Questions tagged [fading-channel]

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Understanding mathematical representation of SINR

I am getting confused in SINR for the following received signal expression. $$y(n) = (h+fg)s(n) + w(n) \tag{1}$$ Where $h,f,g$ are zero mean circularly symmetric Complex Gaussian (ZMCSCG) channels. ...
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How to express signal to noise ratio (SNR) of the following equation

I am trying to obtain SNR of the following received signal but not getting it correctly. $y(n) = [(h_q^{SR}+\textbf{h}_q^{TR}\textbf{G})s(n)+w_q(n)]^Q$ ----(1) where $G$ is $M \times M$ diagonal ...
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Why the transpose of wireless channel vector is taken in SIMO system?

I am getting confused about the received signal expression in case of SIMO wireless channel. SIMO system=> Here we will have one antenna at Tx and multiple ($N$) antenna at Rx. Therefore received ...
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Why exponential decay power delay profiles are used to model fading?

I am trying to understand why exponential decay power delay profiles are used to model fading. In other words, why power of taps of channel impulse response decays exponentially and not, for instance, ...
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Derivation of Clarke's Doppler power spectral density

I am reading Wireless Communications by Andrea Goldsmith. I have some issues in the derivation of Clarke's Doppler power spectral density given there. 1)For beginning the autocorrelation of the in ...
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Derivation of equation 3.8 in Fundamentals of Wireless Communication by Tse and Vishwanath

In the book “Fundamentals of Wireless communication”by Tse and Vishwanath, Can someone help with the how the integration helps derive equation 3.8 ? The equation is $$ p_e= \mathbb P\left\{\left\lvert ...
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How to resolve some inconsistencies in the mathematical model for the narrowband fading channel?

I am reading Wireless Communications by Andrea Goldsmith. There the author mentions that for narrow band channel the received signal can be given as: $$r(t)=\text{Re} \left\{u(t)\text{exp}(j2\pi f_ct)\...
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On-Off keying for wireless communication channel estimation

Let us assume I have $k$ (a fixed number) sensors in a wireless sensor network with unknown channel statistics $\{h_1,h_2 \ldots, h_k\}$. In my system model, each of these $k$ sensors has an ...
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Coherent detection in fading channel

I want to design an optimum receiver for a fading AWGN channel for ML Detection. I know that in the case of non-coherent communication we have to use an energy detector(even when the fading channel is ...
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Log Path Loss Model with Directivity Accounted

Suppose that I have the log Path Loss distance model described here https://en.wikipedia.org/wiki/Log-distance_path_loss_model $$PL(d,\gamma) = P_{t}-P_{r}=PL_{0}+10\gamma log_{10}\frac{d}{d_{0}}+X_{g}...
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Relation between SNR and fading channel coefficients?

I am trying to understand the following thing: Does the average signal to noise ratio (SNR) depends on fading channel coefficients ? Any help in this regard will be highly appreciated.
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Related to successive interference cancellation?

I am trying to understand the following query: " Is it necessary to do channel estimation to perform successive interference cancellation at the receiver operating over fading channel" Any ...
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What are TDL and CDL channel models in principle, and which variation can be used for indoor and outdoor environment, respectively?

I am making a simulation using 5G-toolbox in Matlab. IN 5Gtoolbox we have two kind of channels, CDLChannel and TDLChannel. Now, CDL means Clusteresd Delay Line, and TDL means Tapped Delay Lines. But ...
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Frame synchronization for single carrier burst applications in fading channels

I recently started to implement communication systems with software-defined radios in GNU Radio. In my system design, I am planning to transmit data in burst mode, the frames will be not sequentially ...
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Log-normal shadowing and mean power

Let's assume I'm receiving a signal with power measured in dBm shadowed according to the normal distribution, i.e. $P_{\text{dBm}} \sim N(0,1) $. If there is also a normally distributed noise power $...
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Rayleigh Fading

