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Calculating E1s and Bandwidth

Viewing 15 posts - 1 through 15 (of 15 total)
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  • #41189 Reply

    Hi there,

    Can anyone please help with a formulae to calculate how much bandwidth & number of e1 lines I need for a VoIP project?

    I need to work it out from the number of users.


    #41190 Reply
    kapil likhar

    i want to know
    what is e1 ?
    how it works?
    how the data trasmit through e1?
    what is the A law of companding?

    #41191 Reply

    E1 is 2Mbp/s signal.

    #41192 Reply
    Adel Khader

    E1 is one of the standard Transmission Techniques.
    It is the Infrastructure needed to transmit Traffic (Voice native, Voice over IP, Data…) or to transmit signalling (MAP, ISUP, C7, …)

    it consists of 32 time slots, each can be used for one application or one call channel.

    if the maximum frequency in human voice is 4K Hz this voce should be sampled minimum at 8K sample per Second so that it could be re-constructed without voice quality degradation.
    This 8000 sample is coded with 8 Bits PCM coding the resulting is 64000 bit per second.
    This is one voice sample for one Voice channel at a time.

    for the complete 32 Channel it becomes 32*64000 which is the 2048 K bps or the 2 Mbps.

    For some applications that requires bandwidth more than 64 K, group of channels (5 time Slots for example) can be considered as a one set capable of providing (5*64K =320K).
    some other applications requires the complete 32 Time Slots to be considered as a one channel with complete 2 Mbps Bandwidth)

    E1 is working in Layer 1 and Layer 2 of the OSI Reference Model provided by ISO.

    For Layer 2, it allocates one time slot from the 32 Time Slots for E1 availability and reliability Management; this reduces the number of Time Slots that could be used for transmission to 31 Time Slots.

    #41193 Reply
    Majeed Aslam Raja

    Dear All
    How would you differentiate between a PRI and E1? And what parameters (like PRI has D channel for signalling)are making difference. Which one is preffered.

    #41194 Reply

    i want to know how we allocate the e1 in gsm as well as in cdma?

    #41195 Reply

    please as i know, one GSM TRX = 2TS on A-bis E1, so we use the margin about 0.3 or 0.5, thus 1 TRX = 2.5 E1 ts.
    is it for signaling or what.
    thanks in advance.

    #41196 Reply

    to jood: Why you wrote “thus 1 TRX = 2.5 E1 ts” ? if you have 1 TRX per cell then you have to set BCCH at TS=0 on Air int, so first 2 bits in firtst TS on E1 is free of traffic channels, so you may put LAPD link in those 2 bits,
    so 1 TRX = 2 TS

    #41197 Reply

    Thanks dear elxander:
    let us say i have 12 TRX at GSM site. how many TS on A-bis i need(definetly). is it 24Ts.
    Cuz practically i saw some people using diff way.
    thnaks in advance.

    #41198 Reply

    jood, yes, you right, the minimum amount of TS on A-bis is 24. every TRX need own LAPD link, you may put LAPD link inside traffic channel allocation of that TRX, so 2 bits on A-bis will not be used for traffic, so 1 TS on Air interface also can’t be allocated for traffic, you may put BCCH on that TS on Air int.(if it’s BCCH TRX), or you may put SDCCH . Also Base Station needs O&M link which also allocate at least 2 bits on A-bis, you may alos put it inside traffic channel allocation of some TRX, so 1 TS on Air int will not be allocated for traffic…. but of cource you may put all LAPD links and O&M link on separate TS on Abis, so BS with 12 TRX will need at least 27 TS + 1/4 TS

    #41199 Reply

    how many trx are there in one e1

    #41200 Reply
    Mohd Ismail

    How to derive in-terms of Erlnags in for Each TRX considering all time slots have engaged for 1Hrs duration(Ex:for calculations purpose)….In short Each TRX card generates how much traffic/Erlangs in Hr period.

    #41201 Reply

    How many TRX’s does one E1 support? Is the capacity of E1 is exactly 2mbps or what else. Can U please answer with in details.

    #41202 Reply

    wan link calculator

    #41203 Reply
    Wallis Dudhnath

    A response to Majeed’s question.

    E1 and PRI are based on a 30 Channel PCM system. PCM is Pulse Code Modulation. E1 is a 2.048Mbits/s and uses TimeSlots to convey digital information. PRI is for ISDN. The D channel (Delta) is the signalling Channel. By convention, Time Slot 16 is used. PRI is used with a ISDN PABX – ISPBX.

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