In today’s post, Liping from the Student Programs Team will share her experience on how MATLAB and Simulink can help students to understand wireless communication theories on beamforming and precoding. Let us see what she is going to share.
When I took the course “Fundamentals of Wireless Communications”, I felt it was so hard to concentrate in the classes since the course material was filled with mathematics including matrices, stochastic processes, formula derivations, etc. After working on wireless communication systems such as LTE and 5G for many years, I found understanding the basic concepts and theories was so important since they are fundamental to different applications.
Many examples and reference applications in MATLAB can help you to understand complex wireless communication theories. In this script, I will show how a demo can help you to understand beamforming, a technique that has been widely used in 5G and even in 6G, radar, sonar, medical imaging, and audio array systems.
Table of Contents
What are Phased Arrays?How to do Beamforming? Line-of-Sight Channel Multipath ChannelSummaryFurther ExplorationHelper Functions
What are Phased Arrays?
To understand beamforming, you first need to know what beams are and how they are formed. Briefly, a beam pattern can be formed by a phased array, which refers to multiple elements that can measure or emit waves. The elements are arranged in some configuration and act together to produce a desired beam pattern. You can steer the beams by adjusting the phase of the signals to each element without physically moving the array. For more details, please watch Brian Douglas’ video “What are Phased Arrays?“, where he uses a lot of animations to explain the concept.
In wireless communications, the elements of a phased array could be antennas. From the snapshots below of Douglas’ video, you can see in the right figure that the beams of a Uniform Linear Array (ULA) of isotropic antennas, where signals from each antenna have been superimposed so the signal strength has been enhanced in some directions, while they have been canceled in the other directions.
The beam pattern of an antenna array depends on the settings including the number of antenna elements, spacing between elements, array geometry as well as individual antenna patterns.
The Sensor Array Analyzer App in MATLAB provides you with an interactive tool to set up an antenna array, get its basic performance characteristics, and visualize its beam pattern in a 2D or 3D space. After installing the Phased Array Toolbox in MATLAB, you can find the Sensor Array Analyzer by going to the App Tab in the MATLAB Toolstrip, followed by searching under ‘Signal Processing and Communications’. You also can open the App with the following command in the MATLAB Command Window.
sensorArrayAnalyzer
When looking through the following example on how to use the Sensor Array Analyzer, you notice the App can help with tuning parameters, visualizing the beam pattern of a phased array, as well as steering a phased array to a certain direction. With different steering vectors, you can move beams around without moving the array physically.
Now you may still be curious about how to use beam steering to improve the performance of a wireless communication system. The answer is by beamforming, a scheme to pre-steer beams to a desired direction! The next example will show you how to do beamforming of an antenna array to improve the Signal-to-Noise Ratio (SNR) of a wireless link.
How to do Beamforming?
Antenna arrays have become part of the standard configuration in 5G. Such wireless communication systems are often referred to as Multiple-Input-and-Multiple-Output (MIMO) systems. To show the advantages of multiple antennas, we assume a wireless link deployed at 60 GHz, a millimeter wave frequency that had been newly considered in 5G.
close all; clear; clc;
rng(0); % set the seed of the random number generator
c = 3e8; % propagation speed
fc = 60e9; % carrier frequency
lambda = c/fc; % wavelength
With no loss in generality, we place a transmitter at the origin and a receiver approximately 1.6 km away.
txcenter = [0;0;0]; % center of the transmitter
rxcenter = [1500;500;0]; % center of the receiver
Then the Angle of Departure (AoD) and the Angle of Arrival (AoA) can be calculated based on the center locations of the transmitter and the receiver.
[~,txang] = rangeangle(rxcenter,txcenter); % AoD
[~,rxang] = rangeangle(txcenter,rxcenter); % AoA
Next, we consider two representive channel types.
Line-of-Sight Channel
Line-of-Sight (LOS) propagation is the simplest wireless channel that often happened in rural areas. Does adopting an antenna array under LOS propagation can increase the SNR at the receiver and thus improve the link’s bit error rate (BER)?
