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CDMA GSM comparison

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  • #45111 Reply

    Hi all,

    i am having following doubts on CDMA in comparison with GSM

    1. wht are all the equivalent of IMSI IMEI in CDMA?
    2. In paging, which number will be used IMEI equiv. or IMSI equiv. in CDMA ?
    3. Similary for registration which identity (IMSI or IMEI) will be used ?
    4. whether IMEI and ESN are same or not?
    5. wht is the purpose of ESN in call processing and registration ?
    6. wht is the purpose IMSI if so in call processing?

    Give some basic usage of the terms whichever is used in CDMA
    MIN :: Mobile Identification Number (MIN). The 34-bit number that is a digital representation of
    9 the 10-digit number assigned to a mobile station.
    IMSI_M :: MIN-based IMSI using the lower 10 digits to store the MIN.
    IMSI_O :: Operational value of IMSI used by the mobile station for operation with the base station.
    IMSI_T :: True IMSI not associated with MIN. This could be 15 digits or fewer.
    NAM :: Number Assignment Module (NAM). A set of MIN/IMSI-related parameters stored in the
    35 mobile station.
    ESN :: Electronic Serial Number (ESN). A 32-bit number assigned by the mobile station
    31 manufacturer, uniquely identifying the mobile station equipment.

    Thanks in advance…

    #45112 Reply

    I am working in a GSM Operator.Now, we are facing severe Interference problem (100% interference in TCI 5 band) for another CDMA operator. The sporious signal of the CDMA operator frequency band (880 MHz to 890 MHz downlink) enter in our Band ( 890 MHz to 895 MHz uplink). The energy level of the CDMA operator spourious signal at 890 MHz is about -68 dBm and the average power of their Interfacing signal encroach the our band is abput -76 dBm, which should be less than -110 dBm. Please help us by giving some technical solution that can help us to convince the CDMA Operator and BTRC(Bangladesh Telecommunication Regulatory Commission) to take necessary action for preventing the problem.

    Thanks and Regards

    #45113 Reply

    hello n,

    So the CDMA system is generating spurious emissions after 890.0 MHz ?
    The GSM system starts at 890.2 MHz (central frequency). Therefore you measure -76dBm at 890.2 MHz.

    Trying to convince your government that the CDMA system is overlapping to much with your frequencies is going to be quite complicated. Your measures are not a proof good enough ?
    You could check what is the theoretical maximum spurious emissions a CDMA system should generate outside its own band.

    Does the problem occur only on GSM cells that are collocated with CDMA cells or not ?

    If yes : you can try to install additional “sharp” filters in those GSM sites
    If no : then you’re stuck… can’t you ask the CDMA to move their bands 200 kHz downwards ? That should give enough room for a good isolation.


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