Questions tagged [lte]

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How does higher received signal power enable higher data rates?

On page 30, of the book Fundamentals of LTE by Arunabha Ghosh et al. it is written: This allows broadcast signals from different cells to combine over the air to significantly enhance the received ...
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12 views

LTEcellSearch on ADALM PLUTO error

Im following the example from Matlab in here https://www.youtube.com/watch?v=lcCWTnmKblE im trying to capture an LTE frame and decode the cell id, however i get a false PCI and it changes value ...
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60 views

Is LTE-M better than NB-IoT for low data rate Mobile applications? Why?

If there were a mobile IoT device needing only a low data rate and not needing low latency, would NB-IoT be a good connectivity option? Would LTE-M be better? ‘Mobile’ is key here. A device that will ...
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28 views

LTE: How to distinguish three frequencies within one band?

I'm new to learning LTE. Had some basic queries, I ran over stack exchange couldn't find them because these may be very simple queries but still I'm not able to understand them. For a particular band ...
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27 views

How can we combine carriers in intra LTE CA cases?

For LTE Intra CA cases with say 2 carriers in non contiguous cases can we combine both carrier together and use a single frequency to represent them both? How can we separate them at receiver end?
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20 views

OFDM vs. SC FDMA

I am learning LTE, there are something I want to figure out. Why using single carrier FDMA (SC-FDMA)? and why OFDMA for the downlink? SC-FDMA is designed for solving high PAPR (Peak to average power ...
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20 views

In OFDM, does the parameter time offset is important if there is only one mobile in the cell?

I am learning about OFDM, and in my reading, I have noticed that (mentioned everywhere) synchronization is a very critical aspect of OFDM. Here, I am writing in the context of time synchronization (...
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28 views

Preamble generation of narrowband signals

I have to generate a complex sine wave with a sampling frequency of 1.92MHz and subcarrier spacing of 3.75kHz. The number of FFT points is 512. The narrowband frequency is 180kHz. I also have to ...
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8 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 ...
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18 views

Simulating Rayleigh channel - Problem with adding channel coefficents

I am currently trying to simulate a Rayleigh channel using python (numpy). Full Jupyter Notebook on GitHub: Jupyter Notebook I assume that the channel changes with each new symbol. So I create myself ...
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1answer
47 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!
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1answer
71 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 ...
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37 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 ...
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27 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 ...
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62 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 ...
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1answer
102 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 ...
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1answer
54 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 ...
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1answer
65 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 ...
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52 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 ...
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1answer
52 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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1answer
80 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 ...
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47 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 ...
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1answer
86 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 ...
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19 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
195 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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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.
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2answers
67 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 ...
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1answer
80 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, ...
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189 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 ...
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1answer
441 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 ...
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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 (...
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2answers
141 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.
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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 ...
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1answer
392 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 ...
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1answer
88 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) ...
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1answer
8k 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 ...
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2answers
5k 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 ...
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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 $M$ ($...
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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 ...
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183 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.