aeronautic
Newbie level 2
Would you please help to clarify whether the following statement about MIMO is right? If it is wrong, please give some comments how to implement the same motivation?
1. If we assume each device is equipped with number of n antennas. For a two-user MIMO uplink case, device A and B are two transmitters and device C is a corresponding receiver, the number of total transmit antennas is 2n while the number of receiver antenna is n. The degree of freedom is min {2n, n}. Actually, total number of n transmitter antennas is enough to achieve the same degree of freedom. For example, device A and B just use half of antennas to communicate with device C.
If device A uses remainder antennas to receive streams from a device D by a point-to-point MIMO link at same time and frequency dimensions, what will happen? At device A, the output signals from the former antennas (employed by uplink transmission) interferes the input signals to its remainder antennas.
I think that the interference signal and the point-to-point signal can be separated by device A because it knows the output signal of those former antennas. In other words, the output signal of the former antennas do not interfere the input signal to the remainder antennas.
2. If there may exists multiple pairs of point-to-point MIMO communications, we must consider the co-channel interference. How a transmitter can null its signal at undesired nearby receivers while ensuring acceptable signal gains at a desired receiver? What is the possible constraint?
3. If there may exists multiple pairs of point-to-point MIMO communications, we must consider the co-channel interference. If a receiver want to suppress the interference caused by all nearby transmitters before receiving desired signals, how to implement it? What is the possible constraint?
1. If we assume each device is equipped with number of n antennas. For a two-user MIMO uplink case, device A and B are two transmitters and device C is a corresponding receiver, the number of total transmit antennas is 2n while the number of receiver antenna is n. The degree of freedom is min {2n, n}. Actually, total number of n transmitter antennas is enough to achieve the same degree of freedom. For example, device A and B just use half of antennas to communicate with device C.
If device A uses remainder antennas to receive streams from a device D by a point-to-point MIMO link at same time and frequency dimensions, what will happen? At device A, the output signals from the former antennas (employed by uplink transmission) interferes the input signals to its remainder antennas.
I think that the interference signal and the point-to-point signal can be separated by device A because it knows the output signal of those former antennas. In other words, the output signal of the former antennas do not interfere the input signal to the remainder antennas.
2. If there may exists multiple pairs of point-to-point MIMO communications, we must consider the co-channel interference. How a transmitter can null its signal at undesired nearby receivers while ensuring acceptable signal gains at a desired receiver? What is the possible constraint?
3. If there may exists multiple pairs of point-to-point MIMO communications, we must consider the co-channel interference. If a receiver want to suppress the interference caused by all nearby transmitters before receiving desired signals, how to implement it? What is the possible constraint?
