2. Reduce Quantity of RRC Retransmission
Quantity of RRC setup request Retransmissions: N300
(this can be set to a small value like 1 for special events that last only a temporary
time, a day or 2 or so)
T300, time between Retransmissions (maybe from 600
ms to 2 s), for special events that last only a short time
(a day or so)
3. Reduce Periodic Location Area Update
Timer T3212 (maybe reduce from 10 minutes default
value to 40 minutes
Adjusting GBR
Maybe adjust GBR from 64 kbps to 32 kbps
(for special events)
4. Relieving Congestion on FACH
Adjust timer T381 (def: 600 ms) and N381 (controls retransmissions of RRC
Connection Setup messages by the RNC
The RNC starts T381 after sending the RRC CONNECTION SETUP (or CELL UPDATE
CONFIRM) message. If the RRC CONNECTION SETUP COMPLETE message (or response
message of the CELL UPDATE CONFIRM message) is not received after T381 times out and the
quantity of retransmissions of RRC setup requests is smaller than the value of N381, the RNC
sends the RRC CONNECTION SETUP message (or response message of the CELL UPDATE
CONFIRM message) again and restarts T381. Def value is 600 ms. The default and recommend
values for N381 are 1 (range 1:4)
By limiting the retransmission of RRC Connection setups, the load of FACHs and
CCCHs can be reduced (these can be set to small values particularly for special
events lasting only a day or so)
5. Threshold of Uplink Access Control
The RRC access is controlled by the OLC threshold, the RRC setup
requests and RAB setup requests will be rejected when the uplink
power is congested.
We can adjust the threshold of uplink equivalent subscriber quantity
(Max 200, Def: 95) to achieve balance between access failure and
Uplink power congestion
6. Enable DOWNLINK Power Control Function
(in Congestion times)
To prevent the signaling storm resulting from repeated subscriber
attempts to access the network in congestion times to overload the
node B TX power and hence cause power clipping (which then
affects the KPIs), enable this function.
7. Reducing RTWP
If the power control command issued by the NodeB is not received (within the time the UE
releases the channel resources as controlled by timer T308), some UEs will increase the power by
default, causing an increase in RTWP
This can be prevented by performing the following commands:
Adjust the HSUPA PO:
Set REFETFCI PO1 to PO_15/15
Set REFETFCI PO2 to PO_67/15
This parameter specifies the power offset between E-DPDCH and DPCCH associated with the
reference E-TFCI in the case of the target number of retransmissions on the E-DCH. For details of
this parameter, refer to the 3GPP TS 25.321.
8. Reducing RTWP cont…
Adjust the CQI feedback period on the uplink HS-DPCCH
(def value is D2)
(When CQI Feedback Cycle (k) is not zero, it must be greater than or equal to CQI
Repetition Factor * 2ms)
RACH Related parameters
PowerOffestPpm ( recomm values: -3 and -2 dB)
PreambleRetransMax (def and recomm value: 20)
PowerRampStep (def and recomm values; 2 dB)
The above values can be optimized based on tradeoffs between call set up delays
and load level in the node B.
9. Reducing RTWP cont…
Optimizing CQI feedback period by prolonging the CQI feedback period
on the uplink HS-DPCCH, the impacts on the uplink channel power (RTWP)
can be reduced
