Theoretical Spectrum Utilisation for given amount of radio
spectrum.
Actual Grade of Service (GoS) of cell calculated from Erlang
tables using installed capacity and carried traffic
Spectrum Utilisation based on carried traffic
Spectrum Utilisation based on installed capacity
The percentage of cells with a GoS poorer than the acceptable
level of 2%.
It should be noted that there is no measure of Quality experienced (drive test)
included in the above mentioned data and that the spectrum efficiency should
ideally be measured in relation to a given quality benchmark.
The spectrum utilisation of the networks was evaluated for a number of GSM
networks and CDMA 2000 1x networks.
The following methodology was devised and used to assess the spectrum
utilisation of the Indian networks.
Using the data, the following was calculated for each network:
The spectrum utilisation of the networks in a high traffic
location for an area of around 25 Km
2.
(SU
theoretical
)
The theoretical spectrum utilisation for the given amount of
radio spectrum used (SU
actual
) as derived from section 3.2.2.1.
The grade of service (GoS) of each cell in the area under
consideration using the carried traffic and the installed
capacity
The percentage of cells whose GoS was worst than 2%
A Figure of Merit for the spectrum utilisation (FoM)
A Congested Cell Rating (CCR)
Definition of Congested Cell Rating (CCR)
CCR
=
x
[
.1
+
]
re
whe
=
deviation
standard
the
of
of
GoS
the
cell
each
x
=
of
number
the
GoS
with
cells
>
2%
A scatter graph of the results for all the GSM networks was plotted using the
following scales:
Y Axis:
FoM
=
SU
SU
actual
theoretical
X Axis:
CCR
The ideal value of CCR is 0: all cells are better than 2% GoS. However in
practice, there are possibilities of some cells will exceed 2% GoS
occasionally. Therefore, a threshold value for acceptable value of CCR needs
to be identified. The value used for indication purpose is1.5.
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