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Effet d’un Chiffrage
sur la QoS en VSAT
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Sécurité des informations
dans un modem satellite
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puce Satellite modem NDSatCom

Optimizing the use of the space segment is a key criterion for selecting a satellite modem: the space segment is a recurring leasing cost which can not be avoided. Thus, the choice of multiple access protocol in this segment by a network of station will depend on the duration of the project, investment materials, flexibility and facilities requested.

There are several communication protocols: SCPC FDMA, TDMA, CDMA, etc … that define how VSATs access and use the space segment allocated by the owner of the satellite.

We propose the use of TDMA (Time Division Multiple Access) FM (Frequency multiplier) DAMA (Dynamic Allocation Multiple Access).

For this, we propose the use of SKYWAN family of satellite modems manufactured NDSatcom, IDU 7000, IDU 2070, IDU 1070

This modem is a MF-TDMA VSAT system that can use up to eight frequencies. Each frequency has a maximum capacity of 6 Mega Symbols per second allowing a network capacity up to 80 Mbps, depending on the algorithm of convolution FEC (Forward Error Correction) selected.

A single frequency, with a transmission rate of the aggregate can transmit any type of information ranging from pure data, voice, facsimile to the multimedia applications.

Depending on the size of the required capabilities, transmission rates on different frequencies are configurable from 100 to 6000 kbaud . It is then possible by hopping to spend a transmission rate to another station.

The SKYWAN Series of Modems can be a so-called DAMA (Dynamic Allocation Multiple Access) that can allocate bandwidth on demand, by sharing a set of carriers between all applications. This means that at any time the satellite bandwidth is allocated according to individual demand of the stations, and released as soon as it is no longer used. When a station does not transmit, available capacity can be used by any other station in the network.

Each station is able to apply all the bandwidth from 100 to 125 ms in the frame structure configured. This allocation of capacity is actually less than a second after the demand for bandwidth providing dynamic allocation of bandwidth unmatched in the industry.

Network topology based on a concept Star configuration may then be advanced to migrate to a hybrid or mesh topology where each station can directly communicate with any other station without passing through a hub or a station master. The system can be configured according to a more flexible criteria in terms of priority, minimum bandwidth, permalinks, etc. .. Between each station being more or less important in terms of transmission capacity.

At any time, the user can become their own operator as independently as possible.