performance and to enhance automated services such
as network self-learning, self-optimization and services aimed at Minimization of Drive Tests (MDT).
The range of LBS applications is expanding rapidly. Some common examples include localized
weather forecasts, targeted advertising and applications that can position the nearest bus stop,
or find the location of an object – such as a subscriber’s car keys.
INCREASING DEMANDS ON POSITIONING
Positioning in wireless networks is a challenge owing to the mobility of users and the dynamic
nature of both the environment and radio signals. Positioning QoS is typically defined in terms of
accuracy, confidence level and the time it takes to obtain a positioning result. The current trend
shows that users, network operators, service providers and regulatory bodies are demanding:
• more accurate and reliable positioning for commercial and non-commercial services
• reduced latency from trigger time to the time when a result is available at the requesting node
• environment-agnostic accuracy implying comparable results for rural and urban, and indoor
and outdoor environments
• more exible QoS to support diversication of positioning services and enable user-adaptive
and application-adaptive positioning services
• accurate positioning for emergency services and improved
positioning performance in general. The objective is to meet
the regulatory requirements of bodies such as the US Federal
Communications Commission (FCC), which are becoming
more stringent [2].
Users naturally presume that applications will work regardless
of where they are and whether they are in a fixed location or on
the move. They expect the same level of performance whether
they are indoors at home or at work, outdoors in a rural or urban
environment, or travelling.
From a commercial perspective, different applications require
varying levels of accuracy. As the number and variety of
applications and wireless devices grows, LTE, unlike previous
radio-access standards, is well-positioned to support the higher
level of application-adaptive requirements created by more
advanced user needs and application development. To meet
the requested positioning QoS, the best mix of positioning
technologies should be selected for each case.
For network operators, it is important to provide a wide range
Greater accuracy
everywhere
THE WIRELESS E911 LOCATION ACCURACY
REQUIREMENTS [2]
For terminal-based and terminal-assisted positioning:
• 50m, 67% – within 50m for 67% of all calls measured
at country level
• 150m, 95% – within 150m for 95% of all calls measured
at county level
For network-based positioning:
• 100m, 67% – within 100m for 67% of all calls measured
at county level
• 300m, 90% – within 300m for 90% of all calls measured
at county level
Carriers must provide location, together with confidence
and uncertainty data, for all emergency calls at the PSAPs.