As a benchmark, you could simulate the BER performance of a Single-Input-and-Single-output (SISO) link under a LOS channel as follows, where the scatteringchanmtx function is used to create a channel matrix for different transmit and receive array configurations. The function simulates multiple scatterers between the transmit and the receive arrays assuming the signal travels from the transmit array to all the scatterers first and then bounces off the scatterers and arrives at the receive array. In this case, each scatterer defines a signal path between the transmit and the receive array, so the resulting channel matrix describes a multipath environment. You can read the details of this function by selecting it and then right-clicking to open the function.
Consider a SISO communication link where both the transmitter and the receiver only have a single antenna located at the node center, and there is a direct path from the transmitter to the receiver. Such a LOS channel can be modeled as a special case of a multipath environment.
txsipos = [0;0;0]; % antenna position to the transmitter
rxsopos = [0;0;0]; % antenna position to the receiver
g = 1; % path gain
sisochan = scatteringchanmtx(txsipos,rxsopos,txang,rxang,g); % generate a SISO LOS channel
Nsamp = 1e6; % sample rate
x = randi([0 1],Nsamp,1); % data source
ebn0_param = -10:2:10; % SNRs, unit in dB
Nsnr = numel(ebn0_param); % total number of SNRs
ber_siso = helperMIMOBER(sisochan,x,ebn0_param)/Nsamp; % caculate the bit error rate (BER)
You have got the BER performance of a SISO LOS link. When looking into the details of the helperMIMOBER function given in the Helper Functions session at the end of this script, you should notice BPSK modulation is considered in all the cases.
Now consider a MIMO link. we assume both the transmitter and the receiver are 4-element ULAs with half-wavelength spacing,
Ntx = 4; % number of transmitting antennas
Nrx = 4; % number of receiving antennas
txarray = phased.ULA(‘NumElements’,Ntx,‘ElementSpacing’,lambda/2); % antenna array of the transmitter
txmipos = getElementPosition(txarray)/lambda;
rxarray = phased.ULA(‘NumElements’,Nrx,‘ElementSpacing’,lambda/2); % antenna array of the receiver
rxmopos = getElementPosition(rxarray)/lambda;
With the receive antenna array, the received signals across array elements of the receiver are coherent, so it is possible to pre-steer the receive array toward the transmitter to improve the SNR. Moreover, the transmitter also can pre-steer the main beam of its antenna array toward the receiver for further improvement.
txarraystv = phased.SteeringVector(‘SensorArray’,txarray,…
‘PropagationSpeed’,c);
rxarraystv = phased.SteeringVector(‘SensorArray’,rxarray,…
‘PropagationSpeed’,c);
wt = step(txarraystv, fc, txang)’;
wr = conj(step(rxarraystv, fc, rxang));
mimochan = scatteringchanmtx(txmipos,rxmopos,txang,rxang,g);
ber_mimo = helperMIMOBER(mimochan,x,ebn0_param,wt,wr)/Nsamp;
helperPlotSpatialMIMOScene(txmipos,rxmopos,txcenter,rxcenter,NaN,wt,wr)
With beamforming, the modulated signal needs to be multiplied with wt before sending out at the transmitter, while the received signal needs to be multiplied with wr before demodulation at the receiver. After using the helperPlotSpatialMIMOScene function to visualize the scene in the figure above, you notice the main beams at the transmitter and the receiver have been pointed at each other.
Now you can compare the BER performance in the SISO and the MIMO cases under the LOS propagation channel,
helperBERPlot(ebn0_param,[ber_siso(:) ber_mimo(1,:).’]);
legend(‘SISO LOS’,‘MIMO LOS’);
The BER curve shows the transmit array and the receive array contribute around 6 dB array gain respectively, resulting in a total gain of 12 dB over the SISO case.
Note that the gain is achieved under the assumption that the transmitter needs to know the receiver’s direction or location, and meanwhile the signal incoming direction is known to the receiver, where the angle is often obtained using the direction of arrival estimation algorithms.
Multipath Channel
In most cases, wireless communications occur in a multipath fading environment. The rest of this example explores how phased arrays can help in such a case.
Assume there are 10 randomly placed scatterers in the channel, so there will be 10 paths from the transmitter to the receiver, as illustrated in the following.
