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This page describes using Air-Frame 100 models in Multi-Cell configurations.
Multi-Cell networks are used to increase the number of remote locations that may be serviced in any geographic location from a single Mast or antenna farm. In the above diagram Cell 1 and Cell 2 are shown as slightly overlapping only for the sake of diagrammatic simplicity, in practice they may fully overlap.
In the above diagram Location C is shown as being serviceable from either Cell 1 or Cell 2. In operational use a single parameter controls the Cell number to which it would be dedicated for load purposes or it can be configured to 'roam' and find the best Cell reception. Once found the unit remains in this Cell until instructed to 'roam' again.
The number of customers in each cell is a function of bandwidth requirement and customer network utilization patterns. A typical cell of 16 customers will provide each customer with an average of 128K bit/s of bandwidth with the ability to 'burst' up to the full 1.2 M bandwidth. Air-Frame 100 allows configuration of bandwidth limits on any single link for Transmit, Receive or Total (Transmit + Receive).
For low volume applications such as Telemetry the number of systems in a Cell can be as high as 50 or even more. There are no Air-Frame imposed limits to this number.
The theoretical maximum number of 'Cells' that can be serviced in any given geographic location is 79. In practice the number of cells would be determined by:
Data activity in each of the cells
The surrounding radio environment (there may be other 'foreign' Frequency Hoppers active in the locality)
If both the Air-Frame unit data activity and the 'foreign' system activity is low then 30 to 40 co-located cells is the maximum attainable. For normal traffic volumes 10 to 12 co-located cells should be considered a prudent maximum value.
In a bridged connection (Air-Frame 10 and 100 range) the network traffic is sent from one location to all other locations in the cell and consists of:
Traffic for a PC or system on any other network in the cell i.e. traffic from location A to, say, a system at location F, is also received by Location B (but is only sent once over the radio) and is placed on the local LAN at B by the bridging function.
Broadcast traffic (e.g. network management).
In effect all the locations in a Cell operate as a single, fully transparent LAN. Where one or more locations consist of many PCs or systems the broadcast traffic alone may be considerable and consideration should be given to using a routed network. In addition the 'redundant' traffic received at each non-addressed location can stress the local LAN network as well as cause security concerns. In this case also a routed solution should be considered.
In a routed connection (Air-Frame 100 range) the traffic is sent from one location to all other Locations and consists only of:
Traffic for a PC or system on any other network in the cell i.e. traffic from location A to, say, a system at location F, is also received by Location B (but is only sent once over the radio). The routing function however prevents this redundant traffic from being placed on the local LAN at B.
In this case the LANs operate independently but communication is enabled between them. No data is leaked onto the other sites.
The following table defines inter-working between the Air-Frame Family in Multi-Cell configurations:
|Location A||Location B|
|Air-Frame 100 (any model)||
Air-Frame 100 (any model)
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