immediate assignment issue

[zaebolll]

Guys advice please,
after implementatin of new frequency plan on network, Sdcch assignment success rate of BSC has decreased from 98% to 60%.

I tried to observe the problem, just the cells are degraded which has also SDCCH on TCH Trx. In a cell for a trial i ordered to delete SDCCH from TCH Trx. After deletion, SD ASGSR has increased from %50 to %99 on this cell which uses SDCCH just on BCCH TRx.

Due to drivetest on below cases always ends with block call.
MS2
Immediate Assignment

Time : 19:30:46.71
Vendor Header
L2 pseudo length : 12
Skip indicator : 0
Protocol discriminator : (6) Radio resources management messages
Message type : 63
Two-message assignment (TMA) : (0) No meaning
Downlink assignment to mobile in packet idle mode : (0) No meaning
TBF or dedicated mode (T/D) : (0) Assigns a dedicated mode resource
Page mode : (0) Normal paging
Channel Description
Channel type : (8) SDCCH/8 + SACCH/C8 or CBCH (SDCCH/8)
Subchannel : 6
Timeslot number (TN) : 0
Training sequence code (TSC) : 6
Hopping RF channel : (1) RF Hopping Channel
Mobile allocation index offset (MAIO) : 2
Hopping sequence number (HSN) : 36

and calls are successfull for below cases,
MS2
Immediate Assignment

Time : 19:30:51.12
Vendor Header
L2 pseudo length : 11
Skip indicator : 0
Protocol discriminator : (6) Radio resources management messages
Message type : 63
Two-message assignment (TMA) : (0) No meaning
Downlink assignment to mobile in packet idle mode : (0) No meaning
TBF or dedicated mode (T/D) : (0) Assigns a dedicated mode resource
Page mode : (0) Normal paging
Channel Description
Channel type : (8) SDCCH/8 + SACCH/C8 or CBCH (SDCCH/8)
Subchannel : 3
Timeslot number (TN) : 1
Training sequence code (TSC) : 0
Hopping RF channel : (0) Single RF Channel
Absolute radio frequency channel number (ARFCN) : 528


Vendor is NSN.
Any idea to solve that problem?

[zaebolll]

No idea guys?

When i remove SD channels from TCH TRx, the problem solves.

But i need a permanent solution. Advice please.

[f_tito]

Is there any problem with UL Quality after implementation of new frequency? If the quality degraded so in my mind there is some problem with frequency or related to that.

[m121]

Tell us more about frequency plan. You switched from BBH to SFH? What did you change in you plan?
How about TSC configuration? Do you use different TSCs per TRX or all have default values?
One of reasons could be that for example, BSIC ir 6-1 but for TRX:1 you configured TSC=5. In this case SDCCH assignment will fail.

[RFDude_PMA]

In E/// have a feature immediate assignment on tch which enable the TCH to be use for signaling.

Also the TN needs to be different for each SDCCH if is in the same trx. If you assign 3 SDCCH on one TRX it needs to define a TN for each sdcch ej 2,3,4 TN

[agungpur]

just make sure, .. pls check TSC = BCC (is a must). Run 196 and check quality UL or DL on TRX-HOP only (greater than 95% or below than ?). Regarding Mal_freq, are you using 1/1 or 1/3 ? HSN on the same site ? and MO ? .. pls check ..

[plannerguy]

Hi

to add some more

1) normally there will be priority for TRx normally , BCCH first then Hopping.

2) Normal BCCH TRX qual found to be better , so remapping SD to BCCH can reduce the drops.

same works fine with my network

Regards
Plannerguy