2.4 Handling of
common channels
The common channels provide control information for the mobile
stations, considering power levels, access information and so on. This
information has to be transmitted to the whole sector or cell at all time.
Though when designing a base station with smart antennas, it has to be able to
attend to this task. In [20] [21], it is reported that a smart antenna system
consisting of an antenna array, controlled by some weights, might be able to
cover the whole region by employing some special weights for the common
channels. This is a desirable solution, as it only will require some minor
additions to the smart antenna system, and the gain from all the antennas will
be exploited. If a satisfying set of weights can be found, these can be stored
in some non-volatile memory, and recalled each time information is sent on the
common channels.
However if the weights of the antenna array involves that the
whole region can not be covered sufficiently, it might be more feasible to add
an antenna with a wide beam covering the region [22]. The information for the
common channels can then be switched to this antenna. Such a solution is more
expensive, as it requires more hardware, including an antenna, a switch and
possibly an extra transceiver [13].
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