In general I agree, although I think that there's enough total bandwidth
available that for really low-power/distance transmitters such as
Bluetooth/ZigBee/etc., it's OK for people to have, e.g., wireless keyboards
and mice even if they are no more than a few feet away from what could be a
wired connection instead.
The top of your desk or your room are quite natural entities to form a
cell. However trying to communicate with other devices in a nearby
room would certainly be possible using "sufficient" transmitter power
levels, which would ruin the frequency reuse in nearby rooms.
For that reason, it makes sense to use low power base stations in each
room and connect the base stations together with some wired network.
In this way, frequencies can be reused much more effectively. Thus
allowing much more devices to coexist in a given space and frequency
band, including your next superduper wireless gadget
.
Many modern devices for unlicensed bands are quite good in handling
the congestion. For instance, when new DSSS transmitters are added to
an area, each receiver will suffer a small degradation of the
signal/noise ratio of the wanted signal. With a large number of new
transmitters added, the received (despread) SNR is so low that
communication is impossible.
Assuming that you are the first user of band in your area and you
succeed in setting up links as long as the (often hilarious)
manufacturer claims. Some time later (perhaps next week), when others
have installed their systems in your area and frequency band, the SNR
gets degraded, your weakest links will drop out now and then and
finally the strongest short links work reliably. Thus, you either have
to design your network with sufficient SNR margins at the beginning or
be prepared to split your network later, when there are other signal
sources installed that are reducing the SNR.
