Again BSIC planning

[nofelet]

Dear experts, I do not wish to be stupid, I am learner.
can I ask a simple question:
What would happen if one site, three different NCC, for ex: cellA 51, CellB 62, CellC 73. Or neighbors cells have a different NCC from parent.

[RF engineer]

Dear experts, I do not wish to be stupid, I am learner.
can I ask a simple question:
What would happen if one site, three different NCC, for ex: cellA 51, CellB 62, CellC 73. Or neighbors cells have a different NCC from parent.
different NCC there will be no problem if BCC not the same

[nofelet]

different NCC there will be no problem if BCC not the same

OK, but another question, if BCCs are the same?

[danikd]

OK, but another question, if BCCs are the same?

The problem may occur once you have tight BCCH reuse, see below my explanation (I just copy it from another thread)

Enjoy

Phantom RACH is a process when specific mobile is sending Random Access burst to a serving cell (cell which specific mobile is camping on). The Random Access burst contains TSC (Training Sequence) the TSC is derived from BCC number which is part of BSIC transmitted on Synchronization Channel (SCH) on BCCH TRX i.e. TSC=BCC for BCCH TRX.

Now when mobile transmits Random Access burst, this transmission is OMNI directional i.e. transmitted not only toward serving cell but to all surrounding cells as well.
When network utilizes a very tight BCCH reuse (less than 25 BCCH in use) in urban area, then the BCCH reused with in the limited geographical area many times and BCCH allocation requires proper allocation of BCC in order to prevent BCCH/BCC (not BSIC) reuse.

More over the Phantom RACH is related to UL performance of the cell. The UL performance of the cell is 100% depends on antenna configuration i.e. antenna type and tilt. Correctly designed antenna configuration will prevent appearance of Phantom RACH as well.

[RF engineer]

The problem may occur once you have tight BCCH reuse, see below my explanation (I just copy it from another thread)

Enjoy

Phantom RACH is a process when specific mobile is sending Random Access burst to a serving cell (cell which specific mobile is camping on). The Random Access burst contains TSC (Training Sequence) the TSC is derived from BCC number which is part of BSIC transmitted on Synchronization Channel (SCH) on BCCH TRX i.e. TSC=BCC for BCCH TRX.

Now when mobile transmits Random Access burst, this transmission is OMNI directional i.e. transmitted not only toward serving cell but to all surrounding cells as well.
When network utilizes a very tight BCCH reuse (less than 25 BCCH in use) in urban area, then the BCCH reused with in the limited geographical area many times and BCCH allocation requires proper allocation of BCC in order to prevent BCCH/BCC (not BSIC) reuse.

More over the Phantom RACH is related to UL performance of the cell. The UL performance of the cell is 100% depends on antenna configuration i.e. antenna type and tilt. Correctly designed antenna configuration will prevent appearance of Phantom RACH as well.
This explanation is what i was going to post and plus one more thing is that the surrounding cell may consider this also such a kind of handover so it will deteriorate handover performance for both Co BCCH/BSIC cell.
BR
RF

[nofelet]

Thanks for all, from your suggestions I try to find a more intelligent and reasonable solution.

[mokone]

Can this have an effect on te drop call rate,as we downtilted a single sector and the DCR shot up together with the Phantom ranch,we then changed both the BCCH and BSIC,with no eefect,what other solutions are ther to reduce the DCR and Phantom ranches apart from a fallback?

[pathloss]

Even if it's a very late reply. From my experience Phantom RACH only affects SDCCH Failure rate as there is an huge increase of attempts. Didn't notice any other effects on other KPI's.


Can this have an effect on te drop call rate,as we downtilted a single sector and the DCR shot up together with the Phantom ranch,we then changed both the BCCH and BSIC,with no eefect,what other solutions are ther to reduce the DCR and Phantom ranches apart from a fallback?

[adedia]

What happen if SDCCH are placed in TCH TRX??

[ventinel]

first how can the NCC be 51 or 62. NCC is from 0-7.
Also if SDCCH is placed at TCH TRXs, SD Access success rate might degrade in Rural cells due to SD transmission not at max power.