NARDA SRM-3006 Manual - page 5
AN_1106_SRM_LTE_TDD
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Subject to change
4 Using the SRM 3006 LTE-TDD option
It is now also possible to demodulate LTE TDD signals on the SRM 3006 with firmware release 1.5.0. Sections 1 to 3
above have described how LTE TDD functions differently to LTE FDD and how it therefore needs different treatment
in the SRM. The main distinction between the FDD option and the TDD option is that the particular uplink / downlink
configuration can be set additionally in the TDD option.
If the uplink / downlink configuration being used in an LTE TDD network is definitely known, this can be set
appropriately during a measurement with the SRM 3006, as illustrated in Figure 3. The SRM benefits from a slightly
reduced measurement uncertainty if the correct configuration is set. If a setting is chosen that does not correspond to
the actual uplink / downlink configuration, the risk of over- or under evaluation increases significantly. The
configuration setting “0 (Recommended)” is an exception to this. This setting can be used universally for all network
configurations. When set to “0”, the SRM focuses on sub frames 0 and 5 and also on the reliable downlink
components in the special sub frames (i.e. sub frames 1 and 6). These four sub frames always carry downlink
signals, regardless of the uplink / downlink configuration, as is shown clearly in Figure 3 and by the explanation of
SSF given above. The configuration setting “0 (Recommended)” should therefore be used as the standard setting,
and should also be used if the actual uplink / downlink configuration is not definitely known.
Remember that the SRM can also demodulate TDD signals when the setting “0 (Recommended)” is chosen, even
when this does not correspond to the actual configuration of the network. If the actual configuration is set, this will
merely achieve a slight improvement in the measurement uncertainty. If a configuration other than “0
(Recommended)” is set and this does not correspond to the actual configuration of the network, then the
measurement uncertainty will be significantly degraded and even the basic demodulation function will no longer be
assured!
Figure 4: LTE TDD option in the SRM 3006 with uplink / downlink configuration selection