Questions tagged [mimo]

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110 views

Radar MIMO Virtual Antenna Array Formation

Referring to the figure attached above, is the ordering of the virtual antenna arrays (shown on the right) to measure azimuth and elevation angles of arrival correct? In my understanding, the ordering ...
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36 views

How to calculate received signal power for a Multi-User MIMO OFDM system?

I have a Multi-User MIMO system where there are 2 users served by a base station. The base station consists of 64 transmit elements and the users are equipped with linear antenna array consisting of 3 ...
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2answers
40 views

Can beamforming be created by transmitting same signal with different phase

As known, the basic idea of beamforming is to transmit the same signal using more transmit antennas, let's say we have $4$ transmit; leading to increase the power of the transmitted signal as well as ...
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28 views

Alamouti scheme and MIMO OFDM model, theoretical or practical concept?

I am not an expert in signal processing but last week I attended a class of signal processing. We discussed MIMO, OFDM and Alamouti scheme. On this lecture it was represented a lot of math equations, ...
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37 views

Matlab: Could anyone suggest why Iam getting a different geometry for QPSK constellation diagram

I'm developing a Multi-user MIMO communication model in MATLAB where a base station communicates with 2 users. The model uses OFDM (QPSK) modulation. Channel model, precoding and covolutional encoder ...
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22 views

MIMO Beamforming Switching Speed

Using beamforming, we can steer the radiated beam in a specific direction. This can be done in analog way (simple but not accurate) or digital way ( accurate but needs complicated design and ...
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1answer
39 views

Does same data inserted to all antenna at beamforming?

I wonder do I understand beamforming right. Question 1 Does same data inserted to all antenna at beamforming? Like figure below? The only different is through different phase shift? If it is right how ...
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31 views

Feedback command for MIMO systems in matlab

I have a state space model with 12 outputs and 4 inputs. I want to close the loop of 8th output with 3 input. then in outer loop i want to close outer loop for 1 output and 3 input again (Quadrotor ...
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1answer
37 views

Property of the trace and expectation

I'm reading the paper Model-Driven Deep Learning for Joint MIMO Channel Estimation and Signal Detection by Hengtao He, Chao-Kai Wen, Shi Jin, and Geoffrey Ye Li on Orthogonal Approximate Message ...
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75 views

Blind STBC question

I am working on blind identification of the physical layer parameters of a particular protocol. Everything was going well until I got to the MIMO part. The system contains two transmitter antennas and ...
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1answer
74 views

What is the Co-channel interference in MIMO communication

I try to understand the co-channel interference occurred in MIMO systems with rich multi-path channels, but I couldn't find clear explanation about how it happens and what's its effects to the ...
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1answer
89 views

Inter Channels interference in MIMO system

If we have MIMO system with $2$ transmit antennas, ($T_1$ and $T_2$) and $2$ receive antennas ($R_1$ and $R_2$). The received signal of the first received antennas can be explained: $r_1$ = $h_{11}$$...
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1answer
780 views

FMCW Radar - Range-Doppler Plot

The FMCW radar with the following parameters was implemented: ...
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2answers
214 views

Radar for Vital Signs – Matlab Simulation

Interested to design and simulate FMCW radar for Vital Signs sensing. The initial signal parameters are(1): When using the following Matlab code to generate the waveform: ...
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1answer
59 views

Spatial multiplexing MIMO, antenna critical spacing, antenna isolation

How does antenna isolation affect single user spatial multiplexing MIMO performance in an antenna array? Text books talk about a critical antenna spacing of 1/2 of the wavelength provided that the ...
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2answers
38 views

Multi-input Single-output communication system

In case of communication in MISO system, if we have a system of 4 x 1, which means 4 transmitter with 1 receiver. Will the received signal be a vector of dimension 4 x 1 ? Or it will be 1 x 1 since ...
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1answer
54 views

how to determine a length of a channel? ( given path, delay)

Given a channel matrices for each subcarrier of a frequency selective channel (OFDM): i.i.d.. channel =(randn(ntx,nrx, N)+1i*randn(ntx,nrx, N))/sqrt(2); simulated ...
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27 views

Control of a nonlinear static MIMO System

I am currently writing my master thesis and trying to design a controller for my system. However, the system is somewhat unconventional. It has a large number of inputs and outputs, is static, non-...
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1answer
34 views

What is the difference between ISI and MAI in MIMO system?

