ofdm in labview

[a.g]

hello everyone, my thesis topic is ofdm based multiple access techniques. i design an ofdm vi which is good in cascade and i also add a channel which is AWGN and a plot b/w BER and SNR is comes out. my problem is that the graph is not like exponentially decreasing form. in BER the values are nt comes in decreasing way for e.g 1st come out with value 0.501..and then 0.499.. then 0.432.. then 0.5102 and so on. these values are randomly comes out but i want that values comes in decreasing format due to which my graph may b comes out in decreaing format with respect to SNR. people its my basic structure and my thesis is based on it so plz help me wt should i do that my BER values comes out in decreasing format. is there any way to solve this problem? plz help

my emailid is anugandhi_04@yahoo.com

[derjan]

It is difficult to give a general answer here since there are no details on how you implemented this. However, constantly getting a BER of around 0.5 is usually an indicator that something in the receiver is wrong. A BER of 0.5 is equal to just guessing the bits without receiving anything. Do you get a better BER for better SNR values or does it stay around 0.5 constantly?

[ErikL]

What happens if you pull out the Tx and Rx code and test the system at baseband in simulation?

[a.g]

thanks for rply. i also checked another vi also and i found that i hv a problem with channel estimation. i didnt get hw to design channel estimation vi for my ckt. can u plz help me out with this. i read thereticaly abt it but i didnt get practicaly. so plz help me with this hw can i design channel estimation for ofdm means wt do i do wt concept going to help me. cn u tell me abt the concept of channel estimation for an ofdm?

[a.g]

BER of 0.5 is nt coming constantly. i get BER in format like 0.502, 0.4912, 0.482, 0.503 etc. there is something missing in rx side and i think that is 'channel estimation' so i need help for understanding channel estimation. is there any module and toolkit which cn help me with this? i m using RF modulation toolkit for desiging ofdm. wt do i do for channel estimation?

[HUSAM2324]

Hallo a.g.

Your insights on BER calculations caught my attention, especially as I'm currently working on a project with a similar context which will be a part of my thesis. Could you kindly share more details about how you addressed the challenge of achieving a decreasing BER graph with respect to SNR in your OFDM VI?

Thank you in advance for your consideration.