Interactive HSDPA congestion

[kcrb]

Hi dear,
Im a newbie of 3G optimization, especially Data domain, could anyone give me a favor for my issue?
I have a trouble with RSR (RAB assigment Success Rate), it's not good, when i tried to verify the reason, i found that mainly due to congestion after admission control (just for Interactive HS, and EUL).
And, i realized that it's not beacause of Transport network problem, it originated from "Node Congestion" (im not sure which is node congesdtion from E*******'s point of view), im using E******* RAN P7, RNC version 7.
Did anyone already use 3G E******* equipments ?
Could you give me some tips of advice for this issue?

Thanks in advance!

btw, i attach some documents refering to this problem.