Questions tagged [communication-standard]

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Why the 1L array gives worse result than circular array?

If we place antennas along x-axis and y-axis to make 1L-shaped array and find DOAs(Azimuth and Elevation angles) with it using MUSIC algorithm and then if we place the same antennas in a circle to ...
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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 ...
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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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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 ...
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What are the features/aspects/characteristics of any signal?

When Signal Processing experts measure signals, what are the features they measure in minimum (true to all signals)? Time (discrete/continuous) Amplitude/magnitude/value (discrete/continuous) ...
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OFDM Query : Why In Phase and Quadrature Phase RF Conversion is needed? [duplicate]

OFDM Basic Query- x[n] produced at output of IFFT is in discrete time, so we can use DAC and then RF Upconversion (multiply it with LO Frequency say f) and send it, why are we doing RF up conversion ...
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Did Dialup Modem use closed or open loop power/volume control? How did they determine Tx level?

I have been reading about dialup modems, but one thing I cannot seem to find out about is how implementers determined optimal transmit power/volume. Is this part of the echo cancelation framework? The ...
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NR PUSCH non-codebook based precoding

While reading 3gpp 38.211, Chapter 6.3.1.5 I noticed For non-codebook-based transmission, the precoding matrix equals the identity matrix. So, I guess, non-codebook-based precoding shall be ...
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5G uplink switching from CP OFDM to DFT-s-OFDM

5g NR standards can allow for both CP-OFDM and DFT-s-OFDM in the uplink. Suppose a UE is allocated resources. Can the UE switch from CP-OFDM to DFT-s-OFDM from one slot to the next ? Are these ...
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In wireless communications, is it true to say: The more the range, the more the delay spread?

The general idea which can be drawn by reviewing wireless channel models says that the longer the range/distance, the more the delay spread, even in LOS microwave links. But I really wonder why it is ...
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How to find the bandwidth of the transmitted M-FSK signal?

I'm tried to find the solution, but I failed. my question in the figure below, and the correct answer it's shown at the end of Figure. I'm using this formula but the answer is not correct! Is there ...
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Analysis Received Signal at receiver side

I'm trying to understand something which is really confusing me and I made my best to understand it but still confused. If I have transmitted and receiver. Assume I want to transmit S(t) data and ...
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Viterbi decoder K=3 using ADD-COMPARE-SELECT Operation

I am in trouble with Viterbi decoder for a while. I have some questions. I need to decode messages from a continuous stream which is encoded. I'm reading from book : digital communications bernard ...
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Transition table / matrix for convolutional encoder K=3 understandings

Im trying to understand convolutional encoder $K=3$ , and I almost understand it but still confused about what's called transition matrix which in other words it means what input value ($0$ or $1$) ...
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Cross corelation understanding -Digital Signal Communications (searching for specific vector inside the other vector)

I have two vectors , one called v1 and the other v2 , the size of v1 is 10k , and the other v2's size is 32 , I want to search inside the vector v1 if there's v2 , this means when I find that the ...
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Combiner vs mixer vs coupler?

All these three terms are often used in communication texts and apparently they are some how similar But what is exact difference between each of them?
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Serial to Parallel Converter

in many texts about modulators I have seen there is a component called "Serial to Parallel Converter". For instance, let's consider this scheme and let's focus on the second block (reference): The ...
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WiFi Channelization for 40, 80 and 160 MHz

I have some questions on WiFi channelization in 802.11n and 802.11ac. Here is the snip of List of WiFi channels (source: WiKi): I am working on the L1 layer for 802.11n and 802.11ac model where I am ...
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Hilbert transform Use as a Single Sideband Frequency Translator in Analog communication

How Hilbert transform helps us in communication? What is the practical significance of it? Specifically how is the Hilbert Transform used to create single side-band frequency translators?
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What is the forward error correction in 802.11a?

I am trying to put together a baseband-equivalent simulation of 802.11a signals, which according to Wikipedia has a variable encoding (PSK, QAM, etc.) that have differing coding rates (1/2, 2/3, 3/4) ...
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Is the path loss exponent $\alpha$ is always 2 in friis equation model?