Nscat = 10; % number of scatterers
[~,~,scatg,scatpos] = helperComputeRandomScatterer(txcenter,rxcenter,Nscat);
helperPlotSpatialMIMOScene(txmipos,rxmopos,txcenter,rxcenter,scatpos)
For simplicity, assume that signals traveling along all paths arrive within the same symbol period, so the channel is frequency flat and not frequency selective.
In such a multipath fading channel, the channel needs to change over multiple time slots to simulate the BER curve. Assume the simulation lasts 1000 frames and each frame has 10000 bits. The BER curve of the baseline SISO link under a multipath channel can be simulated as follows.
Nframe = 1e3; % number of frames
Nbitperframe = 1e4; % number of bits per frame
Nsamp = Nframe*Nbitperframe; % total number of data samples
x = randi([0 1],Nbitperframe,1); % generated the source data
nerr = zeros(1,Nsnr);
for m = 1:Nframe
sisompchan = scatteringchanmtx(txsipos,rxsopos,Nscat);
wr = sisompchan’/norm(sisompchan);
nerr = nerr + helperMIMOBER(sisompchan,x,ebn0_param,1,wr);
end
ber_sisomp = nerr/Nsamp;
In SISO cases, if you compare the channel matrix of a LOS channel with that of a multipath channel, you can notice it contains a single element and the value of the element changes from a real number to a complex number due to multipath fading. In such a case, a combining weight calculated as wr = sisompchan’/norm(sisompchan) can be used at the receiver to improve the SNR.
In the MIMO case, the BER curve can be simulated as follows, where the diagbfweights function is used to calculate the precoding weight wp at the transmitter and the combining weights wc at the receiver. You can right-click on the function and open it to see its details.
x = randi([0 1],Nbitperframe,Ntx);
nerr = zeros(Nrx,Nsnr);
for m = 1:Nframe
mimompchan = scatteringchanmtx(txmipos,rxmopos,Nscat);
[wp,wc] = diagbfweights(mimompchan);
nerr = nerr + helperMIMOBER(mimompchan,x,ebn0_param,wp,wc);
end
ber_mimomp = nerr/Nsamp;
To understand how precoding and combining weights are calculated, you first need to understand what Singular Value Decomposition (SVD) is. Use the following command to find the MATLAB documentation on SVD.
help svd
Briefly, an SVD ([U,S,V] = svd(X)) produces a diagonal matrix S, of the same dimension as X and with nonnegative diagonal elements in decreasing order, and unitary matrices U and V so that X = U*S*V’. Try following commands in MATLAB.
bf = wp*mimompchan*wc
[u,s,v] = svd(mimompchan)
Compare bf with s, you now know the diagbfweights function is based on SVD. Due to a rich scatterer environment, the channel matrix of a MIMO multipath channel usually has full rank.
Note that the product wp*mimompchan*wc is a diagonal matrix, which means that the information received by each receive array element is simply a scaled version of the transmit array element. Such a MIMO multipath channel behaves like multiple orthogonal subchannels within the original channel.
Therefore, it is possible to send multiple data streams simultaneously across the MIMO multipath channel, which is called spatial multiplexing. The basic idea of spatial multiplexing is to separate the channel matrix into multiple modes so that the data stream sent from different elements in the transmit array can be independently recovered from the received signal. The goal of spatial multiplexing is less about increasing the SNR and more about increasing the information throughput.
Now you can plot the BER curves of the SISO multipath case, and the first two data streams in the MIMO multipath case. As a benchmark, you also plot the BER curve in the SISO LOS case that has been got from the previous section.
helperBERPlot(ebn0_param,[ber_siso(:) ber_sisomp(:) ber_mimomp(1,:).’ ber_mimomp(2,:).’]);
legend(‘SISO LOS’,‘SISO Multipath’,‘MIMO Multipath Stream 1’,‘MIMO Multipath Stream 2’);
Compared to the BER curve of the SISO LOS channel, the BER curve of the SISO multipath channel falls off much slower due to the fading caused by the multipath propagation. Meanwhile, in the MIMO multipath case, the first subchannel corresponds to the dominant transmit and receive directions so there is no loss in the diversity gain, which refers to the gain on the slope change. Although the second stream cannot provide a gain as high as the first stream as it uses a less dominant subchannel, the overall information throughput can be improved since it is now possible to transmit multiple data streams simultaneously.
