What Is Beamforming Technology On A Wi-Fi Router

For speech audio

Beamforming can be used to try to extract sound sources in a room, such as multiple speakers in the . This requires the locations of the speakers to be known in advance, for example by using the from the sources to mics in the array, and inferring the locations from the distances.

Compared to telecommunications, natural audio contains a variety of frequencies. It is advantageous to separate frequency bands prior to beamforming because different frequencies have different optimal beamform filters (and hence can be treated as separate problems, in parallel, and then recombined afterward). Properly isolating these bands involves specialized non-standard . In contrast, for example, the standard (FFT) band-filters implicitly assume that the only frequencies present in the signal are exact ; frequencies which lie between these harmonics will typically activate all of the FFT channels (which is not what is wanted in a beamform analysis). Instead, filters can be designed in which only local frequencies are detected by each channel (while retaining the recombination property to be able to reconstruct the original signal), and these are typically non-orthogonal unlike the FFT basis.

Schemes

  • A conventional beamformer can be a simple beamformer also known as delay-and-sum beamformer. All the weights of the antenna elements can have equal magnitudes. The beamformer is steered to a specified direction only by selecting appropriate phases for each antenna. If the noise is uncorrelated and there are no directional interferences, the of a beamformer with L{\displaystyle L} antennas receiving a signal of power P{\displaystyle P}, (where σn2{\displaystyle \sigma _{n}^{2}} is Noise variance or Noise power), is: 1σn2P⋅L{\displaystyle {\frac {1}{\sigma _{n}^{2}}}P\cdot L}
  • Frequency domain beamformer

Techniques

To change the directionality of the array when transmitting, a beamformer controls the phase and relative amplitude of the signal at each transmitter, in order to create a pattern of constructive and destructive interference in the wavefront. When receiving, information from different sensors is combined in a way where the expected pattern of radiation is preferentially observed.

For example, in sonar, to send a sharp pulse of underwater sound towards a ship in the distance, simply simultaneously transmitting that sharp pulse from every sonar projector in an array fails because the ship will first hear the pulse from the speaker that happens to be nearest the ship, then later pulses from speakers that happen to be further from the ship. The beamforming technique involves sending the pulse from each projector at slightly different times (the projector closest to the ship last), so that every pulse hits the ship at exactly the same time, producing the effect of a single strong pulse from a single powerful projector. The same technique can be carried out in air using loudspeakers, or in radar/radio using antennas.

In passive sonar, and in reception in active sonar, the beamforming technique involves combining delayed signals from each hydrophone at slightly different times (the hydrophone closest to the target will be combined after the longest delay), so that every signal reaches the output at exactly the same time, making one loud signal, as if the signal came from a single, very sensitive hydrophone. Receive beamforming can also be used with microphones or radar antennas.

With narrow-band systems the time delay is equivalent to a «phase shift», so in this case the array of antennas, each one shifted a slightly different amount, is called a phased array. A narrow band system, typical of radars, is one where the bandwidth is only a small fraction of the center frequency. With wide band systems this approximation no longer holds, which is typical in sonars.

In the receive beamformer the signal from each antenna may be amplified by a different «weight.» Different weighting patterns (e.g., ) can be used to achieve the desired sensitivity patterns. A main lobe is produced together with nulls and sidelobes. As well as controlling the main lobe width (beamwidth) and the sidelobe levels, the position of a null can be controlled. This is useful to ignore noise or jammers in one particular direction, while listening for events in other directions. A similar result can be obtained on transmission.

For the full mathematics on directing beams using amplitude and phase shifts, see the mathematical section in phased array.

Beamforming techniques can be broadly divided into two categories:

  • conventional (fixed or
    switched beam) beamformers
  • adaptive beamformers or phased array
    • Desired signal maximization mode
    • Interference signal minimization or cancellation mode

Conventional beamformers, such as the Butler matrix, use a fixed set of weightings and time-delays (or phasings) to combine the signals from the sensors in the array, primarily using only information about the location of the sensors in space and the wave directions of interest. In contrast, adaptive beamforming techniques (e.g., MUSIC, SAMV) generally combine this information with properties of the signals actually received by the array, typically to improve rejection of unwanted signals from other directions. This process may be carried out in either the time or the frequency domain.

As the name indicates, an adaptive beamformer is able to automatically adapt its response to different situations. Some criterion has to be set up to allow the adaptation to proceed such as minimizing the total noise output. Because of the variation of noise with frequency, in wide band systems it may be desirable to carry out the process in the frequency domain.

