A smart antenna is an adaptive antenna array consisting of multiple antennas. It uses intelligent algorithms to calculate the optimal antenna combination so that the signals transmitted by the antennas are superimposed and enhanced at the receive end. Doing so increases the signal coverage distance and improves the transmission rate. Smart antennas make optimal use of beamforming and antenna array technologies, thereby reaping better benefits.
Why Do We Need Smart Antennas?
Problems Facing Common Antennas
Wi-Fi standards have constantly evolved over time and now come to the sixth generation — Wi-Fi 6 (also know as 802.11ax). Wi-Fi 6 offers a theoretical speed of about 10 Gbit/s but hardly provides users with such an ultra-high speed in actual use. This is because in wireless communications, the Wi-Fi speed experienced by users is affected by Wi-Fi standards as well as various environmental factors such as interference and obstacles.
To improve the user-experienced Wi-Fi speed, we need to expand AP coverage ranges to improve signal quality while reducing interference between signals. Antennas — the core component of a wireless communications system — determine the beams of the transmit signals and affect AP coverage ranges. There are two antenna types by directionality: omnidirectional and directional antennas. In real-world Wi-Fi environments, directional antennas are mainly used in high-density and backhaul scenarios, and in other scenarios, omnidirectional antennas are generally adopted. With regard to today's antennas, three major difficulties need to be overcome:
Coverage at the edge: Common omnidirectional antennas have only limited gains. For this reason, they provide good services for short-distance users, but offer only low-speed services or even no services for medium- and long-distance users.
Coverage over obstacles: In real-world Wi-Fi environments, obstacles, such as planks, glass, and walls, are often unavoidable. Radio signals — when passing through such obstacles between antennas and users — attenuate to different degrees, resulting in poor user experience.
Coverage in high-density scenarios: In high-density user environments, multi-user concurrency greatly increases interference. To address this, Wi-Fi 5 and Wi-Fi 6 have introduced multi-user technologies such as multi-user multiple-input multiple-output (MU-MIMO) and orthogonal frequency division multiple access (OFDMA). Despite this, user experience near the coverage edge is not significantly improved as expected.
Advantages of Smart Antennas over Common Antennas
Smart antennas effectively improve user experience by providing better coverage at the edge, over obstacles, and in high-density environments. Compared with common antennas, smart antennas have the following advantages:
Longer coverage distance: Smart antennas improve the signal strength at the same location as before and increase the user-experienced Wi-Fi speed. As such, fewer APs are required, reducing customers' investments.
Better user experience with coverage over obstacles: The antenna combinations can be flexibly adjusted to enhance the signal strength in the obstacle direction. This in turn increases the user-experienced Wi-Fi speed despite the same attenuation as before. For obstacles that cannot be penetrated, the directions of antenna combinations can also be adjusted to bypass the obstacles by using multipath methods such as reflection and diffraction of radio signals. In this way, uncompromised services are provided for users.
Lower interference in high-density environments: The directions of signal beams can be adjusted based on user locations, reducing interference between users in different directions while improving the user-experienced Wi-Fi speed.
How Do Smart Antennas Work?
Smart antennas are implemented using beamforming and antenna array technologies. Both technologies leverage combinations of multiple antennas to improve the beams of the transmit signals, thereby improving wireless user experience. By combining the advantages of the two technologies, smart antennas achieve better benefits.
Beamforming Technology
Beamforming, also called transmit Beamforming (TxBF), is a technology that transmits signals to STAs in an energy-focused and directional fashion. It comprehensively improves the quality of signals received by STAs and increases the throughput. Beamforming has been supported since Wi-Fi 4 (802.11n). It can be implemented using multiple common antennas.
In a multi-antenna system, when signals transmitted by different antennas arrive at a location, zero-energy signals may occur if two beams have equal attenuation but opposite phases. Beamforming technology enables two beams to be superimposed with the best effect by pre-compensating the phases of transmit antennas. This approach improves the strength of signals received by STAs, thereby improving user experience.
How beamforming improves the strength of signals received by users
For more information, see smart antenna
