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What wavelength do we use when calculating the array manifold vector when transmitting LFM waveforms?

As with many questions like these...it depends. We won't concentrate on LFM waveforms, the following is true for any waveform transmitted. Virtually all of the introductory material to steering a ...
Envidia's user avatar
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3 votes

What is the physical meaning of coherence bandwidth in mmWave massive MIMO channel?

You are right, coherence bandwidth is the frequency domain counterpart of delay spread. However, to achieve diversity across antennas the spacing between the antennas is important "relative to the ...
Dsp guy sam's user avatar
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3 votes
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Dimension of Matrix in MIMO with multi-path

The short answer is: if you transmit one block of $N$ symbols (no data before it for at least $L$ symbol times) over a frequency-selective channel of length $L$, then the channel matrix will be of ...
BlackMath's user avatar
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3 votes

DOA - 1D Music Algorithm

If you have three or more antennas, simply don't put them in a linear array. Any other array setup doesn't suffer from the ambiguity. Linear array is the worst choice here. Of course, that breaks the ...
Marcus Müller's user avatar
3 votes

FMCW Radar - Range-Doppler Plot

So the problem is that when simulating FMCW signals, there is some ambiguity in the convention on the mixing order. MATLAB's documentation makes reference to it here: "The mix operation reverses ...
Envidia's user avatar
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3 votes
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Square Root MMSE

This is just a nice way to rewrite Equation (2). Using Block matrix interpretation: \begin{align} \underline{H}^H\underline{H}=\begin{bmatrix}H_{R\times T}^H&\sigma I_T\end{bmatrix}\begin{bmatrix}...
AlexTP's user avatar
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3 votes
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MIMO reading clarification

However, from sources online, I've found that if $\vec a, \vec b$ are unit complex vectors then $\cos (\theta) = Re(\vec a \cdot \vec b)$, which is clearly not the same as (7.33). Is this a mistake in ...
AlexTP's user avatar
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2 votes

How to solve equations for the MMSE receiver?

I doubt there is general closed-form solution. For the first equation, you essentially want to solve $$\mu=\sum_k \frac{1}{a_k+b_k \mu}$$ for $\mu$ which equals to search for the zeros of a $k+1$th ...
Maximilian Matthé's user avatar
2 votes
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What is the index modulation in OFDM and Subcarrier Index modulation?

Yes OFDM-IM is somehow new and it's very hot topic of searching. That article you have shares is the basic of OFDM-IM. So if you are at the beginning to understand it, that's the right paper to to ...
Zeyad_Zeyad's user avatar
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2 votes

Achievable rate for MIMO channel with estimated channel matrix

I found the following relation which answers my question $$R=\log\det \left(\boldsymbol{C}_{MMSE}^{-1}\right)$$ where $\boldsymbol{C}_{MMSE}$ is the covariance matrix of the error in the data $\...
user3350919's user avatar
2 votes

Notes or books to quickly get started on the basics of signal processing or wireless communication

I would recommend you a book from Emil Björnson. He is a professor on the Linköping University and also produces a lot of content on his Youtube channel (which I will not link to avoid getting ...
TheWirelessClassroom's user avatar
2 votes

Notes or books to quickly get started on the basics of signal processing or wireless communication

One of the most readable (imho) authors on the communication systems is Simon Haykin and the following book from him would probably address most of the issues you would encounter in a wireless ...
Fat32's user avatar
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Problem with Convolution in MIMO System

Convolution and simple product are used according to the channel's frequency selectivity, regardless transmitter and receiver antenna configurations (SISO or MIMO system). If the channel is frequency ...
Sofiane's user avatar
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2 votes
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Using MIMO with DS-CDMA and spread spectrum

Assuming one antenna transmits one symbol per time unit, then 16 symbols require 4 time units to be out. Then it is simply that ...
AlexTP's user avatar
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2 votes

Subcarrier assignment in MIMO-OFDMA system

For a given OFDM symbol, no subcarrier can be assigned to two users simultaneously. Each subcarrier is uniquely assigned to a unique user. Else you have to implement an Interference cancellation at ...
Dsp guy sam's user avatar
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2 votes
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What is the difference between ISI and MAI in MIMO system?

