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Fred Morgan

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  1. There are many wireless communication technologies for the Internet of Things, which are mainly divided into two categories: one is Zigbee, WiFi, Bluetooth, Z-wave and other short-distance communication technologies; the other is LPWAN (low-powerWide-AreaNetwork, low-power wide area network), Namely WAN communication technology. The rapid development of the Internet of Things puts forward higher requirements for wireless communication technology, and LPWAN, which is designed for low-bandwidth, low-power, long-distance, and massively connected IoT applications, is also rapidly emerging. IoT applications need to consider many factors, such as node cost, network cost, battery life, data transmission rate (throughput rate), delay, mobility, network coverage, and deployment type. NB-IoT and LoRa have different technical and commercial characteristics, and they are also the two most promising low-power wide area network communication technologies. These two LPWAN technologies have the characteristics of wide coverage, multiple connections, low speed, low cost, and low power consumption. Both are suitable for low-power IoT applications and are actively expanding their ecosystems. Introduction of NB-IoT and LoRa 1. NB-IOT NB-IOT (NarrowBandInternetofThings, NB-IoT, also known as Narrowband Internet of Things) is a technical standard defined by the 3GPP standardization organization. It is a narrowband radio frequency technology designed specifically for the Internet of Things. 2. LoRa LoRa (LongRange) is an ultra-long-distance wireless transmission scheme based on spread spectrum technology adopted and promoted by Semtech in the United States. The LoRa network is mainly composed of four parts: terminal (with built-in LoRa module), gateway (or base station), server and cloud, and application data can be transmitted in both directions. Frequency band used by NB-IoT and LoRa 1. NB-IOT NB-IoT uses licensed frequency bands and has three deployment methods: independent deployment, guardband deployment, and in-band deployment. The mainstream frequency bands in the world are 800MHz and 900MHz. China Telecom will deploy NB-IoT in the 800MHz frequency band, while China Unicom will choose 900MHz, and China Mobile may rebuild the existing 900MHz frequency band. 2. LoRa LoRa uses the unlicensed ISM frequency band, but the usage of the ISM frequency band in different countries or regions is different. In the Chinese market, the China LoRa Application Alliance (CLAA) led by ZTE recommends 470-518MHz. The frequency band used by radio meters is 470-510MHz. Since LoRa works in an unlicensed frequency band, network construction can be carried out without application. The network architecture is simple and the operating cost is low. The LoRa Alliance is vigorously promoting the standardized Lo-RaWAN protocol around the world, so that devices that comply with the LoRaWAN specification can be interconnected. Communication distance of NB-IoT and LORA 1. NB-IoT communication distance The signal coverage of the mobile network depends on the base station density and link budget. NB-IoT has a link budget of 164dB, GPRS has a link budget of 144dB, and LTE has a link budget of 142.7dB. Compared with GPRS and LTE, the NB-IoT link budget has been increased by 20dB, and the signal coverage of the open environment can be increased by seven times. 20dB is equivalent to the loss of the signal penetrating the outer wall of the building, and the signal coverage of the NB-IoT indoor environment is relatively good. Generally, the communication distance of NB-IoT is 15km. 2. LoRa communication distance LoRa provides a maximum link budget of 168dB with its unique patented technology. Generally speaking, the wireless distance range is 1-2 kilometers in the city, and the wireless distance can reach up to 20km in the suburbs. NB-IoT and LoRa cost comparison No matter how powerful the LPWAN protocol is, its low cost needs to be considered, otherwise they are not a viable IoT solution. LoRa has advantages in this regard. The overall cost of the LoRaWAN module is around US$8-10, which is about half of the price of cellular LTE modules such as NB-IoT. The higher the complexity of the NB-IoT network, the higher the costs related to intellectual property rights (in terms of authorized frequency bands), which increases the total cost of NB-IoT. Upgrading NB-IoT to advanced 4G/LTE base stations is more expensive than LoRa deployment through industrial gateways or tower-top gateways. As the market matures, the cost of LoRa technology is expected to drop further.