Summary
This demo explains how array processing can improve the performance of a MIMO wireless communication system. Depending on the nature of the channel, the arrays can be used to either improve the SNR via array gain or diversity gain; or improve the capacity via spatial multiplexing.
Now you understand some basics of MIMO wireless communications such as beamforming, precoding, diversity gain, and spatial multiplexing. The helper functions used in this demo are attached at the end of this script. Please run the code and reach out to us at studentcompetitions@mathworks.com if you have any further questions.
Further Exploration
Besides intuitively uniformly splitting the power among transmit elements, the capacity of the channel can be further improved by a water-filling algorithm. For details, please refer to the demo “Improve SNR and Capacity of Wireless Communication Using Antenna Arrays”.
To learn how to make beamforming real in 5G, please watch the tutorial video “Beamforming for MU-MIMO in 5G New Radio“. Moreover, a lot of examples and reference applications are available in the documentation on wireless communications, which can help you to understand the relevant concepts and theories more easily and clearly. Various examples of AI for Wireless can also provide you with more reference applications on how to apply AI technology in wireless communications. Have fun!
Helper Functions
The first helper function is for plotting the MIMO scene in a 2D area.
function helperPlotSpatialMIMOScene(txarraypos,rxarraypos,txcenter,rxcenter,scatpos,wt,wr)
narginchk(5,7);
rmax = norm(txcenter-rxcenter);
if size(txarraypos,2) == 1 && size(rxarraypos,2) == 1
spacing_scale = 0;
elseif size(txarraypos,2) == 1
spacing_scale = rmax/20/mean(diff(rxarraypos(2,:)));
else
spacing_scale = rmax/20/mean(diff(txarraypos(2,:)));
end
txarraypos_plot = txarraypos*spacing_scale+txcenter;
rxarraypos_plot = rxarraypos*spacing_scale+rxcenter;
figure
hold on;
plot(txarraypos_plot(1,:),txarraypos_plot(2,:),‘kv’,‘MarkerSize’,10,…
‘MarkerFaceColor’,‘k’);
text(txcenter(1)-85,txcenter(2)-15,‘TX’);
plot(rxarraypos_plot(1,:),rxarraypos_plot(2,:),‘kv’,‘MarkerSize’,10,…
‘MarkerFaceColor’,‘k’);
text(rxcenter(1)+35,rxcenter(2)-15,‘RX’);
if isnan(scatpos)
set(gca,‘DataAspectRatio’,[1,1,1]);
line([txcenter(1) rxcenter(1)],[txcenter(2) rxcenter(2)]);
else
hscat = plot(scatpos(1,:),scatpos(2,:),‘ro’);
for m = 1:size(scatpos,2)
plot([txcenter(1) scatpos(1,m)],[txcenter(2) scatpos(2,m)],‘b’);
plot([rxcenter(1) scatpos(1,m)],[rxcenter(2) scatpos(2,m)],‘b’);
end
legend(hscat,{‘Scatterers’},‘Location’,‘SouthEast’);
end
if nargin > 5
nbeam = rmax/5;
if ~isnan(wt)
txbeam_ang = -90:90;
txbeam = abs(wt*steervec(txarraypos,txbeam_ang)); % wt row
txbeam = txbeam/max(txbeam)*nbeam;
[txbeampos_x,txbeampos_y] = pol2cart(deg2rad(txbeam_ang),txbeam);
plot(txbeampos_x+txcenter(1),txbeampos_y+txcenter(2),‘k’);
end
if ~isnan(wr)
rxbeam_ang = [90:180 -179:-90];
rxbeam = abs(wr.’*steervec(rxarraypos,rxbeam_ang)); % wr column
rxbeam = rxbeam/max(rxbeam)*nbeam;
[rxbeampos_x,rxbeampos_y] = pol2cart(deg2rad(rxbeam_ang),rxbeam);
plot(rxbeampos_x+rxcenter(1),rxbeampos_y+rxcenter(2),‘k’);
end
end
axis off;
hold off;
end
The second helper function is for calculating the BER values of a MIMO link.
