How many neighbor cell can be configured of each cell

[adewijaya]

How many neighbor cell can be configured of each cell?

we can configure 31 intrafrequency neighbor cell, 32 interfrequency neighbor cell and 32 interRAT neighbor cell

any idea?

[rffreeconsult]

For UMTS, The intra-freq neighborlist should have max around 25-26 neighbors...The max number will never reach unless your sector overshoots or is a boomer site. If you fill up the neighborlist to 31 and it hands over to each of them, you need to revise the coverage of that sector (and its desirable containment as well). Remember that your UMTS coverage can be both coverage or noise (to other sectors).

[revolution]

The possible neighbours can be configured is 31 Intrafrequency for each cell

[thuti]

I think there are 32 neighbor include inter-rat and inter-frequence :(

[dk2000]

1 caution.

In NSN Equiq, when the number of neighbor is high, the cell is automatically locked. Please move some neighbor to SIB 11 bis to solve this problem.:p

[twenty8]

The 3GPP specs mentioned that you should be able to define a max of 96 neighbours (32 intraFreq, 32 interFreq and 32 interSystem). However 3GPP have also specified the size of SIB11 in the specs which enables SIB11 to carry only 47 cells. A correction was implemented in Rel6, with the introduction of SIB11 bis which allows to carry a total of 96 neighbours. But this again is only applicable for Rel6 UE onwards.

This is not a NSN limitation since its been specified by 3GPP, all vendors should have same implementation. So if you don't use SIB11 bis, then you should plan for 15 interFreq , 15 intraFreq and 15 interSystem.

/28

[plannerguy]

Hi

if you define Neighbors greater than 47 (SIB 11 recomendation by 3GPP) then
system will go down.

Regards
Plannerguy

[adewijaya]

Above is for Huawei Vendor, How about other Vendor? For 3GPP standard is 96 relation can be made on every single relation, how about performance if its setting maximal value (lets said 96 relation)? any others experiences?

[twenty8]

In NSN, if too many neighbours defined, then the cell will go blocked by system with alarm 7771.

[_lisi4king]

Above is for Huawei Vendor, How about other Vendor? For 3GPP standard is 96 relation can be made on every single relation, how about performance if its setting maximal value (lets said 96 relation)? any others experiences?

ZTE has formula for relations: 287 + 48*Number of Intra Neighbouring Cell + 79*(Number of Inter Neighbouring Cell - 1) + 75*(Number of Gsm Neighbouring Cell - 1)<=3330

[fernguillermo]

We got a Huawei system here & I did some random checks. I found one cell has these much neighbour defined.
Interfrequency = 53
Intrafrequency = 17
Intersystem = 18

SIB11 = all are enabled (Send)

The system is not complaining (no alarms), KPIs are acceptable.
I think as long as you dont reach the 96 neighbour per cell limit, you are allowed to define as many neighbours as you want.

[_lisi4king]

We got a Huawei system here & I did some random checks. I found one cell has these much neighbour defined.
Interfrequency = 53
Intrafrequency = 17
Intersystem = 18

SIB11 = all are enabled (Send)

The system is not complaining (no alarms), KPIs are acceptable.
I think as long as you dont reach the 96 neighbour per cell limit, you are allowed to define as many neighbours as you want.

:D it is not good my frend, because it is Huawei fault (i mean no alarms or notifications). Of caurse you can configure 53 interfrequence, but do you think UE can measure it? And now another qestion which 31 UE measure from 53? Do you know algorithm? Or of you want you can trace this cell and see which neighbours system uses ;)

[fernguillermo]

:D it is not good my frend, because it is Huawei fault (i mean no alarms or notifications). Of caurse you can configure 53 interfrequence, but do you think UE can measure it? And now another qestion which 31 UE measure from 53? Do you know algorithm? Or of you want you can trace this cell and see which neighbours system uses ;)

Yes you're right. This needs to be fixed. Might have some logs here to check the best neighbours. Or probably in MapInfo.

Well anyway, Huawei system needs to detect that this is wrong. NSN does not allow this.

