Internet of Things Classroom: Transmitting Power and Receiving Sensitivity in NB-IoT Wireless Communications

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Internet of Things Classroom: Transmitting Power and Receiving Sensitivity in NB-IoT Wireless Communications [Copy link]

Hello everyone, welcome to the second Internet of Things Technology Class. Today we will give you a detailed explanation of the concepts of transmit power and receive sensitivity in cellular wireless communications. Please listen carefully to the teacher! The above picture is the basic structure of the cellular communication network, which is the mobile phone network structure we use in our daily life. Before getting to the point, let's take a look at the characteristics of several important wireless communication technologies: First, let's look at LoRa, a low-power LAN wireless standard created by Semtech in the United States. The LoRa Alliance, founded in 2015, actively promotes the commercial use of LoRa technology around the world. China's ** Communications initiated the establishment of the China LoRa Application Alliance (CLAA). The communication distance is 2-5km in towns and about 10km in suburbs; the communication rate is about 10 to 100 Kbps; the ISM working frequency bands include 433, 868, 915 MH, etc. Due to its commercial and maturity limitations, the application scale is relatively small and is currently concentrated in enterprise-level private network applications. Looking at Sigfox again, it is actually a top-down ecosystem established by Sigfox, from chips, terminals, networks, background data and cloud services. Sigfox wireless access network uses ultra-narrowband UNB technology to achieve low-power transmission of small data. The ISM working frequency band has a transmission distance of about 30-50km in rural areas and 3-10km in cities. Okay! Enough of the gossip! As Lao Tian said, don't talk so much uselessly. The mainland still has to watch the NB-IoT stage. To get back to the point, the LoRa, SigFox, NB-IoT and eMTC mentioned in the table above all transmit information through electromagnetic waves. The unit of electromagnetic wave energy is W, dBm. Transmitting power refers to how loud our voices are when we shout. The louder the voice, the farther the sound travels, while the softer the voice, the closer the sound travels. It actually refers to the energy of the electromagnetic waves emitted by the transmitter. Receiver sensitivity is the smallest sound that your ear can recognize. The electromagnetic wave sent by the transmitter reaches the receiver after space loss, and the receiver can recognize the lowest electromagnetic wave energy. Generally speaking, the receiving sensitivity of 2G IoT module is around -108dBm. The more negative, the higher the sensitivity and the longer the effective distance. The receiving sensitivity uses dBm instead of W as the unit because its specific value is too small. The relationship between them is as follows: X dm=10log (Y mW) According to this formula, the receiving sensitivity of the NB-IoT module is -130dBm, which can be converted into a milliwatt value of: 0.0000000000001mW. 0Too much, my eyes are blurry, let me be quiet. . . Now imagine that we are on a noisy road, and the other party can't hear us when we speak. The simplest way is to raise the voice; at this time, the noisy environment is equivalent to external interference, and the size of the external interference directly affects the receiving effect of the receiver. At this time, you can increase the transmission power (increase your voice) or increase the receiving sensitivity (get closer to each other). In other words, these two indicators are extremely important for "communication". The wireless communication module is the core component of the IoT communication equipment, helping the IoT terminals to achieve data transmission over the air, which is the role of the transmitter or receiver mentioned above. Transmitting power and receiving sensitivity are two important indicators of module performance. Take the China Mobile IoT NB wireless communication module M5311 as an example: The RF output power of the M5311 module is 22.5dBm, which is about 178mW when converted to W. What is this concept? A 2G module has an output power of 2W under 900M Class 4 conditions. You can tell the difference at a glance. NB-IoT has such low power consumption, how is the receiving sensitivity? In fact, I have already talked about it above. The receiving sensitivity of traditional 2G terminals is about -108dBm, which is converted to 1.610-11mW in watts. For example, the NB-IoT module, taking M5311 as an example, is about 110-13mW under the condition of -130dBm receiving sensitivity. Okay, today's class is shared here. Next time, I will share other little knowledge with you. Thank you for listening. get out of class dismissed. If you want to learn more about IoT communication module product information, industry news, and technological development, remember to follow the editor or directly follow the Tianjian WeChat public account of China Mobile Module! In addition, the editor will draw lucky viewers in each issue and send our module products for you to DIY! China Mobile Internet of Things Co., Ltd. is a wholly-owned subsidiary of China Mobile Communications Group Corporation. In accordance with the overall strategic layout of China Mobile, the company focuses on the strategic positioning of "supporter of IoT business services, provider of special modules and chips, and promoter of IoT special products", professionally operates IoT special networks, designs and produces IoT special modules and chips, creates special products such as Internet of Vehicles, smart homes, and smart wearables, develops and operates the IoT connection management platform OneLink and the IoT open platform OneNET, promotes IoT solutions, and forms a business layout in five major directions and a comprehensive IoT "cloud-pipe-end" system architecture. In order to provide the society with better IoT technologies, products and services and promote industrial development, the company closely cooperates with China Mobile's provincial companies and professional companies, and with the development concept of openness, cooperation and sharing, widely carries out international and domestic corporate cooperation, operates independently with market-oriented mechanisms, and strives to become a leading IoT company based in the country and serving the world, and promotes the scale application of IoT in various industries. This content is originally created by Zhongyi Module, a netizen of EEWORLD forum. If you want to reprint or use it for commercial purposes, you must obtain the author's consent and indicate the source