Questions tagged [lte]
The lte tag has no usage guidance.
33
questions
0
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1answer
28 views
Why do we need >= 95% throughput for LTE Sensitivity measurement according to 3GPP
According to 3GPP 36 series for LTE, for LTE Sensitivity measurements we need >=95% throughput. How is this 95% value determined? Why it is not 98% or 88%.
Thanks in Advance!
0
votes
1answer
45 views
Why is beamforming needed in 5G?
With the advent of 5G Era, base station density
increases, the cell radius decreases, and LOS propagation
gets more dominant. So, why do we need for beamforming in 5G NR, although we have smaller ...
0
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0answers
28 views
Why is NOMA needed in 5G?
Although there is wide band spectrum in 5G from 6GHz to 300 GHz, why is NOMA needed in 5G to enhance spectrum efficiency. We can communicate in different frequencies since we have very large band. Are ...
0
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0answers
22 views
How LTE/5g receiver align phase?
I am trying to demodulate a captured 5g signal using matlab.
But it is likely that the 0-phase time point for each symbol lays between two samples,
which results in a minor phase shift, and such phase ...
0
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0answers
22 views
Retrieving OFDM-based time-domain data from resource grid data in MATLAB
I need to simulate an OFDM-based transmit-channel-receive link in MATLAB and obtain a BER vs SNR curve using the received data. I am using functions from the LTE toolbox. I have been following the ...
0
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1answer
70 views
4G LTE Sampling Frequency Offset
Could someone please explain how the 4G LTE OFDM measures and corrects the sampling frequency offset?
I can see a number of algorithms proposed in the literature, but I am trying narrow it down to the ...
0
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0answers
21 views
Resource block size in freq-selective channel
I asked about the basic of a frequency selective channel [here][1]. It was discussed Resource block (adjacent subcarriers and time indices together into "chunks")
what parameters affect the ...
0
votes
1answer
18 views
What is role of BW and frequency in internet speeds?
First the bandwidth (BW):
It is the amount of data that can be transferred simultaneously.just like more no. of highway lanes so that many cars can travel side by side simultaneously.
Frequency
It ...
1
vote
1answer
51 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 ...
0
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0answers
16 views
What is the QPSK Constellation Diagram used in LTE
I think the question is pretty straightforward. I have to do a class project that requires me to modulate a signal, and one of the steps is Quadrature Phase Shift Keying (QPSK). It is to be done in ...
0
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0answers
40 views
Obtain SIB1 messages from CPRI the captured DL IQ data
I am a beginner in the signal processing, and I know some python and I have a project I'm working on which is about Obtaining SIB1 messages from CPRI the captured DL IQ data.
I have captured some DL ...
0
votes
1answer
41 views
LTE system. How to compute precoder for resourse block
guys!
I am studying a massive Mimo system and 3gpp LTE system and have questions about precoding in the LTE system. In LTE RB (resource block) is used to group consecutive subcarriers. To compute ...
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0answers
25 views
In V2X platooning, how many vehicles can be in a platoon (trucks or car)?
From what I understand, the lead vehicle broadcasts information (like speed, position) to following vehicles. So there will be a limit in the length of the platoon (in terms of no of trucks/cars) ...
1
vote
1answer
60 views
Demodulation of OFDM symbol in LTE for multi-user case
I was trying to understand what exactly happens when you try to modulate an ofdm symbol in the downlink in LTE for multi-user case.
When we modulate, usually we allocate different sets of RBs for ...
0
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0answers
29 views
lte matlab baseband IQ recovery
I am a beginner again to signal processing, I did my degree over ten years ago, and I am relearning all my signal processing stuff.
I am a software developer by trade but now I am looking at some LTE ...
1
vote
1answer
64 views
For a 20 MHz channel, with 1200 usable subcarriers(18 MHz occupied), what should be the size of the FFT on the transmitter before IFFT is applied?
I am trying to simulate the SC-FDMA transmission and I read H Myung's paper and research on the topic but I am not sure exactly on what should be the size of FFT at the transmitter.