[_lisi4king]

Yes you're right. This needs to be fixed. Might have some logs here to check the best neighbours. Or probably in MapInfo.

Well anyway, Huawei system needs to detect that this is wrong. NSN does not allow this.

And ZTE too (but anyway i don't like ZTE :)).

You can check it from Nastar, if you use it. It is possible to keep heigh which you need only.

[twenty8]

Best to check from DT in that cell and check the SIB 11 message to see if all the planned neighbours gets transmitted, otherwise I suspect that only a fraction of the neighbours are send in SIB 11.

[_lisi4king]

Best to check from DT in that cell and check the SIB 11 message to see if all the planned neighbours gets transmitted, otherwise I suspect that only a fraction of the neighbours are send in SIB 11.

I saw 30 intra in trace, but need to analyse about IRAT and total number.

In addtional i've attached file from Huawei - explanation, that 96 is possible. I think it will be useful for optimizators. ;)

[adewijaya]

from your data below, its mean if INTER-RAT over MaxNbrNumber in one cell didn't make any problem or alarm?

[_lisi4king]

from your data below, its mean if INTER-RAT over MaxNbrNumber in one cell didn't make any problem or alarm?

No-no, it case more than 32 will be alarm. But system does't count total number of Nbr. As you can see from explanation, can be 96 and may be no need to count, but 47 from NSN and formula from ZTE (i don't trust ZTE, but anyway) show that may be for old UE limitation exists and system should "tell" you something about it.

[lejun]

Hi all,

As my experience, the number/cell as below:

-Intrafrequency: max = 20, average 12-16

-Interfrequency & IRAT: max 16, average 10-12 (because in the compressed mode, UE can scan about 10 IRAT or InterFrequency neighbors only).


I usually plan neighbors as the above and have a great performance ;)

Regards

[boring]

Hi guys

3GPP allows for

intra-frequency = 31
inter-frequency = (F-1)*32
intra-RAT = 32

(where F is total number of deployed frequencies)

actual planning
intra-frequency (15 - max 20)
inter-frequency (about 15 but depends on delpoyed carriers/scenario)
inter-RAT (again 15-20 max)

it is critical not to exceed the 20 figure for inter-frequency and inter-RAT neighbour lists because:

a) the UE takes longers actually to measure during compressed mode
b) you run the risk to have a truncated neighbour (and hence a drop/failed handover/not efficient performance) because of the truncation issue. this happens when the UE is in soft-handover and the RNC combines e.g. inter-RAT lists into a single measurement control message (always max capacity 32 for inter-RAT). E******* call such neighbours unmonitored.

[harrypotter]

In NSN, if too many neighbours defined, then the cell will go blocked by system with alarm 7771.

Hello,

Do you have the NED 7771 alarm definition?

[TEMS_Engineer]

How many neighbor cell can be configured of each cell?

we can configure 31 intrafrequency neighbor cell, 32 interfrequency neighbor cell and 32 interRAT neighbor cell

any idea?

hi brother,
for your quastion i think depend on your location if in city must be 28 to 32.

Thanks

[wolverine]

There seems to be a lot of confusion on the subject. But lets get the basics right.

By 3GPP the total number of neighbours the UE can measure is

31 intra (32 if you include the serving cell)
32 inter
32 irat

total 96

Now the problem arises because SIB11 has a fixed max length and cannot accomodate 96 cells.

How many it can accomodate is variable and it will depend on what information elements are being broadcasted for each neighbour cell. For example the qQualMin value of a neighbour cell is optional to broadcast. If your vendor includes it for every neighbour cell it will "eat up" SIB11 space.

Additionally if you include HCS information in SIB11 it will "shrink" even more.

All of the above is valid for SIB11. SIB11 is used for IDLE mode reselection and if SIB12 is not available it is also used in CELL_FACH and URA/CELL_PCH.

When in dedicated mode, the UE is informed of its neighbours through the measurement control messages. These don't have a fixed length and can include the max 96 neighbours.If your vendor offers the flexibility to specifiy separate idle and dedicated mode lists this means that you only need to be careful for the idle one.