ISI : inter-symbol interference MAI : Multiple Access Interference I know that multi-path would caused delay spread, and when signal symbol period is less than delay spreaad, ISI would happened. ...
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3answers
70 views

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

I am doing some research about millimeter wave massive MIMO channel now. We first take account about static MIMO channel, cause we only have SISO measurement system now. We use scanner to move our ...
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2answers
71 views

Subcarrier assignment in MIMO-OFDMA system

Is it possible for multiple users to simultaneously transmit on the same subcarrier in a MIMO-OFDMA system?
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53 views

MIMO multipath delay [duplicate]

How is multi-path delay dealt with in MIMO systems? Most of the theory I have read on MIMO doesn't address multipath delay and assumes the multipath interference is limited to secondary antenna ...
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1answer
101 views

how to understand the MIMO zero forcing as a bank of decorrelators?

I am studying the zero forcing as a simple linear receiver for MIMO detection. according to following notes: http://www.ee.ic.ac.uk/bruno.clerckx/All.pdf. The zero forcing can be understood as the ...
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1answer
56 views

LTE system. How to compute precoder for resourse block

guys! I am studying a massive Mimo system and 3gpp LTE system and have questions about precoding in the LTE system. In LTE RB (resource block) is used to group consecutive subcarriers. To compute ...
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55 views

Pairwise Error Probability simulation versus SNR for Space-time code

I have a MIMO system using Space-time coding. I am required to produce simulation results in the form $\text{PEP}=f(\text{SNR})$, meaning a curve representing the Pairwise Error Probability (PEP) for ...
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1answer
61 views

Achievable rate for MIMO channel with estimated channel matrix

In a MIMO system, if the receiver has perfect CSI, i.e. knows that channel matrix $\boldsymbol{H}$, then the achievable rate is: $$ R = \log \left|\boldsymbol{I}+\frac{P}{N_RN_T}\boldsymbol{H}\...
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76 views

Space-Time coding uses large amount of block codes to acheive maximum spectral efficiency

Assume I have a MIMO system with $M=8$ transmit antennas, and an arbitrary number of receive antennas. This MIMO systems uses space-time coding. the block codes (matrices) transmitted are part of a ...
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1answer
62 views

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

I'll soon start working in signal processing, specially wireless communication systems. Hence I'd like to get a quick understanding of MIMO and related systems, for example, the topics like: 1) where ...
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71 views

Range Migration Algorithm in FMCW MIMO RADAR

I’m using a FMCW MIMO radar [77-79 GHz] with a virtual linear array made of 48 channels. I’m wondering if the adaptation of the range migration algorithm (typically used in SAR processing) is ...
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1answer
35 views

Why can we know the best precoding direction after we do the SVD to the channel?

Why can we know the best precoding direction after we do the SVD to the channel?for example $\mathbf y=\mathbf H\mathbf s+\mathbf n$,now we do the SVD to the $\mathbf H$ If the $\sigma _1$ is the ...
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1answer
326 views

Frequency-selective channel: Basic in theory

In a lecture, it was covered a topic "frequency selective and flat fading channel models". For case, the frequency selective channel we have a channel impulse response ...
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1answer
71 views

pairwise error probability and union bound of space time code

i have a question that might seem silly. For a given space time code, say a constellation of 16 unitary matrices. When using the union bound to derive an upper bound on the average error probability (...
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1answer
54 views

Employing MIMO under the two-ray propagation model

I'm a little confused about how 'rich' the scattering environment should be for MIMO to work (i.e. for the channel matrix to be full rank). For instance, let's say we have a Tx and Rx with two ...
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1answer
73 views

Understanding the concept of semi-blind receivers

In the book "Signals and Images: Advances and Results in Speech, Estimation, Compression... ", an overview of using tensor analysis in signal processing is given. On page 243 it is explained that an ...
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1answer
53 views

