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  1. #1
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    interference in ofdma

    hello,

    i just started my research on resource optimization for cooperative communication,
    i just want to know about OFDMA, does it suffer from Interference, what are the types of interference that affects the OFDMA performance.
    In CDMA for example, the received signal can be written as

    y=ax+∑bz+n, where ∑bz represent the interference from other users,

    is this is same in OFDMA?

    Thanks

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  2. #2
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    ofdma mai

    OFDMA suffers from Inter Symbol Interference if the OFDM symbol is not designed properly (less cyclic prefix length). And it also suffers from Inter Carrier Interference due to doppler shift (the carriers are no longer orthogonal)

    However, the relation you have given shows Multiple Access Interference, which I don't think is present in OFDMA since OFDMA (OFDM-FDMA) is orthogonal, so MAI does not occur. correct me if I'm mistaken


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  3. #3
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    ofdma carrier misalignment

    First, thank you for the answer, yeah actually this is the point that i am trying to know, currently i am trying to search about that (MAI in OFDMA), so far, it looks like there is no MAI effects on OFDMA but on the other hand the major interference comes from the other cells, Inter-cell interference rather than from users within the same cell and this is due to the subcarrier reuse.
    well, i am still not sure about the MAI in OFDMA, please update me if you got any information

    regards

    Added after 8 minutes:

    Hi again

    i read few papers and i found that OFDMA can be affected from MAI interference. although subcarriers are orthogonal but MAI may occure due to symbol timing misalignment because carrier frequency offset (CFO) disrupts the orthogonality between the subcarriers and gives rise to MAI among users.
    if you have additional info. please post it

    Regards



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