function nber = helperMIMOBER(chan,x,snr_param,wt,wr)
Nsamp = size(x,1);
Nrx = size(chan,2);
Ntx = size(chan,1);
if nargin < 4
wt = ones(1,Ntx);
end
if nargin < 5
wr = ones(Nrx,1);
end
xt = 1/sqrt(Ntx)*(2*x-1)*wt; % map to bpsk
nber = zeros(Nrx,numel(snr_param),‘like’,1); % real
for m = 1:numel(snr_param)
n = sqrt(db2pow(-snr_param(m))/2)*(randn(Nsamp,Nrx)+1i*randn(Nsamp,Nrx));
y = xt*chan*wr+n*wr;
xe = real(y)>0;
nber(:,m) = sum(x~=xe);
end
end
In the first two functions, a SISO scene/link can be considered as a special case of a MIMO scene/link.
The third function is for calculating the position of the scatterers.
function [txang,rxang,g,scatpos] = …
helperComputeRandomScatterer(txcenter,rxcenter,Nscat)
ang = 90*rand(1,Nscat)+45;
ang = (2*(rand(1,numel(ang))>0.5)-1).*ang;
r = 1.5*norm(txcenter-rxcenter);
scatpos = phased.internal.ellipsepts(txcenter(1:2),rxcenter(1:2),r,ang);
scatpos = [scatpos;zeros(1,Nscat)];
g = ones(1,Nscat);
[~,txang] = rangeangle(scatpos,txcenter);
[~,rxang] = rangeangle(scatpos,rxcenter);
end
The fourth function is for plotting BER curves.
function helperBERPlot(ebn0,ber)
figure
h = semilogy(ebn0,ber);
set(gca,‘YMinorGrid’,‘on’,‘XMinorGrid’,‘on’);
markerparam = {‘x’,‘+’,‘^’,‘v’,‘.’};
for m = 1:numel(h)
h(m).Marker = markerparam{m};
end
xlabel(‘E_b/N_0 (dB)’);
ylabel(‘BER’);
end
FAQs
What is phased array beamforming? ›
A digital beam forming (DBF) phased array has a digital receiver/exciter at each element in the array. The signal at each element is digitized by the receiver/exciter. This means that antenna beams can be formed digitally in a field programmable gate array (FPGA) or the array computer.
What is the difference between beamforming and beamsteering? ›Beamforming simply means using an array of antennas and a combiner to form a spatial filter. Note that beamforming can be in a constant direction (i.e., the combiner can be static). Beamsteering means changing the direction of the antenna array's main lobe.
Which device provides ability to steer the direction of RF energy? ›What are beamforming Antennas? Beamforming is the most commonly used method by a new generation of smart antennas. In this method, an array of antennas is used to “steer” or transmit radio signals in a specific direction, rather than simply broadcasting energy/signals in all directions inside the sector.
How do you test beamforming? ›Testing beamformer ICs requires: A multiport vector network analyzer (VNA) for S-parameter measurements. A custom-switching test set for nonlinear S-parameters, such as distortion and noise figure.
What is 5G beamforming example? ›5G beamforming allows Verizon to make 5G connections more focused toward a receiving device. For example, a typical 5G small cell that does not employ beamforming during its multiple-input multiple-output (MIMO) transmission will not be able to narrowly concentrate or focus its transmit beams to a particular area.
How does beamforming work? ›Rather than sending a signal from a broadcast antenna to be spread in all directions -- how a signal would traditionally be sent -- beamforming uses multiple antennas to send out and direct the same signal toward a single receiving device, such as a laptop, smartphone or tablet.
What is the example of beamforming? ›An example of a beamforming antenna is the uniform linear array antenna in which the distance between each array element is half of the carrier wavelength. Each element is assumed to be an omnidirectional antenna having fixed gains in all directions.
What is the main advantage of beamforming? ›Beamforming improves the spectral efficiency by providing a better signal-to-noise ratio (SNR). Working with other antenna technologies such as smart antennas and MIMO, beamforming boosts cell range and capacity. That means mobile device users get stronger, clearer signals.
