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General Description
R&S
®
CMW-KN5xx
14
User Manual 1176.7690.02 ─ 05
EVM window length settings
Use the settings in the "Config... > Measurement Control > Modulation > EVM Window
Length" section to adjust the length of the EVM window (see
on page 41). The minimum value of 1 FFT symbol actually corresponds to a window
of zero length so that EVM
h
= EVM
l
.
3.6 LTE DL Signal Properties
This section describes the following selected topics related to LTE DL signal proper-
ties.
Resources in Time and Frequency Domain
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3.6.1 Resources in Time and Frequency Domain
The DL radio resources in an LTE system are divided into time-frequency units called
resource elements. In the time domain a resource element corresponds to one OFDM
symbol. In the frequency domain it corresponds to one subcarrier.
For the mapping of physical channels to resources, the resource elements are grouped
into Resource Blocks (RB). Each RB consists of 12 consecutive subcarriers (180 kHz)
and 6 or 7 consecutive OFDM symbols (0.5 ms). The positions of resource elements
carrying reference signals (pilots) are standardized and depend on the number of
transmit antennas.
Fig. 3-4: Resource element grid (7 OFDM symbols per RB, 1 TX antenna)
The total number of resource blocks available per channel depends on the channel
bandwidth as shown in the following table.
LTE DL Signal Properties
深圳德标仪器
135-1095-0799