I am calculating the capacity of $K$ channels between a transmitter and $N$ receivers in a cellular scenario. I use the following equation: $$C_n^k = B\log_2\left(1 + \frac{Ph_n^k}{N_0B + I_n^k}\right)...
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Related to channel power gain

I am having a doubt that why channel power gain is denoted by $|h|^2$. For example, if the signal received is $$y(n) = hx(n)+w(n)$$ where $x(n)$ is transmitted signal with power $P$ , $w(n)$ is AWGN ...
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How is the distribution of the received signal affected if the transmitted signal is changed from complex Gaussian to PSK

Suppose the received signal is $y(n) = h_0s(n)+w(n)$----(1) Where $h_0, s(n), w(n)$ all are distributed as zero mean complex Gaussian. Thus I know that $y(n)$ will also have the same distribution. If $...
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understanding the distribution of received signal

In one of the research paper following equations are given : $y(n) = h_0s(n)+w(n),d = 0$ $y(n) = h_1s(n)+w(n),d = 1$ where $n$ ranges from $1$ to $N$ and $h_0,h_1$ are wireless channel assumed as $\...
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Related to wireless channel fading

I am reading some papers wherein a wireless channel is assumed as zero mean circularly symmetric complex Gaussian (ZMCSCG) with unit variance and it is also mentioned that the channel undergoes ...
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related to random nature of wireless channel

I am reading An Approximate BER Analysis for Ambient Backscatter Communication Systems With Tag Selection wherein it is mentioned that "when the distance between two nodes is very small and line ...
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What is the meaning of the channel gain is normalized

Transmitting the signal $x$ over the channel $h$ and affected by noise $n$ can be expressed: $y = hx + n$ $h$ is the channel gain, that is known for me. I sometimes see phrases saying "when the ...
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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 ...
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How is channel frequency response/channel state information related to free space path loss?

As we know, the path loss can be described by the equation as $$ \frac{P_{r}}{P_{t}}=D_{t} D_{r}\left(\frac{\lambda}{4 \pi d}\right)^{2} $$ In the OFDM system, such as Wi-Fi, there are infinite paths ...
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About discrete time model for wireless channel

I am trying to understand Section 2.2.3 of the book "Fundamentals of wireless communication" by Tse and Viswanath. In this section the authors explain how to go from the continuous time ...
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Received signal's power under Raleigh fading

I am trying to understand how to calculate the power of a received signal under Raleigh fading. What I gather is that the Rayleigh fading is a complex Gaussian random variable and that the multipath ...
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Zero padding OFDM equalization

In ZP-OFDM, The convolution is linear. it's different from CP-OFDM which is circular convolution leading to have one tap equalizer in frequency domain. if I have a ZP-OFDM system, and we have a signal ...
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1 vote
1 answer
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Fast/Slow Fading: How are doppler shift and coherence time related?

In the literature I've read that fast fading happens if the bit duration is larger than the coherence time of the channel. The coherence time of a channel is proportional to $\frac{1}{f_{Doppler}}$. ...
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Non Coherent BPSK with no Channel State Information at the receiver

Where or what is the proof for the failure of BPSK in fading channel when we have no knowledge of the fading coefficient $h$ at the receiver in the equation $y=hx+w$, where $x$ is BPSK symbol equally ...
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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 ...
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Correlated fading channel: transmit and receive antenna correlation matrices

I am trying to create a non-i.i.d channel: correlated Rayleigh fading channel. $$ H= R_H \cdot H_o,$$ where $H_o$ is i.i.d. channel ( uncorrelated) and $ R_H$ is a channel correlation matrix, is ...
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1 vote
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Degrees of freedom in coding (for a communication channel)

I was reading on my lecture slides about how to achieve diversity (i.e. transmit more copies of the same message in order to avoid its corruption; this technique may be realized by repeating the ...
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Rayleigh fading channel as a scalar quantity [closed]

In most cases rayleigh channel is a vector. can a rayleigh channel be a scalar quantity i.e., can we have only one element in rayleigh fading channel.
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Is time varying channels same as circulary symmetric complex gaussian?

