Questions tagged [lte]

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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 ...
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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.
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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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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 ...
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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 ...
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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?
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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 ...
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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 ...
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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 ...
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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 ...
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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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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 ...
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How Decode SIB5 in UTMS

I want to decode SIB5 in UTMS. unfortunately I couldn't find any document that describes the structure of of this message. I mean the bit width of each parameters. can anybody help me?
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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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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 ...
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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 ...
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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 ...
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I am trying to estimate the Channel Impulse Response(time domain) for a 5G-NR signal using the DMRS-PBCH pilots only , any suggestions

I want to obtain the $h(t)$, the channel impulse response for my NR signal using the DMRS PBCH pilots only.
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Why no higher modulation done with odd bits except BPSK?

I know it's easy to have 1 bit denote +-1 2 bits denote ++,+-,--,-+ And similarly even count of bits easily denoting the variations. But can we trade off 3 symbols of 2 bits to 2 symbols of 3 bits, ...
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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 ...
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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 ...
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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 ...
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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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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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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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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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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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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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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%.
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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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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