NB-IoT Signaling
R&S
®
CMW-KM300/-KS300
21
User Manual 1178.5689.02 ─ 06
Table 2-3: Physical DL channels
Physical DL channel
Purpose
Narrowband physical broadcast channel
(NPBCH)
Provides physical layer information of the cell to be read during
cell search, e.g. system frame number, scheduling of SIB-NB,
transmit antenna info, NRS ports
Narrowband physical downlink control
channel (NPDCCH)
Carries UE-specific control information, like scheduling infor-
mation
Carries ACK/NACK indicators for uplink packets
Narrowband physical downlink shared
channel (NPDSCH)
Carries user data
Table 2-4: Physical DL signals
Physical DL signal
Purpose
Narrowband reference signal (NRS)
For demodulation
Narrowband primary synchronization sig-
nal (NPSS)
Narrowband secondary synchronization
signal (NSSS)
Acquisition of cell timing, frequency synchronization, detection
of cell identity
2.2.7
UL Resources in Time and Frequency Domain
The channel bandwidth for NB-IoT is 200 kHz. At both edges, 10 kHz are not allocated
(guard band). The remaining 180 kHz can be allocated to UEs.
The 180 kHz are divided into subcarriers. There are two different modes:
●
3.75 kHz subcarrier spacing, bandwidth divided into 48 subcarriers
●
15 kHz subcarrier spacing, bandwidth divided into 12 subcarriers
In the time domain, the smallest unit is an SC-FDMA symbol. Each symbol contains a
guard time called cyclic prefix (CP). A time slot contains seven SC-FDMA symbols with
normal CP. A time slot for 3.75 kHz subcarrier spacing ends with a guard period (GP,
no UL signal).
Depending on the subcarrier spacing, the slot length is 2 ms or 0.5 ms. A radio frame
of 10 ms contains 5 slots or 20 slots.
Durations are often stated in sample intervals T
s
. T
s
can be calculated from the sam-
pling frequency 30.72 MHz: 1 T
s
= 1/30.72 MHz
≈
32.55 ns.
The following table and figures summarize this information.
Subcarriers
Slots
Symbol duration
Spacing
No.
Duration
Per frame
CP
Data
Note
3.75 kHz
48
2 ms, 61440 T
s
5
256 T
s
8192 T
s
GP at end of slot
2304 T
s
15 kHz
12
0.5 ms, 15360 T
s
20
symbol 1: 160 T
s
symbol n: 144 T
s
2048 T
s
-
General Description
深圳德标仪器
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