MIMO – (multiple input, multiple output) is an efficient transmission technology used in modern wireless communication. As the name implies, MIMO uses multiple antennas for transmission and reception. Combination of multiple transmission sources enhances higher data rate and system efficiency. Smart devices with wireless standard 802.11n support MIMO technology.
In conventional signal transmission, one antenna send signal and another antenna pick up the signal at the receiving end. In a basis MIMO system more than one transmitting antennas and single or multiple receiving antennas used for signal transmission simultaneously.
Applications of MIMO
1. MIMO in LTE, LTE advanced
MIMO technology can be used in LTE and LTE advanced radio networks for improving network efficiency. With the introduction of MIMO technology, signal disturbances due to multipath have been significantly reduced. MIMO technology make use of multipath phenomenon to maximize transmission by receiving bounced signals from obstructions.
Multipath is a phenomenon in wave propagation. Transmitted signals reflected from buildings, vehicles, trees and other terrain. These reflected signals with slight delay will cause confusion at receiver side and information couldn’t be decoded correctly.
In order to increase signal quality and gain, multiple antennas are placed in different directions without interfering the radiation pattern of each antenna. In order to implement MIMO technology, much complex signal processing is required at transmitting and receiver side.
2. MIMO in Wireless LAN
One of the common uses of MIMO technology today is wireless LAN. Wireless routers with multiples antenna become common nowadays. Data rate can be doubled or multiplied many times with effective use of MIMO technology in wireless routers and mobile devices. In order to have an efficient system, both transmitting and receiving devices must be compatible.
3. 5G and Internet of Things
5G and Internet of Things requires massive data rate. MIMO technology with Beamforming is one of the significant transmission terminologies for super charged 5G networks and IoT. Transmission tower will be equipped with multiple antennas. It will locate a particular user at a specific location and will transmit to that user using multiple antennas simultaneously.
Change in user location can be tracked and user will be handled by the antennas located at the specific direction of user. It enables network operators to offers an uninterrupted service effectively.
MIMO can be used in Internet of Things, smart home, smart cities and connected car applications.
Advantages of MIMO
- Higher data rate – with use of multiple Tx and Rx combinations.
- Time diversity – a data packet can be transmitted at different time slots.
- Frequency diversity – different frequency channels can be used for transmission.
- Reduced signal distortion due to multipath phenomenon.
- Higher accuracy.
Disadvantages of MIMO
- System requires higher level of signal processing at transmitter and receiver end.
- Implementation is costly.
More antennas contribute to more data transmission is the basic idea behind MIMO technology. In order to meet higher demands in our wireless networks, MIMO is very promising terminology. Massive MIMO is considered one of the solutions for 5G, wireless LAN and wireless WAN to support larger geographical area.