Mobile GIS is one of the fastest growing areas of the GIS industry, and its benefits are now being realised in many organisations, especially for the mobile workforce.

This section concentrates on explaining some of the key concepts of Mobile GIS, and therefore contains some level of technical detail. For a less technical explanation review the Benefits or Customer Needs of Mobile GIS.

This section is designed to aid an understanding of how Mobile GIS will complement and fit with your existing or proposed GIS and IT infrastructure. This section does not purport to cover all technical aspects of Mobile GIS, and those described here are at a relatively high, often conceptual level.

The basic components of mobile GIS technology are shown in the diagram below and are described in the following paragraphs under the headings :

Mobile or wireless GIS is very similar to wire-line Web GIS. There are three main components common to both:

• The client
• The server (combination of web, map and data servers)
• The network

The main differences are the client devices and the network type (mobile uses wireless communication service providers). The server functions and structures are similar to Internet GIS. Mobile applications are a bit like 'thin client' applications of Internet GIS.

There is an additional element in mobile, which is the location.

Mobile End-User Devices - the clients

These are the client devices utilised in the field. A full range of client devices can be used for mobile GIS, from mainstream laptop computers with all the computing power of a PC to PDAs or Pocket PCs with smaller screens to cellular telephones with even smaller displays, simpler input devices and limited processing power.

Access and use of GIS data and functions through mobile and wireless devices is possible in two main ways :

• On-line, with real-time access to service/corporate data
• Off-line, where data is downloaded and used without a real-time connection to a server/corporate database

On-line Internet Enabled Devices

These devices can access and display Internet services in real-time using technologies such as GSM, HSCSD or GRPS. Users can make requests for data, modify this data and return the results. Using this method, the need to store large amounts of data on the device and to return to the office to synchronise files is eliminated.

Off-line Devices

Users download the data they require onto the device. They can then use a GIS application installed on the device to view and manipulate this data in the field. When complete, the user returns to the office, connects the device to a PC and synchronises the changes. This method eliminates the need to establish live Internet connections in the field.

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Position Determining Equipment (PDE) - the location

Mobile GIS is usually coupled with Global Positioning System satellites (GPS) and wireless communication to facilitate exchanges between the existing spatial server and mobile devices.

Position-determining components determine the location of the mobile devices in real-time. There are generally two ways to determine the location of a mobile device

• A handset-based system that relies on GPS, which is placed at the mobile handset. GPS provides unequalled accuracy and flexibility of positioning for navigation, surveying and GIS data capture, and
• A network-based system that relies on triangulation of the cellular information, where PDE is at the switch centres

Position-Processing Technology (PPT) can then be used to process, track, manage and help other applications to query and retrieve the location information sent from a PDE.

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Telecommunication Service Providers - communication networks

These are the wire-line or wireless communication networks. Internet Enabled Devices rely on the wireless network to transport information. Performance is a function of the wireless network architectures because different wireless networks have different transmission rates.

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GIS Content Providers - the servers

This component of mobile GIS solutions serves data and applications to the user e.g. it offers location information content and information processing services. The type of information and services provided varies depending on the type of application being used.

Typically GIS Content Providers include:

• GIS Servers (with GIS Content)
• Information Processing Services, and
• Gateway Services.

GIS Servers

These contain the GIS Content or Location Information Components.
Location Information is content information about a specific location, whether that be:

• geographic information eg base mapping, addresses or street networks, or
• specific attribute information about a location eg services, customer details, asset details etc

GIS Servers are :

• web
• application
• map
• data servers

Information Processing Services

These are the components which process and output data to feed to mobile devices via Gateway Services and include:

• location, query and display
• geo-coding
• spatial search
• routing
• map display and rendering.

Gateway Services

These are middleware services that link wireless devices to Information Processing Services and the GIS Servers.

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