  2. 1. Ecosystem LoRaWAN is supported by the LoRa Alliance, an open non-profit association composed of more than 500 members. Its members work closely together and share experiences, promote and promote the success of the LoRaWAN protocol, and become the leading and open global standard for secure, carrier-grade Internet of Things LPWAN connections. NB-IoT is supported by two telecommunications standards associations, 3GPP and GSMA, both of which have the same goal of promoting the interests of mobile networks and equipment. 2. Spectrum LoRaWAN is optimized for ultra-low power consumption and remote applications. Therefore, network operators and equipment manufacturers can access the networks running on the license-free ISM Sub-1GHz spectrum for free. NB-IoT uses a cellular spectrum network, which is optimized for spectrum efficiency. The licensing fee for frequency band usage is very high, and it is limited to a few operators. 3. Deployment status According to the LoRa Alliance, 83 public network operators in 49 countries are currently using LoRaWAN, and more private companies are also using LoRaWAN networks. GSMA is an organization representing the interests of NB-IoT, LTE and other mobile networks. According to it, 40 countries will launch NB-IoT networks in the future. 4. Deployment options LoRaWAN network provides highly flexible deployment. It can be installed in a public, private, or mixed network, indoor or outdoor. LoRaWAN signals can penetrate into urban infrastructure, and each gateway can cover 30 miles (approximately 48.3 kilometers) in an open rural environment. NB-IoT uses LTE cellular infrastructure, which is an outdoor public network and requires the deployment of 4G/LTE cellular towers. If the sensor exceeds the coverage area of the base station, the base station is not easy to move. 5. Protocol The LoRaWAN protocol sends data asynchronously, and the data is sent only when needed. This can extend the battery life of the sensor device up to 10 years, and the battery replacement cost is low. NB-IoT needs to maintain a synchronous connection to the cellular network, regardless of whether it needs to send data. For sensor devices, it consumes a long battery life, resulting in high battery replacement costs, which may be too costly in many applications. 6. Emission current LoRaWAN provides 18 mA emission current at 10 dBm, and 84 mA emission current at 20 dBm. Modulation differences can enable LoRaWAN to support very low-cost batteries, including button batteries.  The NB-IoT sensor consumes ~220 mA at 23 dBm and 100 mA at 13 dBm, which means that it needs more power to operate and requires more frequent battery replacement or a larger capacity battery. 7. Receive current LoRaWAN provides lower sensor BOM cost and battery life for remote sensors. The receiving current is about 5 mA, and the overall power consumption is reduced by 3-5 times.  The NB-IoT receiving current is about ~40 mA. The communication between the cellular network and the device consumes more than 110 mA on average, and a communication lasts for tens of seconds. The protocol overhead has a significant impact on the battery life of devices that need to work for 3, 5, or 10 years or more. 8. Data rate LoRaWAN data rate is about 293 bps-50 kbps. The LoRaWAN protocol dynamically adjusts the data rate according to the distance between the sensor and the gateway, thereby optimizing the air time of the signal and reducing conflicts. The peak data rate of NB-IoT is about 250 kbps, which is more suitable for use cases with higher power budget and higher data rate (above 50 kbps). 9. Link budget LoRaWAN's MCL signal varies according to regional regulatory restrictions. The link budget is between 155 dB and 170 dB.  NB-IoT needs to repeat remote sensors at a low bit rate in order to be able to support remote sensors. The link budget is up to 164 dB. 10. Mobility LoRaWAN can support mobile sensors to track the movement of assets from one place to another. Even without GPS, high enough accuracy can be obtained for many applications.
  3. MCU 01 What is MCU? MCU is a PC-like chip. It is not a chip that completes a certain logic function, but integrates a computer system into a chip; it is just not as powerful as a PC, but it can Embedded in other equipment to control it. In a word: a chip becomes a computer The multi-computer application system of the single-chip microcomputer can be divided into a function collection system, a parallel multi-computer processing and a local network system. 02 Advantage It is small in size, light in weight, and cheap in price, which provides convenient conditions for learning, application and development. At the same time, learning to use a single-chip microcomputer is the best choice to understand the principle and structure of the computer. 03 Application The use of MCU has been very extensive, such as smart meters, real-time industrial control, communication equipment, navigation systems, household appliances, etc.; ARM 01 What is ARM ARM is a well-known company in the microprocessor industry and has developed RISC processors, related skills and software. ARM can be considered as the name of a company or as a general term for a class of microprocessors. This article mainly refers to the first RISC microprocessor designed for the low-computing market with the ARM architecture. The ARM core is an embedded system. The instructions, registers and pipeline features of the RISC architecture make it very suitable for parallel computing 02 Advantage Low power consumption, energy saving, high functionality, 16-bit/32-bit dual instruction set, low price, and many partners; Rich embedded on-chip resources; 03 Application Most of the application areas are small household appliances and terminal equipment; DSP 01 What is DSP DSP is a unique microprocessor, a device that uses digital signals to process a large amount of information. It not only has programmability, but also runs at a speed of tens of millions of complex instruction programs per second, far exceeding general-purpose microprocessors. The device is an increasingly important computer chip in the digital electronic world. 02 Advantage Powerful data processing capability and high operating speed 03 Application At present, the main applications of DSP applications are graphics and images, instrumentation, automatic control, medical, household appliances, signal processing, communication, voice, etc. Wireless module 01 What is wireless module? Most of the modules involved in the Internet of Things are wireless communication modules, referred to as wireless modules. The principle of the wireless communication module is to send or receive electromagnetic wave signals and convert them into information that we can understand. The role of the wireless communication module is to connect things with things, so that all kinds of Internet of Things terminal devices can realize information transmission capabilities, and all kinds of smart devices have an Internet of Things information interface. Hardware integration and software design integrate a variety of communication methods. 02 Advantage Low cost, short construction project period, good adaptability and good scalability. 