From the literature i understood that if the channel is non time varying then we can consider it as circularly symmetric complex gaussian distributed. So can we consider the same if the channel is ...
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Hf ionospheric channel model for large bandwidth

I know some models like the Watterson model for HF ionospheric channels but those are limited to narrow band frequencies. Are there some models to bandwidth like 12kHz up to 24 kHz?
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1 vote
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Detect orthogonal sequence with fading

For a set of $N$ orthogonal sequences $\textbf{A}^i = \{a_1^i,a_2^i,...,a_M^i\}, i =1 ..N$, the detection of these sequences can be done by calculating the inner product (dot product) of receive ...
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Is MMSE equalizer necessary?

For observation $y$, channel coefficient $h$ and gaussian noise $w \sim \mathcal{CN}(0,\sigma^2)$, $$y = hx + w \tag{1}$$ Note that for OFDM system, (1) is assumed channel input-ouput equation on ...
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Meaning: channel unknown and known at the transmiiter

What does "channel unknown" and "known at the transmitter" mean? In books about signal processing, it has always mentioned it if capacity or transmission (estimation) is discussed. I can't understand ...
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Why are the following two packet reception probabilities different?

https://www3.nd.edu/~mhaenggi/pubs/broadnets04.pdf In 3 page of this paper, the packet reception probability without interference is $e^{-\theta N Ad^2/ P}$. $\theta$ is sinr threshold. $N$ is a ...
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why if I want to create a rayleigh fading channel with $E[|H_{i,j}|^2]$,I should multiply $\sqrt{\frac{1}{N_R \times N_T}}$?

I want to create a rayleigh fading channel,and my classmate told me that I can create an $N_R \times N_T $ channel $\mathbf H$ with $E[|H_{i,j}|^2]$,that is,$\sqrt{\frac{1}{N_R \times N_T}}\times CN(0,...
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Small Scale Fading time varying or position varying

I would like to ask how small scale fading can affect a transmission with time. The particular system is an antenna transmitting an ASK modulated signal at 915MHz and with bandwidth between 200KHz to ...
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2 votes
2 answers
120 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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Two different models of Rician fading

The amplitude of the signal in Rician fading case is characterized by the Rician distribution (let's call this model 1). However, the received power in Rician fading is sometimes modelled as (model 2)...
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channel gain calculation

I want to calculate the SINR term in an up-link of wireless communication system but there is different models for simulation. I want to know what is the exact meaning of $|h|^2$ in this formula: $\...
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2 answers
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Detecting multi-path propagation when one acoustic signal is dominant

I am sending an acoustic signal from a source to a receiver where there are limited number of paths the signal can travel. I want to detect if there has been multipath propagation or not when one path ...
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Assessing relative wireless channel quality using Capacity and Condition Number CDFs

I have Channel capacity analysis figures for two wireless channels show below: My question: While ergodic capacity in the first subplots are very clear in conveying the channel capacity, How to make ...
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Validating Jakes model in Rayleigh Fading channels

I am trying to validate the Jakes model by comparing the autocorrelation function given by $ \rho(\Delta t ) = J_{0}(2 \pi f_{d} \Delta t)$, where $ f_{d} $ is the maximum Doppler shift, $ J_{0} $ is ...
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-1 votes
1 answer
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What's the effect of spread spectrum on frequency- selective channel

In brief, we consider the channel as frequency-selective channel if the frequency of the signal is larger than then frequency of channel. So, does using the spreading spectrum change the frequency-...
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3 votes
3 answers
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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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BER of QPSK modulation in Rayleigh fading channel model

i am having trouble deriving a BER analytical expression for QPSK modulation system operating in a Rayleigh Fading channel model. Could anyone direct me to a reference that would help in this matter. ...
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