Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

OFDMA question - does it suffer from Interference

Status
Not open for further replies.

nidhalodeh

Member level 2
Joined
Jun 20, 2006
Messages
43
Helped
7
Reputation
14
Reaction score
5
Trophy points
1,288
Activity points
1,511
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
 

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
 

    nidhalodeh

    Points: 2
    Helpful Answer Positive Rating
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
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top