What is the purpose of beam steering? ›Beam steering is a technique for changing the direction of the main lobe of a radiation pattern. In radio and radar systems, beam steering may be accomplished by switching the antenna elements or by changing the relative phases of the RF signals driving the elements.
What are the 2 types of beamforming? ›Depending on who you ask, you'll be told there are two types of beamforming. These are either analog or digital, or switched and adaptive beamforming.
What is another name for beamforming? ›
Beamforming or spatial filtering is a signal processing technique used in sensor arrays for directional signal transmission or reception.
What is the formula for beam steering? ›The diffracted beam is deflected by an angle θ = (ωA/ωo) (c/vA) where ωO is the optical frequency, ωA is the acoustic frequency, c is the velocity of light, and vA the acoustic wave velocity in the cell. Typically this angle is small, of the order of 1–2°.
How do I enable beamforming? ›Some models might use slightly different menu labels, like Settings > Advanced Settings > Wireless Setup. The Advanced Wireless Settings screen displays. Clear the Enable Implicit BEAMFORMING check box to disable implicit beamforming, or select the checkbox to enable implicit beamforming. Click or tap Apply.
Which devices support beamforming? ›Most 802.11ac (WiFi 5) and newer clients support explicit beamforming. Implicit beamforming does not require client devices to support beamforming in order to benefit from improved range and performance.
Does beamforming increase range and bandwidth? ›"Beamforming increases the performance of wireless networks at medium ranges. At short ranges, the signal power is high enough that the SNR will support the maximum data rate.
What is the difference between beamforming and MIMO? ›MIMO (Multiple Input Multiple Output) antennas operate by breaking high data rate signals into multiple lower data rate signals in Tx mode that are recombined at the receiver. Beamforming arrays are inherently different from MIMO in that the multiple columns of dipoles work together to create a single high gain signal.
What is the difference between beamforming and beam tracking? ›Beamforming – People moving around a beamforming-enabled room may move in and out of the beams, which can make them hard to hear. Beam tracking technology, an evolution of beamforming technology, may help reduce this issue by directing beams to “follow” a person speaking.
Does LTE use beamforming? ›Beamforming by Precoding : This is the technique that change the beam pattern (radiation form) by applying a specific precoding matrix. This is the technique used in LTE.
What are the disadvantages of beamforming? ›Disadvantages: Requires support from both the sender and receiver. Use of TXBF doesn't allow the sender to exceed regional ERP, which includes antenna gain. A radio may have to reduce power in order to stay within the mandated limits.
How much does beamforming help? ›Benefits and limits of beamforming
Focusing a signal in a specific direction lets you deliver a higher signal quality to the receiver, which then means faster information transfer and fewer errors, without having to boost the power of the broadcast.
How does phased array work? ›
A phased array antenna enables beamforming by adjusting the phase difference between the driving signal sent to each emitter in the array. This allows the radiation pattern to be controlled and directed to a target without requiring any physical movement of the antenna.
How does digital beamforming work? ›Beamforming is a signal processing technique in which signals are received and aggregated (RX) or disseminated and transmitted (TX) in such a manner that their contributions sum constructively at a desired angle, while summing destructively at other angles.
What are the disadvantages of digital beamforming? ›The disadvantage is the loss from the cascaded phase shifters at high power. Digital beamforming (DBF): DBF assumes that there is a separate RF chain for each antenna element. The beam is formed by matrix-based operations in the baseband where digital amplitude and phase weighting is performed.
Which two types of beamforming do we use for high band? ›Beamforming can be divided into two categories depending on the signal bandwidth: narrowband beamforming and wideband beamforming. Narrowband beamforming is achieved by an instantaneous linear combination of the received array signals.
What is the maximum steering angle of a phased array? ›For phased array transducers, the maximum steering angle (at -6 dB) in a given case is derived from the beam spread equation. It can be easily seen that small elements have more beam spreading and hence higher angular energy content, which can be combined to maximize steering.
What is the maximum beam steering angle? ›If the beam is steered completely to the horizon, then θ = ±90°, and an element spacing of λ/2 is required (if no grating lobes are allowed in the visible hemisphere). But in practice, the maximum achievable steering angle is always less than 90°.