If your vendor doesn't, then you are automatically limited on both and you should request your vendor to change their implementation.

Alternatively you could also ask for support for SIB11bis that can hold all 96 neighbours as well. The problem with this approach is that SIB11bis is optional for rel6 UEs and mandatory for rel7 UEs. So all of your rel99 and rel5 UEs will ignore this..

[q15928]

Can anyone share the information about activating the SIB11bis feature on NSN?

I found the feature ID is ran1323: Extension of SIB11 (SIB11bis) on NED. But there is no activation procedure.

Thanks in advance!

[ventinel]

it also varies from vendor to vendor but most used as per standard is 32 (if defined bothways nbr) and 64 (is defined one-way nbr)

[q15928]

Hello,

Do you have the NED 7771 alarm definition?

With SIB Optimization feature, NSN can turn on SIB as many as 95.

RNC has following restrictions on the maximum number of neighbour cells that can be sent in
SIB11/SIB 11bis.
With SIB Optimization used (PRFILE RN50_MAINT_11 enabled)
a> HCS used : 84
b> HCS not used : 95

Without SIB optimizations ( PRFILE RN50_MAINT_11 disabled)
a> HCS used : 35
b> HCS not used : 47

Please find more information on the technical note attached.

24042

[fahmi]

Set up

Intra-Freq

Inter-Freq

IRAT (GSM)



One WCDMA carrier & GSM

20

-

16



Two WCDMA carriers & GSM

20

16

16



Three WCDMA carriers & GSM

20

32 (16+16)

16



Four WCDMA carriers & GSM *

20

32 (16+16)*

16




Recommended number of defined neighbor relations


* Only 2 of the 3 inter-frequency carrier frequencies can be defined.


In 3GPP specifications, there are inconsistent requirements concerning the maximum number of neighboring cells that can be broadcasted to the UEs in the SIB11.
On one hand the SIB type 11 message can contain information on maximum number of neighbor cells (31 intra-frequency, 32 inter-frequency and 32 GSM),but the length of SIB11 cannot exceed 3552 bits and this is insufficient to accommodate information on maximum neighboring configuration.
The length of SIB11 is variable and depends on:


Total number of neighbor cell relations defined in SIB11.
The distribution of different types of relations (intra-frequency, interfrequency and GSM) in SIB11
Number of WCDMA carriers for inter-frequency neighbors.
Parameter setting per neighbor relation (i.e. setting of qRxLevMin,qQualMin, qOffset1sn, qOffset2sn, maxTxPowerUl,individualOffset).
Usage of HCS and the related HCS parameters.

Rule-of-thumbs:



Using the recommended number of defined neighbor relations for intrafrequency, inter-frequency and GSM presented in Table 4, the maximum limit of number of bits of SIB 11 will never be reached. This includes when HCS is activated for all inter-frequency neighbors.
If the total number of inter-frequency (IEF) and GSM neighbors is limited to a total of 48 neighbor relations (IEF [32] + GSM [16]) as given in Table 4, the total number of neighbor relations can be 76 neighbors per cell. The total number of neighbor relations will then be IAF (28) + IEF (32) + GSM (16) without reaching the SIB 11 limit when HCS is used for all inter-frequency neighbors.
If the number of inter-frequency (IEF) and GSM neighbors are limited to a total of 45 neighbor relations (IEF [30] + GSM [15]), the number of IAF neighbor relations can be set to 31 neighbors per cell without reaching the SIB 11 limit when HCS is used for all inter-frequency neighbors.

