What I understand in MIMO system, the user data is broken down into several chunks and transmitted over the antennas (say 3 Tx antennas) by using same frequency Fc. In order to use the interference as an advantage in this case.

enter image description here

And what I know of OFDM, the large BW is divided into several smaller ones, with each having a specific frequency. For example, 2.4GHz BW is divided into 14 channels, each channel has a different central frequency (say the 6th channel has a frequency of 2.437 MHz).

Now the question is while we combine this 2 method of MIMO-OFDM for transmission, does that transmit in same frequency from each antenna? Or at different frequencies?


1 Answer 1


For a given subcarrier, QAM symbols are transmitted on several antennas (MIMO). And an antenna can transmit several subcarriers (OFDM). One can imagine that QAM symbols are modulated on a 3-dimensional grid frequency-space-time.

  • $\begingroup$ Still a bit confused. Can you provide an analogy for better understanding please. $\endgroup$
    – Nusrat
    Commented Feb 18, 2018 at 19:06
  • $\begingroup$ Lets clarify what make you confused. What do you mean in saying "same frequency" ? $\endgroup$
    – AlexTP
    Commented Feb 19, 2018 at 3:52
  • $\begingroup$ Let's take the example of the commercial routers in our home. Mine has 3 antennas, working at 2.4GHz radio (802.11n--> MIMO-OFDM) in channel 6 (2.437MHz). So what would be the frequency of each antenna as it is transmitting from? As from the concept of MIMO, it should be only 1 frequency (2.437 MHz), but I am confused as it is also under OFDM which has different sub-carrier frequencies. $\endgroup$
    – Nusrat
    Commented Feb 19, 2018 at 19:16
  • $\begingroup$ It is true that 2.437MHz is only 1 frequency but channel 6 at 2.437MHz means a channel of 22MHz-bandwidth with center frequency 2.437MHz. Again, what do you mean in saying "same frequency" ? In clarifying what you wanna ask, you may answer your question by yourself. $\endgroup$
    – AlexTP
    Commented Feb 20, 2018 at 4:47

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.