- More complex than SISO.
- 2 or more transmitters and one receiver.
- MISO is more commonly referred to as transmit diversity.
- The same data is sent on both transmitting antennas but coded in such a way that
the receiver can identify each transmitter.
- Transmit diversity increases the robustness of the signal to fading and can increase
performance in low Signal-to-Noise Ratio (SNR) conditions. - It does not increase data rates as such, but rather supports the same data rates using
less power.
When the eNodeB uses 2 antennas in DL to transmit twice the same data, it is the diversity in transmission, also called the TxDiv. It improve the quality and the coverage at the cell edge. Receive Diversity SIMO = Single Input Multiple Output Principle
- It uses one transmitter and 2 or more receivers.
- It is often referred to as receive diversity.
Benefits
- It is particularly well suited for low SNR conditions in which a theoretical gain of 3 dB
- is possible when two receivers are used.
- No change in the data rate since only one data stream is transmitted, but coverage
- at the cell edge is improved due to the lowering of the usable SNR.
What is Transmit Diversity & Receive Diversity in LTE?
Transmit Diversity and Receive Diversity are techniques used in LTE to improve signal reliability and enhance data transmission performance. These techniques make use of multiple antennas at either the transmitter (evolved NodeB or eNB) or receiver (User Equipment or UE) to reduce the effects of signal fading, interference, and multipath propagation.
Transmit Diversity
Transmit Diversity involves using multiple antennas at the transmitter (eNB) to send the same signal over different spatial channels. This increases the chances of the signal being received correctly by the receiver (UE) even if one of the paths is affected by fading or interference.
- How it Works: The same data is transmitted over multiple antennas, each carrying the same signal but at slightly different phases. The UE receives these signals and combines them to improve signal quality and reliability.
- Benefits: Transmit Diversity improves the signal’s resistance to fading, ensuring that even in challenging radio conditions, the signal is received with better quality and fewer errors.
Receive Diversity
Receive Diversity, on the other hand, uses multiple antennas at the receiver (UE) to receive the same signal from the transmitter (eNB) via different spatial paths. This helps in improving the signal quality by allowing the UE to select the best received signal, based on factors such as signal strength and quality.
- How it Works: The UE uses multiple antennas to receive the same signal from different paths. The receiver then selects the best path or combines signals from different antennas to maximize the received signal quality.
- Benefits: Receive Diversity reduces the impact of interference and fading at the receiver, improving the chances of successful signal reception and reducing errors, especially in areas with poor coverage or high interference.
Benefits of Transmit & Receive Diversity
- Improved Signal Quality: Both techniques reduce signal degradation caused by fading and interference, ensuring better quality communication.
- Higher Reliability: These techniques increase the reliability of data transmission, reducing the likelihood of transmission errors or dropped connections.
- Better Coverage: Transmit and Receive Diversity help extend coverage areas, allowing users to stay connected even in challenging environments or at the edge of the network.
- Enhanced Data Throughput: By improving signal quality, these techniques enable higher data rates and improved user experience, particularly in high-speed applications.
Why Transmit & Receive Diversity Matter
Transmit and Receive Diversity are fundamental in LTE to ensure robust, high-quality communication. By utilizing multiple antennas, these techniques effectively combat issues like fading and interference, leading to better signal reception, higher reliability, and improved data rates. This is especially important in maintaining strong connections for users, even in dense or remote areas with challenging radio conditions.