The Evolution of Mobile Positioning

By Gerry Christensen

Wireless Emergency Calling Drives Initial Infrastructure
As true as it was in 1999 when I went to work for LBS (Location-based Services) middleware industry leader, SignalSoft (now a division of Openwave), location remains a strategic asset to mobile network operators. Shrewd service providers have begun to seriously deploy LBS applications with an emphasis on personal and enterprise applications such as navigation and remote work force management.

Copyright 2006 The Definitive Guide to LBS Applications. (Click for larger image)

One of the main differences between 1999 and 2007 is that today all network operators have deployed mobile positioning infrastructure including Control Plane middleware such as Mobile Positioning Center (MPC) and Gateway Mobile Location Center (GMLC) equipment for CDMA and GSM networks respectively. These middleware components, whose deployment was driven by the mandate for phase II of wireless 9-1-1 calling by the Federal Communications Commission in the United States, provide a control point function between the Positioning Determination Equipment (PDE) and the client applications such as emergency calling and commercial LBS applications. While the PDE, Time Division of Arrival (TDOA) and Assisted GPS (A-GPS) are deployed in the wireless carriers' networks, the MPC and GMLC are either deployed there or at their vendors' datacenter, which includes the likes of Intrado and TCS.

Commercial LBS Drives User Plane Infrastructure
While the control plane infrastructure was initially put in place for wireless 9-1-1, the original vision was for its use in commercial LBS as well. But the reality was somewhat different. Due to concerns over network reliability and potential disruption to the emergency calling network, most operators were hesitant to use the same infrastructure for commercial LBS services. In addition, Control Plane positioning assets also use critical and costly network resources including SS7 signaling and intelligent network elements. Some carriers would consider using an overlay Control Plane for commercial LBS, while others would not even consider it due to the uncertain payback. The industry clearly needed an alternative. That alternative was declared the User Plane and would use a client-server method of positioning rather than relying on centralized control, expensive network equipment and software, and signaling between the Mobile Switching Center (MSC) and the Service Control Point (SCP).

Rather than relying on intelligence, signaling and control within the wireless carriers' core networks, the User Plane infrastructure is based on client software within the wireless device, communication over Internet Protocol (IP), and control and service logic at comparatively much less expensive servers rather than at the SCP. One of the unique attributes of the client-based positioning model is the ability of the client to have intelligence, to be self-aware of its position, and to be able to autonomously report position events. This can support a wide array of LBS applications that depend on leveraging a GIS context such as "geo-fencing" (determining through GIS whether a target wireless device has entered or left a given geographic area or "geo-fence"). While many non-standard, proprietary client software products and servers are available from many LBS applications providers, most industry proponents of commercial LBS applications agree that proliferation of standards-based User Plane infrastructure will drive massive deployment and adoption of commercial LBS. One such standard is referred to as Secure User Plane (SUPL).

Another key component of the overall User Plane infrastructure is the availability of GPS in the mobile device. Whereas U.S.-based GSM carriers T-Mobile and AT&T initially deployed T-DOA (time difference of arrival) for phase II of 9-1-1, they now have aggressive plans for GPS deployment.

Copyright 2005 Mobile Positioning and Location Management. (Click for larger image)

The combination of standards-based clients, server-based control and service logic, and GPS will most certainly usher in the advent of much more cost effective and nimble deployment of LBS applications. However, it will most likely not be enough to ensure a robust ecosystem that addresses the concerns of carriers, application providers and LBS users.

The Need for Mobile Positioning Mediation
There is something missing from the client-server model of the User Plane. There is a need for mediation. The type of mediation needed is Authentication, Authorization, and Accounting (AAA) as well as privacy management and user control. The Control Plane infrastructure was built with certain AAA and privacy management functions, but was arguably never flexible enough for robust commercial LBS offerings. In contrast to the more expensive Control Plane, the User Plane lends itself to more flexible and inexpensive methods to manage positioning requests. However, it is important to note that LBS application providers will not necessarily voluntarily implement robust management controls but rather simple privacy mechanisms.

