Signal Guide

Service Description Selection LTE

Here you will find information about the selected service, along with measurement examples.

LTE Theory & Details
Communication
Typical Frequency Range:

FDD (frequency division duplex):
Uplink 832 – 862 MHz, 880.1 – 885.1 MHz, 1710.0 – 1730.1 MHz, 2500 – 2570 MHz;
Downlink 791 – 821 MHz, 925.1 – 930.1 MHz, 1805.1 – 1825.1 MHz, 2620 – 2690 MHz.
TDD (time division duplex): 2570 – 2620 MHz.

General:

LTE (long term evolution) is a fourth generation mobile wireless communications system (following UMTS as the third generation). It allows data communications at high transfer rates. LTE is maintained by the 3rd Generation Partnership Project (3GPP) just as UMTS.

Modulation: OFDM, QPSK, QAM, SC-FDMA

LTE uses SC-FDMA (single carrier frequency division multiple access) modulation for the uplink. The downlink uses OFDM modulation and is more important for measurements. Each resource block there has a length of 0.5 ms. It comprises 12 OFDM subcarriers separated at intervals of 15 kHz, giving a spectrum that is 180 kHz wide. The individual channels are modulated using QPSK, 16-QAM or 64-QAM. 7 OFDM symbols are transmitted within the 0.5 ms of a resource block. The repetition rate is every 10 ms.

LTE Measurement Examples
Spectrum
LTE downlink with display of instantaneous (black) and maximum values (red). OFDM in the range 811 – 821 MHz can be clearly seen.
Spectrogram
Same frequency range as Spectrum. The device delivers a “snapshot” every 41 ms. Because the device cannot capture the set frequency range with just one FFT, the individual spectrums are made up from several measurements made one after the other (»Stitched Mode«). The rectangular shaped frequency occupancy with separate bursts is typical.
HiRes Spectrogram Full
Display of one LTE channel over a frequency range of 12.8 MHz and a time period of 15.8 ms, without time gaps.
HiRes Spectrogram Zoom
Section from the HiRes Spectrogram Full. The width of the displayed frequency range remains at 12.8 MHz. The time axis can be shifted as with a magnifier. The burst at -4.3 ms (circled red) is now highly resolved.
Persistence Spectrum
Calculated from the same data as HiRes Spectrogram Full. Shows the frequency of occurrence over about 15.6 ms. The steep slope of the neighboring channel at 811 MHz is typical.
Magnitude
Time domain display based on the same data as HiRes Spectrogram Full, detailed over 2 ms. The display is without time gaps, the displayed channel bandwidth (CBW) is 10 MHz. Magnitude provides a clear display of all bursts occurring within the CBW. Longer recording times up to 24 h are possible in Long-Time / Hi Scope mode.
Scope