Beamforming can be computationally intensive. Sonar phased array has a data rate low enough that it can be processed in real-time in software, which is flexible enough to transmit or receive in several directions at once. In contrast, radar phased array has a data rate so high that it usually requires dedicated hardware processing, which is hard-wired to transmit or receive in only one direction at a time. However, newer field programmable gate arrays are fast enough to handle radar data in real-time, and can be quickly re-programmed like software, blurring the hardware/software distinction.

History in wireless communication standards

Beamforming techniques used in have advanced through the generations to make use of more complex systems to achieve higher density cells, with higher throughput.

  • Passive mode: (almost) non-standardized solutions
  • Active mode: mandatory standardized solutions
    • — Transmit antenna selection as an elementary beamforming
    • — WCDMA: Transmit antenna array (TxAA) beamforming
    • — LTE/UMB: (MIMO) based beamforming with partial (SDMA)
    • Beyond 3G (4G, 5G, …) — More advanced beamforming solutions to support (SDMA) such as closed loop beamforming and multi-dimensional beamforming are expected

An increasing number of consumer Wi-Fi devices with MIMO capability can support beamforming to boost data communication rates.

Analogue and digital antenna beam forming

As with may areas of electronics and with digital techniques extending further into all areas, it is hardly surprising to see that there are two methods of implementing antenna beam-forming:

  • Analogue antenna beam forming:   The analogue method of beam forming is probably the most intuitive. Using the analogue approach, a single data stream is handled by a set of data converters and an RF transceiver. The RF output is split into as many paths as there are antenna elements, and each of these signal paths is passed through a phase shifter, it is then amplified and passed to the individual array element.
    Analogue antenna beam forming in the RF path is the last complicated and it also uses a minimal amount of hardware, making it the most cost-effective way to build a beam-forming array. The main drawback is that the system can only handle one data stream and generate one signal beam. This limits its effectiveness in terms of the requirements for applications such as 5G where multiple beams are required.
  • Digital antenna beam forming:   Using digital antenna beam forming, each antenna has its own transceiver and data converters. It can handle multiple data streams and generate multiple beams simultaneously from one array. Antenna beam-forming with two beams as used with mobile or cellular telecommunications
    Using digital antenna beam forming, it is possible to generate several sets of signals and superimpose them onto the antenna array elements. In this way it enables a single antenna array to serve multiple beams, and hence multiple users in a scenario like 5G. This normally occurs on the same frequency channel, thereby enabling the optimum spectrum efficiency.
    The approach using digital beam forming requires more hardware and puts a greater burden on the signal processing in the digital domain than the analog approach, but enables much greater flexibility and capability.

Antenna beam forming and antenna beamsteering are two powerful antenna techniques that, even though complicated to implement are providing significant benefits.

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Sonar beamforming requirements

beamforming utilizes a similar technique to electromagnetic beamforming, but varies considerably in implementation details. Sonar applications vary from 1 Hz to as high as 2 MHz, and array elements may be few and large, or number in the hundreds yet very small. This will shift sonar beamforming design efforts significantly between demands of such system components as the «front end» (transducers, pre-amplifiers and digitizers) and the actual beamformer computational hardware downstream. High frequency, focused beam, multi-element imaging-search sonars and acoustic cameras often implement fifth-order spatial processing that places strains equivalent to Aegis radar demands on the processors.

Many sonar systems, such as on torpedoes, are made up of arrays of up to 100 elements that must accomplish over a 100 degree field of view and work in both active and passive modes.

Sonar arrays are used both actively and passively in 1-, 2-, and 3-dimensional arrays.

  • 1-dimensional «line» arrays are usually in multi-element passive systems towed behind ships and in single- or multi-element .
  • 2-dimensional «planar» arrays are common in active/passive ship hull mounted sonars and some side-scan sonar.
  • 3-dimensional spherical and cylindrical arrays are used in ‘sonar domes’ in the modern and ships.

Sonar differs from radar in that in some applications such as wide-area-search all directions often need to be listened to, and in some applications broadcast to, simultaneously. Thus a multibeam system is needed. In a narrowband sonar receiver the phases for each beam can be manipulated entirely by signal processing software, as compared to present radar systems that use hardware to ‘listen’ in a single direction at a time.

Sonar also uses beamforming to compensate for the significant problem of the slower propagation speed of sound as compared to that of electromagnetic radiation. In side-look-sonars, the speed of the towing system or vehicle carrying the sonar is moving at sufficient speed to move the sonar out of the field of the returning sound «ping». In addition to focusing algorithms intended to improve reception, many side scan sonars also employ beam steering to look forward and backward to «catch» incoming pulses that would have been missed by a single sidelooking beam.

