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GPRS routers


  • Low operating cost communications for roadside ITS
  • Widely used in UK variable message signs
  • Supported by all manufacturers of UTMC-compliant VMSs
  • Over 2,000 installed and monitored continuously

Overview

GPRS offers a means of highly effective wide area data networking where communications are initiated from the remote node for example, when collecting email using a notebook PC or handheld device.

Unfortunately, as supplied by the service providers, GPRS networks are not as effective when a communications session needs to be initiated from the centre, for example, in remote, telemetry applications such as ITS.  IDT's GPRS router has been specifically designed for these circumstances by enabling you to extend your centre's local area network as a secure virtual private network across the GPRS network.   Proven reliability on the roadside (and designed to operate at temperatures as low as -15°C) have helped us achieve an installed base approaching GPRS routers in the UK alone.

Security

IDT's GPRS Router establishes a secure IP tunnel (using the IPsec protocol through the public GPRS network) which is terminated at a VPN router at the instation.

Using IDT's GPRS routers for VMS networks

A typical solution using GPRS routers is shown below. This drawing shows a UTC instation communicating with a car park counter (bottom right) which is counting vehicle movements via two inductive loops. The car park counter is in a cabinet together with one of IDT's GPRS routers.    The UTMC common database requests data periodically from the counter (the interval is set by the system operator at the instation).

The instation processes the count data along with information obtained from other datasources in the UTMC system such as air quality monitors and UTC.  By following strategies at the instation (such as car park fill rates, congestion at specified junctions), system managers can set messages on the variable message signs (shown top right).

Click image to enlarge

A VPN router is required at the instation to route data via the service provider to the roadside equipment (which can be any IP-capable equipment). To provide adequate levels of security, private GPRS networks are complex to set up but, once implemented, have low maintenance requirements.   We normally design and implement all networks which use our GPRS routers.

Connectivity
GPRS Class 10 - Quad band
900/1800/850/1900 MHz
GPRS Speeds 80kbps downlink, 20kbps uplink
Interfaces
10/100baseT Ethernet RJ45
RS232 (9-way D-type) for terminal
Dimensions
290 x 230 x 44 mm
Weight
1.5 Kg
Power
110/230V (auto switching) 10W Max
Environmental
IP54
Operating temperature
15 to + 60°C
Networking features
GPRS connecitivity
IPsec tunnelling protocol with RSA or pre-shared Key authentication
IP routing and filtering
Network Address Translation (NAT)
Internal firewall
DHCP server options
SSH server for router administration

VPN routers

Security in our GPRS router is provided using a protocol called IPsec. 'Tunnels' are created between the GPRS router and the instation which go through the public GPRS network and the Internet. At the instation, the tunnels are terminated at a VPN router.
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