The notation used in MIMO (Multiple Input Multiple Output) technology, such as 2x2, 4x2, or 2x4, specifies the number of transmit and receive antennas involved in the communication system. The first number represents the amount of transmitting antennas, and the second number represents the amount of receiving antennas.
Each MIMO configuration offers a trade-off between data throughput, signal quality, and reliability, allowing network equipment and devices to be optimized for different scenarios and user needs.
Here's what each configuration means:
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2x2 MIMO: This configuration has 2 transmitting antennas and 2 receiving antennas. It is the most common MIMO setup in many wireless devices and networks.
- Can theoretically double the data rate compared to a single antenna system (SISO - Single Input Single Output) under ideal conditions.
- Improves reliability and signal quality through spatial diversity, reducing the impact of fading and interference.
- Widely used in LTE, Wi-Fi (such as 802.11n/ac), and 5G devices for both uplink and downlink.
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4x2 MIMO: This setup involves 4 transmitting antennas and 2 receiving antennas.
- Allows the transmitter (e.g., a base station) to send more data streams or use advanced techniques like beamforming for better coverage and throughput.
- Provides additional spatial diversity, which can help maintain a stable connection in environments with obstacles or interference.
- Commonly used in cellular networks where the base station has more antennas than the user device, optimizing downlink performance.
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2x4 MIMO: This configuration has 2 transmitting antennas and 4 receiving antennas.
- While the maximum number of parallel data streams is still limited to 2 (the lesser of transmit and receive antennas), the extra receiving antennas provide significant benefits.
- Enhances signal robustness, reception quality, and reliability, especially in challenging environments with multipath fading or interference.
- Often used in user devices or access points to improve reception and maintain higher data rates at longer distances from the transmitter.
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General Note: In MIMO notation, the format is XxY, where X is the number of transmit antennas and Y is the number of receive antennas. The maximum number of independent data streams (spatial streams) is limited by the smaller of X or Y.