What is WIFI MIMO technology? How does it bring benefits? Is it truly the most promising candidate in high-speed data transmission?

WIFI MIMO technology is widely used with potentials to optimize data speed and improve WIFI transmission capabilities, making your electronic devices such as smartphones, tablets, or laptops smoother to use. So, what is WIFI MIMO technology? What are its benefits and applications in daily life? Let's find out the answers in today's article!

The article is referenced from technology-specialized websites: SSLA, TechTarget, ElectronicsNotes and RFwireless.

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1. What is WIFI MIMO technology? 

MIMO stands for Multiple-Input Multiple-Output, a wireless technology that increases the data capacity of the radio frequency by using multiple antennas to transmit and receive signals.

MIMO technology was first discovered in the mid-1970s. It wasn't until 1993 that Arogyaswami Paulraj and Thomas Kailath propelled MIMO forward with Spatial Multiplexing method, receiving a patent in 1994 from the United States, once again emphasizing the application of wireless broadcasting.

In 1996, Greg Raleigh and Gerard J. Foschini further refined new approaches to MIMO technology, specifically considering configurations where multiple antennas would be placed on the same transmitter to improve link throughput. However, Bell Labs was the first to apply Spatial Multiplexing in a laboratory setting in 1998 and demonstrated that Spatial Multiplexing is the key technique to enhance the performance of MIMO technology.

Basic configurations of MIMO technology:

- 2x2 MIMO (two transmitting antennas, two receiving antennas).

- 3x3 MIMO (three transmitting antennas, three receiving antennas).

- 4x4 MIMO (four transmitting antennas, four receiving antennas).

- 8x8 MIMO (eight transmitting antennas, eight receiving antennas).

2. How MIMO Technology Works

Previous Wifi technologies like SISO on a router only utilize one antenna on the router to connect with the single antenna on the receiving device. Wi-Fi signals transmit and receive data packets through antennas.

In a MIMO system, signals are transmitted through multiple antennas on the same path and bandwidth. Therefore, each signal received by the receiving antenna will go through a different path, making the data more reliable. The signal speed also increases due to the number of transmitting and receiving antennas. MIMO technology allows the use of more antennas on both devices to increase signal stability and transmission speed, overcoming the limitations of obstacles that previous wifi technologies faced.

MIMO relies on three basic methods: Beamforming, Spatial Multiplexing, and Space-time coding. These methods are used individually or combined to achieve efficiency such as lower transmit power, larger range, better noise immunity, or higher bandwidth.

• Spatial Multiplexing

In this method, high-speed signals are divided into lower-speed signals (streams), and each stream is transmitted from a different antenna operating at the same center frequency. The number of receiving antennas must be equal to or greater than the number of transmitting antennas to accurately decode each transmitted stream.

• Space-time coding

This is a mechanism that allows multiple copies of data to be transmitted through multiple antennas. Furthermore, this method helps improve the reliability of data transmission with similar benefits achievable when using multi-antenna reception. In Space-time coding, the signal (data) is transformed into different versions of the same information and transmitted through multiple antennas.

Then, the receiver combines all the copies of the received signal (data) through different antennas in an optimal way to extract as much information as possible from each antenna. Space-time coding also enhances the receiver's ability to prevent signal interference. This method utilizes both spatial and temporal diversity to achieve significant improvement. Additionally, using multiple copies of the signal compensates for channel issues such as fading and white noise.

• Beamforming

It is a method that creates a specific forced antenna pattern at the transmitter with appropriate phase and gain weights, so that the signal power at the receiver is maximized. Beamforming is achieved through intelligent antennas that can be divided into phased array systems or adaptive systems.

3. Benefits and Limitations of MIMO Technology

• Benefits

The waiting time for data reception of each device is reduced to the minimum level. Additionally, Wifi MIMO allows continuous data transmission, sending data to multiple connected devices simultaneously. Enhancing user experience to a new level like watching movies on a laptop while browsing the web on a phone.

MIMO technology helps minimize fading effects, reducing the bit error rate (BER). MIMO algorithms transmit signals outward through two or more antennas, and information is also received through multiple antennas. Additionally, MIMO provides more accurate power levels compared to conventional single-antenna RF systems, along with improved reliability in transmission.

• Limitations:

The main disadvantage of this technology lies in its complexity. Resource requirements and hardware complexity are higher compared to single-antenna based systems. Each antenna requires separate RF units to process radio signals. Moreover, advanced DSP (digital signal processor) chips are necessary to run sophisticated mathematical signal processing algorithms.

Additionally, hardware resources increase power requirements. Specifically, batteries will deplete faster due to processing complex and deep signal algorithms. This reduces the lifespan of MIMO-based devices. On the other hand, MIMO-based systems are more expensive than single-antenna systems due to increased hardware and software requirements.

4. Comparing SU-MIMO and MU-MIMO

MIMO technology comprises two main types: SU-MIMO and MU-MIMO. In SU-MIMO systems, data streams can only interact with one device on the network at a time. Therefore, MU-MIMO systems outperform SU-MIMO. SU stands for Single User, referring to one user, introduced in 2007 with the Wifi 802.11n standard allowing increased Wifi speeds by enabling two wireless devices to transmit and receive data simultaneously. This technology enables a router to send and receive data to one device at the same time.

MU stands for Multiple User, the next generation of SU-MIMO introduced in 2015 to address the shortcomings of SU-MIMO. With the Wifi 802.11ac standard, MU-MIMO allows Wifi routers to interact with multiple devices simultaneously, minimizing the waiting time for each device, reducing signal wait time, and increasing network speed.

Issues arise with SU-MIMO when multiple users attempt to use the network simultaneously. If one person is uploading a video and another is participating in a conference, data streams will be congested, causing latency or skyrocketing delays. MU-MIMO was developed to address the drawbacks of SU-MIMO, as MU-MIMO has the advantage of streaming multiple data sets to multiple devices simultaneously.

5. Future and Applications of MIMO Technology

MIMO technology is utilized for Wi-Fi networks and long-term evolution (LTE) technology, specifically in fourth-generation (4G) and fifth-generation (5G) wireless communication technologies, including various markets such as politics, society, and entertainment. It is also employed in wireless local area networks (WLANs) and supported by all wireless products with 802.11n.

This technology is deployed in various forms across most wireless communication devices and is increasingly exerting its influence with practical applications such as digital television (DTV), wireless local area networks (WLANs), mobile communications, and home networks...

Conclusion

MIMO technology is gradually becoming a primary tool for enhancing all aspects of wireless communication. It plays a crucial role in 5G technology and is shaping how users interact with these technologies on a daily basis. What are your thoughts on WIFI MIMO technology? Will MIMO lead wireless technology in the future? Feel free to share your thoughts below!

Sources: SSLA, TechTarget, ElectronicsNotes, and RFwireless.

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