NB-IoT technology, enough to read this article!

In response to these goals, many communication companies and operators have put forward their own design of air interface proposals, hoping to be adopted as a formal standard by the 3GPP standardization organization. At the RAN#69 meeting in September 2015, after a fierce PK, the air interface solution of the cellular Internet of Things was finally determined to be NB-IoT.

1. What is NB-IoT

NB-IoT technology, enough to read this article!

In order to cope with the growing demand for the Internet of Things, the International Mobile Communications Standards Organization 3GPP decided to formulate a new cellular Internet of Things (CIOT: Cellular Internet of Thing) standard.

This new standard has to achieve four goals:

Super coverage, compared with the original GPRS system, increase the signal gain by 20dB

Ultra-low power consumption, the terminal node must be able to reach 10 years of battery life

Ultra-low cost, the target price of the terminal chip is US$1, and the module price is US$2

Large connection, 200kHz cell capacity up to 100k user equipment

In response to these goals, many communication companies and operators have put forward their own design of air interface proposals, hoping to be adopted as a formal standard by the 3GPP standardization organization. At the RAN#69 meeting in September 2015, after a fierce PK, the air interface solution of the cellular Internet of Things was finally determined to be NB-IoT.

This NB-IoT air interface standard is a fusion of NB-CloT recommendations led by Huawei, Qualcomm, and Vodafone, and NB-LTE recommendations led by Ericsson and Nokia. Among them, NB-CIoT has more components, in other words, Huawei and Qualcomm has more core patents in the NB-IoT field.

2. Key knowledge points of NB-IoT

NB-IoT is an air interface standard. This standard is mainly an agreement between the terminal and the base station eNB, including some design regulations for the physical layer and the data link layer.

Taking into account the compatibility with LTE, the NB-IoT standard has many similarities or similarities with the LTE air interface standard. For example, NB-IoT follows the frequency band number defined by LTE, and Release 13 specifies 14 frequency bands for NB-IoT.

The multiple access technology of NB-IoT uses SC-FDMA in the uplink and OFDMA in the downlink; the downlink transmit power is 43dBm, and the uplink is 23dBm. The modulation method is mainly QPSK and BPSK.

Release 13 NB-IoT only supports FDD half-duplex type-B mode. FDD means that the uplink and downlink are separated in frequency, and half-duplex means that the UE will not process reception and transmission at the same time.

3. CIoT access network architecture diagram

The access network architecture of CIoT is the same as LTE, and has not changed. The eNB is also connected to the MME (MobilityManagementEntity) and S-GW (ServingGateWay) through the S1 interface. If there is any difference between the CIoT access network and LTE, it is that NB-IoT messages and data are transmitted on the S1 interface.

Fourth, how NB-IoT achieves low power consumption

Compared with GPRS, NB-IoT’s biggest feature is low power consumption. In addition to the relatively low transmission rate of NB-IoT itself, NB-IoT has introduced eDRX power saving technology and PSM power saving mode, which are also the main reasons for power saving.

In the PSM mode, the NB-IoT terminal is still registered on the network, but does not accept signaling, so that the terminal stays in deep sleep for a longer time to save power.

In addition, the eDRX power-saving technology extends the sleep period of the terminal in idle mode and reduces unnecessary activation of the signal receiving unit. In general, these measures are to make the terminal sleep more time, sleep quality better, and thus lower power consumption.

5. How to deploy NB-IoT

NB-IoT occupies a bandwidth of 180KHz, which is the same as the bandwidth of a resource block in the LTE frame structure. There are three possible deployment methods for NB-IoT:

1) Standalone operation

It is suitable for re-cultivation of GSM frequency band. The channel bandwidth of GSM is 200KHz, which is sufficient for the 180KHz bandwidth of NB-IoT, and a guard interval of 10KHz is set aside on both sides.

2) Guardband operation

Suitable for LTE frequency band. Use the guard band at the edge of the LTE frequency band to deploy NB-IoT.

3) In-band operation

Suitable for LTE frequency band. The resource block in the middle of the LTE carrier is directly used to deploy NB-IoT.

6. Application of NB-IoT

For long-distance high-speed data transmission, LTE networks and future 5G networks can meet this demand; for long-distance low-speed data transmission, especially non-real-time low-frequency data transmission, NB-IoT systems are used.

NB-IoT is very suitable for applications such as wireless metering (Metering) and sensor tracking (SensorTracking). The implementation of Internet of Things technology in these fields can greatly reduce management costs and allow network managers to grasp various operational data at any time .

As the three major operators actively promote the construction of NB-IoT network infrastructure in China and the cost reduction of NB-IoT chips, we will see more and more NB-IoT applications landed.

In summary, it is the introduction of NB-IoT technology. Although NB-IoT technology is now facing competition like LoRa technology, in China, I believe that NB-IoT technology will definitely become the most mainstream technology in the field of Internet of Things.

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