Code multiplexing with numHscchCode

[electron]

Hi Guys,

Can some body let me know what can be the affect of change of numHscchCode in a cell (Increase and decrease ) ?

Any affect on average cell throughput ?
Any affect on User perceived throughput?
Which counter/KPI can show it's affect properly?

Thx

[dadoba]

First check if the feature Flexible Scheduler is active in your Node, this is mandatory to get some result with HS-SCCH. In theory if you have Flexible Scheduler active and set a number of HS-SCCH greater than 1 you can have a best performance in codes usage, I mean the feature + HS-SCCH greater than 1 will put more users in same TTI 2ms and will try to use all codes available, instead of have codes unused you will have all codes used by the users in that TTI.

CONCLUSION: You will have a better HSDPA performance and the KPI that will show it is the HSDPA Tput in the Node-B and the number os HS Codes used.

Suggestion: Activate Flexible Scheduler and set HS-SCCH in 2 if you have just one.

[electron]

Thanks for the answer, So more question occurred now :)
Suppose Dynamic code allocation is activated and i already have multiplexing with 2 HS-SCCH . What will happen if i make it 3 ? so my code usage will increase and amount of scheduled user per TTI will increase What affect practically should i expect in HS ip volume and HS throughput?


First check if the feature Flexible Scheduler is active in your Node, this is mandatory to get some result with HS-SCCH. In theory if you have Flexible Scheduler active and set a number of HS-SCCH greater than 1 you can have a best performance in codes usage, I mean the feature + HS-SCCH greater than 1 will put more users in same TTI 2ms and will try to use all codes available, instead of have codes unused you will have all codes used by the users in that TTI.

CONCLUSION: You will have a better HSDPA performance and the KPI that will show it is the HSDPA Tput in the Node-B and the number os HS Codes used.

Suggestion: Activate Flexible Scheduler and set HS-SCCH in 2 if you have just one.

[karna]

If you make HSSCCH=3 then 3 users will be scheduled simultaneous for 2msTTI so number of scheduled users per TTI will increase to 3.(*only if there are atleast 3 UE in a cell and simultaneously using PS service).
Code usage generally remains constant as most of the UEs now support 10 to 15 HSDPA codes.
As far as HSDPA throughput is concerned it depends on what queue algorithms you use. However i have observed reduction in throughput by increasing HSSCH beyond 2, the reason is that code power now is divided between 3 users(if HSCCH=3) so it also depends on the ue geographical location w.r.to Base station.

,karna

[electron]

Yes i have similar observation but with some differences related to below subjects:

1. Average Scheduled user per TTI will increase by increasing HS-SCCH code
2. Code & Power usage will increase as we actually do not know how is UE with 10 up to 15 code support penetration(I saw increasing the utilization after change practically by myself)
3.As for Throughput based on "proportional fair" algorithm no changes observed even data volume is the same it is strange that when code utilization and average number of user per TTI increasing in this case either throughput or amount of IP volume should be changed but in my case no any changed observed. How we can analyze it ? this is actually my main question
4. So as a conclusion what will be the gain or loss of increase or decreasing HS-SCCH code for a cell KPI or user perception?
Thanks
If you make HSSCCH=3 then 3 users will be scheduled simultaneous for 2msTTI so number of scheduled users per TTI will increase to 3.(*only if there are atleast 3 UE in a cell and simultaneously using PS service).
Code usage generally remains constant as most of the UEs now support 10 to 15 HSDPA codes.
As far as HSDPA throughput is concerned it depends on what queue algorithms you use. However i have observed reduction in throughput by increasing HSSCH beyond 2, the reason is that code power now is divided between 3 users(if HSCCH=3) so it also depends on the ue geographical location w.r.to Base station.

,karna

[dadoba]

In our network here we use 2 or 3 HS-SCCH, as our friend mention it was observed a Tput loss increasing this number beyond than 2 but as he said it happens cause you will share HS power, you can solve that increasing also the hsScchMaxCodePower, but note just if you have enough power in your cell.

You can monitor by pmNoOfHsUsersPerTti and pmSumOfHsScchUsedPwr and other Kpi related to lack of DL power and RRC Accessibility.

I think in some cases you will see gain in others no, my suggestion is set 2 in cells that do not have high load and set 3 in high load cells, and if these cells does not have power issues you can try to increase hsScchMaxCodePower.