BER and FER calculation

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  • #10325
    liow
    Participant

    Hi,
    I am trying to do comparison study across different waveform. Example, comparing A (OFDM) and B (f-OFDM). i set up 2 BS and each BS only have 1 UE. I also set the scStr.topology.attenuation to a very large value, example 100 or 1000.

    The second simulation i am try to do is do a control experiment to ensure my setting are correct, i am comparing OFDM to OFDM. Again is 2 BS and each BS only have 1 UE. both are set to identical parameters (same sub carriers, same carrier spacing and etc). i notice the BER always have a differences at different SNR. Example i have a different of 4×10^-3 and 8×10^-3 at SNR 38dB. May i know is this normal or i miss out some setting? Should this should we get a identical result for both user? (since same setting is applied to 2 BS)

    Thanks

    #10326

    Hi,

    interesting, thank you for your comment! I have some further questions regarding your issue.

    How many frames did you use for this simulation and how big are the confidence intervals at this point at 38dB SNR?
    Did you employ a fixed CQI (MCS) or did you use feedback?
    Is the schedule of the users the same, i.e., are they scheduled the same amount of subcarriers?

    best
    Stefan

    #10331
    liow
    Participant

    Hi Stefan,

    I am using fixed CQI (scStr.modulation.mcs= [8, 8]; ).

    Same # of sub carrier for each UE.
    scStr.schedule.fixedSchedule{1} = [ ‘UE1:60,none:12’];
    scStr.schedule.fixedSchedule{2} = [ ‘none:12,UE2:60’ ];

    #10335

    Hi,

    since the BER value is quite low at 38dB SNR, I recommend to try a simulation of this point (only one SNR point to save time) with a high number of frames, e.g., 2000 or even 5000. The values for the two users should be in the same order and the confidence intervals should get quite small.

    best
    Stefan

    #10338
    liow
    Participant

    Hi Stefan,

    After change frame to 5000, result look good.
    Two UEs that belong to two different BS with same parameters setting, plot results is almost overlap each other.

    By the way,
    1.where can we set the parameters where selective SNR or range of desired SNR for simulation.

    2.The frame, is the actual number of frame send or just a iteration for simulation purpose? 5000 is the frame size?

    #10485

    Hi,

    1. typically the SNR is determined by the pathloss over which is normally swept. Alternatively you may change the transmit power.

    2. Yes, the nFrames is the actual number of frames (or subframes as called in LTE-A) that are simulated.

    best
    Stefan

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