Transcript Network failure detection Failure detection

地杰通信
Network failure detection
and MW failure disposition
Provided by BEIJING DG TELECOMMUNICATIONS
EQUIPMENT CO.LTD
地杰通信
Network failure detection
地杰通信




Failure detection
After receiving the report that the site is offline,
FOPS O&M engineer contact the DG
maintenance engineer and detect the failure
according to the network map.
Many sites are offline or single site is offline;
If many sites are offline , is there same upper
site for these sites?
The disposition for scattered sites is same as
single site.
地杰通信
The disposition for the offline sites
which have same upper site



The upper sites is PDH MW
The upper site is SDH MW(HUBSITE)
The upper site has optical transmission
equipment.
地杰通信




Upper site is PDH MW
First check the upper site whether there is no
AC Power by OMC.
If there has no AC Power , please arrange the
generator by ZTE.
FOPS O&M engineer do the loopback test at
BSC.
If the BSC is ok, DG would arrange
maintenance engineer to check mw equipment.
地杰通信
Upper site has optical transmission
equipment


When several links which belong to one
WATEEN site are offline at the same time, ZTE
maintenance engineer should do the loopback
test at BSC side first.
If the BSC is ok, ZTE engineer should do the
loopback test on the WATEEN site.
地杰通信
Upper site is SDH MW


When all sites which belong to SDH MW are
offline, ZTE maintenance engineer would check
whether there is power at the HUBSITE.
If power is available there, DG engineer would
go to check SDH MW.
地杰通信
Single site is offline
First confirm whether there is down site.
 If there is but it is online:
The mw link is ok in this case, first check whether
there has AC Power .
If there AC Power is available, do the loopback
test at BSC side first.
If BSC is ok, the E1 patching may have caused
this problem ,the maintenance engineer would
go to check.

地杰通信
Single site is offline
If there has no down site of the site:
ZTE maintenance engineer should check whether there
has AC Power by OMC firstly. Then check the mw
equipment by mw NMS. If there is problem of the mw
equipment, DG maintenance engineer would go to
check the mw equipment.
If there is AC Power and the mw is ok too, do the
loopback test at BSC side.
If the BSC is ok, the E1 patching might have caused this
problem, maintenance engineer should go to check it.
地杰通信
DG SUPERSTAR MW
TESTING
Equipment problem
地杰通信
DG SUPERSTAR MW FAILURE
TESTING



Mw failures are classified by equipment problem
and system problem.
Equipment problem means the problem of IDU
and ODU, these can be detected by Indicator
light/AIS/LOOPBACK easily.
System problem means the equipment is ok, but
the system not, generally speaking, this kind of
problems is difficult to detect and solve.
地杰通信
MW equipment failure
Detect the failure by indicator light
1,Power light is not on: the power module of IDU
is broken, replace it.
2,Cable light is not on: IF cable or ODU problem.
3,ODU light is red: replace ODU.
4,Run light is not blink: restart IDU, if the
problem is same as before, then replace IDU.

地杰通信

MW equipment failure
Login to the IDU to solve failure
Use the cat-5 cable to connect the NMS
interface of IDU and the network port of
laptop, then open the IE ,input the local ip
address which is showed on the IDU (Detail
instruction is in the 5.2-USING WEB of guide
instruction)
Check the technical parameter on the homepage.
地杰通信
Detect equipment failure by laptop
One: Whether IDU is connected with ODU.
When it is not , the homepage shows :NO DATA FROM ODU RF
POWER=OFF , so we can know there is problem of the IDU or ODU:
1，Check whether the output voltage at the N interface of IDU is normal, the
normal value is +24V, if it is not, the IDU is broken
2，If the output voltage of IDU is normal, check the connection wire
3，If the above two items are all ok, use multimeter to test N connector of
ODU ,Switch to LED, when the direct test is high impedance, the value of
reverse test is around 542, the IDU is broken otherwise the ODU is broken.
地杰通信
Detect equipment failure by laptop
Two: Check the RXL of equipment
check RXLEV=? on the homepage
the operation range:
16E1:-20~-79dBm
8E1 :-20~-81dBm
4E1 :-20~-83dBm
If the RXL is less than the RXL alarm threshold, the equipment
can’t work normally, continue checking the equipment to recover
the normal RXL.
Normally the RXL is larger than-50dBm. If the actual RXL is
less than -50dBm,we should increase the RXL by increasing the
TX power or align dish. The best RXL range for equipment is 30~-35dBm
地杰通信
Detect equipment failure by laptop
Three: Check the TX power
Check the TX POWER=? On the homepage
If it shows TX power=OFF, the equipment won’t work,
we can switch the TX power to solve this issue. The
method is click the LINK CONFIG, then type the
username: sstar, password: test, choose the available
value at the drop-down menu of TX power(10~20dBm), then click OK. Finally click SAVE
CONFIG to finish adjusting the TX power of ODU.
After adjusting the TX power, check the RX power of
far end site. Find the best RX power value by
increase/decrease TX power
地杰通信
Detect equipment failure by laptop

