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BsCvMax – GPRS parameter

Viewing 15 posts - 1 through 15 (of 15 total)
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  • #62128 Reply
    jane
    Guest

    Hello guys,

    Can anyone explain to me this parameter? I can’t seem to find a documentation about this.

    Thank you.

    #62129 Reply
    Bijoy
    Guest

    Hi
    This parameter specifies the maximum countdown value of the MS.

    This parameter determines BS_CV_MAX and is used for the MS to calculate the CV. The parameter also determines the duration of the T3198 timer.

    Every time the MS sends an uplink RLC data block, the receive state of the data block is set to Pending and the T3198 is started. If the MS receives a Packet Uplink Ack/Nack message before T3198 expires, it updates the receive state of each uplink RLC data block based on the acknowledgment bitmap contained in the message. If T3198 for the RLC data block in the Pending state expires, the MS sets the receive state of this data block to Nack and retransmits the data block.

    #62130 Reply
    Mania
    Guest

    What is the usual value ot BS_CV_Max and what is it normally based on.

    #62131 Reply
    Bijoy
    Guest

    If the value of this parameter is set to a modest value, the MS may retransmits the RLC data block before the BSC sends an Uplink Acknowledgment message. Thus, many radio resources are not used but occupied.

    If this parameter is set to an excessive value, the speed of the sliding window decreases and the probability of the uplink TBF transmission countdown increases, thus decreasing the performance of uplink transmission.

    To make this value more accurate, you need to estimate the delay in the transmission between the MS and the BSC first. This value is set based on the transmission delay.
    Default value:10

    Br\\
    Bijoy

    #62132 Reply
    Mohit
    Guest

    Hi.I get BS_CV_MAX value from Sys_info13 message. But still not get CV value.

    My querrys
    (1)Is both BS_CV_MAX & CV same?
    (2)If not where we get Countdown Value(CV)?

    #62133 Reply
    Bijoy
    Guest

    Mohit
    1.The MS shall send the Countdown Value (CV) in each uplink RLC data block to indicate the current number
    of remaining RLC data blocks for the uplink TBF.

    Lets assume

    x=round((TBC-BSN-1)/(NTS x S))
    then CV=x ,if x=< BS_CV_Max or CV=15,if x> BS_CV_Max

    TBC=total number of RLC data blocks currently to be transmitted in the TBF.
    BSN=Block sequence no. of the RLC
    NTS=number of timeslots assigned to the uplink TBF
    S=2,usually.

    2.I think you can check the CV value in the UL mode reports.

    Br\\
    Bijoy

    #62134 Reply
    Mohit
    Guest

    Thanks Bijoy. I will check and confirm that.

    #62135 Reply
    b2002
    Guest

    Hi Bijoy

    Now am studying the RLC/MAC. May i thought u know about the that protocol…
    Can u explain for me..?

    #62136 Reply
    Pix
    Guest

    To make it better, tell us in how many words you want that…

    But why not have a look at this first?

    etutorials.org/Mobile+devices/gprs+mobile+internet/Chapter+5+Radio+Interface+RLC+MAC+Layer/

    #62137 Reply
    b2002
    Guest

    hi pix
    Thank u for reply.
    i studied that book.i have lot of doubts.That is reason am asking the explanation.

    #62138 Reply
    Pix
    Guest

    Hi,

    What are your doubts? It’s more efficient if you do an effort in writing a long question, rather than us second-guessing whih part of RLC/MAC is troubling you.

    It is a huge protocol.

    Regards
    pix

    #62139 Reply
    b2002
    Guest

    Hi Pix,
    my doubt is when RLC/MAC is one phase acess and when is two phase acess?

    #62140 Reply
    pix
    Guest

    1 phase access when the MS is planning to send less tha 8 RLC blocks – it asks for 1 PDCH only.

    2 phase access when the MS is planning to send more than 8 RLC blocks, or when it is planning to use EGPRS, as far as i remember – it sends its multislot configuration so that the PCU can allocate as many PDCH as possible for the MS.

    In both cases, it is up to the MS to decide whether to do 1 or 2 phase access.

    There are other constraints to do a 1 or 2 phase access, but I forgot them (RLC ack or unack mode, EGPRS modulation, etc etc)

    But the principle is the same.
    Big transfer = 2 phase
    Tiny transfer = 1 phase
    Decision’s criteria are hard coded in the MS.
    regards
    pix

    #62141 Reply
    b2002
    Guest

    hi
    thanks for explanation.But when we know about the RLC/MAC is Less then 8 blocks?

    Regards
    b2002

    #62142 Reply
    pix
    Guest

    hi,

    well, we don’t know, but the MS knows how much data needs to be transmitted.
    If the user has just switched on the phone, the MS has to send a GPRS ATTACH, which is = nn bits = k RLC blocks (values which are known by MS)

    if the user is uploading a file, then the MS knows the size of the file, so it will see that it is more than 8 RLC blocks.

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