LTENBIOT协议介绍
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NB-IOT protocol collection
1. NB-IOT基本概念
➢ Improved indoor coverage, support for massive number of low throughput devices,
low delay sensitivity, ultra low device cast, low device power consumption
➢ NB-IOT should support 3 different modes of operation：
✓ ‘Stand-alone operation’ utilizing for example the spectrum currently being used by GERAN
systems as a replacement of one or more GSM carriers, as well as scattered spectrum for potential
IoT deployment.
✓ ‘Guard band operation’ utilizing the unused resource blocks within a LTE carrier’s guard-band
✓ ‘In-band operation’ utilizing resource blocks within a normal LTE carrier
➢ 180kHz UE RF bandwidth for both downlink and uplink
➢ 上行支持15kHz和3.75kHz两种subcarrier spacing；下行仅支持15kHz 的sub-carrier
spacing
✓ 3.75kHz 只支持single-Tone； 可以提供更大的覆盖，CP较长，对timing要求放松了；
✓ 更小的功耗
➢ 仅支持type-B half-duplex FDD operation(type-B定义参考3GPP 36.211 R13 chapter 6.2.5)
➢ NB-IOT vs eMTC vs legacy LTE
LTE R9 NB-IoT
系统带宽 1.4M/3M/5M/10M/15M/20M 200kHz
工作模式 full duplex FDD/TDD half-duplex FDD
最大传输速率 DL: 150Mbps; UL 50Mbps DL/UL: < 200kbps
频带部署方式 LTE授权频段 带内，带外，保护带 三种部署方式
覆盖范围(MCL) ~145dB 164dB
子载波间隔 DL/UL: 15kHz DL: 15kHz, UL: 15kHz or 3.75kHz 传输模式 TM1-TM9 TM1/TM2 (单天线或双天线发送分集)
同步信号 PSS/SSS NPSS/NSSS，构造以及相对间隔都与R9 PSS/SSS不同
随机接入 Preamble/RAR/MSG3/MSG4 NPRACH/NPDSCH
解调信号 DL: CRS UL: DMRS DL: NRS UL: NDMRS
上下行信道探测 下行CSI， 上行SRS 没有CSI， 没有SRS
下行数据信道 PDSCH NPDSCH
QPSK, 16QAM, 64QAMP QPSK
1/3 turbo coding 1/3 Tail biting convolutional coding
单子帧传输一个传输块 单个或多个子帧传输一个传输块
下行控制信道 PDCCH NPDCCH
和PDSCH在同一个子帧，占用前几个OS 占用单独的下行子帧，类似于EPDCCH
DCI Format 0/1/1A/2/2A/3/3A… DCI Format N0/N1/N2
上行数据信道 PUSCH NPUSCH
15kHz sub-carrier spacing 15kHz or 3.75kHz sub-carrier spacing
1/3 turbo coding 1/3 turbo coding
单子帧传输一个传输块 以Resource Unit(可以跨多个子帧)作
为传输块的传输单位
UL-SCH和UCI在同一个子帧发送 UL-SCH 和 UCI 在不同子帧发送
省电技术 DRX PSM, eDRX
✓ eMTC can only be deployed within LTE system, while NB-IoT has more flexibility as it
can be deployed in-band, guard band and standalone.
✓ NB-IoT can support up to 200k devices per cell per 200kHz
✓ The NB-IoT uplink transmission (3.75kHz, 15kHz) is much more efficient than eMTC
wideband uplink transmission
✓ NB-IoT has about 6.3dB better coverage than eMTC
In-Band 操作的一些特殊处理？？？
➢ Symbols and abbreviations
ULslotsN Number of consecutive slots in an UL resource unit for NB-IoT
2. 36.211-d20
2.1 Uplink(10.1)
2.1.1 Uplink Physical channels and signals(10.1.1.1)
The following narrowband physical channels are defined:
- Narrowband Physical Uplink Shared Channel, NPUSCH
- Narrowband Physical Random Access Channel, NPRACH
The following uplink narrowband physical signals are defined:
- Narrowband demodulation reference signal
Comment: 新增上行信道NPUSCH和NPRACH，新增上行信号NDMRS；
2.1.2 Uplink slot structure and physical resources(10.1.2.1)
The uplink bandwidth in terms of subcarriers ULscN, and the slot duration slotT are
given in Table 10.1.2.1-1.
Table 10.1.2.1-1: NB-IoT parameters.
Subcarrier
spacing ULscN slotT
kHz 75.3f 48 s61440T
kHz 15f 12 s15360T
A single antenna port 0p is used for all uplink transmissions.
Comment: 上行有两种时隙结构，一种是针对子载波间隔15kHz的，和legacy LTE的时隙结构相同；一种是针对子载波间隔3.75kHz的，一个RB内包含的子载波数是48，是legacy LTE的4倍。同时时隙长度是2ms，是legacy LTE的4倍。一个无线帧只包含5个Slots。所以一个无线帧仍然是10ms。
NB-IOT上行总是使用p=0的单天线发送。
2.1.2.1 Uplink resource unit(10.1.2.3)
Resource units are used to describe the mapping of the NPUSCH to resource elements. A
resource unit is defined as ULslotsULsymbNN consecutive SC-FDMA symbols in the time domain
and RUscNconsecutive subcarriers in the frequency domain, where RUscN and ULsymbN are
given by Table 10.1.2.3-1.
Table 10.1.2.3-1: Supported combinations of RUscN, ULslotsN, and ULsymbN.
NPUSCH format f RUscN ULslotsN ULsymbN
1 3.75 kHz 1 16
7 15 kHz 1 16
3 8
6 4
12 2
2 3.75 kHz 1 4
15 kHz 1 4
Comment: NPUSCH资源分配的基本单位称之为Resource Unit。一个Resource Unit定义为ULslotsULsymbNN个连续的SC-FDMA symbols以及RUscN个连续子载波。
2.1.3 Narrowband physical uplink shared channel(10.1.3)
The narrowband physical uplink shared channel supports two formats:
- NPUSCH format 1, used to carry the UL-SCH - NPUSCH format 2, used to carry uplink control information
Comment: NPUSCH包含两种format，Format 1用于传输UL-SCH，Format 2用于传输UCI。不存在同时传输UL-SCH和UCI的NPUSCH。
2.1.3.1 NPUSCH scrambling(10.1.3.1)
Scrambling shall be done according to clause 5.3.1. The scrambling sequence generator
shall be initialised with NcellID9s1314RNTIinit2222mod2Nnnncf where sn is the
first slot of the transmission of the codeword. In case of NPUSCH repetitions, the
scrambling sequence reinitialised according to the above formula after every NPUSCHidenticalM
transmissions of the codeword with with sn and fn set to the first slot and the
