TECHNICAL SUPPORT

Terminology explained: MIMO technology

Time of issue:

2019-01-29 14:59

Origin：

The so-called MIMO, as it literally means, is the abbreviation of Multiple Input Multiple Output. Most of the statements you see refer to the simultaneous transmission and reception of wireless network signals through multiple antennas, so data can be increased. transfer rate. However, a more correct explanation should be to say that after the network data is cut through multiple times, it is transmitted synchronously through multiple antennas. Since the wireless signal will take different reflection or penetration paths in order to avoid interference during the transmission process, so The time to reach the receiver will be inconsistent. In order to avoid data inconsistency and cannot be recombined, the receiver will have multiple antennas to receive at the same time, and then use the DSP recalculation method to recombine the separated data according to the factor of time difference, and then transmit the correct and fast data stream.

The so-called MIMO, as it literally means, is the abbreviation of Multiple Input Multiple Output. Most of the statements you see refer to the simultaneous transmission and reception of wireless network signals through multiple antennas, so data can be increased. transfer rate. However, a more correct explanation should be to say that after the network data is cut through multiple times, it is transmitted synchronously through multiple antennas. Since the wireless signal will take different reflection or penetration paths in order to avoid interference during the transmission process, so The time to reach the receiver will be inconsistent. In order to avoid data inconsistency and cannot be recombined, the receiver will have multiple antennas to receive at the same time, and then use the DSP recalculation method to recombine the separated data according to the factor of time difference, and then transmit the correct and fast data stream.

Since the transmitted data is divided and transmitted, not only the single data flow is reduced, the transmission distance can be increased, and the antenna receiving range can be increased. Therefore, the MIMO technology can not only increase the data transmission speed of the existing wireless network spectrum, but also does not need to occupy additional spectrum range. More importantly, it can also increase the signal receiving distance. Therefore, many wireless network devices that emphasize data transmission speed and transmission distance have begun to abandon the compatibility requirements of the existing Wi-Fi Alliance, and use MIMO technology to launch wireless network products with high transmission rates.

MIMO technology can be simply considered as Multiple Input Multiple Output (MIMO: Multiple Input Multiple Output) technology, which is a multi-antenna communication system proposed by Bell Labs in the United States at the end of the last century. antenna) and multi-channel. So most of the MIMO products we see today have more than one antenna. (pictured above). The concept of MIMO wireless communication technology is that in any wireless communication system, as long as multiple antennas or antenna arrays are used at the transmitter and receiver, a wireless MIMO system is formed. MIMO wireless communication technology uses space-time processing technology for signal processing. In multipath environment, wireless MIMO system can greatly improve spectrum utilization and increase the data transmission rate of the system. MIMO technology is very suitable for use in wireless local area network systems in indoor environments. The spectral efficiency of the wireless local area network system using MIMO technology can reach 20 to 40 bps/Hz in indoor environment; while the spectral efficiency of traditional wireless communication technology in mobile cellular is only 1 to 5 bps/Hz, and the point-to-point fixed microwave There are only 10 to 12bps/Hz in the system.

 

The term "MIMO" generally refers to any system that has multiple inputs at the transmitter and multiple outputs at the receiver. Although a MIMO system may include wired devices, the overall system is usually a wireless system, such as a multiple antenna system, a Code Division Multiple Access (CDMA) system used in 3G mobile phone systems (wireless systems), or even a system using multiple telephones A DSL system (cable system) for crosstalk. MIMO is not a single concept, but consists of multiple radio frequency technologies, so we must fully understand the operation and performance of MIMO. When applied to WLAN, some MIMO technologies are compatible with current WLAN standards (such as 802.11a, 802.11b, and 802.11g), thus extending their transmission range; on the contrary, some MIMO technologies can only be used with general WLAN standards Incompatible MIMO devices.

MIMO Features

 

Send and receive at the same time through multiple antennas to increase the coverage of the wireless network base station.

 

Using multi-path design to reduce the number of base stations,

 

It can not only increase the data transmission rate, but also increase the number of wireless network client services

Previous：

Advantages of ZigBee's Direct Sequence Spread Spectrum Communication

Next：

Terminology Explanation: 802.11n