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Questions tagged [fading-channel]

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2 answers
73 views

Channel impulse response (CIR) and OFDM relationship

In Chapter 3 of the [Goldsmith book] (https://faee.sut.ac.ir/Downloads/AcademicStaff/1/Courses/7/Andrea%20Goldsmith-Wireless%20Communications-Cambridge%20University%20Press%20(2005).pdf) we can see ...
0 votes
2 answers
3k 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 ...
1 vote
1 answer
46 views

frequency selective channel $\ne$ multi-tap channel?

A frequency selective wireless channel is necessarily a multi-tap channel, in the tap-delay line model, as the delay spread is significantly larger than the symbol duration. And a single-tap channel ...
0 votes
0 answers
23 views

Free space path loss and Rician fading

Let a be a qam symbols vector , they pass through ofdm modulator by applying ifft and adding cyclic prefix and I apply comm.RicianChannel function for modeling rician fading I want to introduce also ...
1 vote
2 answers
60 views

Understanding about correlation between random variables in context of Wireless Communication

I am trying to understand about correlation between random variables in context of wireless communication. In research papers related to 6G, I came across the following statements: Suppose there is a ...
0 votes
0 answers
18 views

Modeling channel for Multiple users using Rayleigh

I am trying to reproduce the results of a given paper using their approach and model. I have a difficult time understanding a statement in the paper and have doubts about how to interpret it. The ...
0 votes
0 answers
33 views

Understanding the additive white Gaussian noise (AWGN) representation

In my research work in wireless communication, I came across an equation of received signal wherein the AWGN is denoted by $n\sim\mathcal{C}\mathcal{N}(\textbf{0},\textbf{I}_L)$. Note that dimension ...
0 votes
0 answers
17 views

Related to dimension of wireless channel , transmitted signal and received signal

I am working on wireless research project and I had query in understanding dimensions. Consider a MIMO system, where a base station with $N$ antennas transmits signal $x$ to receiver with $M$ antennas....
0 votes
1 answer
48 views

Regarding SINR (Signal to Interference Plus Noise Ratio) in wireless communication

I am working on a research paper related to wireless communication, wherein I am facing some doubt while writing expression of SINR (which is a ratio of Signal variance in numerator to Interference ...
0 votes
0 answers
38 views

Related to SNR in wireless communication

I am working on a research paper related to wireless communication, wherein I am facing some doubt while writing expression of SNR (which is a ratio of Signal variance in numerator to Noise variance ...
0 votes
1 answer
165 views

Which are the realictic enviroment will be suitable for TDLC300 channel model?

TR 38.901 Section 7.7.2 mentioned that the TDL-A, TDL-B, and TDL-C channel models are constructed for NLOS scenarios. In TS 38.101-4 Annex B.2.1, in Table B.2.1.1-1 (picture is attached), delay ...
1 vote
1 answer
27 views

Transmit/receive signal of two-path propagation model

In wireless communication, when the transmitted signal is $x$ and the received signal is $y$. Please tell me why the formula below holds true. \begin{align} y(t) &= \left( e^{-\jmath 2\pi f_c\...
1 vote
0 answers
83 views

Channel equalization in uplink

I have a multiuser uplink signal $$ Y=h_1x_1+h_2x_2$$ where, $h_1$ and $h_2$ are channels for user 1 and user2 respectively. At the receiver how can I equalize the signal $Y$, assuming known $h_1$and $...
0 votes
1 answer
231 views

Rayleigh flat fading channel and pulse shaping

I'm trying to implement the Rayleigh flat fading channel in MATLAB using SRRC (Square-root raised cosine) pulse shape. The modulation scheme is BPSK. Here is my code: ...
0 votes
1 answer
81 views

Need information about following channel model

The following research paper is for blind channel equalization and the author has modeled the channel as 7 tap weights https://ieeexplore.ieee.org/document/1096877 On page 3 it has shown the ...
1 vote
2 answers
63 views

How to determine Transmission Rate for Task Offloading in edge computing?

I am new to communication systems and am working on a model for task offloading on edge computing. One key parameter I'm aiming to determine is the data transmission rate. While I am familiar with ...
0 votes
0 answers
98 views

How to calculate capacity using Shannon and path-loss?

I am working on tasks offloading on edge computing. I need to find the transmission delay, through calculating Shannon capacity-theoretical maximum data rate- when sending results from the server back ...
0 votes
1 answer
54 views

How to understand Fading Channel with no CSI at the Receiver

From the book Fundamentals of Massive MIMO, the section 2.3.4 shows that the expression of the received signal in fading channel with additive non-Gaussian noise and no CSI at receiver is dervied as: $...
1 vote
0 answers
53 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 ...
0 votes
1 answer
2k views

Rayleigh Fading Simulation

I have a question about simulating Rayleigh Fading channel. I know theory behind the Rayleigh channel and it is sum of two Gaussian random variable where the amplitude is Rayleigh distributed and the ...
0 votes
1 answer
618 views

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 ...
0 votes
2 answers
145 views

How do random processes add in Rayleigh fading to get a Guassian random process?

