1. 31/1/2014
Parameter Check list for TCH Drop in Huawei system-2 - Blogs - Telecom Source
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Parameter Check list for TCH Drop in Huawei system-2
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Parameter Check list for TCH Drop in
Huawei system-2
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1. SACCH Multi-Frames This parameter
determines whether an uplink radio link is faulty. Each
time the BTS fails to decode the measurement report
on the SACCH from the MS, the counter decreases
by 1. Each time the BTS successfully decodes the
measurement report on the SACCH, the counter
increases by 2. When the value of this counter is 0,
the BTS regards the radio link as faulty. In the traffic
measurement, if there are many call drops (M3101A)
related to radio link failure, you can infer that the radio
propagation conditions are poor. In this case, you can
set this parameter to a greater value.
2. Radio Link Timeout This parameter determines
whether a downlink radio link is faulty. Each time the
BTS fails to decode the measurement report sent
over the SACCH by the MS, the counter decreases
by 1. Each time the BTS successfully decodes the
measurement report sent over the SACCH, the
counter increases by 2. When the value of this
parameter is 0, the BTS regards the radio link as
faulty. In the traffic measurement, if there are many
call drops (M3101A) related to radio link failure, you
can infer that the radio propagation conditions are
poor. In this case, you can set this parameter to a
greater value.
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http://www.telecomsource.net/entry.php?59-Parameter-Check-list-for-TCH-Drop-in-Huawei-system-2
Coverage problem troubleshooting
by hh401
Parameter Check list for TCH Drop in
Huawei system-3
by tinyiko
Parameter Check list for TCH Drop in
Huawei system-2
by krish
Parameter check list in Huawei System for
high TCH Drops.
by krish
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2. 31/1/2014
Parameter Check list for TCH Drop in Huawei system-2 - Blogs - Telecom Source
3. RXLEV_ACCESS_MIN This parameter specifies
the minimum receive level of an MS to access the
BSS. If this parameter is set to a too small value,
some MSs with low receive levels may access the
network and call drops are likely to occur. You can set
this parameter to a great value to reduce the TCH
call drop rate. The counters such as call setup
success rate and the counters related to traffic
volume, however, are accordingly affected.
4. RACH Min.Access Level This parameter
determines whether an MS can access the network
over the RACH. If this parameter is set to a too small
value, some MSs with low signal levels may access
the network and call drops are likely to occur. You can
set this parameter to a great value to reduce the
TCH call drop rate. The counters such as call setup
success rate and paging success rate, however, are
affected.
5. Min DL Power on HO Candidate Cell and Min
Access Level Offset The sum of the values of the
two parameters specifies the minimum downlink
receive level of a candidate neighboring cell for a
handover. If this parameter is set to a too great
value, some desired cells may be excluded from the
candidate cells; if this parameter is set to a too small
value, an unwanted cell may become the candidate
cell. Both conditions may lead to the increase of call
drops.
6. Timer T3103 series Timer T3101 series consists
of T3103A, T3103C, and T8. These timers are
started to wait for a handover complete message. If
the lengths of the timers are set to small values,
probably no message is received when timer T3103
series expires. In this case, the BSC considers that
the radio link in the originating cell is faulty. Then, the
BSC releases the channel in the originating cell. Thus,
call drops occur. In the traffic measurement, if many
call drops are related to handovers (CM331: Call
Drops on Radio Interface in Handover State), you
can set this parameter to a greater value. If this
parameter is set to a too great value, channel
resources are wasted and TCH congestion occurs.
7. Timer T3109 This parameter specifies the period
for waiting for a Release Indication message after the
BSC sends a Channel Release message to the BTS.
If this parameter is set to a too small value, the link
may be released before the Release Indication
message is received. As a result, a call drop occurs.
You can set this parameter to a greater value to
reduce the TCH call drop rate. It is recommended
that timer T3109 be set to 1–2 seconds longer
than timer Radio Link Timeout.
8. Timer T3111 This parameter specifies the
interval between the time that the main signaling link
is disconnected and the time that a channel is
deactivated. The purpose is to reserve a period of
time for repeated link disconnections. If this timer is
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3. 31/1/2014
Parameter Check list for TCH Drop in Huawei system-2 - Blogs - Telecom Source
set to a too small value, a channel may be
deactivated too early. Thus, call drops increase.
9. Timers T305 and T308 Timers T305 and T308
are used on the MSC side. Timer T305 specifies the
period during which the MSC monitors the on-hook
procedure. Timer T308 specifies the period during
which the MSC monitors the resource release
procedure. You should set the two parameters when
adding BSC data. Note that the modification of the
data in the timer table does not take effect. If timers
T305 and T308 are set to invalid or great values, the
MSC clears the call a long time after the MS hangs
up. After the T3103 and Radio Link Timeout timers
expire, the number of call drops is increased and thus
the TCH call drop rate is significantly affected.
