Smart Antennas

What is the Smart Antenna?

A smart antenna is an array of multiple antennas with tight signal processors. It can automatically adjust or adapt its beam pattern. A smart antenna often includes a switched beam system and an adaptive beam formation system. The switched beam system has several available fixed beam patterns, the access of which is decided by the system requirement. The adaptive beam formation system allows the antenna to adjust the beam to the target direction to null out interfering signals.

What is the Smart Antenna Technology?

The industry-leading smart antenna technology mainly includes antenna arrays and antenna selection algorithms. The antenna array defines the design of the antenna hardware itself, and the antenna selection algorithm refers to how to select antennas from the antenna array.

The antenna array is achieved by beam-switching technology, which intelligently selects multiple antenna elements to transmit and receive signals. Different antenna combinations form different signal radiation directions, so as to choose the optimal antenna for STA in various positions, improve signal receiving quality, and promote the system throughput. 

The Wi-Fi smart antenna selection algorithm is essential to the WLAN link adaptive feature. Through the transmitting data package, the appropriate antenna combination is selected from the antenna array according to the location of the terminals to improve network performance. Replacing the legacy omnidirectional beam with the directional beam to concentrate energy, enhance signal reception quality and improve system throughput.

Why is a Smart Antenna Necessary?

First, smart antennas address three tricky challenges faced by ordinary antennas. 

Poor Edge Coverage: Ordinary omnidirectional antennas can provide close-range users with a good Wi-Fi experience. However, it cannot meet the requirements of high-performance networks for the signal strength in long-distance AP users dropping significantly due to limited Gain, which leads to low connection speed and even disconnection issues. 

Poor Cross-obstacle coverage: In actual usage, signals will be severely attenuated when passing through obstacles such as walls and glass, decreasing signal quality. Especially in physical occlusion scenarios, it is difficult for ordinary antennas to provide stable Wi-Fi services.

Serious High-density Scenario Interference: In high user-distributed scenarios, multi-user concurrency can easily lead to signal interference, decreasing overall network performance. Even with the introduction of MU-MIMO and OFDMA technologies in modern Wi-Fi standards, it isn't easy to ultimately improve users' experience at the edge of coverage.

Second, smart antenna owns the following advantages over ordinary antenna:

Extend Coverage Distance: By flexibly adjusting beam direction, smart antennas can improve signal strength, extend coverage range and decrease AP deployment expense.

Improve Cross-obstacle Coverage Experience: Smart antennas can enhance signal strength in the direction of existing obstacles. When facing obstacles that cannot be penetrated, the antenna combination can be adjusted to bypass the barriers through multipath methods such as reflection and diffraction of wireless signals.

Reduce Interference in High-Density Scenarios: The Samart antenna can adjust signal beam directions according to the user location to lower the interference from different directions, thereby improving the user's experience.

What are the Application Scenarios for Smart Antenna?

The following manifests three typical application scenarios for a smart antenna:

Medium to Long Distance Coverage

When the AP sends data to terminals, the smart antenna algorithm will choose the most suitable directional beam according to the terminal location. The directional beam that replaced the omnidirectional beam has a high Gain, which improves the coverage capability for medium-to-long-range and edge users. 

Figure 1: Schematic diagram of the smart antenna beam selection in medium-to-long-range scenarios

Complex Wi-Fi Coverage with Obstacles

The smart antenna can enhance the AP coverage range in scenes with partitions, such as meeting rooms and tea rooms with partitions or half-height partitions. The smart antenna with a high-gain directional beam has significant advantages in scenarios where signals need to penetrate walls or floors. In scenarios with impenetrable obstacles, the smart antenna can choose other directional beams to overcome the barriers by using multipath methods such as reflection and diffraction.

Figure 2: Schematic diagram of the smart antenna beam selection in scenarios with obstacles

High-Density Scenarios with Multi-User Concurrency

In high-density scenarios, multiple users in downlink transmit concurrently. MU-MIMO can be enabled to improve data transmitting efficiency. The smart antenna uses identical directional beams for users in the same direction, which can enhance the terminal signal receiving strength and decrease the interference among terminal data in different directions.

Figure 3: Schematic diagram of the smart antenna beam selection in the high-density scenario where multiple users in downlink transmit concurrently