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Hi All,
I want to use 1/3 frequency reuse pattern and would like to take your advice on how I should plan the HSN and MAIO. Necessary info is as follows:
1. I have 30 frequencies. I reserved 12 of them for BCCH,and divided the remaining into 3 frequency groups. When doing it I divided them in such a way that there’s adjacency within one group. Frequency groups are as follows:
FG1: 1 4 7 10 13 16
FG2: 2 5 8 11 14 17
FG3: 3 6 9 12 15 18So I have 6 MAIOs (0..5). Since I have mostly 4/4/4 TRX per cell and one is BCCH (non-hopping) TRX, I have 3 TRXs per cell and 6 frequencies these TRXs can hop.Frequency load is 50% so I should have no adjacent channels while hopping. I’m going to plan MAIOs as follows:
Cell MAIO
1 0,2,4
2 1,3,5
3 0,2,4I guess above configuration will work. My question is how should I plan HSN? Should I give same HSN for co-site cells or different? What is the criteria for this? And what about the neighbour sites?
Briefly speaking how should I assign HSNs considering the sites and their neighbours?Thanks in advance for your answers.
Erkan Okay
Erkan Okay,
If you´re using a reuse pattern like the one you just mentioned, The MAIO distribuition is correct… This way you will avoid co-channel and adjacent frequencies between co-site cells.
The HSN should be planned in a way that neighbours cells don´t have same HSN (it means they’ll hopp in differents pseudo-random sequences).
Remember of the basics, your network should be the most homogeneous possible (which means equals azimuths, no huge cells coverage overlaps, etc)Dear Erkan,
MAIO, Mobile Allocation Index Offset means from which frequency the system shall start hopping.
HSN, Hopping Sequence Number means how pseudo-random the system shall start hopping.So, by assigning HSN you are avoiding co-channel/adjacent channel interference and collision, how can you do this? by setting the same HSN for the cells within the same site thus providing synchronization.
As for neighbor cells you’ll do the same making sure to have different HSNs for neighbour cells.
I hope I made it clear
Fabio and Rami,
Thanks a lot for your answers. So I’m going to have same HSN for co-site cells and different HSNs for neighbour sites.
There’s one more thing related to this discussion:
As far as I know “being synchronous” means TRXs on a site hop at the same exact time, and in general their frame numbers are identical.
Does the assignment of same HSN to cosite cells make them synchronous or are cosite cells already synchronous (or asynchronous) by their nature? Or is there a specific feature which makes cosite cells synchronous?I admire your answering my questions. Thanks again.
Erkan
Dear Erkan,
HSN has a value from 0-63 and each value corresponds to a certain hopping sequence. i.e. frequencies to hope on.
What same HSN does is that it reserves the same hopping sequence for the same cells in a certian manner, i.e. it reserves the same frequencies to be selected for hopping in order to avoid co-channel and adjacent channel interference.
Co-site Cells are already synchronous, and, that´s the purpose of the MAIO, as Rami just said.
The MAIO will say to the TRX, with which frequency it should start hopping.
And as said before, the same HSN with different MAIO will make the TRX´s hopp in a same sequence but with a offset in the frequency list (they´ll begin in different frequencies to avoid co-channel or adjacent collision).Hi Erkan
you need to use same HSN for a site n different HSN for other sites…
this pattern will avoid collision between cells, hence reduce interference..
n all other thingss are assumed to work properly…
that depends on probility of mutually exclusive events..u r doing things in a rite way, dont get confused
thanks
RF LearnerHi All,
I’m working with NOKIA system. I want to know about HSN2 i.e. when we use baseband hopping. I also want to know which hopping method (RF or Baseband) is most likely??
Iam working in tyco electronics Project in Hutch O&M. I want to know everthing about the BTS.
Hi Jitendra,
BTS is nothing dont worry about it.Erkan Okay,
If you have on your site all TRXs connected to only one BCF then you can say that they all are synchroonized .
If you have more then 2 BCF on one site then the trxs from different bcf not sinhroized by default.Then you should use “an extra powerful” feature from your suplier for sinchronizations.
(Nokia Multi BCF)
If you do not have a feature for bcf synchronizations then you must use different HSN for different bcf.BR,
ValerijsAs an RF Engineer i know that all the sctor of a site are sync.
that is y we say sync HO.
What’s the different between RF hopping and baseband hopping (both in GSM)?
Which one is better,why? And what parameters I should know ?(beside MAIO,HSN).
I hope u can help me.Thanks 4 ur informationRF hopping is better than BB hopping
In case of BB hpping the no. of frequencies are limited due to da no. of TRX’s.
thus if u add one more TRX u have to accordingly for hopping.
In RF hopping u can use any no. of frequencies. hence better results than BB hop.
For parameters Enable Hopping then use HSN, MAIO Offset, MAIO STEP, MA List.
in BB hop
Rf learner,
just because u have defined a neighbour as SYNC y (does not mean that the neighbours are in SYNC).
But the Sector of same site are always synchronised , we can synchronise BTS sites in a cluster also to improve the quality of the netwoek.
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