Multiple-input and multiple output (MIMO) is a multiple antenna scheme that exploits degrees of freedom in the spatial domain using multiple antennas at both the transmit side and the receiver side. Using precoding and post-coding techniques, MIMO systems can achieve higher multiplexing gain than single antenna systems.
There are precoding oriented or post-coding oriented approaches. While precoding oriented approach requires higher-level complex signal processing at the transmit than that at the receiver, post-coding oriented approach requires higher-level complex signal processing at the receiver.
Single User MIMO (SU-MIMO)Edit
Single user MIMO (SU-MIMO) systems exploits the spatial dimension of a one link constructed by the multiple antennas at a transmitter and the multiple antennas at a receiver.
Multiuser MIMO (MU-MIMO)Edit
Multiuser MIMO (MU-MIMO) systems can achieve higher multiplexing gain than single antenna systems within the same time, bandwidth and power limitation even when the mobile equipment has a single antenna. This advantage of the simplification on mobile equipments is come from the precoding at the transmitter based on knowledge of channel states information at the transmitter.
- Higher rate vs. high reliability
- More higher rate: voice, text, picture vs. high definition, ultra high definition
- Ultra high definition vs. high definition
- Downlink vs. uplink communications
- MU-MIMO vs. MIMO
- Interference aware vs. simple beamforming
- Zero-forcing beamforming vs. DPC precoding
- Limited feedback vs. perfect feedback
- Effective spectral efficiency (or net spectral efficiency) vs. spectral efficiency
- Maximum effective spectral efficiency and optimal feedback time
- Approximate vs. exact effective spectral efficiency
- High/low SNR approximation vs. uni-range or full range approximation
- Instantaneous vs. long-term effective spectral efficiency
- Many users (user scheduling) vs. limited users (no user scheduling or fixed user scheduling)
- Two-stage vs. one-shot user scheduling
- Expected SNR based two stage user scheduling vs. theoretical ESE based user scheduling
Cooperative MIMO (CO-MIMO)Edit
We can categorize cooperative MIMO (CO-MIMO) systems as three items: transmit side CO-MIMO, receiver side CO-MIMO and both side CO-MIMO systems.