It is well-known that communication protocols such as Bluetooth and ZigBee have been widely used in short-range IoT communication due to their low power consumption. However, in the areas of greater coverage such as smart cities and car networking, these short-range communication technologies obviously Can not meet the demand. At present, the LPWAN, such as NB-IoT, LoRa, SigFox and RPMA, is promoted both upstream and downstream of the Internet of Things industry chain, even more than the near field communication technology. However, only three of these LPWAN technologies work on the spectrum licensed by the Third GeneraTIon Partnership Project (3GPP), eMTC, NB-IoT and EC-GSM-IoT respectively. The biggest advantage of these low-power WANs under these licensed bands is that they can be over-ridden at existing sites, what about each of them? Internet of Things communications technology, the three licensed low-power WAN you have to know Internet of Things communications technology, the three licensed low-power WAN you have to know eMTC Coverage: 15dB more than GPRS Number of nodes: single carrier 100,000 Power consumption life: 5Wh power, at least 10 years Rate: up and down the peak 1Mbps Band: LTE Bandwidth: 1.08MHz The full name of eMTC is LTE enhancements for Machine Type Communications. In order to adapt to the massive low-cost and low-bandwidth terminal access in the Internet of things environment, the 3GPP expert group retains the compatibility of the original LTE protocol on the hardware environment on the one hand and deletes the high speed for the special application scenario of the Internet of Things Transmission and other unnecessary additional capabilities, and ultimately tailored based on LTE, optimized eMTC. The notion of "eMTC" was formally identified in Release 13 of the 3GPP release, which was referred to as Low-Cost MTC and LTE-M (LTE-Machine-to-Machine) in previous releases. In the future, eMTC will evolve along with the LTE protocol families according to the development of technologies and application scenarios. The eMTC, defined in Release 13, supports 1.08MHz RF and baseband bandwidths, up to 15dB over GPRS coverage, up to 100,000 devices per carrier, direct access to existing LTE networks and compatibility FDD and TDD two technical standards. More importantly, because LTE is compatible, eMTC can support Voice over LTE (VoLTE) voice technology and may be applied to various smart hardware in the future. In addition, eMTC also supports peak rates of up to 1Mbps upstream and downstream, far exceeding other technical standards such as GPRS, NB-IoT and LoRa. Moreover, in order to apply to the Internet of Things scenario, the terminal module compatible with the eMTC protocol is also required to be able to stand by for more than 10 years at a power of 5 Wh and the target cost requirement is controlled between 1 and 2 US Dollars, and the power consumption and cost Networking applications made full consideration. In January of this year, South Korea's KT Telecom Group has joined hands with Nokia to complete the first commissioning of the eMTC standard. NB-IoT Coverage: 20dB more than GPRS Number of nodes: 200,000 single carrier Power consumption life: 5Wh power, 10 years Rate: peak downlink 250Kbps; uplink single-channel peak 20Kbps, multi-channel 250Kbps Bands: LTE, LTE Edge, Independent Bands (eg GSM) Bandwidth: 180KHz The full name of NB-IoT is Narrow Band Internet of Things. Compared with eMTC, its main feature is based on the Internet of Things for more in-depth optimization, to ensure communication while further reducing the network load. NB-IoT depth optimization for the Internet of Things mainly in two aspects: one is to increase the coverage, one is to enhance the system capacity. According to the introduction of 3GPP, NB-IoT greatly improves the demodulation efficiency of the system by reducing the coding rate and reduces the signal transmission power of a single device (the maximum is 200mW in the protocol and at least 10 years in standby at the 5Wh power), reducing Upload and download the highest level (upload and download speeds up to 250Kbps), overall coverage of GPRS than the increase of 20dB, each carrier can support up to 200,000 network connections. In addition, according to capacity requirements, NB-IoT can also increase the system bearer scale by adding more carriers, with the ability to support millions of IoT connections at a time with a single base station. In deployment mode, NB-IoT is not based on LTE as simply as eMTC, but supports three different deployment modes simultaneously. The first is Standalone, which uses a separate frequency band, the advantage of not creating interference, simple and direct. The second is the Guard Band, which utilizes the protection band at the edge of the LTE band. The advantage is that an independent band is not required, but the disadvantage is that the signal strength is weak and interference with the LTE system is easy. The third is In Band, which directly uses a band of idle LTE band, fully compatible with LTE. The reason why NB-IoT has such a complex deployment, stems from its own complex origin. NB-IoT technology sources mainly include two parts: one is by Nokia, Ericsson and Intel and other companies proposed NB-LTE (Narro Handheld Laser Welder Price,Mold Laser Welding Machine,Fiber Laser Welding Machine Price,Handheld Fiber Laser Welding Machine Shenzhen You Kong Laser Technology Co., Ltd , https://www.youkonglaser.com