HSDPA accessibility vs Max users HSUPA

[nabil el haddani]

Hello bros,

my problem is the following:

i have very bad HSDPA accessibility in several cells last days..I have HSUPA activated on my cells...I did some investigations and i found out this:

the behavior of the two counters: M1002C402(REJ_HS_DSCH_RET_BGR) and M1002C516(UL_DCH_SEL_MAX_HSUPA_USR_BGR) have merely the same behavior. It means in another way that in the busy hours we reached the max users of HSUPA users(24 per BTS, 20 per cell in my case), we have setup fail on E-DCH, so we should use (DCH return channel,HDSCH) to access the cell, but according to the counter M1002C402 shows that we have rejection on DCH return channel which affects drastically the HSDPA accessibility.

I still can't grasp why we reject directly the return channel when we have setup failure on the EDCH due to HSUPA max user limitation.

N.B:
1. we have enough channel elements on the BTS and the issue is not related to resource problem.
2. we cannot activate the licence 60 users for HSUPA because we didn't buy it.

Please help...SOS experts.

Br,

Nab

[nabil el haddani]

Reminder :=(

[nabil el haddani]

2nd Reminder ((((

[cococrunch]

I think it makes sense because failure with cause "REJ_HS_DSCH_RET_BGR" is due to PrxTotal>PrxTarget+PrxOffset. This can be due to interference, some discrepancy in site parameter commissioning or just high UL load.

I think you're case is high UL load since you mentioned that the cell is already reaching more than 20 HSUPA users per cell hence failing in "UL_DCH_SEL_MAX_HSUPA_USR_BGR". Activating 60 HSUPA users per cell will just worsen the situation since you're accepting more HSUPA traffic.

The failure "REJ_HS_DSCH_RET_BGR" only means that PrxTotal is more than PrxTarget+PrxOffset. As a workaround solution you can try to increase PrxTarget(NSN default is 4dB, you can set it up to 30 dB max), this way there will be a lot more room for UL load. If you want to improve you're HSDPA Accessibility you can optimize this parameter.

[salamanda1969]

To isolate your root cause, you may have to:

- disable HSUPA and see if the HSDPA accessibility improved;
- check for CE congestion before and after enabling HSUPA;
- check for UL noise rise before and after enabling HSUPA.
- check HSDPA accessibility when there are less HSDPA users (in early morning?)

2 known issues:
1) HSUPA consumes more CE;
2) large number of active HSDPA users generates high UL noise (resulting in UL return channel rejection).

Hope that helps.
cheers.

[manson]

Salamanda...
can u explain about this problem:

PS Interactive RAB, excluding PS Interactive for HS, RAB fails due to node configuration error, node limitation or transport network layer service unavailability.

To isolate your root cause, you may have to:

- disable HSUPA and see if the HSDPA accessibility improved;
- check for CE congestion before and after enabling HSUPA;
- check for UL noise rise before and after enabling HSUPA.
- check HSDPA accessibility when there are less HSDPA users (in early morning?)

2 known issues:
1) HSUPA consumes more CE;
2) large number of active HSDPA users generates high UL noise (resulting in UL return channel rejection).

Hope that helps.
cheers.

[salamanda1969]

I dont recall RAB failures due to Node configuration error.
Have seen counters for failures due to Iub, transmission, AC, etc.

Can you elaborate if 'Node configuration failures' you mentioned, came from stats (such as reporting suite) or from another vendor's counter ? Thx

[amadeo]

Hi there,
I think you have problem to setup the UL DCH return channel after max E-DCH user is reached.

In my opinion, you need to increase your PrxTargetPSMax (if you set PrxTargetPSMin the same, this parameter also should follow). Prxtarget is only meant for Non Controllable load, as for NRT, it's controlled by above parameter. However, you better adjust prxtarget as well at least equal to PrxtargetPSMax.

regards,

Amadeo

[kyokuman]

Amadeo,

Interesting information !
My question is following :
- Would you as well increase value of PRXMAXTargetBTS ?

And also, I'm not sure, but what if both PrxTargetPSMax and Min have same values... Is there, in that case, dynamic adjustment of the PrxTargetPS ?

Thanks!

[b20ruo]

Hi

Is this available for wcells with no HSUPA? I have Hsdpa failures due to UL DCh and no HSUPA enabled. Prxtarget is set to 30db and Prxtargetpsmin and max is default 4dB.