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TRX and E1

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  • #51539

    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




    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.


    thx fedex ๐Ÿ™‚


    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

    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™‚


    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



    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.


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


    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™



    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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