Each transmission bandwidth corresponds to a fast Fourier transform (FFT) size of 128, 256, 512, 1024, 1536, and 2048 points, respectively. This reference design implements a 1536-point FFT as a stand-alone core. This core satisfies the FFT size requirement of 1536 points for a bandwidth of 15 MHz in an LTE project.

## What is FFT size?

The FFT size defines the number of bins used for dividing the window into equal strips, or bins. Hence, a bin is a spectrum sample , and defines the frequency resolution of the window. By default : N (Bins) = FFT Size/2.

## How do I choose my FFT length?

The frequency resolution of each spectral line is equal to the Sampling Rate divided by the FFT size. For instance, if the FFT size is 1024 and the Sampling Rate is 8192, the resolution of each spectral line will be: 8192 / 1024 = 8 Hz. Larger FFT sizes provide higher spectral resolution but take longer to compute.

## Why subcarrier spacing is 15 kHz in LTE?

August 6, 2019. Simply, It is because 3G and LTE have the same clock timing for multi technology handsets. For BW=5MHz, Fs=512*15kHz=7.68MHz => Fs=2*3.84MHz (3.84MHz is chip rate in UMTS). …

## What is channel bandwidth in LTE?

The supported LTE system bandwidths are {1.4, 3, 5, 10, 15, 20} MHz including guard bands. … These low-cost devices are sometimes referred to as Bandwidth-reduced Low-complexity (BL) devices in the standard specifications. The simplest LTE-M device supports a maximum channel bandwidth of 6 PRBs [6].

## What is output of FFT?

You can find more information on the FFT functions used in the reference here, but at a high level the FFT takes as input a number of samples from a signal (the time domain representation) and produces as output the intensity at corresponding frequencies (the frequency domain representation).

## Why is FFT needed?

The “Fast Fourier Transform” (FFT) is an important measurement method in the science of audio and acoustics measurement. It converts a signal into individual spectral components and thereby provides frequency information about the signal.

## What is FFT frequency?

A fast Fourier transform (FFT) is an algorithm that computes the discrete Fourier transform (DFT) of a sequence, or its inverse (IDFT). Fourier analysis converts a signal from its original domain (often time or space) to a representation in the frequency domain and vice versa.

## What is the length of a signal?

In other words, the length of the signal limits the frequency resolution. This is distinct from the first factor, because the length of the input signal does not have to be the same as the length of the DFT. For example, a 256 point signal could be padded with zeros to make it 2048 points long.

## What is the frequency range of FFT?

2 Answers. An FFT by itself has no frequency range. It could be anything. The frequency range of an FFT result depends on the sample rate frequency at which the input data points were evenly sampled.

## What is subcarrier bandwidth in LTE?

Each subcarrier is able to carry data at a maximum rate of 15 ksps (kilosymbols per second). This gives a 20 MHz bandwidth system a raw symbol rate of 18 Msps.

## What is PRB in LTE?

PRB Dimensioning: Helping to Ensure a Quality User Experience while Lowering CAPEX. When it comes to spectrum, with OFDMA, users are allocated a specific number of subcarriers for a predetermined amount of time. In LTE specifications, these are referred to as physical resource blocks (PRBs).

## What is subcarrier spacing?

Subcarrier spacing is equal to the reciprocal of the symbol time. As a result of the longer symbol time, the subcarrier size and spacing decreases from 312.5 KHz to 78.125 KHz. The narrow subcarrier spacing allows better equalization and therefore enhanced channel robustness.

## Is LTE good or bad?

LTE is a very good, easily deployable network technology, offering high speeds and low latencies over long distances. … AT&T’s LTE service was much better than Sprint’s, but still bad with an average download speed of 7.6Mbps and an average upload speed of 2.4Mbps.

## Is 4G and LTE is the same?

LTE, sometimes known as 4G LTE, is a type of 4G technology. Short for “Long Term Evolution”, it’s slower than “true” 4G, but significantly faster than 3G, which originally had data rates measured in kilobits per second, rather than megabits per second.

## How is LTE bandwidth calculated?

To calculate LTE throughput the following steps should be performed:

- Define bandwidth. It can be 1.4, 3, 5, 10, 15 or 20 MHz. …
- Choose/define radio link quality. …
- The last step is to take a look at Transport Block Size table to determine how many bits can be transmitted per 1 TTI and multiply it by 1000 to get bps.