In the friis equation, the reference distance is 1m at the log distance path loss. Then the formula would be: $$P_r = P_tA_rA_t(\lambda/(4\pi))^2 /d^\alpha$$ where $d$ is distance between terminals,...
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Convolutional coding that payload length does not change

This is the question about Sigfox radio specification. The stack: Specifically, in Section 3.10 of the specification, we have a convolutional coding (after CRC) with three possible polynominals. I ...
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How can 802.11p ensure 1 Mbps in 1 km range?

Using the 802.11p standard, mobile vehicles can communicate each other. IEEE 802.11p standard typically uses channels of 10 MHz bandwidth in the 5.9 GHz band (5.850-5.925 GHz). And the transmission ...
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Radio Signal Stationarity

A radio signal recording of a wireless communication system (e.g: Wi-Fi traffic) is beaconized, channelized and subject to noise. When working with such an RF signal, numerically transformed to a ...
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What is Received power value when distance value is 0 in Friis equation [closed]

The Friis equation is as follow. $$P_r = P_tA_rA_t(\lambda/(4\pi d))^\alpha$$ where $d$ is distance between terminals, $P_r$ is received power, $P_t$ is transmission power, $A_r, A_t$ are the rx, tx ...
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No. of Cyclic prefix for 5G NR signal with 100Mhz bandwidth different subcarrier spacing?

I want to generate a 100Mhz bandwidth 5G NR signal with different subcarrier spacing(15,30,60,120Khz) in matlab. What is the no. of CP to be added for 1st OFDM symbol and the other symbols and also ...
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3 answers
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Quality of experience engineer

I have noticed certain overlap between digital signal processing and quality assurance for jobs that require expertise in evaluating the quality of the transmitted signals on telecommunication systems ...
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What is the difference between Antenna port and Physical Antenna in LTE?

I have just started working on the 5G NR physical layer and I have difficulty understanding the concept of Antenna Port at the downlink. In release 10 there supposedly 15-22 antenna ports for CSIRS (...
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File size adjustment using FFT

I have been given the task of doing audio compression using FFT. The assignment is below. Below is my MATLAB code: ...
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3 answers
6k views

Capacity of cascade binary symmetric channels

Let's imagine that we have interconnected in cascade $L$ binary symmetric channels each with the same transition probability $p(y|x) \in \{p, q=1-p\}$, where the output of each BSC is connected to the ...
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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 ...
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2 answers
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System Frame Number in LTE Specifications

What exactly is System Frame Number in LTE specifications? What is the use of it? I have read that it is a 10 bit number and used for synchronization purposes. But it's not clear how it helps for ...
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2 answers
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Difference between diversity gain and coding gain

I am reading about space-time codes. They break down further into 2 sub categories called space-time trellis codes and space-time block codes. It says that trellis codes offer both diversity and ...
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1 answer
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P2 symbol constellation in DVB-T2

DVB-T2, 32K SISO, not extended. I've acquired P2 symbol, PRBS bits have matched with bits recovered from pilots. Then equalization was applied to all subcarriers. The constellation I've got looks ...
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How often do a LTE eNodeB scheduler schedule?

Scheduler schedules the resource for each UE. How often do a LTE eNodeB scheduler schedule? Is the time between each scheduling fixed? any idea/reference will be great help on this regard. Thanks.
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748 views

Transport Block calculation in LTE Downlink

I would like to understand the relation between the TB size calculation in the TS36.213 document and in the simulator (https://www.nt.tuwien.ac.at/research/mobile-communications/vienna-lte-a-...
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3 votes
3 answers
2k views

How to determine the FFT size of LTE downlink receiver?

I'm puzzled about the LTE FFT size. Assuming an LTE base station works at 20M mode, the FFT size is 2048. Then, many users can be served by this base station. Do all these users work at 20M mode (...
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Why 1536 FFT size for 15 MHz in LTE

Why we use 1536 point FFT for 15 MHz bandwidth, when we can use 1024 point FFT, as in bandwidth of 15 MHz we have only 900 subcarriers.
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