# Questions tagged [channel-estimation]

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### Least Squares Solution Using the DFT vs Wiener-Hopf Equations

Least Squares channel estimation (or equalization) can be accomplished using the "Wiener Hopf Equations", or the Discrete Fourier Transform. Both appear to be least squares solutions. How do ...
• 53.8k
361 views

### System Identification with a Limited Bandwidth Input Signal and Region of Interest

Given a FIR filter $h[n]$. Its action can described as: $$\mathbf{y} = \mathbf{H} \mathbf{x} \\ \mathbf{y} = \mathbf{X} \mathbf{h}$$ where $\mathbf{H}$ and $\mathbf{X}$ is a Toeplitz matrix. If $h$...
• 473
221 views

### Fractionally spaced equalizer using LMS algorithm

I am doing a project about the fractionally spaced equalizers on matlab. The goal is to mitigate ISI on the signal using the LMS algorithm to update the tap weights of the FSE. Below i have uploaded ...
• 81
2k views

### How determine the delay in my signal practically

I am trying to practically determine filter group delay so that I can try to reduce or adjust for it. I have tried all kinds of methods but still can't get the right result. I know that theoretically ...
• 93
73 views

### OFDM channel estimation using the transmitted signal multiplied with a matrix

I have OFDM system, where the modulated signal $x$ with length $N$, and $N$ is the number of subcarriers in OFDM symbol. $x$ is multiplied with a well-known unitary matrix $G \in N \times N$ before ...
• 317
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### Time-domain channel estimation using identical guard interval vectors

Assuming we have the received signal $y = h * x$ where $*$ is circular convolution, $x$ is the transmitted signal, $y$ is the received signal and $h$ is frequency selective channel. The signal $x$ is ...
• 317
1 vote
165 views

### Why SRS signalling is used in 5g?

Since DMRS is also being used as a reference signal in PUCCH and PUSCH channel, so why an extra SRS signalling is required.
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1 vote
96 views

### Capacity and channel estimation algorithms: explanation of results

I study a spectral efficiency of a system with a precoding scheme with different channel schemes. Algorithm A for channel estimation gives a smaller estimation error instead of Algorithm B. I have ...
1 vote
89 views

### LTE PSS Channel Estimation for coarse SSS Equalization

In LTE the Primary Synchronisation Signal (PSS) can be detected by taking a correlation with the known 3 zadoff chu sequences (roots: 25,29,34). Once the peak has been detected the receiver knows ...
1 vote
278 views

### LTE Channel Estimation

I am trying understand LTE channel estimation. I have multiple questions: How much phase shift does a typical LTE channel have? Can all that be corrected using pilots? Where do we typically implement ...
• 15
1 vote
202 views

### A Delay Between Two Filtered Chaotic Signals

it is a common practice to use a shift of cross-correlation peak to evaluate a group time delay of two signals (chaotic signals are included). Can one synchronously and equally filter these chaotic ...
• 17
1 vote
157 views

### Calculation of the LMMSE Channel Estimator

Consider a MIMO system equipped with $N_t$ transmit antennas and $N_r$ receive antennas. The received signal over $L$ snapshots are given by $$Y = H X + Z,$$ where $X$ is the $N_t \times L$ transmited ...
1 vote
201 views

### 5G strandard pilot allocation, channel estimation method

I'm trying to create an OFDM simulation, but I don't know the 5G standard pilot allocation estimation method. Is this simulation good? One transmission unit has $64$ subcarriers and $14$ OFDM symbols. ...
1 vote
125 views

### Perfect channel estimation for OFDM (via H=Y/X) in MATLAB

Despite using the same channel for convolution, each time I get a different estimated channel. Could you please tell me what I'm doing wrong? I want to demonstrate that I can estimate the same channel ...
• 13
1 vote
92 views

### Channel estimation using bit reversed order of FFT matrix

Is it possible to use the bit-reverse order of FFT instead of FFT to estimate the channel? Based on my reading, I found that bit reversed order of FFT matrix can diagonalize the channel, but ...
• 639
1 vote
142 views

### Eigen Beamforming: Explanation [closed]

It's been a few days that I have been searching the term eigen beamforming, but still haven't get any satisfactory literature reference. It would be great if you could give any details or point to any ...
• 135
1 vote
57 views

