SU-MIMO = Single User MIMO
- It is the most common form of MIMO.
- Each user is served by only one BS and it occupies the resource exclusively, including
time, frequency. - It can be applied in the uplink or downlink. But it is generally applied only in DL. The UE can easily have 2 antennas in reception but only 1 antenna can transmit
The Single User MIMO is used in DL and means that the 2 TB send by the 2 antennas using the same radio resources are for the same UE.
In UL, it is not possible to use this MIMO.
There are two operation modes in SU-MIMO spatial multiplexing: The closed-loop spatial multiplexing mode
- The UE reports the CQI, the RI (Rank Indicator) and the PMI (Precoding Matrix indicator)
The open-loop spatial multiplexing mode
- The reports only the CQI and the RI.
- The RI (Rank Indicator) indicates the number of spatial layers (data streams) that can be supported by the current channel experienced at the UE.
- The PMI (Precoding Matrix Indicator) is the UE feedback.
The required UE feedback for the MIMO are:
- RI, Rank Indicator. By this one the UE can indicate if it is able to separate 2 TB. If Yes the eNodeB can use the MIMO. If not it uses the TxDiv
- PMI, Precoding Matrix indicator. It is used only for the Closed Loop MIMO. The UE indicates the eNodeB how to map the data on the 2 antennas to optimize the reception.
What is MIMO Single User in LTE?
MIMO (Multiple Input Multiple Output) Single User in LTE refers to the use of multiple antennas at both the transmitter (evolved NodeB or eNB) and the receiver (User Equipment or UE) to increase the data throughput and improve signal quality for a single user. This technology leverages spatial diversity and multiplexing to enhance communication efficiency and capacity.
How MIMO Single User Works
- Multiple Antennas: In MIMO Single User, both the eNB and the UE are equipped with multiple antennas. The eNB uses these antennas to send multiple streams of data simultaneously, which the UE can receive using its own set of antennas. This increases the total data rate without requiring additional bandwidth.
- Spatial Multiplexing: This technique allows multiple data streams to be transmitted in parallel over the same frequency band. Each stream travels along a different spatial path, effectively increasing the throughput.
- Channel State Information (CSI): The UE provides feedback on the quality of the communication channel to the eNB. Based on this information, the eNB adjusts the transmission parameters (such as power and modulation schemes) to optimize the performance of the MIMO system.
- Transmit Diversity: MIMO also improves the reliability of the signal by using diversity techniques, where multiple copies of the same data are transmitted across different antennas. This helps mitigate the effects of interference and fading.
Benefits of MIMO Single User
- Higher Data Rates: By transmitting multiple data streams simultaneously, MIMO Single User increases the overall data rate, allowing faster download and upload speeds for the user.
- Improved Coverage and Reliability: The use of multiple antennas and diversity techniques reduces the impact of signal fading and interference, leading to more stable and reliable connections, especially in challenging environments.
- Better Spectral Efficiency: MIMO Single User maximizes the use of available spectrum, enabling higher data rates without needing additional frequency resources.
Why MIMO Single User Matters
MIMO Single User is essential in LTE because it allows for significant improvements in data transmission speed and network reliability. By using multiple antennas, the network can provide high-quality services, even in areas with weak signals, and deliver higher throughput without requiring more spectrum. This technology is key to supporting bandwidth-intensive applications like video streaming and online gaming.