Techniques

To change the directionality of the array when transmitting, a beamformer controls the and relative of the signal at each transmitter, in order to create a pattern of constructive and destructive interference in the wavefront. When receiving, information from different sensors is combined in a way where the expected pattern of radiation is preferentially observed.

For example, in , to send a sharp pulse of underwater sound towards a ship in the distance, simply simultaneously transmitting that sharp pulse from every in an array fails because the ship will first hear the pulse from the speaker that happens to be nearest the ship, then later pulses from speakers that happen to be further from the ship. The beamforming technique involves sending the pulse from each projector at slightly different times (the projector closest to the ship last), so that every pulse hits the ship at exactly the same time, producing the effect of a single strong pulse from a single powerful projector. The same technique can be carried out in air using , or in radar/radio using .

In passive sonar, and in reception in active sonar, the beamforming technique involves combining delayed signals from each at slightly different times (the hydrophone closest to the target will be combined after the longest delay), so that every signal reaches the output at exactly the same time, making one loud signal, as if the signal came from a single, very sensitive hydrophone. Receive beamforming can also be used with microphones or radar antennas.

With narrow-band systems the time delay is equivalent to a «phase shift», so in this case the array of antennas, each one shifted a slightly different amount, is called a . A narrow band system, typical of , is one where the is only a small fraction of the center frequency. With wide band systems this approximation no longer holds, which is typical in sonars.

In the receive beamformer the signal from each antenna may be amplified by a different «weight.» Different weighting patterns (e.g., ) can be used to achieve the desired sensitivity patterns. A main lobe is produced together with nulls and sidelobes. As well as controlling the main lobe width () and the sidelobe levels, the position of a null can be controlled. This is useful to ignore noise or in one particular direction, while listening for events in other directions. A similar result can be obtained on transmission.

For the full mathematics on directing beams using amplitude and phase shifts, see the mathematical section in .

Beamforming techniques can be broadly divided into two categories:

  • conventional (fixed or switched beam) beamformers
  • adaptive beamformers or
    • Desired signal maximization mode
    • Interference signal minimization or cancellation mode

Conventional beamformers, such as the , use a fixed set of weightings and time-delays (or phasings) to combine the signals from the sensors in the array, primarily using only information about the location of the sensors in space and the wave directions of interest. In contrast, adaptive beamforming techniques (e.g., , ) generally combine this information with properties of the signals actually received by the array, typically to improve rejection of unwanted signals from other directions. This process may be carried out in either the time or the frequency domain.

As the name indicates, an is able to automatically adapt its response to different situations. Some criterion has to be set up to allow the adaptation to proceed such as minimizing the total noise output. Because of the variation of noise with frequency, in wide band systems it may be desirable to carry out the process in the .

Beamforming can be computationally intensive. Sonar phased array has a data rate low enough that it can be processed in real-time in , which is flexible enough to transmit or receive in several directions at once. In contrast, radar phased array has a data rate so high that it usually requires dedicated hardware processing, which is hard-wired to transmit or receive in only one direction at a time. However, newer are fast enough to handle radar data in real-time, and can be quickly re-programmed like software, blurring the hardware/software distinction.

Beamforming techniques for wireless communications, radar, sonar, medical imaging, and audio array systems

Beamforming is a key technique that is used to improve the signal-to-noise ratio of received signals, eliminate undesirable interference sources, and focus transmitted signals on a specific location. Beamforming is at the heart of modern wireless communications systems such as 5G, LTE and WLAN, and is used in sensor arrays in radar, sonar, medical imaging, and audio systems.

Developing a beamformer and evaluating algorithm alternatives is only the first step toward achieving the required performance of a wireless communications or radar system. To assess performance, the beamformer must be integrated into a system-level model and evaluated over a collection of parameter, steering, and channel combinations. Another challenge involves system-level tradeoffs between performing beamforming in the radio frequency (RF) and/or digital baseband domain. All of these activities are best done early in the design process.

Modeling beamforming algorithms in the context of an entire system including RF, antenna, and signal processing components can address these challenges. MATLAB and Simulink provide a full set of modeling and simulation tools and algorithms needed to design, test, and integrate beamformers, and to perform full system-level analysis.

