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LTE PRACH Measurement
R&S
®
CMW-KM5xx/-KS5xx
747
User Manual 1173.9628.02 ─ 16
mine the physical root sequence number u as defined in table 5.7.2-4 and 5.7.2-5 in
3GPP TS 36.211.
From the u
th
root Zadoff-Chu sequence, random access preambles with zero correla-
tion zones of length N
CS
−1 are generated by cyclic shift. The parameter N
CS
depends
on the parameters Zero Correlation Zone Config and High Speed Flag, both provided
by higher layers. It is also used for calculation of the cyclic shift.
If the root sequence allows less than 64 cyclic shifts, the next root sequence is used to
generate additional preambles via cyclic shift, and so on until the set of 64 preambles
is complete.
To allow the R&S
CMW to determine the used preamble sequence, the parameters
"Logical Root Sequence Index" and "Zero Correlation Zone Config" must be configured
correctly. In this software version the "High Speed Flag" is fix so that only the unrestric-
ted set of N
CS
values can be used. Which of the 64 preamble sequences has been
selected by the UE can be determined automatically by the R&S
CMW or configured
manually as "Sequence Index".
For a detailed mathematical description of preamble sequence generation please refer
to 3GPP TS 36.211 section 5.7.2 "Preamble sequence generation".
4.2.8 Limit Settings and Conformance Requirements
Conformance requirements for LTE transmitter tests are specified in 3GPP TS 36.521,
section 6, "Transmitter Characteristics".
The following sections give an overview of the PRACH measurement limit settings and
the related test requirements.
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4.2.8.1
Transmit Modulation Limits
A poor modulation accuracy of the UE transmitter increases the transmission errors in
the uplink channel of the LTE network and decreases the system capacity. The Error
Vector Magnitude (EVM) is the critical quantity to assess the modulation accuracy of
an LTE UE.
According to 3GPP, the EVM measured at UE output powers ≥ −40 dBm and under
normal operating conditions shall not exceed 17.5 % for random access preambles.
The EVM limits can be set in the configuration dialog, depending on the modulation
scheme and along with limits for the other measured quantities.
General Description
深圳德标仪器
135-1095-0799