What is a steerable beam? ›COJOT Steerable Beam Antennas (SBAs) feature enhanced beam steering functionalities that provide superior operability and advanced capabilities to modern and future C4I, EW and ISR Systems as well as P2P and P2MP networks.
What is the difference between analog and digital beamforming? ›Analog beamforming uses phase-shifters to send the same signal from multiple antennas but with different phases. Digital beamforming designs different signals for each antennas in the digital baseband. Precoding is sometimes said to be equivalent to digital beamforming.
How does beamforming improve network services? ›Beamforming technology directs a wireless signal to a single receiving device rather than spreading the signal in all directions as a broadcast antenna does. With Beamforming, the direct connection that results is quicker and more dependable.
How does antenna spacing affect beamforming? ›If the antenna element spacing (d) is increased above 0.5λ, the beamwidth decreases resulting in higher directivity.
What is the difference between beamforming and spatial multiplexing? ›
Generalized beamforming makes use of only one of the modes available, while Spatial Multiplexing (SM) makes use of all of them. Low complexity is one of the main advantages of the beamforming (BF) approach. However, BF may be suboptimal. Spatial Multiplexing has the ability to approach the maximum channel capacity.
What is a beam calculator? ›The above steel beam span calculator is a versatile structural engineering tool used to calculate the bending moment in an aluminium, wood or steel beam. It can also be used as a beam load capacity calculator by using it as a bending stress or shear stress calculator.
Is beamforming good or bad? ›Using beamforming, wireless access points can direct their signal in a particular direction. The advantages are substantial if the receiving device points in this direction: faster throughput, fewer interferences, and improved signal.
What are the advantages of beamforming in 5G? ›Benefits of beamforming
Beamforming effectively uses the science of electromagnetic interference to enhance the precision of 5G connections, working in tandem with MIMO to improve throughput and connection density of 5G network cells.
A phased array antenna enables beamforming by adjusting the phase difference between the driving signal sent to each emitter in the array. This allows the radiation pattern to be controlled and directed to a target without requiring any physical movement of the antenna.
What is phased array technique? ›Phased Array is an ultrasonic testing technique that uses specialized multi-element “array” transducers and pulses those elements separately in a patterned sequence called “phasing”. This phasing sequence allows wave steering, focusing, and scanning. This is all performed electronically.
What is the meaning of phased array? ›A phased array is a group of sensors located at distinct spatial locations in which the relative phases of the sensor signals are varied in such a way that the effective propagation pattern of the array is reinforced in a desired direction and suppressed in undesired directions.
What are the advantages of phased array technique? ›Advantages. The advantages of phased arrays over conventional ultrasonic probes include improved portability, convenience, inspection speed, and safety.
What are the advantages of beam steering? ›Beam steering technique reduces interference, saves power, increases gain and directivity of the micro-strip antenna.
Which is an advantage of phased array coils? ›They give you more signal
Multi-channel technology increases signal and thereby, scan quality.
What are the three methods of array? ›
There are three different kinds of arrays: indexed arrays, multidimensional arrays, and associative arrays.
What are the limitations of phased array? ›The main disadvantages of phased-array systems are that (i) they are more expensive to purchase, (ii) operation and data interpretation are more difficult and (iii) there can be greater difficulty in achieving good ultrasonic coupling due to the larger probe dimensions.
What are the disadvantages of phased array? ›Disadvantages of Phased Array Ultrasound Testing
While PAUT has a wide range of abilities, it's not a preferred testing method for the detection of surface cracks, metal fatigue, or bolt hole inspections compared to eddy current testing.
Calculating antenna gain in a phased array
The number of elements required in an electronically-scanning phased array antenna can be estimated by the gain it must provide. A 30 dB gain array needs about 1000 elements and a 20 dB gain array needs about 100.
The near-$900 million structure, operated by the U.S. Missile Defense Agency (MDA), is by far the largest phased-array radar system on Earth.
How efficient are phased arrays? ›In terms of aperture efficiency, these antennas achieve efficiencies in the 85% to 90% range when scaled up to a size suitable for satellite communications.
What is an array in simple terms? ›An array is a collection of elements of the same type placed in contiguous memory locations that can be individually referenced by using an index to a unique identifier.