Questions tagged [communication-standard]
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34
questions
0
votes
2answers
54 views
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 ...
1
vote
1answer
39 views
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 ...
0
votes
0answers
27 views
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 ...
0
votes
1answer
67 views
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 ...
1
vote
1answer
106 views
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 ...
0
votes
1answer
53 views
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 ...
0
votes
1answer
23 views
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 ...
0
votes
0answers
12 views
How is CFi related to Code Rate and link Quality of the lte network?
Im trying to understand the relation between CFi and Code Rate and Quality of the network?
like if I have bad quality then we need to decrease CFi? what about Code Rate we need to increase?
About ...
0
votes
1answer
79 views
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 ...
0
votes
1answer
105 views
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 $1$) ...
-1
votes
1answer
31 views
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 ...
0
votes
1answer
725 views
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?
0
votes
1answer
253 views
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 ...
0
votes
1answer
73 views
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 ...
0
votes
1answer
123 views
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?
1
vote
1answer
157 views
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) ...
0
votes
1answer
124 views
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,...
1
vote
0answers
20 views
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 ...
0
votes
0answers
60 views
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 ...
0
votes
1answer
36 views
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 ...
-2
votes
2answers
76 views
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 ...
0
votes
0answers
183 views
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 ...
0
votes
3answers
133 views
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 ...
1
vote
2answers
6k views
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 (...
0
votes
1answer
560 views
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:
...
3
votes
3answers
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 ...
4
votes
2answers
83 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 ...
2
votes
2answers
6k views
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 ...
0
votes
2answers
1k views
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 ...
2
votes
1answer
234 views
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 ...
1
vote
0answers
189 views
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.
0
votes
1answer
730 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-...
3
votes
3answers
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 (...
-3
votes
1answer
2k views
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.
