Developing effective location service solutions is extremely challenging. As standards bodies are continuing to define network nodes, functionality, and interfaces, mobile operators are faced with the reality of integrating their location servers with network elements that have varying levels of standards compliance and back-end systems with unique interfaces. No "one-size-fits-all" solution will work.

Over the last seven years TCS has developed an architecture and platform that are specifically designed to enable the development of location server solutions in this challenging environment. The Voyager distributed architecture provides a carrier-grade foundation for TCS solutions, while the Xypoint Location Platform uses the Voyager distributed architecture to provide a suite of location technology components that are designed to be integrated into systems that meet the mobile operator's needs.

Voyager Distributed Architecture
The Voyager distributed architecture is at the heart of every TCS location server solution. The advantages of Voyager are realized in a robust, state-of-the-art server platform that is inherently flexible, scalable, highly available, and cost-effective, allowing installations in configurations that meet the wireless operator's current and future needs. TCS Voyagerbased systems are built using C++ on the Sun Solaris platform, with the Voyager framework providing common facilities for database access, messaging, transaction management, logging, management and configuration (see Figure 1, next page). These systems in their entirety are a mix of proprietary and third party software.

Voyager has been extensively field proven in a variety of applications (including commercial and emergency location services), and it is under constant improvement based on feedback from TCS customers as well as from experience operating the Xypoint E9-1-1 service within TCS data centers. This hands-on operational experience ensures that TCS solutions meet the high operation and performance requirements of the wireless operator environment.

Features of the Voyager distributed architecture include:

Common Operational Support Systems (OSS) - TCS solutions use a common set of OSS tools and interfaces for system monitoring, management, provisioning, reporting, and billing. This means features can be added or removed from installations without requiring re-integration with the wireless operator's OSS or re-training operations staff.

Peer-to-Peer (P2P) - Solutions built on the Voyager platform operate as a collection of redundant individual processes that interact with each other as peers, as opposed to a clientserver model in which client processes communicate with centralized server processes. Processes are automatically aware of and can communicate with any other process running across any number of machines. By eliminating single points of failure and congestion, this architecture drastically improves system performance, resiliency, and ease of maintenance.

Multi-Threading - Voyager is heavily multi-threaded. Systems are designed to support thousands of concurrent sessions, each operating in its own thread of control. This optimizes system performance and resiliency by minimizing resource conflicts between concurrent requests.

Internal Messaging - Voyager uses proprietary binary encoded message protocol (similar in structure to TCAP) for all internal process communication. Messages are carried via TCP/IP for inter-machine messages and via the Sun Doors IPC mechanism for intra-machine messages. System load information is used to route internal messages to the least utilized systems to optimize overall performance. As new systems are added, traffic is automatically routed to them. Likewise, machines that are taken down either for maintenance or due to fault are automatically removed from the routing tables, and messages are re-routed to other machines. With this feature, system resiliency is dramatically improved while scaling and maintenance activities can occur extremely rapidly with little or no down time.

High Availability - In addition to the benefits of peer-to-peer distribution and internal messaging mechanisms, Voyager provides additional measures to ensure high-availability. Every piece of the system (hardware, network, database, and process) is redundant. There are no single points of failure. Unlike other solutions with stand-by systems that are only used in the event of primary system failure, TCS solutions use an "all-hot" model in which all systems are active. This eliminates the risk associated with fail-over to inactive back-up systems that may themselves be inoperable. Keeping all systems active ensures that all systems are constantly used and monitored. In addition, the system has capabilities such as automatic process de-registration and alternative database selection to adapt to single element failures, while SNMP alarms notify operations staff so that appropriate measures can be taken as soon as possible.

Multi-Site Support - An extension of the peer-to-peer capability, multi-site support allows implementation of TCS solutions across multiple geographically redundant data centers, in a variety of configurations. Sites may be operated as separate entities with fail-over capabilities or together as a single "federated" system, depending on the wireless operator's capacity and availability requirements. Multi-site installations are resilient to inter-site network failures, with the ability to function, be managed, and be monitored independently while the connection is down, as well as recover with minimal human intervention when the network connection is restored.

Figure 1. Voyager^TM Distributed Architecture

The Xypoint® Location Platform
The Xypoint Location Platform (XLP) was first launched in the commercial market in 2002, with the initial deployment in Hutchinson's 3G (H3G) UK network; XLP® deployments are currently underway in eleven additional H3G networks, including Italy, Sweden, Austria, Hong Kong, and Australia. The XLP has been operating in TCS' own data center since 1997, providing E9-1-1 services to over 25 mobile operators in the US covering an estimated 30M wireless subscribers.

In operation, the XLP is a uniquely integrated solution that gathers and manages data from the core network, the precise positioning solution, and the various applications - as well as providing centralized privacy controls and customer profile management. The XLP is a mature, state-of-the-art, standards-based system that delivers high performance and flexibility based on modular functional elements that include a standards-based Gateway Mobile Location Center (GMLC) and Mobile Position Center (MPC), Privacy Server, Profile Manager, Watcher Module, Application Interface Module, and positioning technology such as PDE, A-GPS server or SMLC. The XLP's modular architecture is designed to isolate core functionality from specific interfaces and standards. This flexible design enables the XLP to be integrated easily with equipment from various manufacturers or enhanced to embrace new and emerging protocol standards.

Figure 2. Xypoint® Location Platform

The XLP's design supports a wide range of service strategies, enabling the mobile operator to deliver a broad set of cost-effective location applications. In addition, the XLP gives the mobile operator the opportunity to generate revenues from value-added services with minimal systems risk and uncertainty.

Having already been deployed in analog, 2G (digital), 2.5G (high speed digital), and 3G (ultra high speed digital) environments, the XLP is designed to evolve alongside both changing technologies and operator requirements. The XLP supports 3GPP standards for GMLC and SMLC, while within the Application Interface Module support is also provided for the 3GPP OSA interface and the OMA-LIF Mobile Location Protocol (MLP) interface to Location Services (LCS) clients. The XLP also has OSS functions for provisioning, usage data collection, configuration management, fault management and performance management.

Engineered to interact efficiently with core network elements, the XLP's proprietary and intelligent location technology enables location applications to gather location data without placing too much of a load on core network resources, allowing new services to be introduced safely and reliably. By building its location server solutions on the Xypoint Location Platform, TCS is able to quickly and cost effectively create systems that are adapted to the unique environment of each installation, while maintaining a robust core of common functionality.