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It may be possible to start a new workbook and link it to the data in the Access
model, and do the further analysis there.
For example:
•
there are also some useful results calculated in the sheet
"C_Resources_Used", giving results by geotype and by zone.
•
Table 1.2 in the sheet O_to_Consolidat ion gives a summary of costs
below the scorched node broken down into about 20 major cost
categories.
Q9: How can I optimise the Access network?
A9: The main opportunity for reducing the cost by optimisation (as opposed to
reducing costs or reducing the capacity of the network) is by varying the design of
the copper part of the Access network. This is done in Table 5 in the sheet
I_Zones_Data. For each zone in the sample, you can vary the following:
•
Inside the Tätort(main urban area for the zone):
− size of PDPs and of SDPs. The suggested approach is to aim for a ratio,
going up from NTP towards MDF, of successive nodes serving 10x to
30x the number of customers served by the nodes in the next layer down;
hence some zones may have three layers in their access network (MDFPDP, PDP-SDP, and SDP-NTP) whilst others have two layers, or (where
there are very few lines in the zone) even only one layer. This approach is
only a suggestion and the user should experiment with different solutions.
The true optimum will depend on the geographical parameters for each
sample zone and on the cost-volume relationships for both cable sizes and
for distribution points.
− strategy for locating the PDPs and SDPs - close to the MDF (minimise
total pair-km) or close to the customer (minimise total cable km). The
suggested approach is to use a location parameter in the range 0.25 to 0.5,
but it is worth experimenting with values in the range 0 to 1 and
occasionally higher.
− if the RSS is outside the Tätort– decide whether to connect the Tätort,
using one large “Super-PDP” serving the Tätort as a satellite from the
MDF. If using a “Super-PDP”, you can vary the strategy for locating it.
•
Outside the Tätort:
− Same set of parameters – all of which can be set independently of those
for the network inside the Tätort- except that there is no “Super-PDP”.
Q10: I have changed the details of the 25 sample switch zones - eg weightings, and numbers of
lines in each zone - but the cost of the copper network has not changed much. Why?
A10: The model uses the figures that you input for the total number of copper
lines (NTPs), and the total area of the country, as a control total. These are input
in Tables 1.1 and 1.2 and 5 of the worksheet I_Access_Services. If the weighted
sum of the results for the sample zones gives too few lines and too small an area,
the model adjusts the data for the zones in the sample, to correct for this bias.
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