I was studying Rayleigh channels from Wireless Communications, Second Edition by Andreas F. Molisch. The book states that by adding different in-phase and quadrature components multipath components ...
5 votes
0 answers
138 views

Capacity of channels with pilots?

Question is about "channel capacity". I guess it is pretty elementary for experts, however I have not seen it discussed in e.g. Proakis book or Tse "Fundamentals of Wireless Com". ...
1 vote
3 answers
82 views

which type of diversity is used by rake receivers?

My question is: Which type of diversity technique is used by the rake receivers? In Bahai, et. al. "Multi-Carrier Digital Communications Theory and Applications of OFDM," Second Edition, ...
2 votes
1 answer
1k views

How to code Rician fading channel gains from k-factor?

I know that MATLAB provides some built-in functions but I am not interested in those. I want to know how can we code to obtain the Rician fading channel gains from normal or Gaussian distributions. ...
-1 votes
2 answers
422 views

Elevation angle or Azimuth angle?

Suppose my ULA(Uniform Linear Array) is along x-axis only, then definitely we can estimate elevation angle with this ULA. But if we lift this array from x-axis and place it along y-axis, then which ...
3 votes
1 answer
239 views

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 ...
1 vote
2 answers
3k views

what does mean quasi-static channel [closed]

When I read papers about channels, I usually see something Quasi-static Channel, Does "Quasi-static Channel" mean "time-variant channel" or "time-invariant channel"?
0 votes
0 answers
119 views

What is physical significance of Bit Error Rate (BER) and Outage Probability?

I am trying to understand the physical significance of Bit Error Rate (BER) and Outage Probability especially in low power wireless communication such as internet of things (IoT). Any help in this ...
0 votes
1 answer
172 views

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 $...
0 votes
2 answers
36 views

$\min(\{Z_i\})$ for non-i.i.d. random variables $Z_i$ the same as for i.i.d.?

My question is with reference to wireless communication. There are $N$ independent and identically distributed random channels i.e., $Z_i \in \{ Z_1, Z_2,\ldots, Z_N\}$ with PDFs $f_{Z_i}(z)$ ordered ...
0 votes
1 answer
43 views

Order statistics: always applicable tool in wireless communication?

I have seen few papers where generalized order statistics is used to obtain statistics of the instantaneous SNR. "Performance analysis of monostatic multi-tag backscatter systems with general ...
0 votes
0 answers
75 views

Related to wireless channel variance?

I am reading wireless research papers and found that mostly the wireless channel is considered to be Zero mean circularly symmetric Complex Gaussian (ZMCSCG) with variance 1 or 2 or 5 or 10 etc. My ...
1 vote
1 answer
57 views

Understanding Pathloss and latency

In my class on wireless communication, I came across the following sentence: The round trip path-loss can be defined to include aspects such as attenuation and/or latency etc Hence I am looking for ...
0 votes
0 answers
70 views

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. ...
-1 votes
2 answers
100 views

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 ...
0 votes
1 answer
32 views

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 ...
5 votes
2 answers
132 views

Actual measurements of the influence of fading and multipath on HF radio communication

I'm looking for papers or books that contain actual measurements of the influence one has to expect in HF radio communication. I'm interested in this, because i've simulated the influence of a ...
1 vote
1 answer
127 views

channel estimation for cdma

I am looking for a method to make a multi-user channel estimation with CDMA. Here is my question: Is there a way to estimate multi-user channels with their spreading codes? If yes, what is the ...
0 votes
1 answer
520 views

Flat vs frequency selective fading in MC-CDMA?

I am trying to simulate an MC-CDMA system. I have NXK matrix $S$ which consists of subcarriers ($s_n,_k$ represents subcarrier $n$ of user $k$) and KX1 vector $X$ consists of user symbols. So my ...
1 vote
2 answers
503 views

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, ...
-1 votes
1 answer
241 views

Performance evaluation in terms of channel MSE and BER

The first figure on the left (in this paper) provides the channel NMSE performance and the the second figure from left provides detector's BER performance. I am curious, when the channel MSE ...
0 votes
1 answer
433 views

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.
0 votes
0 answers
73 views

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 ...
1 vote
0 answers
50 views

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)\...
2 votes
2 answers
227 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 ...
1 vote
1 answer
60 views

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 ...
0 votes
3 answers
17k views

Matlab: Correct method of generating Rayleigh fading channel

A Rayleigh flat fading channel has 1 tap and so there will be no intersymbol interference. if N= 1000; Then, h=(1/sqrt(2))*(randn(N,1)+1i*randn(N,1)); will ...
0 votes
0 answers
101 views

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 ...
0 votes
1 answer
33 views

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}...