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TRX and E1

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  • #51539 Reply

    Dear all,

    Can u help me to give some info, how many TRX maximum for 1 E1 2M,

    how many slot and how many BCCH and TCCH must active?

    Thankyou very much


    #51540 Reply


    About TRX/E1 I cut &paste from a previous Pix’s message:
    with standard OML/RSL multiplexing :
    1 E1 has 32 timeslots, with:
    1 TS for physical signalling/synchro
    1 TS per group of 4 RSL (=4TRX)
    2 TS per TRX

    a BTS with 4 TRXs use 10 E1 TS (1×4)
    a BTS with 5 TRXs use 13 E1 TS
    a BTS with 6 TRXs use 15 E1 TS
    a BTS with 7 TRXs use 17 E1 TS
    a BTS with 8 TRXs use 19 E1 TS (2×4)
    a BTS with 9 TRXs use 22 E1 TS
    a BTS with 10 TRXs use 24 E1 TS
    a BTS with 11 TRXs use 26 E1 TS
    a BTS with 12 TRXs use 28 E1 TS (3×4)
    a BTS with 13 TRXs use 31 E1 TS
    a BTS with 14 TRXs use 32 E1 TS (4/4/6)

    In Alcatel, with a more agressive multiplexing, one can reach more TRXs per E1
    (but less radio timeslots for TCH can be defined) (up to 16 TRX / E1).
    But this is not recommended, because nobody wants to loose TCH capacity ๐Ÿ™‚
    It can be useful for remote BTS with Abis over satellite.

    The previous TRXs are grouped in several Cells. Then only a single TRX per Cell will have a BCCH channel.
    Other timeslots are coonfigured for signalling or traffic (TCH) in a variable ratio.

    #51541 Reply

    thx fedex ๐Ÿ™‚

    #51542 Reply

    For Siemens equipment we have:

    1 TS Synch
    1 TS(16 or 64 Kbps) for signaling LPDLM
    30 TS shared between TCH and GPRS
    Without GPRS and more SDCCH TS we can reach 16 or 17 TRXs

    #51543 Reply
    Assia Mek

    i just wannna be sure for this information please help me i’ve an examination tomorow
    1 E1 (32) = 16TRX with 4 voices of 16kbits/s =>
    16 TRX of 64 kbit/s =16 kb/s *4
    64 *32 = 2Mb/s

    this is my demonstration for :
    1E1 = 16 TRX ๐Ÿ™‚

    #51544 Reply

    Hi Assia

    The assumption of 1 TRX with 4 voices of 16kbits/s is incorrect 1 TRX is 8 channels of 16kbits/sec so 1 TRX takes 2.25 TS of the E1, so 12 trx = 27 TS + 1 ts for omu + 3 ts for rsl (i.e for 3 cells + the first ts of e1 is not usable for tch) so practically 1 e1=12 trx

    #51545 Reply


    it is possible to put 16 TRX on 1 E1, using some special Abis multiplexing strategies (OML/RSL combined with the TS0 if each TRX) – read older post.

    i must admit that the mathematics you did are starting with wrong assumptions, but ending correctly.

    #51546 Reply

    One E1 is how many trx
    and one TRX is how many E1
    and one TRX can support how many people in second

    #51547 Reply

    Simple way checking of E1 Vs TRX Mapping is E1 is 2Mbps links which is divided into 64KbpsX32 TSs,& each 64Kbps TS further divided into 16KbpsX4 nibbles,
    so we can assume that 2Mbps link consist of =4*32=128 nibbles
    While a TRX consist of 8 TS & each TS can be mapped one one Abis nibble.
    so if we assume that 03 Abis TS are reserved for OM & Signalling purposes, then we have available Abis TSs=29 & nibbles are 29*4=116.
    hence Max Possible TRXs on Abis = 116/8=14.5, i forgot how much TS required for RSLs ๐Ÿ™

    #51548 Reply


    4 RSL are usually carried by one TS.
    In case of high loaded RSL, you can configure 2 RSL per TS.

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