The need for AAA is driven by the concern over what entity (LBS application and/or company) is attempting to position a mobile device. There is a need to authenticate the request as genuine and authorized, and account for the number of positioning requests for auditing, billing, clearing and settlement purposes. The accounting portion is not absolutely required currently by wireless carriers that care more about driving wireless data adoption and usage than directly monetizing mobile positioning requests. But authentication and authorization is critical from a network security perspective and as a foundation for end-user privacy. As LBS applications become increasingly commonplace due to the proliferation of the User Plane, end-users will demand the ability to manage preferences and privacy in terms of what entity may position them, when, for what application, etc. Long-term, as wireless carriers begin to realize that positioning is a strategic asset that can and must be monetized in its own right, they will demand the accounting function as well. They will also demand third-party mediation.

It is not enough for the LBS application providers to provide the User Plane infrastructure and also police themselves. Keep in mind that, due to the User Plane and its use of IP communications, an LBS application provider could literally run its business out of the proverbial garage! Will the wireless carriers want to vet each one of these LBS application providers? Certainly not! Before User Plane-based LBS applications can reach critical mass, wireless carriers will require an independent third-party(s) to provide the Mobile Positioning Mediation (MPM) function.

The MPM function that I envision would be placed between the mobile device positioning client and the User Plane server, mediating requests for position from the server to the client as well as mediating requests for autonomous push of position information from the client to the server. The MPM would be operated by a neutral third party on an Application Service Provider (ASP) basis, and managed on behalf of both LBS subscribers and the LBS application providers to provide preference and privacy controls to end users. The ASP solution would also vet LBS application providers in advance, providing necessary background checks and procedures to ensure authentication and authorization processing is effective and efficient. Finally, the ASP would also provide an accounting function consisting of recording events, rating events, and clearing and settling payments between payer (LBS application provider) and payee (the wireless carrier).

Many Methods of Positioning Demands Centralized Management
Another requirement for driving the widespread adoption and usage of commercial LBS will be centralized positioning management. There are many emerging non-traditional methods of positioning wireless devices including Wi-Fi, WiMAX, RFID and others. Many of these methods will be used for non-cellular devices such as laptops and PDA's, while others will be included in cell phones in the future. Couple these methods with more traditional cellular positioning methods such as TDOA, GPS, cell ID, timing advance, radio fingerprinting, etc. and you have many procedures, protocols, formats, etc. to manage. There will be a need for an intermediary entity to aggregate, manage, and distribute position information to all authenticated and authorized entities. This positioning management function is functionally separate from the MPM and can be managed by multiple entities but could be physically co-located with it and/or run by the same neutral third party.

Summary and Recommendations
The intent of this article is not to scare wireless carriers or end-users, or place undue burden on the many LBS application developers and service providers. Quite the contrary, the purpose of this article is to alert the ecosystem to an issue that will most likely be critical to the long-term success of the entire LBS value chain for commercial LBS applications.

Wireless carriers should continue to deploy pre-standard solutions, work with wireless device providers to roll out standards-based clients, and work with LBS application providers to deploy well-chosen services. However, wireless carriers should limit their deployments to strategic partners while working with industry leading service bureaus and (Managed Communications Service) providers, the most likely entities to provide the MPM and mobile positioning management functions on an ASP basis on behalf of the carriers and the LBS application providers.

Some of these MCS providers are the same companies that offer both Control Plane and User Plane solutions today. While many of the AAA and privacy features are built into the various vendors' User Plane infrastructure, there are arguments for and against these same companies offering privacy and preference management, clearing and settlement functions along with core client-server operation, but I will leave that to another article.

Ed. note: Detailed reports on this and other related topics are available.

Published Wednesday, August 22nd, 2007

Written by Gerry Christensen

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