Rohde & Schwarz R&S CMW-KM300, Руководство пользователя, Страница: 18 / 388

NB-IoT Signaling
R&S
®
CMW-KM300/-KS300
18 User Manual 1178.5689.02 ─ 06
Additional transitions
The list of transitions in Figure 2-2 is not complete. The "Off" state can be reached from
any state by turning off the cell signal. Moreover, incidents like a loss of the radio link
cause additional transitions.
2.2.5 Operation Modes
There are three NB-IoT operation modes defined by 3GPP. All three modes are sup-
ported by the signaling application.
This section provides background information for the three operation modes.
● Standalone Operation ............................................................................................. 18
● Guard-Band Operation ............................................................................................18
● In-Band Operation ...................................................................................................19
2.2.5.1 Standalone Operation
In the standalone operation mode, the used spectrum is dedicated to NB-IoT only. So
the frequencies are not shared with another technology.
One possible deployment scenario is, to use no longer needed GSM spectrum for NB-
IoT. An NB-IoT carrier fits perfectly into a no longer used GSM channel.
Another scenario is, to use new spectrum for NB-IoT.
2.2.5.2 Guard-Band Operation
In the guard-band operation mode, the NB-IoT carrier is located in the guard band of
an LTE carrier. So the NB-IoT carrier uses already available LTE spectrum, without
reducing the capacity of the LTE carrier. But there can be interference between NB-IoT
and LTE.
The NB-IoT signaling application generates an NB-IoT cell signal and an LTE cell sig-
nal. The LTE signal contains no synchronization signals and no broadcast information.
So the UE cannot synchronize to the LTE cell signal. But the LTE signal contains cell-
specific reference signal (CRS) symbols. The other LTE OFDM symbols contain QPSK
modulated uncorrelated pseudo-random data. All LTE OFDM symbols have the same
power level.
Carrier frequency and channel raster offset
To maintain the orthogonality to the LTE carrier, the NB-IoT center frequency must fol-
low the subcarrier raster. So the possible NB-IoT frequencies in each guard band have
a spacing of 15 kHz, the downlink subcarrier spacing.
Another aspect is, that the UE uses the 100-kHz channel raster for cell search. For that
reason, 3GPP allows only NB-IoT DL frequencies with the smallest possible offset from
the 100-kHz channel raster. For cell BWs with an even total number of RBs, a DL
General Description
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