For a 20 MHz ...
0
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0answers
18 views
Can you explain me in a easy way what the use of Cyclic Prefix in OFDM is? [duplicate]
I cannot understand why cyclic prefix is used. I know that it mitigates the effect of ICI but I can't see how. Can you explain please? Formulas and mathematics is well accepted. Thanks.
I read this ...
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2answers
159 views
Frequency Domain Correction of Frequency Offset or Doppler Frequency in LTE
We are working on LTE Uplink CFO Correction for 3 MHz band. The time domain CFO correction is easy, which depends on the processing of 3840 samples step by step multiply by $\exp(-j 2\pi f_\text{...
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0answers
25 views
Is there a software/application that shows the FM base stations nearby us?
I want to collect a list of FM base stations near me. I have found apps/software for finding LTE base station but found no success in finding an app for FM base station.
0
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2answers
57 views
How multi layer map to different beams in LTE Beamforming
I understand for SU-MIMO Beamforming single layer maps to all antennas with phase shift applied to create beam. Also I understand in this case all beams will be carrying same signal (say s1).
But in ...
1
vote
1answer
68 views
Quantized error in scatter plots for a hamming windowed LTE signal
I have a time domain signal based on LTE standards.
Carrier spacing = 15KHz, Symbols per slot = 6, extended Cyclic Prefix = 512 samples
FFT size = 2048, No. of sub carriers = 1200, channel BW = 20MHz, ...
0
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0answers
155 views
How to do carrier aggregation?
I have generated 20 MHz bandwidth LTE waveform. I wanted to do carrier aggregation of this signal to get 100 MHz Signal.
I want to understand how carrier aggregation is done mathematically, so using ...
1
vote
1answer
384 views
am I recording LTE uplink signals?
I have this app in my phone which tells me the LTE UL frequency and power:
so I went with my SDR and measured the received signal at that frequency:
Now, how can I be sure this is the transmitted ...
1
vote
2answers
4k 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 (...
-1
votes
2answers
132 views
What is the transmission frequency of mimo antennas?
I was wondering what is the operating frequency of different antenna's in a MIMO system? Do they work in the same band or separate band that the LTE(22 bands) assigned with?
Thank you.
3
votes
3answers
1k views
Why is LTE either FDD or TDD?
In LTE systems, up- and downlink are duplexed either using FDD or TDD. Why has this not been designed to utilize the same multiplexing technique as used for the downlink (OFDMA)? Resource blocks could ...
2
votes
1answer
347 views
SC-FDMA in LTE system
I am trying to understand how SC-FDMA is used in LTE system. Every description I found so far refers to DFT and IDFT.
However, when I checked 3GPP TS 36.211 chapter 5.4 (SC-FDMA baseband signal ...
0
votes
1answer
78 views
Why OFDM is more appropriate with MIMO than other multiple access method?
As read from MIMO-OFDM wikipidia page says
Research conducted during the mid-1990s showed that while MIMO can be used with other popular air interfaces such as time-division multiple access (TDMA) ...
4
votes
1answer
6k views
The necessity of null subcarrier in OFDM?
In looking to LTE specifications, with the subcarrier spacing $\Delta f = 15 \textrm{kHz}$,
for bandwidth $10 \textrm{MHz}$, fft size $N_{fft} = 1024$ that needs a sampling rate $F_s \geq 1024 \times ...
2
votes
2answers
4k 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 ...
1
vote
1answer
1k views
SC-FDMA disadvantages
I understand the advantages of SC-FDMA over OFDM and I also understand the disadvantage of additional complexity (FFT block), are there another disadvantages?
Also, if $N$ has to be bigger than $M$ ($...
0
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0answers
1k views
Difference between single layer and dual layer beamforming in LTE
I'm trying to understand the difference between single and dual layer beamforming in LTE as described in TS 36.101 section B.4.1 and B.4.2 respectively. Also refer to TS 36.211 section 6.3.4.2.3 for ...
1
vote
0answers
172 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.