Integrate Antenna and RF Models

  • Design of Cutting Edge Antennas and Antenna Arrays using MATLAB (36:12) — Video
  • WLAN 802.11ad Simulation (3:12) — Video
  • Develop Wireless Digital Video Broadcasting with RF Beamforming — Example
  • Modeling Mutual Coupling in Large Arrays Using Embedded Element Pattern — Example
  • Visualize Antenna Coverage Map and Communication Links — Example

Pattern Synthesis and Adaptive Beamforming

  • Synthesizing an Array from a Specified Pattern: An Optimization Workflow — Article
  •  — Example
  • Design Conventional and Adaptive Beamformers — Example
  • Integrate Direction of Arrival with Beamscan and MVDR — Example
  • Implement Wideband Beamforming — Example

MIMO Communications Systems

  • Hybrid Beamforming for Massive MIMO Phased Array Systems — White Paper
  • Massive MIMO Technology — Overview
  • Introduction to Hybrid Beamforming — Example
  • Develop Beamforming for MIMO-OFDM Systems — Example
  • LTE MIMO Beamforming on Ray Tracing Channels (5:53) — Video
  • WLAN 802.11ad Simulation (3:12) — Video

Sonar and Acoustics

  • Underwater Target Detection with an Active Sonar System — Example
  • Acoustic Beamforming Using Microphone Arrays — Example

See also:

wireless communications,

LTE Toolbox,

WLAN Toolbox,

Communications Toolbox,

Phased Array System Toolbox,

Antenna Toolbox,

RF system,

software-defined radio,

FPGA design and codesign,

MATLAB,

Simulink,

OFDM,

massive MIMO,

channel model,

radar system design,

5G wireless technology

Better Wi-Fi is right here

Beamforming can improve your Wi-Fi.

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by
Daniel Nations

Daniel Nations has been a tech journalist since 1994. His work has appeared in Computer Currents, The Examiner, The Spruce, and other publications.

Updated March 24, 2019

Beamforming is a new buzzword that is often associated with new Wi-Fi routers, but what exactly is beamforming? Will it actually improve your signal? And more importantly, is it worth it to upgrade?

Digital beamforming technology is part of the 802.11ac standard for Wi-Fi routers. Sounds confusing, right? Don’t worry about the jargon. A standard for computers is much like a language. We both need to know the rules — grammar, spelling, etc. — to effectively communicate with each other. Our Wi-Fi router and our laptops, smartphones, and tablets also need rules on how to talk to each other. The 802.11ac standard is simply the newest set of rules.

So what’s the deal with beamforming? Older routers are omnidirectional, which means they send out their signal in all directions. As you might imagine, this dilutes the signal. Beamforming is a way for our device to give its location to the router and for the router to form a beam within the signal directed toward the device. This will help strengthen the signal, which in turn should help us when we stream movies or browse the web.

Do You Need a Beamforming Wi-Fi Router?

Unfortunately, beamforming isn’t a magic pill that will solve all of our Wi-Fi woes. The beam will help improve a signal over distance, so if you are having a problem in part of your house or office that is far away from the router, beamforming could improve the signal.  

However, distance isn’t always the problem when it comes to slow Internet speeds. Every time the signal passes through an object like a wall, it can lose strength. In this instance, a beamforming router may not help the signal. The beam is going to be disrupted in the same way a normal signal would be disrupted.

If your router is on one side of your home or office, and you are having problems on the other side, beamforming might be the golden ticket to Internet speed bliss. But if your router is in the middle and you are having issues on one end but not the other, there is probably something disrupting the signal and beamforming may not help. This is an issue where a Wi-Fi extender or other Wi-Fi signal solutions may be better (and likely cheaper).

Does Beamforming Make My Internet Speed Faster?

Yes and no. Beamforming alone will not increase your maximum Internet speed, but it can improve the signal, which can boost your effective speed as you travel further away from your router.

However, a side benefit many people receive when upgrading to an 802.11ac router with beamforming is the addition of MIMO, which stands for multiple-in and multiple-out. Most new routers include this feature, and it is fundamental to beamforming. If your device supports MIMO, which most current mobile devices do, your router and your smartphone, laptop or tablet will use multiple streams to communicate. This can provide a dramatic boost to your Internet speed.

MIMO was supported before the 802.11ac standard and your current router may already support it.

What’s the Difference Between Implicit Beamforming and Explicit Beamforming?

Beamforming can potentially boost the signal strength of devices that don’t actually support beamforming, although not as much as it could on a supported device. Explicit beamforming means the beam is only formed if the device on the other end supports beamforming. Implicit beamforming will attempt to form the beam even if the endpoint device doesn’t support it. While it may not be as accurate, implicit beamforming can help with some connections.

Do All New Routers Have Beamforming?

