LTE NB-IOT 协议介绍

1、NB-IOT protocol collection1. 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

2、 blocks within a LTE carriers 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 LTELTE R9NB-IoT系统带宽1.4M/3M/5M/10M/15M/20M200kHz工作模式full duplex FDD/TDDhalf-duplex FDD最大传输速率DL: 150Mbps;

3、UL 50MbpsDL/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)145dB164dB子载波间隔DL/UL: 15kHzDL: 15kHz, UL: 15kHz or 3.75kHz传输模式TM1-TM9TM1/TM2 (单天线或双天线发送分集)同步信号PSS/SSSNPSS/NSSS，构造以及相对间隔都与R9 PSS/SSS不同随机接入Preamble/RAR/MSG3/MSG4NPRACH/NPDSCH解调信号DL: CRS UL: DMRSDL: 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PDSCHNPDSCHQPSK, 16QAM, 64QAMPQPSK1/3 turbo coding1/3 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PDCCHNPDCCH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EPDCCHDCI Format 0/1/1A/2/2A/3/3A

4、DCI Format N0/N1/N2上行数据信道PUSCHNPUSCH15kHz sub-carrier spacing15kHz or 3.75kHz sub-carrier spacing1/3 turbo coding1/3 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DRXPSM, 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 e

5、MTC 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 abbreviationsNumber of consecutive slots in an UL resource unit for NB-IoT2. 36.211-d202.1 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, NPRACHThe following uplink narrowband physical signals are defined:-Narrowband demo

6、dulation reference signalComment: 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 , and the slot duration are given in Table 10.1.2.1-1.Table 10.1.2.1-1: NB-IoT parameters.Subcarrier spacingA single antenna port 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。

7、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 consecutive SC-FDMA symbols in the time domain and consecutive subcarriers in the frequency domain, where and are given by Table 10.1.2.3-1.Table 10.1.2.3-1: Supported combinations of , , and .NPUSCH format13.75 kHz116715 kHz116386412223.75 kHz1415 kHz14Comment: NPUSCH资源分配的基本单位称之为Resource Unit。一个Resource Unit定义为个连续的SC-FDMA s

8、ymbols以及个连续子载波。2.1.3Narrowband 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 informationComment: 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 where is the first slot of the

9、transmission of the codeword. In case of NPUSCH repetitions, the scrambling sequence reinitialised according to the above formula after every transmissions of the codeword with with and set to the first slot and the frame, respectively, used for the transmission of the repetition. The quantity is given by clause 10.1.3.6.Comment: NPUSCH和legacy PUSCH一样，在调制之前需要做加扰。由于NPUSCH资源映射的单元包含最多16个Slots，因此加扰使用的初始参数需要使用第一个Slot index。如果NPUSCH 有重传，那么在重传范围内，每次传输重新初始化一次扰码，使用该次重传中首个无线帧号和时隙号做初始化。因此在次重传范围内可以做解调前的数据合并，增加解调信噪比。具体可以参考4.42.1.3.2 NPUSCH modulation(10.1.3.2)Table 10.1.3.2-1: NPUSCH modulation schemes

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