# Questions tagged [channel-estimation]

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### 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 ...
• 85
1 vote
30 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 ...
• 11
17 views

### How to proprely rescale measured channel statistics

I’ve got a vector of measured instantaneous power at the receiver side. The vector is normalized in a way that the average is 1W. Now I would like to apply this vector to my channel model to check if ...
• 63
79 views

### Pilot-based channel estimation in OFDM systems with fractional delays

Most studies on OFDM-based communication systems consider that multipath channels consists of a limited set of taps in the discrete-time domain. However, this only holds if the tap delay is a multiple ...
34 views

### Do you recommend a textbook on channel estimation of narrowband communications?

I would like to learn the channel estimation of narrowband communications (i.e., not OFDM). Do you recommend a textbook (chapter from a textbook) on this subject?
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### 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?
37 views

### I am trying to estimate the Channel Impulse Response(time domain) for a 5G-NR signal using the DMRS-PBCH pilots only , any suggestions

I want to obtain the $h(t)$, the channel impulse response for my NR signal using the DMRS PBCH pilots only.
• 1
39 views

### Pilot Signal Overhead

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 ...
68 views

### Do the effects of OFDM pilot tones spacing appear in time or in frequency domain?

As known, the pilot tones are transmitted via subcarriers predefined and known in the transmitter and the receiver. The pilot spacing is repeated with a certain rate that depends on how fast the ...
• 570
32 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 ...
366 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 ...
• 15
57 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 ...
80 views

### bit reversed order of FFT matrix for channel estimation

Although the question seems similar to this one HERE, but what I want to ask about is little bit different. Assume we have a signal $X$ whose length is $N$x$1$, we convert that signal into time ...
• 649
1 vote
61 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 ...
• 649
69 views

### time-domain channel estimation based on two vectors optimization

Let's the input data vector $X = [X_1, X_2, X_3, X_4, X_5,X_6,X_7,X_8];$ where $[X_7,X_8]$ are well known, and the vector $y = h*X$ where $*$ is the convolution operation and $h = [h_1,h_2]$ is the ...
• 570
113 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 ...
• 649
55 views

### Multipath channel estimation in single carrier modulation

I think it’s a basic question, but I couldn’t get it’s clear answer. If we have data symbols $x$ vector of length $N$ x $1$ ; it’s convoluted with a multipath channel $h$ of length $L$ x $1$; the ...
• 570
54 views

### What can be a limit to the maximum possible power of a pilot signal

In practice, what can be a limit to the maximum power of a pilot signal in wireless communication?
• 45
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### 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 ...
• 311
1 vote
108 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.
• 11
1 vote
85 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
80 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 ...
• 570
58 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 ...
• 570
194 views

### Should we upsample the channel when upsample the signal

I have an OFDM system with Number of sub-carriers $N= 1024$, modulated data using $QAM$ modulation is transmitted via those subcarriers as follows: ...
• 570
171 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" ...
• 25
1 vote
125 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
279 views

### OFDM pilot allocation block type and comb type

As known, the pilot insertion in OFDM can be either bock type or comb type, I think comb type is appropriate for double-selective channel while block type is for frequency selective channel: In the ...
• 570
47 views

### 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 ...
• 145
1 vote
135 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
735 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 ...
• 83
547 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 ...
• 83
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 $h$...