Zte ZXG10 BS21, Руководство по обслуживанию

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ZXG10 BS21 (V2.2) Compact Outdoor BTS for GSM Maintenance Manual
162 Confidential and Proprietary Information of ZTE CORPORATION
12 dB or 14 dB greater than that of the current cell, does MS start
the cell selection. Adjust the ratio of SDCCH with TCH and add
SDCCHs if it does not produce distinct effects.
iii. Judge whether the SDCCH congestion is caused by the over-
concentrated traffic. If yes, try adjusting the following parameters:
Increase T3122 to 15 s ~ 25 s to prevent subscribers from
frequently sending channel request messages to increase the load
of RACH and CCCH in the case of deficient system resources.
Increase T3212 by setting it as 3 or 6 hours for the area with
medium traffic, setting it as 16 or 20 even 25 hours for the area
with a large traffic. For the area with a traffic which severely
overruns the capacity of the system, T3212 should be set as 0.
Adjust the related parameters influencing the C2 value to make it
smaller (the C2 parameter has to be activated), which will reduce
the valid coverage of the cell to reduce the traffic of the cell and
the difficulty for MS to select the cell, making the calls established
in the adjacent cells as possibly as you can. For example, increase
RxLAMin (minimum receiving level allowable for access) by setting
it as 12 (-99 dBm ~ -98 dBm) or decrease the Cell Reset Offset
value.
iv. Eliminate the hardware faults.
¾
Confirm whether the TIC board was replaced at the BSC side
recently and check whether the DIP switch of it is configured
correctly. According to experiences, the incorrect matching
impedance of the DIP switch will cause big bit errors to be
transmitted. BS may have a great capability of anti-bit-error, but
the bit errors can still be measured by the bit error tester.
¾
Test the availability of TCH to confirm the unstable carrier module.
Replace the unstable carrier module to avoid the problem caused
by a time slot of the carrier (DSP chip).
7. Precautions
i.
Set T3122 as little as possible, usually 10 s, when little traffic is in
the channel.
ii. Do not set RxLAMin too large. Otherwise, “Blind area” will appear
on the border of the cells. We suggest that it should not surpass -
90 dBm.
iii. The value of the T3212 parameter should be relevant to the
location upgrade parameter in MSC/VLR. Setting it as larger than
the parameter in VLR may make MS unable to access the network.
iv. If the SAGEM mobile phone is used for testing, the phenomenon
may appear, but the phenomenon does not appear in the other test
mobile-phones.