STBC Rank Criteria Explanation

I am learning about space-time block coding and I am trying to understand why the rank criteria is a good measure of diversity gain. I know that we want to maximize the distance between codewords $X_i,...
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3answers
377 views

Explanation a flat fading channel in case MIMO OFDM

I am trying to understand flat fading and frequency selective channels. As I understood, in the case of flat fading channels MIMO channel elements, $h_{i,j}$, are random variables. Which assumption ...
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1answer
30 views

BER performance of a space-time code over Rayleigh channel model

For a given space-time code, and in general terms, how would one proceed in the evaluation of the BER performance of this code ? In order to be more clear, say i have 16 code matrices(who's elements ...
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2answers
75 views

Dimension of Matrix in MIMO with multi-path

In a MIMO system, the received signal is supposed to be $y = Hx + n$, where $H$ is the channel of dimension $N_t \times N_r$, $x$ is the transmitted signal with dimension of $N_t\times 1$ , and $n$ is ...
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1answer
70 views

Is it possible to use MRC with DS-CDMA-MIMO [closed]

I'm wondering how to use the Maximum Ratio Combining with MIMO-DS-CDMA, I have used the MIMO with DS-CDMA using Walsh code, then at receiver I couldn't recover the transmit signal using the MRC. here ...
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1answer
39 views

Possibility of using Power allocation with Maximum likelihood estimation

I have a basic question about maximum likelihood (ML) estimator and its implementation with power allocation. Suppose we are using $MIMO$ system with $4$x$4$ transmit and receive antennas, so the ...
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2answers
68 views

How multi layer map to different beams in LTE Beamforming

I understand for SU-MIMO Beamforming single layer maps to all antennas with phase shift applied to create beam. Also I understand in this case all beams will be carrying same signal (say s1). But in ...
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112 views

Region of convergence for discrete system

I am confused by two questions on the region of convergence (ROC) when applying the $Z$-transform. Consider a discrete-time linear system $$x[n+1] = Ax[n]+Bu[n], \qquad y[n]=Cx[n]+D$$ whose transfer ...
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1answer
759 views

Channel model: LOS Component and Rician K-factor

I am asking about Rician K- Factor in this model: I know that if $K=0$ then it is a pure Rayleigh fading, if $K= \infty$, then non fading Channel. What is it, if $0<K<\infty$ ? If i represet ...
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40 views

On $H_\infty$ norm for transfer function

For a given scenario in the context of control system, I'm trying to investigate how the $H_\infty$ norm can be calculated for a transfer function as follows: $$G(s)= \frac{w_n^2}{s^2 +2\zeta w_ns +...
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117 views

On the transmit weight vector in MIMO-MRC systems

Recently, I am reading paper [1]. In this paper, the author wrote: In MIMO-MRC systems in the absence of interferers, the signal vector at the received $n_R$ antennas is given by $$\mathbf{r} = \...
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1answer
105 views

Using MIMO with DS-CDMA and spread spectrum

I have a question about using MIMO with DS-CDMA. suppose we are using 4 TX antennas, and 4 RX antennas, then the Reyleigh ...
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2answers
153 views

MU-MIMO Sensitivity to Line of Sight (LOS)

Why do researchers talk about MU-MIMO being "less sensitive to line of sight" / "LOS Okay"? For example in this video, time=[00:40,00:42] Similarly, "User separation based on spatial channel ...
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1answer
55 views

Channel direction

I am reading a book called Massive MIMO Networks: Spectral, Energy, and Hardware Efficiency, and it implies that $$\frac{\mathbf{h}}{\sqrt{\text{E}\left\{\|\mathbf{h}\|^2\right\}}}$$ is the channel ...
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1answer
631 views

What is the index modulation in OFDM and Subcarrier Index modulation?

I'm new here, I'd like to ask about the OFDM-IM (OFDM - Index modulation), what is it and how it works? Is it the same as SIM-OFDM? I checked white papers, I see it's using the index of sub-...
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1answer
930 views

Use of Long Training Field (LTF) of 802.11 standard

In 802.11a/n the preamble part has L-LTF(Legacy-Long Training Field) and HT-LTF(High Throughput-Long Training Field). I want to clarify my understanding of these two fields: Are the only difference ...