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Cellular Networks
from:Author: David Chow
Article:
To efficiently reuse wireless spectrum, wireless network are
divided into cells. In general a cell is a hexagon in shape.
Based on the radius of the cells, there are three types of
cellular networks, including (1) macrocells, (2) microcells, and
(3) picocells.
Macrocellar wireless network
A macrocell can cover a large area with a radius ranging from 1
to 10 km. a distinction can be further made to for large
macrocells and small macrocells. A large macrocell can cover a
range with a radius of 5 to 10 km, which is mainly used for
rural areas with little traffic. In contrast, a small macrocell
generally covers a range with a radius between 1 and 5 km. This
types of cells are used if traffic density is high. Macrocellar
wireless networks transmit a very high radio power to cover a
large cellar area. They have low spectrum efficiency due to its
large cell coverage. The typical rms delay for a macrocell is at
the range of 10us.
Microcellar wireless network
Microcellar networks are deployed in area with high density of
traffic such as suburb. Each microcell generally covers a radius
ranging from 200m to 1km. Microcellar networks can be deployed
as a chain or in two dimensions. The chain-like deployment is
often made along a highway with high traffic densities, while
the two-dimension deployment is often made in the city streets.
In this deployment, buildings help block signal from
neighbouring cells, thereby decreasing co-channel interference.
Comparatively, microcellar networks have better spectrum
efficiency than that of macrocellar networks. Typical rms delay
for microcell is around 2us due to its smaller coverage area.
Picocellar wireless network
Picocellar wireless network is a type of wireless network with
the smallest radio coverage. Its radius ranges from 10 to 200m.
Such a type of network is often deployed in a room. Thus, it is
often called indoor wireless network. Picocellar wireless
networks have the best spectrum efficiency among the three types
of cellar networks. Also, due to its smallest coverage, it
transmits the lowest radio power and has the smallest rms delay
ranging from 50 to 300ns.
Summary
Three types of cellar wireless networks are introduced. They
cover different cellar areas and are applicable to different
wireless communication scenarios. In general, a macrocellar
network covers the largest area, but requires the highest
transmission power and shows the lowest spectrum efficiency. In
contrast, a picocell network transmits the weakest radio signal
to cover the smallest area like a conference room. It achieves
the best spectrum efficiency.
This article was contributed by
Wireless Technology: http://www.ylesstech.com
About the author:
David Chow has more than 10 year experience in
telecommunications and IT. Visit
Wireless Technology
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