Generic selectors
Exact matches only
Search in title
Search in content
Search in posts
Search in pages

QoS Degrading

  • This topic has 15 replies, 1 voice, and was last updated 11 years ago by awahma.
Viewing 15 posts - 1 through 15 (of 16 total)
  • Author
    Posts
  • #58068 Reply
    Zo
    Guest

    Hi,

    The Hopping mode is Baseband.

    I have 6 TRX (Siemens CU)-TRX NO: 0 to 5. There was some QoS degrading issue. But after Disable Hopping the quality for TRX 1:4 is improved while that of TRX:5 is degraded.

    After replacement of TRX:5 CU and enable Hopping again the quality of ALL TRXs improved.

    why one bad CU should affect the overall quality of all hopping TRXs despite the operation of baseband hopping.

    can u guys explain a bit.

    Thanks

    #58069 Reply
    Pix
    Guest

    Hello Zo,

    In BBH, your cell works like this:

    each TRX-CU is transmitting only one frequency.

    for example:
    one call is allocated on TS3… each TDMA frame, the call changes TRX-CU. If cell has 3 TRX, then the call is allocated like this:
    TDMA n1 = TRX1
    TDMA n2 = TRX2
    TDMA n3 = TRX3
    TDMA n4 = TRX1
    TDMA n5 = TRX2
    TDMA n6 = TRX3
    etc.

    If TRX3 is faulty, you see that it impacts all the calls in the cell. Indeed, all calls in the cell are carried by all TRX. One faulty TRX is enough to degrade the whole quality.

    In alcatel-lucent, the calls are not hopping from TRX to TRX. It is the TRX itself that is changing frequency. So one faulty TRX impacts only the 8 calls (or so) that it carries.

    Cheers,
    Pix

    #58070 Reply
    zo
    Guest

    Hi,

    Pix/ thanx a million for your explaination.

    Is there any way to detect this type of occurance and whats the procedure to solve? Is there any recommendation?

    Also we are facing some problems like…

    1. T200 timer expiry
    2. 3 consecutive DL TRAU/PCU frames bad

    What should we do and how we investigate?

    Kindly help.

    Thanks.

    #58071 Reply
    awahma
    Guest

    @Pix:”In alcatel-lucent, the calls are not hopping from TRX to TRX. It is the TRX itself that is changing frequency. So one faulty TRX impacts only the 8 calls (or so) that it carries.”

    Not in Alcatel-Lucent only but in all the vendors where you are using Synthesized Frequency hopping(SFH)a faulty hopping TRX shall affect only 8 TCHs which are being carried by this TRX.
    While in baseband hopping each call hops from one TRX hardare to other TRX hardwre to achieve hopping so one faulty TRX will affect all the calls and this is true for BCCH also as timeslots 1 to 7 of BCCH carriers are also hopping in baseband hopping scenario.

    #58072 Reply
    Pix
    Guest

    Awahma,

    In ALU, even in BBH, it is the TRX which is changing frequencies. Our BBH is actually a kind of SFH ๐Ÿ™‚

    #58073 Reply
    zo
    Guest

    Guys, can anyone help me about below alarms;

    1. T200 timer expiry
    2. 3 consecutive DL TRAU/PCU frames bad

    What should we do and how we investigate?

    Thanks.

    #58074 Reply
    Zo
    Guest

    Hi,

    Can you please explain a bit more.. about QoS degradetion by 1 bad Quality of 1TRX.

    I my case there are 6 TRX (0 to 5). The KPI RxQualUl shows 50% and after disable Hopping the quality for TRX 1:4 is improved (almost 100%) while that of TRX:5 is degrede (almost 10%).

    My question is how 1 TRX’s bad quality degrade the all TRXs quality to 50% (50% reduction). It should be 20% reduction. Isn’t it? I might be wrong. Please explain a bit.

    Thanks

    #58075 Reply
    Pix
    Guest

    Hello,

    What exactly does it measure, this KPI ? (rxqualUL)
    RxQual ranges from 0 to 7, so I am lost with your percentages ๐Ÿ™‚

    Cheers,
    pix

    #58076 Reply
    ATTO
    Guest

    Hi Pix,

    “In ALU, even in BBH, it is the TRX which is changing frequencies. Our BBH is actually a kind of SFH :)”

    Even in Alu, the TRX is assigned a fixed frequency i think, really think. Please check from ur side to be sure.

    #58077 Reply
    zo
    Guest

    Hi pix,

    It is RxQualUL6 (6). The avarege parcentage was 50% when the Hopping enabled (BBH). but after disable Hopping the 1st 4 TRXs quality becomes average 100% and TRX5 quality is 5-10%. So my question is how 1 Bad TRX degred overall TRXs qualty 50%.

    Thanks for you understanding.

    #58078 Reply
    zo
    Guest

    Hi Pix,

    Sorry to misguide u. It is RxQualDL.

    #58079 Reply
    Pix
    Guest

    ATTO, i am 100% sure, i checked with the guy that is the head designer of the ALU BSS equipments ๐Ÿ™‚

    zo > i’m really trying to understand, but your answer does not clarify much.
    RxQual ranges from 0 to 7.
    You are saying 10%, 50% and 100%.

    You must know that the RxQual is not a linear scale, the correlation with the BER is rather logarithmic, I recall.

    So I am not surprised by those values.

    #58080 Reply
    zo
    Guest

    Hi Pix,

    Can I have your e-mail address? Actually this cse is vesy interesting. I want to sent you the case history and proposed action. The problem is resolved but I am a bit confused about the nature of RxQual graph.

    Thanks.

    #58081 Reply
    Pix
    Guest

    Well, you give me your email address , and i’ll send you an email… ๐Ÿ™‚

    #58082 Reply
    zo
    Guest
Viewing 15 posts - 1 through 15 (of 16 total)
Reply To: QoS Degrading
Your information:




<a href="" title="" rel="" target=""> <blockquote cite=""> <code> <pre class=""> <em> <strong> <del datetime="" cite=""> <ins datetime="" cite=""> <ul> <ol start=""> <li> <img src="" border="" alt="" height="" width="">