Determining network topology

1 . A method for determining a topology of a cable television (CATV) network segment, wherein the network segment comprises a network node and a plurality of broadband amplifiers in one or more branches of the network segment arranged in a tree or branch configuration, the method comprising steps of

a) providing a first broadband amplifier with instructions to adjust downstream signal level;

b) monitoring changes of signal level or parameters of gain/slope alignment elements in one or more broadband amplifiers in said network segment, said changes being caused as a compensation to the first broadband amplifier adjusting its downstream signal level;

c) storing information about each of said one or more broadband amplifiers changing their signal level or said parameters as a compensation to the first broadband amplifier adjusting its downstream signal level, the information indicating each of said one or more broadband amplifiers locating in downstream direction from the first broadband amplifier;

repeating steps a-c for all subsequent broadband amplifiers in the network segment; and

determining the topology of the broadband amplifiers of the network segment based on the information of broadband amplifiers locating in downstream direction in respect to each broadband amplifier, said information being obtained based on the changes of the signal level or the parameters as a compensation to one broadband amplifier adjusting its downstream signal level.

2 . The method according claim 1 , comprising, after step c, steps of

d) providing the first broadband amplifier with instructions to adjust the downstream signal level to opposite direction;

e) monitoring changes of signal level or parameters of gain/slope alignment elements in one or more broadband amplifiers in said network segment, said changes being caused as a compensation to the first broadband amplifier adjusting its downstream signal level to the opposite direction;

f) storing information about each of said one or more broadband amplifiers changing their signal level or said parameters as a compensation to the first broadband amplifier adjusting its downstream signal level to the opposite direction;

repeating steps d-f for all subsequent broadband amplifiers in the network segment; and

confirming the topology of the broadband amplifiers of the network segment based on the information of broadband amplifiers changing their signal level as a compensation to any broadband amplifier adjusting its downstream signal level to opposite direction.

3 . The method according to claim 1 , wherein said broadband amplifiers are provided with a transponder for bi-directional communication between each broadband amplifier and a remote control unit.

4 . The method according to claim 1 , wherein said gain/slope alignment elements of the broadband amplifiers comprise at least one of an automatic level and slope control (ALSC) unit or an automatic gain control (AGC) unit, wherein said changes performed as a compensation to another broadband amplifier adjusting its downstream signal level are carried out automatically by the ALSC unit or the AGC unit.

5 . The method according to claim 4 , wherein the downstream signal level is adjusted by a value larger than deadband of the ALSC unit or the AGC unit.

6 . The method according to claim 4 , comprising

adjusting the slope of the downstream signal more predominantly at a low frequency part of a downstream signal band than at a high frequency part of a downstream signal band.

7 . The method according to claim 1 , wherein the network segment comprises one or more cable modems connected to each of the plurality of broadband amplifiers, the method comprising steps of

g) providing a first broadband amplifier with instructions to adjust upstream signal level;

h) monitoring changes of upstream signal level in one or more cable modems in said network segment, said changes being caused as a compensation to the first broadband amplifier adjusting its upstream signal level;

i) storing information about each of said one or more cable modems changing their upstream signal level as a compensation to the first broadband amplifier adjusting its upstream signal level, the information indicating each of said one or more cable modems locating in downstream direction from the first broadband amplifier;

repeating steps g-i for all subsequent broadband amplifiers in the network segment; and

determining the topology of the broadband amplifiers of the network segment based on the information of cable modems locating in downstream direction in respect to each broadband amplifier.

8 . The method according claim 7 , comprising, after step i, steps of

j) providing the first broadband amplifier with instructions to adjust the upstream signal level to opposite direction;

k) monitoring changes of upstream signal level in one or more cable modems in said network segment, said changes being caused as a compensation to the first broadband amplifier adjusting its upstream signal level to opposite direction;

l) storing information about each of said one or more cable modems changing their upstream signal level as a compensation to the first broadband amplifier adjusting its upstream signal level to opposite direction;

repeating steps j-l for all subsequent broadband amplifiers in the network segment; and

confirming the topology of the broadband amplifies of the network segment based on the information of cable modems changing their upstream signal level as a compensation to any broadband amplifier adjusting its upstream signal level to opposite direction.

9 . A computer program product, embodied on a non-transitory computer readable medium, the computer program product comprising instructions causing, when executed on at least one processor, at least one apparatus to perform the method according to claim 1 .

