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NET_13.TXT
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1992-07-02
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NET_13.TXT
BACKBONE TRUNK WITH REGENERATOR
-------------------------------
A variation of the cross-band full-duplex configuration would be to add a
full-duplex regenerator, either embedded within a trunk, or at a junction of
the backbone trunk. A cross-band full-duplex regenerator is fairly economical
to install and on a less then fully loaded network operates reasonably well.
There is a performance penalty though since it doesn't have the same high
throughput as a full duplex-link. However in terms of a cost vs. performance
trade-off, it's worth considering at selected sites.
-------------------------------------------------------------------------------
FULL DUPLEX CROSS BAND BACKBONE TRUNK WITH DUPLEX REGENERATOR
NODE A NODE B NODE C NODE E
====== ====== (REGEN) ======
147.5 TX ------------> 147.5 RX =======
446.1 RX <------------ 446.1 TX
147.52 RX <------- 147.52 TX -------> 147.52 RX
446.2 TX -------> 446.2 RX <------- 446.2 TX
147.54 RX <----
| | 446.1 TX ---->
| NODE F |
| ====== |
`-> 147.52 RX |
446.2 TX >-'
.-> 147.56 RX
| 446.3 TX >-.
| |
| |
| |
Figure 13-1
-------------------------------------------------------------------------------
There are other possible frequency/equipment configurations that are workable.
But the full-duplex backbone approach offers advantages of flexibility and
efficiency. It won't become obsolete in the foreseeable future. While more
expensive than a simplex backbone trunk, full-duplex is economical in terms of
yielding increased throughput even at 1200 baud. Indeed, its performance
is comparable to that of a simplex 4800 to 9600 baud system.
Full-duplex is flexible from the viewpoint that it can be upgraded on a link,
rather than a system basis as assets become available. For instance, if the
basic trunk is initially installed as a 1200 baud system, individual links can
be upgraded to higher data rates on an independent schedule.
Obsolescence is forestalled by the mechanics of the configuration. Assume in
five years chronic network overload will have set in. If RF path engineering
was done with the view of eventually phasing in microwave, link segments can
be installed as funds and equipment become available. Surplus equipment could
either be held on site for backup use or relocated/sold as necessary.
For this system configuration concept to be satisfactory, it's important the
network is engineered on an intra and inter-state basis. The primary emphasis
would be directed to building a robust backbone trunking system served by
isolated frequency LANS supporting both 1200 and 9600 baud access nodes. It
would be a good policy to include state and county emergency service offices
into the project planning so the network's digital support capability could be
utilized by them in case of emergency. In the same light, local governments
may be able to provide site support, and possibly, help with project funding.