If more neighbors than the recommended number of neighbors in Table 4 are needed to be defined in the network, the risk of reaching the size limit for SIB 11 cannot be discarded. The following principle can be used. This includes that HCS is enabled for all inter-frequency neighbor relations:


If no inter-frequency neighbors are defined (one WCDMA carrier) for a cell then max configuration of 31 + 32 can be used for intra-frequency and GSM neighbor relations.
If no GSM neighbor relations are defined for a cell then max configuration of 31 + 32 can be used for intra-frequency and interfrequency neighbor relations.
In the two WCDMA carriers set up, approximately 11 intra-frequency, or 16 inter-frequency or 16 GSM neighbors can be added on top of the recommended number of neighbor relations in Table 4, if absolutely needed in especially difficult cells.
In the three or four WCDMA carriers set up, approximately 8 intrafrequency (11 if HCS is not used) or 7 GSM neighbors (13 if HCS is not used) can be added on top of the recommended number of neighbor relations in Table 4, if absolutely needed in especially difficult cells.

This is though highly correlated to parameters not set to the default/recommended values. If SIB 11 limit of number of bits is reached when defining the neighbor relations the cell will be blocked. If maximum number of defined neighbors is exceeded either on intra-frequency, inter-frequency or GSM, there will be an alarm when defining the neighbor relations


Nice extract from E******* WCDMA RADIO ACCESS NETWORK (see attachment)


BR,
Fahmi.

26273

[lejun]

Hi,

The most important in neighbor planning is "number of neighbor per cell is enough, not missed but not too many".

Problem is what is "enough neighbor"? I think depend on the site/cell and experiences.

Best Regards

[VitalyK]

From my experience - "enough neighbor" these are neighbors which serve 80-85% HO. Usually I run measurements, add neighbors, after this check HO stat and delete redundant neighbors.

[cococrunch]

Check the AUTODEF measurements or cell to cell handover stats(Huawei) to define "enough" neighbours. Use 1 week data just to be sure then aggregate. Just be careful with deleting neighbours, some sites might be down so they wont trigger in the stats.

[nupong]

* Only 2 of the 3 inter-frequency carrier frequencies can be defined.

26273

What's happened if we have 4 carriers deployment or even multi-band 6-8 carriers?

It seems we could add only 2 inter-freq carriers as neighbor regardless number of neighbor,right?

I've heard that it is no issue for idle mode, we could add them all but measurement control for UE to handover, is that right?

[s52d]

What's happened if we have 4 carriers deployment or even multi-band 6-8 carriers?

It seems we could add only 2 inter-freq carriers as neighbor regardless number of neighbor,right?

I've heard that it is no issue for idle mode, we could add them all but measurement control for UE to handover, is that right?

No big issue: for MC it is enough to define one.
grouping them together does not count here.

so, in UTRAN cell you need:
- same ch. layer: define them (2.1 GHz)
- one neighbor for "coverage layer" (900 MHz)
- one neighbor for "capacity layer or R99 layer". (2.1 GHz, other freq)
with some thinking you can fix most scenarios.

For some uniqe cases we are happy with idle mode: UTRAN f1 -> GSM -> UTRAN f2. Works.

BR
s52d

[nupong]

Now I'm on the operator side and at least 2 vendors here recommended us to add only upto 2 inter-freq carriers only (we have 4,5 and 6 carriers deployment scenario) and they are said it is limitation on UE itself can read upto 2 inter-freq carrier only. That's why they said MC should send 2 inter-freq otherwise UE just ignore the third and forth

However, it is also make me confuse more as

Vendor A: 32 interfreq cells per carrier (32+32 in total for 2 inter-freq carrier, 5-6 carriers deployment)
Vendor B: 32 interfreq cells per all carriers (only 32 in total for 2 inter-freq carrier, 5-6 carriers deployment)
Vendor C: Regardlest cells per deployment and just following the crappy formula (you knew that it is only one vendor in the world)

Edited:

I found some more info from 3GPP:

For idle mode cell re-selection purposes, the UE hsall be capable of monitoring:
-32 intra-freq cells (including serving cell), and
-32 inter-freq cells, including
- FDD cells on max 2 additional carriers, and
- TDD cells up to 3 carriers (UE cap)
-up to 32 GSM cells and up to 32 GSM carriers
-up to 4 E-UTRA FDD carrier and
-up to 4 E-UTRA TDD carrier