### fractionally spaced channel equalizer code [closed]

I want to write a program in matlab for an adaptive fractionally spaced equalizer with lms algorithm.consider each packet with 150 bits that 25 first bits are pilot and used to train weights of the ...
• 11
1 vote
201 views

### Mapping from Antenna ports to Antenna Elements 5G NR

I have a question related to CSI-RS channel estimation. Let us assume that the base station has 64 antennas and we decide to use 32 antenna ports for CSI-RS transmission. Also, UE has 4 antennas. My ...
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1 vote
89 views

### Compressive sensing based sparse vector estimation

I am newbie in compressive sensing (CS), I read about compressive sensing and its use for sparse vector estimation. As I understood CS can be used either in time or frequency domain. For me, The part ...
• 618
786 views

### How to reliably compute the group delay of a comb filter

I applied the following FIR comb filter in real-time: y[n]=x[n]-x[n-40] Since this is an FIR, the group delay is D=(N-1)/2=20 samples. After applying the filter ...
• 93
79 views

### Radar Signal Modelling based on Channel Estimation

I am a newcomer to digital signal processing. Recently, I have been interested in this question: If we model a reflected radar signal from a target as $$y(t)=h \ast x(t) + n(t),$$ where $h$ is a ...
• 37
94 views

### Numerical Stability for Channel Estimation

In this post: Compensating Loudspeaker frequency response in an audio signal I derive the Wiener-Hopf equations for least squares equalization (and channel estimation if we swap Tx and Rx) from the ...
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86 views

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### Obtaining perfect channel estimates in simulated channel estimation

In SISO systems of OFDM, I am interested in applying deep learning for channel estimation, but I am unsure of how to obtain perfect channel estimation as the label in simulations. If you have any ...
• 1
66 views

### QPSK Channel Detection Algorithm

I send a QPSK signal over pluto sdr and receive it from rtlsdr. As you can see from the screenshot below SNR of the received signal is very high, and the signal is very distinguishable. Hence, it is ...
• 125
40 views

### Is there any sampling offset when using external reference signal

I perform real experimental tests for optical communications using DCO-OFDM. The transmitted signal is uploaded into an AWG (arbitrary waveform generator), then bias (2.5 V) is added before adopting ...
• 317
147 views

### Tapped Delay Line channel model in wireless communication

Can someone explain the difference between tdl (Tapped Delay Line) -a , tdl-b and tdl-c and their use cases?
67 views

I have a doubt regarding Pilot signals such as CSI-RS in NR. Using a large number of CSI-RS affects Datarate significantly? or it is negligible? Because I wonder it is meaningful that optimize the ...
125 views

### Generating a 2D delay-Doppler channel matrix

I was wondering if anyone here has any idea on 2D delay-Doppler channel and how to generate the channel matrix? Even a hint or a resource would be helpful. I just want to understand and visualize the ...
122 views

### Unstable Phase in Channel Impulse Response

I'm using DW1000 UWB radio transceiver and extract its channel impulse response (CIR). The CIR output by the transceiver is the complex baseband CIR. In a static environment, the CIR is a LTI filter ...
64 views

### Unable to estimate for AR model using OLS, Yule Walker and MLE

I am learning estimation methods following the book of Steven Kay, "Fundamentals of Statistical Processing, Volume I: Estimation Theory " Theory says that if the measurement noise is ...
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97 views

### channel estimation based on time-domain pillots

I am confused if it's possible to estimate the channel based on the time-domain pilots. I mean I have such signal $x$ with length $N$ after taking its $iFFT$ we get $X = ifft(x)$. I have perfect ...
• 618
446 views

### Calculation of channel autocorrelation for LMMSE

I am currently trying to implement an LMMSE estimator/equalizer for a python based ofdm receiver. The actual reception is done with a SDR and iq-samples are stored in a file for the "ofdm-receiver" ...
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### Can someone explain or elaborate on the channel estimation and noise variance estimation algorithms used in HF receiver?

For different type of communication, there is different type of algorithms to acquire CSI. For instance 4G (LTE) network have SRS or DMRS to estimate the channel based on pilots. I am designing a ...
• 315
1k views

### Understanding MMSE equalizer equation

I have read many online materials and journal paper where the equation for MMSE equalizer is given as: $G_{MMSE}$ = $H^H(HH^H+\nu^2I )$ where $H$ is the channel, $H^H$ is its hermitian. $\nu^2$ is ...
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