Page 38 - Proceedings of the 2018 ITU Kaleidoscope
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2018 ITU Kaleidoscope Academic Conference




           spectrum is not as affected as in the fifth. In C4, there is also
           more variability around the cluster centroid.





















                                                                   Figure 9 - Geographical disposal of all clusters.










               Figure 8 - View of clusters between 869MHz and
                               894MHz.

           In addition, in Figure 8, there is a decrease in cluster C4. This
           is another type of impairment, called tilt, which consists in a
           loss  of  the  signal  strength  throughout  the  spectrum.  The
           analysis of its causes and implications is beyond the scope of
           this paper.

           In  clusters  C2,  C3  and  C6,  there  is  no  clear  evidence  of
           ingress, though the signals in C3 seem noisier than the other   Figure 10 - Localization of cable modems grouped in
           two.                                                               cluster with ingress.


                  4.3 Geographical localization of the clusters                5.  SUMMARY
           For  the  purpose  of  inferring  the  possible  location  of  the   We  obtained  six  clusters  (Table  4),  in  which  we
           damage,  which  provokes  the  presence  of  ingress  -among   characterized ingress: in the first group, C1, there are traces
           other possible impairments, such as  tilt-, we proceeded to   of the signals from the public digital TV, the FM radio and
           locate the cable modems in a map, as shown in Figure 9.    the 3G downlink channels. It is similar to what we see on
                                                              cluster C5, except for the fact that in the latter, there are two
           In  Figure  9,  it  does  not  look  like  the  patterns  group   3G-downlink channels that have a greater impact.
           geographically.  After discarding the clusters  where  we do
           not suspect that there is a presence of ingress, we can see that   Table 4 - Characterization of ingress in the clusters.
           different types of ingress are all over the service group, and
           not in one particular block.
                                                                                  Public   LTE       3G
                                                                   Cluster   FM   digital   downlink   downlink
                                                                                   TV
                                                                     C1                            
                                                                     C2
                                                                     C3
                                                                     C4                             
                                                                     C5                            
                                                                     C6






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