Method and apparatus for multiple access

1. A method for performing wireless communication by a user equipment (UE) in a first cell, the method including:

obtaining first N streams based on precoding of a transmit symbol vector obtained based on N data symbols; and

transmitting the first N streams to an access point (AP) based on first M antennas,

wherein the first N streams are received by the AP included in the first cell based on second M antennas,

wherein the precoding is performed based on a cross-channel from the UE to a second cell which is different from the first cell, and

wherein the N is equal to half of the M, and the M and the N are positive integers.

2. The method of claim 1 , wherein the precoding is performed by a precoder including four cascaded sub-precoders,

wherein a first sub-precoder and a second sub-precoder among the four cascased sub-precoders are for interference alignment, and

wherein a third sub-precoder and a fourth sub-precoder among the four cascased sub-precoders are for signal alignment.

3. The method of claim 2 , wherein the first sub-precoder inverses the cross-channel from the UE to the second cell.

4. The method of claim 2 , wherein the second sub-precoder is a reference precoder used for all devices in the first cell.

5. The method of claim 4 , wherein the second sub-precoder is in a null space of an aggregation beamformer of the second cell.

6. The method of claim 2 , wherein the third sub-precoder inverses a direct channel from the UE to the AP of the first cell.

7. The method of claim 2 , wherein the fourth sub-precoder is related to an orthogonal matrix used for all devices in the first cell.

8. The method of claim 2 , wherein the first sub-precoder inverses the cross-channel from the UE to the second cell,

wherein the second sub-precoder is a reference precoder used for all devices in the first cell,

wherein the third sub-precoder inverses a direct channel from the UE to the AP of the first cell, and

wherein the fourth sub-precoder is related to an orthogonal matrix used for all devices in the first cell.

9. The method of claim 1 , wherein second N streams are transmitted from another UE in the first cell to the AP based on third M antennas, and

wherein the first N streams from the UE and the second N streams from the another UE are transmitted to the AP simultaneously.

10. A UE in a first cell for performing wireless communication, the UE including:

at least one memory storing instructions;

at least one transceiver; and

at least one processor connected to the at least one memory and the at least one transceiver,

wherein the at least one processor is configured to:

obtain first N streams based on precoding of a transmit symbol vector obtained based on N data symbols, and

transmit the first N streams to an access point (AP) based on first M antennas,

wherein the first N streams are received by the AP included in the first cell based on second M antennas,

wherein the precoding is performed based on a cross-channel from the UE to a second cell which is different from the first cell, and

wherein the N is equal to half of the M, and the M and the N are positive integers.

11. An apparatus configured to control a first terminal in a first cell, the apparatus comprising:

at least one processor; and

at least one computer memory operably connectable to the at least one processor, and storing instructions,

wherein the at least one processor executes the instructions to cause the first terminal to:

obtain first N streams based on precoding of a transmit symbol vector obtained based on N data symbols, and

transmit the first N streams to an access point (AP) based on first M antennas,

wherein the first N streams are received by the AP included in the first cell based on second M antennas,

wherein the precoding is performed based on a cross-channel from the first terminal to a second cell which is different from the first cell, and

wherein the N is equal to half of the M, and the M and the N are positive integers.