03 Application Agriculture, security, industry, smart home, mobile payment, smart community, industrial applications, etc. CPU Central Processing Unit: A very large-scale integrated circuit, which is the core and control unit of a computer. Mainly interpret computer instructions and process data in computer software. Just like the human brain, it processes thousands of data. The main frequency of the CPU, the number of cores, and the cache are the three major factors that determine the computing power of the CPU. The higher the CPU frequency, the more cores, and the larger the cache, the stronger its computing power. From the perspective of realizing operations, single-chip microcomputer, ARM, DSP can all be called CPU. Difference between MCU, ARM, DSP and CPU Although MCU, ARM, and DSP are all called CPUs, there are still obvious differences between them. 1. The MCU is a chip with a complete computer system, suitable for simple measurement and control systems, and its functions are relatively simple. Both ARM and DSP can do the work of single-chip microcomputer. The MCU has much fewer instructions for digital calculation. In order to perform fast digital calculations and improve the efficiency of commonly used signal processing algorithms, DSP adds many instructions, such as single-cycle multiply-add instructions, Reverse order addition and subtraction instructions, block repeat instructions, etc., even a sequence composed of many commonly used operations is specially designed for one instruction to be completed in one cycle, which greatly improves the speed of signal processing. Because the amount of readings and write-backs in digital processing is very large, in order to increase the speed, the instruction and data spaces are separated, and two buses are used to access the two spaces respectively. At the same time, there is generally a high-speed RAM inside the DSP, and data and programs are required. Load into the high-speed on-chip ram before running. 2. ARM is a microprocessor with powerful transaction processing functions and can be used with embedded operating systems. The biggest advantage of ARM lies in its fast speed, low power consumption, and high chip integration. Most ARM chips can be counted as SOC. Basically, a small system can be made by adding power and drive interfaces to the periphery. Based on the ARM core processor Embedded systems are more and more used in various embedded systems that require complex control and communication functions due to their rich resources, low power consumption, low price, and numerous support manufacturers. At present, microprocessors with ARM cores, which we usually call ARM microprocessors, have spread across various product markets such as industrial control, consumer electronics, communication systems, network systems, and wireless systems. Microprocessors based on ARM technology Processor applications account for more than 75% of the market share of 32-bit RISC microprocessors, and ARM technology is gradually infiltrating all aspects of our lives 3. DSP is suitable for digital signal processing, such as FFT, digital filter algorithm, encryption algorithm and complex control algorithm. The real-time running speed of DSP can reach tens of millions of complex instruction programs per second. DSP devices are 8 to 10 times faster than the single instruction execution time of a 16-bit single-chip microcomputer, and 16 to 30 times faster to complete a multiplication and addition operation. The design adopted is that the data bus and the address bus are separated, so that the program and data are stored in two separate Space allows the fetch and execution of instructions to completely overlap. Its working principle is to receive analog signals, convert them to 0 or 1 digital signals, then modify, delete, and enhance the digital signals, and interpret the digital data in other system chips. Back to the simulation data or actual environment format, its powerful data processing capabilities and high operating speed are the two most commendable features. DSP chip, because of its strong computing power, high speed, small size, and high flexibility of software programming, it provides an effective way for engaging in various complex applications. Its main application is to realize various digital signal processing algorithms quickly in real time.
  4. With the rapid development of the Internet of Things, more and more intelligent products such as intelligent home, intelligent transportation, intelligent city and so on have emerged in the market. These terminals rely on wireless transceiver module to realize information transmission and reception. As a result, we know that wireless modules are indispensable in the use of the Internet of Things.Wireless modules often need a backplane to match them, enabling them to perform better in their application.So the design of our backplane is particularly important. How to design is our concern. Today, let's briefly talk about how to design the backplane of our wireless module. Most importantly, we should pay attention to the space reserved for wireless modular antennas. Our most common antennas are ceramic antennas, PCB loaded antennas, and external antennas (just a generic name here). External Antenna Fig.1 is a typical external antenna-based wireless module backplane design.From Fig.1, Fig.2, we can see that on the left are USB interface, LDO, plug-in interface, Jing Zhen, USB-TTTL chip, module bottom without components and line. When we design the module, we try not to walk high-speed lines and place components sensitive to RF signals. The module is placed in a separate area to prevent interference with other functional modules from causing communication problems. The outboard antenna SMA is on the far right, preventing the effects of RF signals on other sensitive devices after they are radiated through the antenna. As we can see from Fig.3, when we draw the RF line from the base plate to the outside SMA head, the RF line needs to have an accompanying hole, which allows a vortex between the RF signal and the ground, a circuit in space, to absorb part of the radiated signal, thereby reducing the effect of radio-frequency signal radiation on other signals inside the plate.Another reason is the Faraday shield, together with a hole that effectively prevents other signals from interfering with it. Ceramic Antenna, PCB Board Antenna Ceramic antennas and PCB loaded antennas are similar in design. This is the unified explanation here. From Fig.4, we can see that the left side is the same design as Fig.1. This is no longer the case here, but focus on the placement of the right antenna. We can see that when we are designing, we need to place ceramic antennas at the edge of the board (sometimes because of some restrictions, the antenna needs to be placed inside the backplane, then we need to carve out the position of the antenna and hang the antenna outside the backplane so that the antenna can radiate out the radio signal better and communicate better. Of course, there are more factors involved in baseplate design, which requires a combination of actual conditions and often a compromise.
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