A straightforward but extremely effective way to increase the
network capacity is to make the cells smaller. This approach has been demonstrated over several cellular generations [24], [25].
The first such generation, in the early 1980s, had cell sizes on
the order of hundreds of square kms. Since then, those sizes
have been progressively shrinking and by now they are often
fractions of a square km in urban areas. In Japan, for instance,
the spacing between BSs can be as small as two hundred meters,
giving a coverage area well under a tenth of a square km.
Networks are now rapidly evolving [26] to include nested small
cells such as picocells (range under 100 meters) and femtocells
(WiFi-like range) [27], as well as distributed antenna systems
[28] that are functionally similar to picocells from a capacity
and coverage standpoint but have all their baseband processing
at a central site and share cell IDs.
A straightforward but extremely effective way to increase thenetwork capacity is to make the cells smaller. This approach has been demonstrated over several cellular generations [24], [25].The first such generation, in the early 1980s, had cell sizes onthe order of hundreds of square kms. Since then, those sizeshave been progressively shrinking and by now they are oftenfractions of a square km in urban areas. In Japan, for instance,the spacing between BSs can be as small as two hundred meters,giving a coverage area well under a tenth of a square km.Networks are now rapidly evolving [26] to include nested smallcells such as picocells (range under 100 meters) and femtocells(WiFi-like range) [27], as well as distributed antenna systems[28] that are functionally similar to picocells from a capacityand coverage standpoint but have all their baseband processingat a central site and share cell IDs.
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