Page 206 - DCAP311_DCAP607_WIRELESS_NETWORKS

Wireless Networks

Notes a computer system with tailormade software. The price for a complete network such as this,
installed and tested, would be about 5 million Euro. The time between sending and receiving a
message for such a network is around 5 minutes. Leaving out one ground station would decrease
the investment but increase the waiting time.
All network subsystems are described below.

Meteor Burst Base Station

Using meteor trails, a meteor burst base station (MBBS) can communicate with remote stations,
either mobile or fixed, over distances between 500 and 1500 km. Using meteor burst technology,
a few tens of base stations provide the infrastructure for the pan-European data communication
network. The data exchange between a base station and a remote station is initiated by a test
signal (probe) transmitted into space by the base station. If and when a meteor trail is in the right
position and reflects the signal back to Earth, the remote station answers the call by the base
station and data is exchanged. The base stations are connected directly to the Data Center of the
network.

Auxiliary Station

For communication in a densely populated, industrial area, auxiliary stations might be installed
to supplement the coverage by the base stations. The auxiliary stations do not use the meteor
burst phenomenon, but work in a Line-of-Sight (LOS) mode. The data received can be transferred
to one of the base stations using a meteor burst connection after which it will be delivered at the
Data Center. A direct link between the auxiliary station and the Data Center is possible as well.
In the current network planning, no auxiliary stations have been adopted.

Remote Station

A remote station can either be mobile or fixed. Mobile stations are for example the trucks and
cars from the FleetTrak and ProTrak service. The mobile stations use a radio modem and an
omni-directional antenna that is mounted on the roof of the vehicle. Fixed stations, for example
meteorological sites located in remote areas, use the same radio modem. For the fixed stations,
however, a directive antenna can be used to communicate with the meteor burst base stations.
The use of a directive antenna will improve the communication link and reduce the waiting
times. The power necessary to operate the equipment can be generated via solar cells.

Data Center

The heart of the network is the Data Center, where the information from the remote station and
customer terminal is gathered and passed on. Until the data is passed to either base station or
customer terminal, it is stored in so-called Call Detail Records (CDRs). The CDRs contain a flag
indicating whether the message is delivered or not. After a message is delivered, the CDR is used
for Billing and Accounting purposes and deleted from the database.
The customer is able to contact the Data Center by means of a modem. In the future, the Data
Center will be accessible via the Internet. As a standard SMS protocol is used to transfer the data
across the MBC network, the customer is free to use any SMS interface at the remote station or at
the customer end of the network.

12.2.7 Meteor Scatter

Meteor Scatter (MS) propagation is not new, it has been used for many years especially on 2M
using SSB and HSCW (high speed cw). The advent of WSJT modes FSK441 and JT6M has shown

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