OFDM with beamforming

I'm trying to compute the the interference that one OFDM user with beamforming causes to another user. The two systems are fully overlapped in frequency and time. I know how to generate an OFDM signal in MATLAB and compute its BER in AWGN and fading channels, I just don't know how to implement beamforming. The beamform is a circular sinc, I believe I need multiply my signal with the gain of the main lobe of the sinc function. I don't know how to calculate the interference caused on the other user. I'm not asking for anyone to provide me with a code, I'm just hoping that someone here can provide some directions on how to approach this or if there are any other resources that I can check.

• Beamforming describes the distribution of transmit power in space so I think there should at least one spatial dimension be involved. – Deve Aug 30 '13 at 7:31

1 Answer

The interference you cause to the other user is determined by:

• The total transmit power of your transmitter
• The gain of your beampattern in the direction of the other user
• The path loss to the other user
• If the other user uses receive beamforming, then also by the gain of its beampattern in the direction of the transmitter

So if you transmit with a power of 10dBm, have a gain in the users direction of -20dB and a pathloss of 60dB, the other user receives -70dBm of interference power from the transmitter. Whether or not this is bad then depends also on how powerful the useful signal of the other user is.

More information is required here for a more detailled answer.

• Thanks for the answer. The scenario I have is 3 users located within range of each other. Users 1 and 2 are communicating with each other, user 1 is the transmitter and user 2 is the receiver. These two users will cause interference to user 3, all are using the same frequency resources. Of course if user 1 is using an omnidirectional antenna, the interference caused will be high. I want to compute the interference at user 3 when user 1 is transmitting with a beamforming antenna for different angles of the beam. I'm particularly interested in evaluating the performance under different ante – user34626 Sep 5 '13 at 15:55