SFH (freq hopping), HUAWEI 2G

[Onigece]

Hello Guys,

I noticed an indoor cell/sector where sometimes, in dedicated mode, it hops to different frequency (SFH) but sometimes it only stays in BCCH frequency during dedicated mode. Why this happens? I suppose that it should only be either of the two and should not experience both scenario. Pls. explain what might be happening here.
P.S. I am using Nemo Analyze to process logfiles.

[Optimustron]

It can be because of traffic, when traffic raises then you get more interference so the system avoids the frequencies with interference, the channel hopping can be interfered, check the cells near to the place you are testing, generally the spacing between frequencies is better with BCCHs because you have one frequency per sector cell and you can plan carefully this including planning by hand is ease to put a good separation between frecuencies and then your conditions in the BCCH frecuencie are more stable, but hopping is more unstable because it get worst with traffic conditions and is worst if you have little spectrum for reuse. You need to check your frequency planning for HOPPING.
The condition when only stays in BCCH is maybe because the HOPPING is interfered because of high traffic in the surrounding sites and the best channel is the BCCH, then when traffic goes down you get the HOPPING frequencies because it gets clean or you move of the interfered zone.
Maybe in a large area you have small places where you get more interference and in another places are cleaner than the previous one. For example in a MALL some places have self interference or external interference and you walk some meters and cross a corner and you get a place cleaner.

I hope this can help you, regards,

[Onigece]

Hi Optimustron,

Does the 'automatic on/off switching of frequency hopping (based on interference, as you stated)' a GSM Standard or vendor Huawei feature ?

[Optimustron]

Hi Onigece
If you turn on the HOP SWITCH, you only prepare the cell/network for hopping, this is not related to interference. If you have de ICM active, IDLE CHANNEL MEASUREMENT, I think you do, Then your network is measuring interference.
For HUAWEI SYSTEMS, you need to see the parameter CHANNEL ALLOCATE STRATEGY or CHALLOCSTRATEGY if is set to QUALITY this from command GCELLCHMGBASIC then the quality is prioritized.
For quality in HUAWEI you have this order:
Quality > capacity > PS coordination > continuity > management
For Capacity you have this other:
Capacity > quality > PS coordination > continuity > management
From above you have another settings, i.e., PS COORDINATION, CONTINUITY, MANAGEMENT and of course, another order.
You have too the command GCELLCHMGAD with parameter INTERFPRIALLOW or Interference Priority Allowed, check if it is set to Yes, then you have the conditions that I told you, another parameter in this command is TRXPRIALLOW or Allocation TRX Priority Allowed the default value is Yes, then you need to see the command GTRXDEV for parameter OPTL or TRX Priority.
By the way in E******* systems there are two parameters FBCHALLOC that selects between NO SELECTION PREFERENCE, BCCH FREQUENCY BAND SELECTED FIRST or BCCH FREQUENCY BAND SELECTED LAST this is set at BSC LEVEL and the second at CELL LEVEL is CSPSALLOC that sets the preference for QUALITY, MAIO or MULTI. Best regards,