R&S CMW-KM5 Series, User Manual

Page: 745 / 856

LTE PRACH Measurement
R&S
®
CMW-KM5xx/-KS5xx
745 User Manual 1173.9628.02 ─ 16
EVM window settings
Use the settings in the "Config... > Measurement Control > Modulation > EVM Window
Length" section to adjust the length of the EVM window (see
"EVM Window Length"
on page 767). The minimum value of 1 FFT symbol actually corresponds to a window
of zero length so that EVM
h
= EVM
l
.
Use the setting "Config... > Measurement Control > Modulation > EVM Window Posi-
tion" to select whether the result diagrams (traces) are calculated for low or high EVM
window position (see
"EVM Window Position" on page 767). Statistical tables provide
results for both window positions.
4.2.7 LTE PRACH UL Signal Properties
This section describes the following selected topics related to LTE UL PRACH signal
properties. For a description of the frequency bands see
chapter 3.2.4.2, "Frequency
Bands" , on page 508.
● Preambles in the Frequency Domain ....................................................................745
● Preambles in the Time Domain .............................................................................746
● Preamble Sequences ............................................................................................746
4.2.7.1 Preambles in the Frequency Domain
There are five preamble formats defined by 3GPP, see table below. For preamble for-
mat 0 to 3 a preamble occupies 839 adjacent subcarriers with a spacing of 1.25 kHz, in
total 1.04875 MHz. For preamble format 4 there are 139 subcarriers with a spacing of
7.5 kHz, in total 1.0425 MHz. In both cases 6 Resource Blocks (RB) are reserved in
the frequency domain for the preamble.
Table 4-1: Preambles in the frequency domain
Preamble format Subcarriers (SC) SC spacing
0 to 3 839 1.25 kHz
4 139 7.5 kHz
The location of the 6 RBs within the channel bandwidth, i.e. the number of the first RB
to be used, is determined by higher layers. For FDD it equals a parameter called
PRACH frequency offset, for TDD it is calculated from this parameter and the parame-
ter frequency resource index (determined by the PRACH configuration index). For
details see 3GPP TS 36.211 section 5.7.1 "Time and frequency structure". Both the
PRACH frequency offset and the PRACH configuration index can be configured for the
PRACH measurement.
The total number of resource blocks available per channel depends on the channel
bandwidth as shown in the following table.
General Description
深圳德标仪器
135-1095-0799