 This topic has 13 replies, 1 voice, and was last updated 13 years, 3 months ago by Nitin.

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NitinGuest
Hi All,
What is the maximum limit of neighbours of any serving cell & what is the use of this limit?akefaGuestNeighbouring should be optimized such that only the necessary cells are defined. extra defined neighbours will reduce the precise of signal strengths reading.
NitinGuestHi Akefa,
I know that neighbour should be optimised, because it will increance tch drop rate, decrease HOSR etc etc. But here my main concerned is that for any cell we have to give I think(not sure) max.31 neighbours.Why we are restricted for upto 31 not more than 31 & what will happen if we give more than 31 neighbours for a serving cell????Thanks
PixGuestIt just depends on your vendor… most vendors stop at 31 neighbours, maybe because it is the limit to keep an acceptable measurement rate from MS…? I dunno exactly.
Some vendors might offer additional neighbours (as a optional feature for instance ?)
NitinGuestHi Pix,
Thanks.
But one more thing, Is MS rejects the measurements after that certain limit or paging will be descarded???PixGuestHi Nitin,
Sorry I don’t understand your question exactly.
NitinGuestHi Pix,
I want to know that after 31 Neighbours list what will happen??Why a vendor set these limits??Is MS did not search the neighbors list after 31.PixGuestIt is a limitation in your OMCR : you can’t write more than 31 neighbours.
If you CAN write more than 31 neighbours, the MS will listen to all of them.
KalboNaSaRFGuestNitin,
The reason why there are only 31 neighbors defined is because the GSM specs allocated only 5 bits (031) to represent a specific neigbor cell’s ARFCN position in the neighbor list (lowest to highest number i think). There is no point in putting more than 31 neighbors since the phone will not be able to report or scan for that matter the last (high number) channels anyway.
NitinGuestOk might be possible
PixGuestthis limitation is indeed defined in the standard, but i believed it was possible to define more than 31 neighbours in some OMCR… I guess I was wrong, but i’ll doublecheck with my colleagues.
NitinGuestAs you get the exact answer, thn please let me know.
Thanks
PixGuestOk…
Actually there is a limitation of 32 neighbour ARFCN in a cell. Which means : Not 32 neighbour cells, but 32 neighbour BCCH frequencies.It implies that you can define several neighbours with identical BCCH frequencies but with different BSIC.
In such a case, you can increase the number of adjacencies (up to 96 as far as I understood).
Of course, having neighbours of one cell with identical BCCH is damn weird !
I hope it’s clear for you.. I think this answer is more theoretical than practical, and doesn’t require to spend so much time talking/researching about it 😀
NitinGuestOk,Good one
Thanks for the help… 
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