NB-IoT Signaling
R&S
®
CMW-KM300/-KS300
19
User Manual 1178.5689.02 ─ 06
channel raster offset of 2.5 kHz is allowed. For cell BWs with an odd total number of
RBs, a DL channel raster offset of 7.5 kHz is allowed.
The UL/DL separation for the guard-band mode and the in-band mode differs from the
UL/DL separation for the standalone mode by 7.5 kHz. In the lower guard band, the
spacing is greater. In the upper guard band, it is smaller. The UL channel raster offset
differs by 7.5 kHz from the DL channel raster offset.
The following tables list the used NB-IoT carrier position in the upper guard band
depending on the LTE cell BW. For the lower guard band, all values have the opposite
sign.
Table 2-1: NB-IoT carrier positions in the upper guard band
5 MHz
10 MHz
15 MHz
20 MHz
Downlink
Frequency offset to LTE
2400 kHz
4600 kHz
7200 kHz
9100 kHz
Channel raster offset
7.5 kHz
-2.5 kHz
7.5 kHz
-2.5 kHz
Uplink
Frequency offset to LTE
2400 kHz
4600 kHz
7200 kHz
9100 kHz
Channel raster offset
0 kHz
-10 kHz
0 kHz
-10 kHz
The NB-IoT signaling application takes care of all the dependencies. You configure the
NB-IoT RF frequency as for the standalone mode, for example via a channel number.
And you select the upper or lower guard band. The software calculates the resulting
LTE carrier frequencies and the channel raster offsets automatically. The channel ras-
ter offsets are added to the configured NB-IoT RF frequencies.
2.2.5.3
In-Band Operation
In the in-band operation mode, an NB-IoT carrier uses a small part of an LTE carrier.
The resources are flexibly assigned to LTE or to NB-IoT, only to one technology at a
time. So there is no interference between LTE and NB-IoT. But the capacity available
for LTE is reduced by NB-IoT.
As for the guard-band operation mode, the NB-IoT signaling application generates an
NB-IoT cell signal and an LTE cell signal. If both cells share a physical cell ID (mode
"Inband-SamePCI"), the UE can use the LTE CRS OFDM symbols for NB-IoT.
Carrier frequency and channel raster offset
In the in-band operation mode, the NB-IoT carrier uses exactly the frequency span of
an LTE resource block (RB). In the LTE downlink, the center subcarrier is not used. A
resource block covers 180 kHz, a DL subcarrier 15 kHz.
The following figure illustrates the DL frequencies in the center of a 10-MHz LTE chan-
nel.
General Description
深圳德标仪器
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