10. TCH Traffic Busy Threshold If the current
channel seizure ratio exceeds the value of this
parameter, the BSC preferentially assigns a half-rate
channel to a dualrate-enabled call. Otherwise, the BSC
assigns a full-rate channel to the dualrate-enabled call.
Compared with a full-rate channel, a half-rate channel
has weak antiinterference capabilities. Therefore, if a
large number of half-rate channels are assigned, the
TCH call drop rate increases. It is recommended that
this parameter should not be set to a too small value
if congestion is unlikely to occur.
11. Call Reestablishment Forbidden This
parameter specifies whether to allow call
reestablishment. In case of burst interference or radio
link failure due to blind areas caused by high buildings,
call drops occur. In this case, MSs can initiate the call
reestablishment procedure to restore communication.
To reduce the TCH call drop rate, you can set this
parameter to No to allow call reestablishment. In
certain conditions, allowing call reestablishment greatly
reduces the TCH call drop rate. Call reestablishment
lasts for a long time, and therefore some subscribers
cannot wait and hang up. This affects user
experience.
12. Parameters related to edge handover When
the receive level drops greatly, an edge handover
cannot be performed in time in any of the following
conditions: The parameter Edge HO UL RX_LEV
Threshold or Edge HO DL RX_LEV Threshold is set to
a small value; the parameter Inter-cell HO Hysteresis
is set to a great value; the parameters Edge HO
Watch Time and Edge HO AdjCell Watch Time
are set to great values; the parameters Edge HO
Valid Time and Edge HO AdjCell Valid Time are set to
great values. As a result, a call drop occurs. To
reduce the TCH call drop rate, you can appropriately
set these parameters so that edge handovers can be
performed in time to avoid call drops.
13. Parameters related to BQ handover When
the signal quality deteriorates, a BQ handover cannot
be performed in time in any of the following
conditions: The parameters ULQuaLimitAMRFR,
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4. 31/1/2014
Parameter Check list for TCH Drop in Huawei system-2 - Blogs - Telecom Source
ULQuaLimitAMRHR, UL Qual. Threshold,
DLQuaLimitAMRFR, DLQuaLimitAMRHR, and DL Qual.
Threshold are set to great values; the parameter BQ
HO Margin is set to a small value; the parameter
Inter-cell HO Hysteresis is set to a great value. As a
result, call drops occur. To reduce the TCH call drop
rate, you should appropriately set these parameters
so that BQ handovers can be performed in time to
avoid call drops.
14. Parameters related to interference
handover If the parameters RXQUAL1 to RXQUAL12
are set to great values or if the RXLEVOff parameter
is set to a great value, strong interference may
occur. In this case, if interference handovers are not
performed in time, call drops occur. To reduce the
TCH call drop rate, you can appropriately set these
parameters so that interference handovers can be
performed in time to avoid call drops. If the
parameters RXQUAL1 to RXQUAL12 are set to small
values, the number of handovers due to other
causes increases greatly, thus affecting the handover
success rate.
15. Parameters related to concentric cell
handover A call at the edge of the overlaid subcell
cannot be handed over to the underlaid subcell in any
of the following conditions: In the case of a normal
concentric cell, the parameters RX_LEV Threshold and
RX_LEV Hysteresis are set to great values; in the
case of an enhanced concentric cell, the parameter
OtoU HO Received Level Threshold is set to a great
value. As a result, a call drop is likely to occur. If the
Call Drop Ratio on TCH on the TRX in the OverLaid
Subcell (RM330a) is high, you can appropriately set
these parameters so that calls at the edge of the
overlaid subcell can be handed over to the underlaid
subcell in time. When a call in the underlaid subcell has
interference, the call cannot be handed over to the
overlaid subcell if the RX_QUAL for UO HO Allowed
parameter is set to Yes and the RX_QUAL Threshold
parameter is set to a great value. Thus, a call drop
occurs. If the Call Drop Ratio on TCH on the TRX in
the Underlaid Subcell (RM330) is high, you can set
these parameters properly so that the call can be
handed over to the overlaid subcell at the earliest.
To know about more parameters click below:
Parameter check list for TCH Drop in Huawei
System
Tags: huawei parameter, tch drop
Categories: GSM
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5. 31/1/2014
Parameter Check list for TCH Drop in Huawei system-2 - Blogs - Telecom Source
krish - 04-092012 01:56 AM
GOOD ONE BUDDY SHARE MORE
RELATED TO TCH DROP
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