Related expressions
Database, communication standard, RFID

Explanation

The users of the Indisputable KEY system need to have access to applications to retrieve data associated with the identified objects – logs, boards etc. The access to the applications is through the internet and an internet connection is therefore needed at all locations (applications) where the Indisputable KEY data is to be accessed. The applications in the Indisputable KEY system use XML-messages (Extensible Markup Language) to communicate with each other and to access data. The data communication system (or systems) is used to transfer these messages. The architecture is illustrated in Figure 5.

Figure 5 : Data communication system architecture

Most of the communications between the applications and is carried out using commercial internet services through the existing telephone network or other wired network. However, there are applications where a specialised wireless connection is needed – such as the connection to/from the harvester in the forest. For this purpose a long range data communication system is developed in the Indisputable KEY. In a saw mill the RFID readers and other equipment reading and writing the IAD need similarly a data communication connection. For fixed installations this can be achieved using a standard cabling based (wired) connection, but for mobile applications (forklifts etc.) a wireless short range data communication system is needed.

For the application access via the internet any terminal (radio transceiver & modem) providing a wireless internet connection can in principle be used in the applications. In remote areas satellite communications can be used – data transfer services with global or nearly global coverage are for example provided by Iridium, Globalstar and Inmarsat. The terminal connects to a satellite, which relays the signal carrying the data to a ground station where there is a connection to the internet. These services and the required terminals are rather expensive and should be used only when terrestrial wireless communications are not available.

The mobile phone network, the GSM (Global System for Mobile communications), can be used to transfer data wirelessly. The operation of the GSM network is based on base stations (BTS) to which a phone or a data modem (mobile terminal) is connected. The base station relays the data from the mobile terminal to other mobile terminals or to the conventional phone network and to the internet via switching centres. The GSM network architecture is illustrated in Figure 6.

Figure 6 : GSM System Architecture

The digital mobile phone network, the GSM (Global System for Mobile communications), can be used to transfer data wirelessly. The operation of the GSM network is based on base stations (BTS) to which a phone or a data modem (mobile terminal) is connected. The base station relays the data from the mobile terminal to other mobile terminals or to the conventional phone network and to the internet. In Europe, GSM may operate at three frequencies: at 900 MHz, 1800 MHz, and recently also at 450 MHz (the old analogical mobile phone frequency, NMT).

General Packet Radio Service (GPRS) is a packet data service in the GSM network. It is used transfer data packets, i.e., data is transferred only when needed in packets instead of continuous transmission. This makes the GPRS more efficient allowing higher data transfer rates up to 53 kbit/s. The GPRS allows easy wireless access to the internet. Currently Enhanced Data rates for GSM Evolution (EDGE) and Universal Mobile Telecommunications System (UMTS) with High-Speed Downlink Packet Access (HSDPA) provide data connections up to about 2 Mbit/s, but their coverage is still limited. The transfer data rate is typically lower in the uplink from the mobile terminal to the network than in the downlink from the network to the mobile terminal.

Wireless Local Area Networks (WLANs) can be used for wireless internet access at ranges up to a few tens of metres. Typical data transfer rates are up to 54 Mbit/s. The operation of the WLAN is based on base stations as in the GSM networks: The terminals connect to the base stations which provide the access to the internet. The network architecture is somewhat simpler as the number of the mobile terminals (computers with the transceiver & antenna) is typically much lower.

Application/usage in Indisputable KEY

Long range data communications using the existing commercial GSM networks are used in the Indisputable KEY to connect the remote forestry applications in harvesters, forwarders and in trucks to the internet and to the applications. The communication hardware consists of a GSM modem and transceiver with the associated antenna. The communication system may operate in GSM 400/900/1800 –networks depending on the coverage of the each network. As a back-up a satellite datalink can be used in remote areas without GSM service.

WLAN connections can used to short range data communications in mobile applications such as RFID readers installed on a forklift in a saw mill. The working area in the mill is equipped with WLAN base stations and repeaters to allow flexible straight forward access to the applications.

Institutions with teaching capabilities
A lot of training courses exist about GSM and GPRS in Europe. Here are three examples.

• TELECOM Bretagne (France) organizes training (3 days) about GSM and GPRS.
• NET2S Institute (France) organizes different trainings for companies interesting in GPRS technology
• Apis Training Center (Sweden) organizes also different trainings about GSM and GPRS.

Available text books and training material

“The GSM System for Mobile Communications” (Michel Mouly and Marie-Bernadette Pautet): This book aims to bridge the gap between a reader’s basic knowledge of telecommunications and the complexities of the 5000-page GSM technical specification. It describes the system as a whole, covering all aspects of the standard, including mobile stations, switching equipment, the radio interface, infrastructure, transmission methods, and signaling protocols. System architects involved in the design of personal communications systems will find the book to be a complete description of the GSM communications system. It also may serve as a general introduction to digital cellular systems. http://portal.acm.org/citation.cfm?id=573838

General Packet Radio Service (GPRS): guide to answer such fundamental questions as "What is it?" "How does it work?" and "How much is it going to cost me?" The author, telecom expert and best-selling writer R.J. "Bud" Bates, reveals GPRS's features, functions, and architecture, information crucial whether you're providing or applying GPRS. His straightforward, abundantly illustrated, step-by-step presentation of how GPRS works, how it connects the Internet, and how to implement it will help you put GPRS in place quickly and profitably as you explore: The complete layout of GPRS system architecture, The function of GPRS elements, Interfaces--radio and MS-PCUSN, MS-SGSN, PCUSN-SGSN, SGSN-GGSN, and GGSN-PDN.

In an application different from IK project but for the same aim, it can be interesting to read the following publication of George A. Giannopoulos : “ Implementation of a Data Communication System for the Adriatic-Ionian Sea Area ”, Transition Studies Review, Volume 12, Number 3 / December, 2005. This paper presents the state of the art for communication of data and information between the various participants in the port community, as well as between the port administrations themselves. It also presents an innovative application of a port community communication platform in the Adriatic-Ionian corridor. The system is accessible by both electronic data interchange and Internet and has been applied on a pilot status in the ports of the Adriatic, Ionian, and part of Northern Aegean Sea areas.