MAI is when there is Interference due to multiple users accessing a common wireless media. So if you consider an OFDM system then as long as users are trasmiting in their allocated sub carriers there ...
Dsp guy sam's user avatar
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2 votes
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Radar MIMO Virtual Antenna Array Formation

An application report from Texas Instruments, MIMO Radar (Rev. A), gives a good insight into the MIMO radar virtual antenna array arrangement method. In the report, on Slide-4; $p_{m}$ and $q_{n}$ ...
Karakoncolos's user avatar
2 votes

High frequency and received signal power? Why using massive MiMo?

Massive MIMO is not related to received power and its decrease with increasing frequency. The point of massive MIMO is that the diversity order is huge, and the equations for receiver processing ...
MBaz's user avatar
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2 votes

High frequency and received signal power? Why using massive MiMo?

It is not true that "high frequency carries a lot of energy". See This and This. The story of Massive MIMO unfolded as we people look for a way to dramatically increase communication ...
AlexTP's user avatar
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2 votes

MMSE is approximately zero-forcing at high SNR

Before I answer the question we need to understand the concepts involved: $\mathbf{K}_{z_k}$ is the covariance matrix of the noise plus interference for the kth data stream (excluding the ...
Ahsan Yousaf's user avatar
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1 vote

What is the physical meaning of coherence bandwidth in mmWave massive MIMO channel?

In contrast to your previous question(Why multi-path channel has linear phase within the coherence bandwidth?), the coherence BW in mmWave may not be relevant considering delay spread alone. If you ...
jithin's user avatar
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1 vote

What is the physical meaning of coherence bandwidth in mmWave massive MIMO channel?

Looking at the equation you have posted, it seems $l$ is the variable for $N_p$ multipaths and for each path, there will be a constant delay $\tau_l$, an attenuation $\alpha_l$, a doppler shift in the ...
DSP Rookie's user avatar
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1 vote

Subcarrier assignment in MIMO-OFDMA system

It is possible if the system supports MU-MIMO.
ClaytonA's user avatar
1 vote

How to understand MIMO zero forcing as a bank of decorrelators?

It seems like you understand your question already but are unsure it is correct? Let the decorrelator be $\mathbf{D}=(\mathbf{H}^T\mathbf{H})^{-1}\mathbf{H}^T$, then the symbols post-decorrelator are $...
Engineer's user avatar
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1 vote

MU-MIMO Sensitivity to Line of Sight (LOS)

There is no mention of light-of-sight (LOS) on the time you mentioned. There is a mention of point-to-point, however. Point-to-point channels could be LOS or multipath. MU-MIMO is better than point-...
BlackMath's user avatar
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1 vote

Channel direction

You should double check the formula. The classic single input multiple output (SIMO) equation with $N_T$ receive antennas is: $\mathbf{y}=\mathbf{h}x+\mathbf{w}$. Where $x$ is the transmitted symbol ...
Engineer's user avatar
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1 vote
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Why can we know the best precoding direction after we do the SVD to the channel?

First you have to know that the vector in $U$ and the vector in $V$ are orthonomal,that is ,$\vec u \vec u^H=I$,and $\vec v \vec v^H=I$. So now $H=U\Sigma V^H$,and $y=Hs+n=(U\Sigma V^H)s+n$ and $U^...
electronic component's user avatar
1 vote
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pairwise error probability and union bound of space time code

The union bound can indeed result in a BER higher than 1. As you say, it is just an upper bound, and it becomes tighter as the SNR increases. For low SNR, the union bound can be quite loose.
MBaz's user avatar
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1 vote
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Employing MIMO under the two-ray propagation model

The Channel Impulse Response (CIR) for a beamforming vector $\mathbf{w} \in \mathbb{C}^{N_T \times 1}$ (which corresponds to your spatial streams) is the following $$\mathbf{c}(n) = \sum\limits_{k=1}^...
Ahmad Bazzi's user avatar
1 vote

Understanding the concept of semi-blind receivers

Let us consider a very simple example of a frequency-flat quasi-static MIMO communication system. In such a setup, we can write the received signal from, say, $M_{\rm R}$ receive antennas as $$\mathbf ...
Florian's user avatar
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