Questions tagged [lte]

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Computing Channel Power from file containing RMS measurements from tri-axial spectrum analyzer

I have some files from a spectrum analyzer in RMS mode equipped with a tri-axial antenna. I am supposed to compute the channel power evolution for two distinct LTE channels. I have files containing ...
marco890's user avatar
1 vote
1 answer
66 views

LTE PSS Channel Estimation for coarse SSS Equalization

In LTE the Primary Synchronisation Signal (PSS) can be detected by taking a correlation with the known 3 zadoff chu sequences (roots: 25,29,34). Once the peak has been detected the receiver knows ...
Sonny Wandel's user avatar
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1 answer
148 views

CFO limit for correct LTE Zadoff-Chu Synchronization

I am working with Zadoff-Chu sequences in a Python simulation of an LTE-like communication system and need to understand the effects of carrier frequency offset (CFO) on these sequences. Specifically, ...
Sonny Wandel's user avatar
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1 answer
47 views

Multipath Propagation Correction for LTE signals

How can I correct multipath propagation for LTE signals generated from different eNodeBs? My end goal is to implement localization of my USRP using LTE or FM signals. Currently I am carrying out a few ...
Ahsan Yousaf's user avatar
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Raw BER or Uncoded BER in LTE/5G

Could you please tell me what would be the benefit of using Raw BER (or uncoded BER) in comparison to BER? Thanks
Aragorn's user avatar
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How to accomodate feedback bits from Base Station to devices in LTE or 5g?

I am trying to think of a way in which the base station (BS) can send say 100 bits of feedback to devices in my cell. My confusion is what is a good way to send this feedback bits. This is during the ...
wanderer's user avatar
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OFDM design considerations for choosing the number of subarriers $N$

I was trying to think of all possible constraints or factors that needs to be taken into consideration while designing an OFDM-based wireless communication system (For example, LTE, 5G technologies ...
wanderer's user avatar
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LTE Standard. Where to begin?

I've started working as a wireless engineer fresh from college. I wanted to learn LTE standard and I don't know where to begin. I was wondering if you could guide me through this process. I found some ...
Jacob's user avatar
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3 answers
373 views

OFDM Signal and IQ Paths

I understand that we have analog complex signal after it passes DAC after coming out of IFFT in OFDM Transmitter. After that we do orthogonal upconversion on it and send it. I've question now for OFDM ...
Reddi Suresh's user avatar
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2 answers
105 views

What is use of Quadrature Converter in OFDM?

I'm learning about OFDM Transmitter and see that output of IFFT Block produces complex digital signal and we need DAC to convert it to analog and then use RF Frequency mixing to send it out of ...
Naresh Upadhyay's user avatar
1 vote
0 answers
26 views

How to model Additional EVM (TxEVM) with LTE waveform?

I would like mention my understanding in the following, In an LTE OFDM signal assume, Nfft=8; scs=15 kHz; BW=5MHz; Sampling Rate N=7.68 MHz; We are taking 1msec of sample; Therefore total sample =...
Md. Hasan Rahman's user avatar
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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 ...
Aragorn's user avatar
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144 views

Understanding the In-band Emission limit in TS 38101-1 Table 6.4.2.3-1?

I am sharing the IBE table 6.4.2.3-1 on TS 38101-1 For General emission requirement, there are three parts.The third part is (-57 dBm+10*log10(scs/15kHz))-P_RB. Where, P_RB is the average transmitted ...
Md. Hasan Rahman's user avatar
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37 views

Can I use FIR interpolator while modeling a DAC (Digital-to-Analogue converter) in 5G NR transmitter?

Problem statement: I am explaining my concept on The DAC implementation in 5G NR using an example. For a CBW=20 MHz, SCS=15 KHz, the sampling frequency= 30.72 MHz. After the time domain signal ...
Md. Hasan Rahman's user avatar
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235 views

Pulse shaping filter (e.g. RRC) implementation in OFDM transmission?

I am a bit confused regarding the implementation of Pulse shaping filter in OFDM (Both CP-OFDM & SC-FDMA) system. I am explaining my concept in the following, The difference between CP-OFDM and ...
Md. Hasan Rahman's user avatar
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Concept clarification on baseband system model of LO leakage impairments in 5G NR?

I am trying to generate a baseband (BB) system model with LO leakage impairments and correction. The channel bandwidth $BW = 20$ MHz, Subcarrier Spacing $= 15$ kHz, oversampling rate = $4$ (just ...
Md. Hasan Rahman's user avatar
3 votes
2 answers
292 views

What type of LO lekage Correction algorithm is used in 5GNR?

I have done a base-band modeling of a 5G NR OFDM (CP-OFDM/ DFT-s-OFDM) transmission system. And I have added a DC leakage as an RF impairment and transmitted the signal through a PA (Power Amplifier). ...
Md. Hasan Rahman's user avatar
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0 answers
161 views

some questions about CRS collision in LTE

In the case of CRS collision in LTE, is the serving cell and the neighbouring cell always PRB aligned? For example, if they are PRB aligned, port0 will always collide with port0, otherwise port0 will ...
c1119's user avatar
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130 views

Why don't we have LTE EARFCN for frequency in decimal to second place?