Four: Check whether the TX frequency is matching
The TX frequency of local site must be equal to the RX
frequency of far end site, and the RX frequency of the local site
must be equal to the TX frequency of far end site.
Check TX=?RX=? on the homepage, compare this with far end
sites, If it does not match, modify the frequency. The method
is :click LINK CONFIG, type username: SSTAR, password:
TEST, choose available value on the drop-down menu of chan,
click SET, finally click SAVE CONFIG to finish the
modification.
After modify the frequency check it on the homepage to confirm
it’s modified correctly.
地杰通信
Detect equipment failure by laptop
Five: Check the capacity
 The equipment capacity must be same on both
sites.
Click WEST TRIB CONFIG to check the
equipment capacity, if it’s different from remote
site, we should modify it. The method is: choose
the correct capacity on the drop-down menu of
capacity(8MB,16MB,34MB),click Ok, then save
the configuration.

地杰通信
Detect equipment failure by laptop

Six: detect the failure by loopback function
If the configuration, power, and frequency are all ok, but the transmission
is down, By the loopback function we can know it’s local site or far end
site problem also we can know it’s IDU or ODU problem. Method is:
Click LINKCONFIG, type the username and password, choose “on”on
the drop-down menu of loopback, then back to homepage, check the rxlev.
If it’s larger than -65, and the indicator light of IDU,ODU and RA are all
off, it means the local site equipment is ok and the far end site equipment is
broken .Unlock the RF loopback after the loopback test.
Notice: On the TX- High side, use the lower frequency when do the RF
loopback, at the TX –LOW side, use the higher frequency when do the RF
loopback test.
地杰通信
DG SUPERSTAR MW
FAILURE TEST
SYSTEM PROBLEM
地杰通信



System problem
System problem means the mw equipment of both
sites are ok( confirmed by loopback) but the
transmission is down..
System problem may be caused by the change of
communication environment because of natural or
man-made activity.
System problem include: frequency interference,
deviation of mw dish, block by construction, multipath
interference, waterish dish/IF cable system and etc.
地杰通信





Frequency interference
The frequency resource is limited in Pakistan because many MW
are used. So the mw may encounter frequency interference.
Reason: The distance between two hops mw which use same or
adjacent channel is short and the direction is same.
Symptom: The mw equipment is ok and the RX power is good
on both sites but there is high BER at one site.
Testing: Switch one site’s equipment off, but there is still
intensive RX power larger than -60dBm for example.
Solution: If there is frequency interference at local site, switch
off far end site’s equipment, then adjust the frequency of local
site’s equipment, take the frequency point which get the
minimum interference and make record.
地杰通信




Deviation of MW dish
Reason: The mw dish is not fixed, the mw dish deviate
from transmission direction under inclement weather.
Symptom : The RX power is very low on both sits, and
the mw equipment is ok, the problem occur with the
inclement weather, check whether the mw dish deviate.
Solution :Align the mw dish, get the maximum RX
power.
Notice: The deviation of mw dish caused by natural
activity is just in the horizontal direction, it will not
happen in the vertical direction, so just do the
alignment in the horizontal direction.
地杰通信





Obstruction by construction
This case almost happens in the downtown
Reason: The transmission is down caused by the high
construction which block the transmission of Electromagnetic
wave.
Symptom : The RX power is low on both site, it takes long time
from the worse of communication quality to the communication
is definitely down, the rx power decrease gradually.
Testing : There is block in front of the mw dish.
Solution: Increase the height of dish when it’s possible, if the
tower is not high enough, we can change the upper site, when
the --route can’t be changed, we can use the obstruction as relay
transmission.
地杰通信




Multipath interference
Multipath interference occurs at the river, lake, sea,
paddy field, smooth ice surface, smooth gobi and etc.
Reason : The phase in different between interference
signal and normal signal.
Symptom : Because the interference signal is unstable,
the rx power fluctuates between -30dBm~-60dBm.
Solution :SD is the best way to solve this issue, but if
it’s not available we can sacrifice the RX power to solve
this but the disadvantage is that the fade margin is not
enough, so it’s not suggested.
地杰通信



Waterish Dish/IF cable
Reason :Dish/If cable is destroyed by man-made
activity. Dish/If cable aging. The waterproof is poor,
the dish and If cable would get waterish when it rains,
then the communication will be down.
Symptom :When the If cable is waterish, check the N
type connector by multimeter it’s short circuit. When
the feed horn is waterish, there is aeruginous rust at the
hole of feed horn The inside of the feeder horn is
damp.
Solution: Replace the feed horn or IF cable.
地杰通信
Thanks!