10 . An apparatus comprising at least one processor and at least one memory, said at least one memory stored with computer program code thereon, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to perform:

a) provide, in a cable television (CATV) network segment comprising a network node and a plurality of broadband amplifiers in one or more branches of the network segment arranged in tree or branch configuration, a first broadband amplifier with instructions to adjust downstream signal level;

b) monitor changes of signal level or parameters of gain/slope alignment elements in one or more broadband amplifiers in said network segment, said changes being caused as a compensation to the first broadband amplifier adjusting its downstream signal level;

c) store information about each of said one or more broadband amplifiers changing their signal level or said parameters as a compensation to the first broadband amplifier adjusting its downstream signal level, the information indicating each of said one or more broadband amplifiers locating in downstream direction from the first broadband amplifier;

repeat steps a-c for all subsequent broadband amplifiers in the network segment; and

determine a topology of the broadband amplifiers of the network segment based on the information of broadband amplifiers locating in downstream direction in respect to each broadband amplifier, said information being obtained based on the changes of the signal level or the parameters as a compensation to one broadband amplifier adjusting its downstream signal level.

11 . The apparatus according claim 10 , comprising computer program code configured to, with the at least one processor, cause the apparatus to

d) provide the first broadband amplifier with instructions to adjust the downstream signal level to opposite direction;

e) monitor changes of signal level or parameters of gain/slope alignment elements in one or more broadband amplifiers in said network segment, said changes being caused as a compensation to the first broadband amplifier adjusting its downstream signal level to opposite direction;

f) store information about each of said one or more broadband amplifiers changing their signal level or said parameters as a compensation to the first broadband amplifier adjusting its downstream signal level to the opposite direction;

repeat steps d-f for all subsequent broadband amplifiers in the network segment; and

confirm the topology of the broadband amplifiers of the network segment based on the information of broadband amplifiers changing their signal level as a compensation to any broadband amplifier adjusting its downstream signal level to opposite direction.

12 . The apparatus according to claim 10 , wherein said broadband amplifiers are provided with a transponder for bi-directional communication between each broadband amplifier and a remote control unit.

13 . The apparatus according to claim 10 , wherein said gain/slope alignment elements of the broadband amplifiers comprise at least one of an automatic level and slope control (ALSC) unit or an automatic gain control (AGC) unit, wherein said changes performed as a compensation to another broadband amplifier adjusting its downstream signal level are carried out automatically by the ALSC unit or the AGC unit.

14 . The apparatus according to claim 13 , wherein the downstream signal level is adjusted by a value larger than deadband of the ALSC unit or the AGC.

15 . The apparatus according to claim 13 , comprising computer program code configured to, with the at least one processor, cause the apparatus to

adjust the slope of the downstream signal more predominantly at a low frequency part of a downstream signal band than at a high frequency part of a downstream signal band.

16 . The apparatus according to claim 10 , wherein the network segment comprises one or more cable modems connected to each of the plurality of amplifiers, the apparatus comprising computer program code configured to, with the at least one processor, cause the apparatus to

g) provide a first broadband amplifier with instructions to adjust upstream signal level;

h) monitor changes of upstream signal level in one or more cable modems in said network segment, said changes being caused as a compensation to the first broadband amplifier adjusting its upstream signal level;

i) store information about each of said one or more cable modems changing their upstream signal level as a compensation to the first broadband amplifier adjusting its upstream signal level, the information indicating each of said one or more cable modems locating in downstream direction from the first broadband amplifier;

repeat steps g-i for all subsequent broadband amplifiers in the network segment; and

determine the topology of the broadband amplifiers of the network segment based on the information of cable modems locating in downstream direction in respect to each broadband amplifier.

17 . The apparatus according claim 16 , comprising computer program code configured to, with the at least one processor, cause the apparatus to

j) provide the first broadband amplifier with instructions to adjust the upstream signal level to opposite direction;

k) monitor changes of upstream signal level in one or more cable modems in said network segment, said changes being caused as a compensation to the first broadband amplifier adjusting its upstream signal level to opposite direction;

l) store information about each of said one or more cable modems changing their upstream signal level as a compensation to the first broadband amplifier adjusting its upstream signal level to opposite direction;

repeat steps j-l for all subsequent broadband amplifiers in the network segment; and

confirm the topology of the broadband amplifiers of the network segment based on the information of cable modems changing their upstream signal level as a compensation to any broadband amplifier adjusting its upstream signal level to opposite direction.