Zigbee and WiFi are so easy to use, what advantages does LoRa have?
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Just as ZigBee and ZWave were competing openly and secretly, a new type of network technology that can transmit data over long distances and has ultra-low energy consumption has quietly developed. This technology is called LoRa, which is a technology dedicated to radio modulation and demodulation released by Semech. It competes with other modulation schemes such as FSK (frequency shift keying), GMSK (Gaussian minimum shift keying), BPSK (binary phase shift keying) and their derivatives. LoRa LoRa combines digital spread spectrum, digital signal processing and forward error correction coding technology, and has unprecedented performance. Previously, only high-level industrial radio communications would integrate these technologies, but with the introduction of LoRa, the situation in the field of embedded wireless communications has changed completely. Forward error correction coding technology adds some redundant information to the data sequence to be transmitted, so that the error code elements injected during the data transmission process will be corrected in time at the receiving end. This technique reduces the need to create “self-healing” packets for retransmission and performs well in dealing with bursts of errors caused by multipath fading. Once the packets are grouped and forward error correction coding is injected for reliability, they are fed into a digital spread spectrum modulator. This modulator feeds each bit in the packet into a “spreader” that divides each bit time into a number of chips. LoRa modems can be configured to spread the bits in a range of 64-4096 chips/bit. AngelBlocks configures the modem to use the highest spreading factor (12) of 4096 chips/bit. ZigBee, by comparison, can only spread the bits in a range of 10-12 chips/bit. By using a high spreading factor, LoRa technology can transmit a small amount of data over a large area of the radio spectrum. In fact, when you measure it on a spectrum analyzer, the data looks like noise, but the difference is that the noise is uncorrelated, while the data is correlated, and based on this, the data can actually be extracted from the noise. In fact, the higher the spreading factor, the more data can be extracted from the noise. At a well-functioning GFSK receiver, a minimum signal-to-noise ratio (SNR) of 8dB is required to reliably demodulate the signal. Using the AngelBlocks configuration, LoRa can demodulate a signal with a signal-to-noise ratio of -20dB. The difference between the GFSK method and this result is 28dB, which is equivalent to a much larger range and distance. In outdoor environments, a difference of 6dB can achieve twice the original transmission distance. In order to effectively compare the transmission range performance between different technologies, we use a quantitative indicator called "link budget". The link budget includes every variable that affects the signal strength at the receiver. In its simplified system, it includes the transmit power plus the receiver sensitivity. AngelBlocks has a transmit power of 100mW (20dBm) and a receiver sensitivity of -129dBm, with a total link budget of 149dB. In comparison, GFSK wireless technology, which has a sensitivity of -110dBm (which is already its excellent data), requires 5W of power (37dBm) to achieve the same link budget value. In practice, most GFSK wireless technologies have a receiver sensitivity of -103dBm. Under this condition, the transmitter transmission frequency must be 46dBm or about 36W to achieve a link budget similar to LoRa. Therefore, using LoRa technology we can achieve a wider transmission range and distance with low transmission power. This low-power wide-area technology is exactly what we need. OpenRF Protocol There are many "standardized" protocols currently used in the field of home automation. ZigBee and ZWave are two mainstream choices, and there are also 6LowPan and other protocols. Most protocols rely on wireless mesh networking to some extent, and some rely on the whole system to achieve reasonable transmission distance, but this cannot be powered by batteries. LoRa uses point-to-point communication to achieve long-distance transmission, so we don't need a mesh network. In fact, we need a "lightweight" protocol that is suitable for long-term battery-powered mode. OpenRF was developed for battery-powered applications, such as water and gas meter data reading. OpenRF defines a standardized interface for the media access layer (MAC Layer), allowing various other radio frequency integrated circuit devices (RFICs) to work together. OpenRF also provides a unified network layer that supports 32-bit device addresses to ensure message delivery, as well as multiple network topologies. In theory, OpenRF can also support wireless mesh networking, although we don't have that functional requirement at present. OpenRF provides two interfaces, one of which is the API interface that allows OpenRF to be integrated in an embedded application on a microcontroller. We built the AngelBlocks application using this interface. The other interface is the command interface, which allows an external host controller to use the AT command set to send and receive data packets on a serial link. Our application development adapter uses the command interface to control AngelBlocks on a host, where the Arduino and Pi adapters use a TTL-level serial port, and the PC/MAC adapter uses a USB/COM port. The same command interface can be used. The emergence of LoRa shocked ZigBee and ZWave, the leaders in the field of network technology, and caught these big guys off guard. Ultra-low power consumption and long-distance transmission make LoRa very popular as soon as it is known. In this era of the Internet of Things, LoRa, a technology dedicated to radio modulation and demodulation, will be used in more and more fields, which will make the connection of things more flexible, and the future market potential is huge.
At present, compared with NB-IoT, LoRa is the most mature and stable narrowband IoT communication technology. Its private network with free networking is far superior to the NB network that operators charge continuously, and LoRa does not need to pay for a lifetime after networking once. However, the application of LoRa for IoT communication development is difficult, has a long cycle, and has a high entry threshold. It is understood that in order to lower the entry threshold for entrepreneurs in the IoT industry, Xiecheng Wisdom provides a complete set of mature LoRaWAN source code + LoRa Gateway gateway customization solutions, which greatly reduces the half-year cycle and huge development costs spent by entrepreneurs on IoT link adjustment, making it easier to quickly enter the specific application of the IoT and create their own independent IoT operation brand. Dapu Communication has invested in LoRa research and development for many years. It has a full set of LoRa products (including modules, gateways, servers, etc.) and a variety of node (smoke, temperature and humidity, etc.) finished products. It also has a variety of solutions (smart home security, wireless reversing radar, smart meter reading system, etc.), and is committed to providing customers with integrated IoT system services. In 2017, Dapu Communication established in-depth cooperation with Semtech of the United States. The two parties will carry out in-depth cooperation in the LoRa chip and application levels, and carry out product and solution design in the fields of smart cities, smart agriculture, smart animal husbandry, etc. to promote the development of the industry. Dapu Communication and various manufacturers will work around the application innovation of LoRa technology in various industries. Actively promote the progress of the Internet of Things industry and formulate unified LoRa application specifications. Actively create a "technical exchange platform", "solution verification platform" and "market cooperation platform" for distinctive LoRa applications.
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提升卡
变色卡
千斤顶
