The network spectrum utilisation obtained from the performance data 

submitted by operators is combined with a theoretical measure of spectrum 

utilisation.  The results are plotted on a scatter graph and the location of the 

various scatter points indicates the relative performance. 

Acceptable Utilisation 

Good 

Implementation 

More Spectrum 

Needed 

Good Network Implementation 

Unacceptable GoS 

Poor Network 

Implementation 

Unacceptable Utilisation 

Figure 3.5 Example of Scatter Graph 

The graph in Figure 3.55 shows the relative performance of each network.  

The position of the network rating point in the scatter graph gives a good 

indication of how well the network has been implemented and if it is in need of 

more radio spectrum.  For example, the top left hand side region of the chart 

indicates good network implementation.  The further right in the top region of 

the chart indicates more radio spectrum required.  The bottom left hand side 

region indicates poor network implementation and that no additional spectrum 

should be allocated as better network implementation will improve the GoS 

with the same spectrum allocation. 

Thus the chart provides an instant indication of the state of a network and will 

enable the change in performance to be tracked and an indication of reaching 

a stage when more spectrum is needed. 

Some results are given here.  Three benchmarks are used: 

Reuse: Macro Layer  = 9; Micro Layer = 3 

Cell Radius: Macro Layer = 300m; Micro Layer = 80m 

Macro Cell Layer and No micro cells 

15 % area covered by micro cells 

Different spectrum is used for Macro and Micro layers: this is a 

representative of the practical implementation of the networks.  

Graphs for Spectral Utilisation are plotted for planned capacity and carried 

capacity for GSM networks for the selected 25 Sq Kms area.  

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