Method and apparatus for transmitting and receiving signal in frequency-asynchronous non-orthogonal multiple access system

A method for receiving a signal by a first user equipment (UE) in a frequency-asynchronous non-orthogonal multiple access (FA-NOMA) system, the method comprising:

• receiving a signal including at least one pilot from a base station;
• estimating a channel based on the at least one pilot;
• demodulating a second signal transmitted to a second UE based on the received signal;
• obtaining a first signal transmitted to the first UE by removing the demodulated second signal from the received signal;
• generating a frequency offset compensated signal by performing frequency offset compensation on the first signal;
• generating a post-processed signal by performing post-processing on the frequency offset compensated signal using at least one post-processing factor;
• and
• obtaining a demodulated signal by demodulating the post-processed signal,
• wherein the at least one post-processing factor is determined based on at least one pre-processing factor received from the base station.

A base station in a frequency-asynchronous non-orthogonal multiple access (FA-NOMA) system, the base station comprising:

• a transceiver;
• and
• at least one processor configured to:
• determine a frequency offset to be applied to a first signal transmitted to a first user equipment (UE) based on a second signal transmitted to a second UE,
• determine information for interference caused by the frequency offset, determine at least one pre-processing factor for the first UE based on the information for the interference, and
• control the transceiver to transmit a third signal including at least one first pilot to the first UE using the at least one pre-processing factor,
• wherein the second signal includes at least one second pilot.

A first user equipment (UE) in a frequency-asynchronous non-orthogonal multiple access (FA-NOMA) system, the first UE comprising:

• a transceiver;
• and
• at least one processor configured to:
• control the transceiver to receive a signal including at least one pilot from a base station,
• estimate a channel based on the at least one pilot,
• demodulate a second signal transmitted to a second UE based on the received signal,
• obtain a first signal transmitted to the first UE by removing the demodulated second signal from the received signal,
• generating a frequency offset compensated signal by performing frequency offset compensation on the first signal,
• generating a post-processed signal by performing post-processing on the frequency offset compensated signal using at least one post-processing factor, and
• obtain a demodulated signal by demodulating the post-processed signal,
• wherein the at least one post-processing factor is determined based on at least one pre-processing factor received from the base station.