While the 802.11ac standard includes standards for beamforming, it isn’t a requirement for all Wi-Fi routers to support it. And unfortunately, different manufacturers like to dress it up with special names when bragging about it on the package. So you may want to look for variations of the word ‘beam’ such as Advance Beam Technology or Smart Beam Technology. But don’t worry, no matter how the manufacturer words it, the beamforming will be compatible with your devices.  

Continue Reading

Antenna beam forming the basics

As already mentioned the beam-forming antenna system consists or a number of individual antennas set up as an array.

Each antenna element is fed separately with the signal to be transmitted. However each antenna feed is controlled so that the phase and amplitude to each element can be controlled. This creates a pattern of constructive and destructive interference in the wavefront.

The individual feed signals are controlled so that the overall sum of the instantaneous amplitudes from the different antenna elements add or subtract in such a way that the required beam is created.

A beam forming antenna array can be created by using a number of closely spaced antenna elements. If they are equispaced a distance «d» apart, then we can see the performance as below.

Application of antenna beam-forming as used with mobile or cellular telecommunications

Ψ=2πdλ(sinθ)

Where
    Ψ = phase difference between two adjacent beams.

If all the elements in the array are isotropic, i.e. they radiate equally in all directions, they all have the same gain, and are driven with a signal at the same phase and power, the resultant beam will point straight out of the plane on which they are mounted.

it is also possible to alter the phasing progressively between the antenna element synth e array to form a beam at a different angle. The case difference between the elements determines the angle of the beam.

As with any antenna, the law of reciprocity applies and the equivalent performance is obtained in the receive direction — it is just easier to visualise the power distribution in the radiated pattern from the beam forming antenna.

Difference between beamforming beamsteering

Two terms are mentioned when looking at this type of antenna technology. Although inextricably linked, there are two different aspects to the technology which are described by the two different terms:

  • Beam forming:   This term refers to the basic formation of a beam of energy from a set of phased arrays. Using phased antenna arrays it is possible to control the shape and direction of the signal beam from multiple antennas based on the antenna spacing and the phase of signal from each antenna element in the array. Accordingly, the creation of the beam using the technique of interfering and constructing patterns is called beamforming.
  • Beam steering:   Beamsteering takes the concept of beam forming a stage further. It is the way in which a beam pattern can be dynamically altered by changing the signal phase in real time without changing the antenna elements or other hardware.

Beamforming and beamsteering are two linked techniques, but both are incorporated into the types of antennas that are being utilised with many new communications technologies like 5G.

Sidelobes

As with any directional antenna a number of sidelobes are formed. For the cases where the spacing is less than a wavelength, the side-lobes appear either side of the main lobe with decreasing levels.

However, if the array elements are spaced more widely, the strength of the side lobes increases until, when the separation distance «d» matches the signal wavelength λ, unwanted beams with the same power level as the main beam appear at ±90°.

Sidelobes are normally unwanted as they result in power being radiated in directions that do not align with the main beam. This means that the efficient of the antenna is reduced compared to what is desired.

Digital, analog, and hybrid

For receive (but not transmit), there is a distinction between analog and digital beamforming. For example, if there are 100 sensor elements, the «digital beamforming» approach entails that each of the 100 signals passes through an to create 100 digital data streams. Then these data streams are added up digitally, with appropriate scale-factors or phase-shifts, to get the composite signals. By contrast, the «analog beamforming» approach entails taking the 100 analog signals, scaling or phase-shifting them using analog methods, summing them, and then usually digitizing the single output data stream.

Digital beamforming has the advantage that the digital data streams (100 in this example) can be manipulated and combined in many possible ways in parallel, to get many different output signals in parallel. The signals from every direction can be measured simultaneously, and the signals can be integrated for a longer time when studying far-off objects and simultaneously integrated for a shorter time to study fast-moving close objects, and so on. This cannot be done as effectively for analog beamforming, not only because each parallel signal combination requires its own circuitry, but more fundamentally because digital data can be copied perfectly but analog data cannot. (There is only so much analog power available, and amplification adds noise.) Therefore, if the received analog signal is split up and sent into a large number of different signal combination circuits, it can reduce the signal-to-noise ratio of each.

In MIMO communication systems with large number of antennas, so called massive MIMO systems, the beamforming algorithms executed at the digital can get very complex.
In addition, if all beamforming is done at baseband, each antenna needs its own feed. At high frequencies and with large number of antenna elements, this can be very costly, and increase loss and complexity in the system. To remedy these issues, hybrid beamforming has been suggested where some of the beamforming is done using analog components and not digital.

There are many possible different functions that can be performed using analog components instead of at the digital baseband.

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