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One way speech

Viewing 11 posts - 1 through 11 (of 11 total)
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  • #54185


    What could be the possible reasons for one way speech, I mean…In our network(ericsson) we are facing this problem that around 2% of calls are becoming one way.
    The connection is established and only one party is able to hear the conversation of other while the second can’t.

    To overrule the possibility at other end i have tested the same with the GSM to PSTN call also. It happens here also.

    One more point is that the call will not drop, you have to END it. Does this overrules the interference also.

    The transcoders are inbuilt in the BSC itself(Ericsson new design). The BSC is connected to media gateway/msc server.

    Media Gateway?
    MSC Server?

    which one has the normal chance for One Way speech causes, if you have encountered the similar situation before.

    Thanks and regards.


    This most probably inter-connection or interface issue which related to TX. Ask from your transmission team to check whether they configure links and interfaces correctly.

    We also had same problem, the reason was wrong connectivity between two MSCs. Im not a TX or Core Network engineer. So I dont know much details of exact issue.


    Let me provide my views in this issue. Oneway speech is case in which only one of the two subscriber is able to hear the other’s voice. Oneway speech and crosstalk are related. First restrict the problem so that it can be easily sorted. Gather maximum number of complaints and analyse them.
    If the oneway speech is restricted to one particular location area or BTS service area, check with the frequency plan, MAIO and HSNs.
    If the problem is with subscribers serving particular BSC, check for the CIC and physical order of links between BSC and MGw. Even though BSC & TRC are integrated, both have devices which have to be properly configured.
    If the problem is with several BSCs then check with the links from the connected MGw to other links. In this case the troubleshooting will be little bit tough.

    Two procedures can be performed,
    1.Making of test calls in individual E1s.
    2.Breaking the digital path or DIP and monitoring on both ends whether correct DIP is reporting alarm.

    for further suggestions pls mail me @


    Bib Smoth

    Does it happen in Busy Hour ?


    After testing i have observed that it is in some particular CELL/BTS only.

    It is not linked with the Busy Hour only rather it happens any time.

    What could be the reason in a particular BTS only?

    If hardware then what? TRU

    or can a software also?




    When we talk about FER,ie Frame Erasure Rate then which frame we are referring to?

    Is it the TDMA frame of 4.615 msec of GSm or a some different frame.

    As the name a suggests a frame is erased. The question here why a frame gets erased. A frame is erased at the air interface only or it can be erased at any of GSM interfaces?

    If the frame is erased at other interfaces of GSM then do we still have the same values in the drive test or different ones?

    Also, if we have high values of FERs then apart from the causes what will be consequences of high FER’s?

    Will the muting of speech is related to FER or not? If yes then does that means the FER affects only UL or DL at a time?

    In the drive test I think the FER which we see corresponds to the DL channel only.( please correct)



    We have the option to LOCK ARFCN in TEMS.

    I think with this it is possible for us to test the BCCH TRX of a cell. ie we can make our call to be forced to latch on the BCCH TRX only.

    In the same manner we can test the other TRX’s of the cell by locking the other TRX’s of the cell( as the BCCH will shift).

    Thus can we say that the above method is one of the possible ways to test your hardware? please correct if i am wrong.

    Why i am talking about the above ….

    As I said in continuation with my current discussion that the problem of speech muting in UL is in some cells only?

    Thus i have only two possibilities to explore…

    1. The BTS harware
    2. The RF drive test of the cell

    Also the muting ratio is around two percent.

    I am confused…



    I am not an expert in BTS and channel concepts. But i could suggest simple steps to troubleshoot. As u mention that the problem is with a single BTS, the following things can be performed.

    1. Re-integrate the cell to the BSC.
    2. Verify the frequency plan.
    3. Mainly check MAIO,HSN and ARFCN.
    4. It could be even due to faulty BTS equipments.
    5. Finally verify the Abis path.



    I don’t understand why the signal in handset will go down suddenly and will comeback immediately.

    Is it a hardware issue of BTS?

    or in Antenna?

    Antenna’s were ok just a few days back…and they are working fine with nokia bts…

    but immediately after swapping to ericsson 2694RBS the problem is coming…

    Any encounter with similar situation…


    “signal in handset”… it’s not very clear. What do you mean ? The RXLEV DL ?

    If it goes down suddenly, then go up again:
    – bad power control settings
    – strong fast fading (urban areas, lots of reflections)
    – hardware problem: the ericsson BTS is having trouble in generating the Tx Power
    – cable problems / connectors: it’s possible the cable is a bit loose, there is water, or too much bending?


    Yes it is with reference to Rxlevel DL only.

Viewing 11 posts - 1 through 11 (of 11 total)
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