Build-Ahead

It makes no sense to design a network to support the traffic demand that
we expect today. This means that we must return tomorrow to enhance the
network capacity. Instead, we need to design the network to support the
demand that we expect at some point in the future so that we are not
enhancing network capacity on a daily basis. Moreover, a reasonable buildahead
provides extra capacity so that the network is prepared to handle
extra traffic in case subscriber growth is greater than projected. Buildahead
also provides a buffer in case of a sudden change in marketing tactics.
For business reasons it may be necessary to introduce new pricing
plans or incentives, which can significantly change subscriber numbers or
usage patterns. It is wise to have the network prepared in advance for such
eventualities.
So how much build-ahead is reasonable? Typically, it is wise to design the
network to support the traffic demand expected 6 to 12 months in the
future. If for example we launch a network in December of 2001, then a 12-
month build-ahead would mean that we use the subscriber forecasts and
usage projections applicable to December 2002 as input to the network
design process. In general, the build-ahead can be larger at the beginning
and be reduced over time. If for example we include a 12-month build-ahead
at the beginning, we might want to reduce this to a 6-month build ahead
after 2 years as we will have a better understanding of traffic growth patterns,
and usage forecasts (assuming they are updated on a regular basis)
will be more dependable.