When selecting an IoT communication protocol, various factors at the technical and commercial levels must be carefully evaluated for different application scenarios. The product design concept is a key factor in determining the communication protocol. It is generally accepted that the pointer parameters used to evaluate the Internet of Things communication protocol include network node capacity, battery life, network transmission quality, etc., among which power consumption is most concerned by developers.
When selecting an IoT communication protocol, it is necessary to carefully evaluate various factors at the technical and commercial levels for different application scenarios. Different communication protocols are suitable for different application products, and the design concept of the product will be a key factor in determining the communication protocol. The following are generally accepted indicators for evaluating IoT communication protocols: network node capacity, battery life, network connectivity, transmission range, network reliability, data security, cost, and in-house development and disclosure standards.
The previous issue of "Narrowband Low-Power Network Protocol Maximizes IoT Node Capacity" explores the number of network nodes accommodated, and this time will explore its role in IoT communication for "power consumption."
The IoT market covers many disparate applications, and no single protocol can satisfy all products and applications at the same time. It is stated here that this article is not intended to be specific to the industry. This article will explore battery power consumption, so if your end product is powered directly from the power supply, you can simply ignore this factor and skip this article.
If you are still reading this article, then we can assume that battery power consumption will be one of the important factors affecting your product. For these applications, battery power is undoubtedly a key factor in choosing a communication protocol. Most of the Use Cases are unlikely to make users tired of changing batteries, and the battery life of IoT devices is often calculated as "years".
The formula for calculating battery life is actually quite complicated, although the most important factors can be divided into two types: Idle and power consumption during data transmission. But the devil is hidden in the details, let us continue to watch.
The length of sleep of a device often depends on whether the battery life is expected to be long or the latency is short.
The best sweet spots are different for different applications. For some applications, you only need to connect to the device once a day, and some applications need to be connected once every few seconds (like a mobile phone); The best system allows the IoT device to flexibly determine the length of idle time based on pre-programmed parameters.
Once the length of sleep is determined, the next key is to minimize the time it takes to receive data.
Some systems require each device to scan for any information on each channel. Some methods are smarter, and a discriminant label is added at the top of the data packet to help each device decide whether to receive the data. In addition, support The transmission of multiple sub-channels means that the receiving end only needs to lock one of the specific channels, thereby reducing the receiving time.
Compared to the received data, the power consumption when transmitting data is greater, but the power consumption during transmission can be effectively reduced by proper design. Some of the obvious ones are the proper modulation, avoiding the use of linear amplifiers and operating at the proper operating voltage; however, the most important thing is to reduce the amount of data that needs to be transmitted. In essence, all systems inevitably face the energy attenuation caused by wireless transmission, and therefore develop many coping mechanisms to extend the time required to transmit each bit, for example, in ultra-narrowband (Ultra-Narrow) Band) ultra-low transmission rate; or multiple spreading codes (MulTIple Spreading Code Bits) represented by each bit in the Spread Spectrum system.
All IoT communication protocols face the same energy efficiency (E/bit). The biggest gap between the various industry players is the amount of data actually transmitted. For example, one of the solutions is to repeatedly transmit the same data to improve the success rate of the transmission, for example, three times of repeated transmission, and this method will undoubtedly increase the transmission power by three times, thus reducing the battery life by three. Times. Assuming that other factors remain the same, a system that requires a battery replacement every three years cannot meet the standard for a usage scenario that requires a 10-year device.
For any low-power wide area network (LPWAN) solution, battery life of more than 10 years is common, and it is theoretically feasible to increase sleep time and reduce transmission frequency.
I believe that we have all experienced battery storage power that is much shorter than what the manufacturer claims, or that some "smart" devices react slowly to make people want to turn the table. In fact, it is difficult to evaluate the real life of the battery during the testing phase. It is often necessary to wait until the entire network is racked up and running for a period of time before there is enough data to calculate the actual life of the battery. If an IoT system with a set of 50 million devices is installed after it is completed, it will be a very crashing thing to replace the battery when it is used halfway through the use of these devices - presumably all the villagers will? Turn it over. In any case, if the engineer doesn't want to lose his job, be extra cautious when judging the relevant marketing data provided by the manufacturer; for example, a recent company press release indicates that the product's button battery life can be as long as 10 to 20 years. My personal favorite point is where to find the Uranium-235 button battery that lasts so long.
In the process of selecting LPWAN technology, may you ask the manufacturer's technicians to really understand how to extend battery life by reducing the amount of data transferred? Still optimizing on hibernation? Is the power consumption optimized for radio communication (RF) parameters and using nonlinear amplifiers wherever possible? Or is it to avoid blindly transmitting the same data? Still using a larger package?
Many IoT end products rely on battery power, so low power consumption becomes a necessary condition. It is reasonable to say that all LPWAN communication protocols operating in the license-free spectrum are low-power, but Weightless-P achieves the best performance while reducing power consumption through many of the latest technologies. The total energy consumed during transmission is equivalent to the power consumption during transmission multiplied by the time required for transmission. Weightless-P uses GMSK and Offset-QPSK modulation to maximize the efficiency of the power amplifier; otherwise, Offset-QPSK In complex environments, it can also have both anti-jamming and stable online quality; the limited transmission power in the ISM band can only be up to 17dBm, meaning that the terminal device can be driven by the button battery; the adjustable transmission rate allows the terminal The device transmits data with minimal power consumption through the cleanest transmission channel, which in turn increases battery life, and because the terminal device is in a sleep state for most of the time, making transmission power more critical. Based on reliable measurement data, the Weightless-P communication protocol requires only 100μW of power consumption during sleep.
(The author of this article is Chairman of the Marketing Working Group of the Weightless Technology Alliance)
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