EARFCN 3302 means 2675.20 MHz EARFCN 3303 means 2675.30 MHz What about 2675.25 MHz? Why don't we have values defined for decimals with two places.
Reddi Suresh's user avatar
1 vote
0 answers
176 views

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 ...
gkami's user avatar
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1 answer
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A question on communication system without modulation

I know that these sort of platforms are strict and you need to have an idea of what you are doing before asking a question. I am not really that knowledgeable about signal processing though I have an ...
Tshepang's user avatar
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0 answers
121 views

gnuradio: eCPRI link implementation for LTE

Need to build eCPRI link in xRAN network between eRE and eREC devices. In eRE I'm capturing via osmocom source (SDR device) and I have a stream of float32 complex IQ numbers as usual output. Now I am ...
Sabyrzhan Tasbolatov's user avatar
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1 answer
191 views

How to measure NB-IoT signal quality with GNU Radio?

I need to measure the quality of an NB-IoT signal. Is it possible to obtain RSRP, RSSI RSRQ or SINR using GNU Radio?
Nicolas's user avatar
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How can I perform semi-blind non-orthogonal successive interference cancellation (SIC) / source-separation with SISO in 4G/5G Downlink?

Semi-blind non-orthogonal successive interference cancellation in the single antenna case with 4G/5G signals (applies generally though). This is very similar to NOMA in 5G, except that I have no ...
joemelsha's user avatar
1 vote
1 answer
749 views

IFFT and DAC relationship in OFDM Transmitter

Say, for LTE BW 20 MHz, I have total 2048 SubCarrier at IFFT Input leading to 2048 Output (Complex) at IFFT Output, and in 1 OFDM Symbol (useful symbol length) of time 66.67 usec, the sampling rate ...
Reddi Suresh's user avatar
0 votes
1 answer
369 views

How is SNR Calculated in OFDM Reciever? [closed]

Can you please guide me on the information to calculate SNR for OFDM Reciever? Is OFDM Pilots used for it? And do we need to follow channel estimation like steps of interpolation to determine it? I'm ...
Reddi Suresh's user avatar
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1 answer
1k views

What's practical interpretation of showing DC Offset in frequency domain?

In homodyne reciever, we read about LO Leakage causing DC Offset. Say my output at downconversion is in analog voltage range +5 and -2, and there is a DC offset of 1 unit So, it can be added right? To ...
Reddi Suresh's user avatar
0 votes
2 answers
249 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 ...
Reddi Suresh's user avatar
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Resource related to real world measurment vs simulated data for RACH LTE

I am trying to find resources where I can study the comparison of the various features of the Random access channel in LTE using simulated and real-world measurement data. It would be great if you can ...
Aragorn's user avatar
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1 answer
609 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 ...
Dmitriy's user avatar
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3 answers
1k views

OFDM SubCarrier and its relationship with IFFT in context of Real and Complex

In the process of OFDM Signal generation. We take symbols (constellation symbols) and map it to a sub-carrier (real analog time domain) harmonics of 15khz, add different sub-carriers separated by ...
Reddi Suresh's user avatar
1 vote
1 answer
125 views

Doesn't use of Duplexer in FDD system limits it's capability?

I read FDD has separate Rx and TX frequency to operate on, so it can work simultaneously and do Receive and Transmission. When I use Duplexer ( I read Duplexer needed if we want a single antenna to do ...
Reddi Suresh's user avatar
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0 answers
222 views

Where is SNR and CNR calculated for LTE?

I read below that SNR and CNR are different and we have difference of post/pre modulation. In context of LTE which modulation do we refer to- Digital Data modulated using QAM/QPSK to IQ, or Baseband ...
Reddi Suresh's user avatar
1 vote
0 answers
32 views

Why do adjacent cells use different channels?

In chapter 15 of the book Wireless Communications by Andrea Goldsmith, Goldsmith gives a formula for an estimate of the signal-to-interference-ratio for the node on the edge of a cell in a cellular ...
awelkie's user avatar
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LTE SIB based query

We knows SIBs are transmitted from BCCH down to PDSCH and we use them to configure PHY, MAC, RLC layer. Now when UE gets to SIB so it will already have decoded PDCCH and DCI info, right. So, can UE ...
Reddi Suresh's user avatar
0 votes
1 answer
32 views

How to determine Carrier Aggregation Class

We see classes defined for Carrier Aggregation. The number of continuous carrier determines which class of CA it is. what are the criteria to decide contiguous carriers? Do the carriers need to stick ...
Reddi Suresh's user avatar
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1 answer
59 views

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 ...
Shashank V M's user avatar
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0 answers
73 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 ...
David's user avatar
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0 answers
39 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 ...
Reddi Suresh's user avatar
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0 answers
221 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 ...
Y.Y.Lin's user avatar
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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 (...
Aragorn's user avatar
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1 vote
0 answers
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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 ...
StarStrider's user avatar
-1 votes
1 answer
121 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%.
dac adm's user avatar
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1 answer
155 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 ...
ozi2020's user avatar
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0 answers
56 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 ...
ozi2020's user avatar
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1 answer
278 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 ...
Sampath's user avatar
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1 vote
1 answer
362 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 ...
Shashank 's user avatar
1 vote
1 answer
245 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 ...
Sampath's user avatar
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0 answers
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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 ...
HassanSh__3571619's user avatar
-1 votes
1 answer
72 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 ...
LenaPark's user avatar