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Coding Scheme

Viewing 7 posts - 1 through 7 (of 7 total)
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  • #47526 Reply
    Ajay
    Guest

    Hi All,
    We are checking the EGPRS using our TEMS Mobile (Sony Ericsson W600i). We check the features of this mobile and we found that it supports EDGE which means it supports MCS-1 to MCS-9. We check the MCS but it is using only MCS-6 data even with good C/I and Recieved Level. I have attached the log files from TEMS. With such good C/I and good received level why it is not going to MCS-9?
    ajaya.maharjan@spicenepal.com

    #47527 Reply
    Tomar
    Guest

    Hi Ajay,
    I saw sometimes similar problem. C/I is between 30 and 35 dB, but MS stay on coding scheme MCS6 in downlink. Probably MCS6 is defined as starting coding scheme. At first check if you have Link Adaptation – true. You could try behavior of data downlink transfer during busy hour and during midnight (probably no other user will used EDGE).
    If the problem is only during day, than the problem could be on ABIS (check PM counters), if there is enough space. 4 radio timeslot for MCS9 for Siemens technology need 20 ABIS subslots. Then check counters for PCU. One PCU could serve only some limit of PDCH (ABIS and radio channels)
    BR
    Tomar

    #47528 Reply
    Pix
    Guest

    Ajay,

    Check you have enough EXTRA TS on the ABIS to carry the additional data.

    Check also that your ATER is not congested, or in “high load”, in which case it will automatically reduce the max MCS.

    Check also that you authorize your cells to carry a coding scheme up to MCS-9. Check also the parameters to move from one MCS to another MCS.

    Hope it helps…

    #47529 Reply
    Ajay
    Guest

    What is the parameter to move from one MCS to another MCS?

    #47530 Reply
    Pix
    Guest

    they should be located under “link adaptation”, or something like this.

    #47531 Reply
    Ajay
    Guest

    We have parameter of Link Adaptation and for this we can only set TRUE or FALSE.
    IS THERE ANY PARAMETER BEHIND THIS FOR CHANGING ONE CODING SCHEME TO ANOTHER?

    #47532 Reply
    Pix
    Guest

    Ajay,

    Yes, certainly. But you must be aware that those parameters might be highly dependent on the vendor, and nowhere did you state the vendor you’re using 🙂

    Normally those parameters are hard-coded in a “link adaptation table” defined by 3GPP. Those tables depends on :
    RLC Mode,
    ARQ Type,
    Mean BEP and CV BEP (= mean and normalized variation of bit error rate = estimations of the quality of the radio signal).

    So depending on the quality of the signal, the system knows which is the targeted MCS.
    If your system stops at MCS6 while excellent radio quality, read again my first post… because it has probably nothing to do with radio parameters, but rather a congestion or high load somewhere.

    Regards,

Viewing 7 posts - 1 through 7 (of 7 total)
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