To understand the future of low-power wireless technology, just read this article!

In recent years, wireless technology has developed rapidly, especially in consumer scenarios, with various applications emerging one after another. This article mainly discusses the application and prospects of mainstream low-power wireless technology.

In terms of communication distance and networking mode, it is divided into local area network and wide area network; in terms of application scenarios, it is divided into high-speed multimedia audio and video, medium-speed wireless audio streaming, and low-speed control sensor data. These standards have their own strengths and play an important role in their respective fields, and together they have built a rich and moving modern information world.

As the number of smart devices increases rapidly, more and more devices need to be able to connect to the Internet. It is predicted that by 2020, more than 30 billion devices will have the ability to communicate wirelessly with other devices. Among them, the largest proportion is low-power wireless LAN devices.

Taking smart accessories as an example, more and more devices support Bluetooth protocol. Bluetooth protocol is divided into classic Bluetooth and low-power Bluetooth. Classic Bluetooth is suitable for audio streaming transmission, such as wireless headset microphones, etc., and low-power Bluetooth is suitable for remote controls, bracelets, lights, home appliances and other devices that need to be directly connected to smartphones and receive control. It is predicted that the number of Bluetooth devices will exceed 4.4 billion in 2019, of which low-power Bluetooth accounts for the vast majority.

In terms of networking, Bluetooth uses a star-shaped network, with a mobile phone or computer as the center, and other devices connected to the center through the Bluetooth protocol (Figure 1). The advantage of this networking method is that it is simple and easy to use, and the networking method is clear and intuitive. Users can pair and use devices through very simple connection logic.

Figure 1. Bluetooth star network connection

The latest versions of Bluetooth Low Energy specifications are BLE 4.2 and BLE 5.0. In the BLE 4.2 specification, the security mechanism is enhanced, which is very necessary for applications involving electronic payment and security applications. In the BLE 5.0 specification, a 2Mbps mode is added, which is a significant improvement in data transmission rate. In addition, some new features are added.

As a leading semiconductor company, NXP's latest products in the field of low-power Bluetooth can support BLE 4.2 specifications and BLE 5.0, and are widely used in many fields such as consumer, industrial, and medical.

With the development of smart home, this star networking mode has also exposed its limitations. Therefore, a new networking mode is needed, namely Mesh network. In Mesh network, data can be directly transmitted between nodes, which effectively improves work efficiency and has better performance in complex indoor environments.

At present, the latest Mesh protocol of the Bluetooth organization (hereinafter referred to as BLE Mesh) is a protocol based on network flooding, mainly because this flooding mode is simple and easy to implement. However, this implementation method also has both advantages and disadvantages, because it is network flooding, which is not conducive to the low power consumption optimization of nodes, nor is it conducive to the large-scale increase of the number of nodes.

Figure 2. Bluetooth Mesh network connection topology (Image source: https://www.bluetooth.com, Mesh Profile Specification 1.0)

In low-power wireless mesh networks, there is another standard called ZigBee. ZigBee is a natural mesh network. The difference from BLE Mesh network is that ZigBee is based on routing protocol, which is better than BLE Mesh. We can see that ZigBee has shined in many current IoT applications. For example, Amazon's latest product Echo plus fully supports ZigBee and can be used to directly control other ZigBee devices such as lights.

Figure 3. Amazon Echo plus. (Image source: https://www.amazon.com )

The latest version of ZigBee is ZigBee 3.0, which takes interoperability and compatibility to a new level and is fully prepared for applications such as smart homes.

Figure 4. ZigBee protocol framework (Image source: http://www.zigbee.org/zigbee-for-developers/zigbee )

There is another standard similar to ZigBee, called Thread. As you can see, Thread and ZigBee use the same physical layer, namely IEEE802.15.4. The difference of Thread is that it is based on the IPv6 routing protocol, and each node has an IPv6 address. The advantage of this is that the node can be easily addressed by the cloud.

Figure 5. Thread protocol framework diagram

NXP provides single-chip solutions for both ZigBee and Thread protocols, and even provides a multi-mode solution that can run ZigBee/Thread and low-power Bluetooth protocols on the same chip. This dual-mode design provides a more flexible way for product design. For example, for door lock applications, customers can connect to the door lock through the Bluetooth of their mobile phone to unlock it. After leaving home, the door lock can access the home gateway through the ZigBee network and then access the cloud service to realize many applications such as remote doorbells and security.

In addition to the above-mentioned low-power wireless LAN protocols, there are also several low-power wide-area network (LPWAN) technologies, such as NB-IoT and LoRa.

NB-IoT mainly uses the base stations of operators, which can provide low-power and low-speed connections. It has a large number of application scenarios in smart cities, such as street lights, water and electricity meter collection, vehicle management, etc. At present, driven by domestic operators, some cities have carried out large-scale commercial operations and achieved good results.

LoRa technology requires users to build base stations themselves, but due to the use of advanced channel coding technology, the receiving sensitivity of LoRa nodes can reach -142dBm, which can achieve long-distance communication with ultra-low power consumption, and the longest communication distance can reach 30 kilometers. For LoRa applications, NXP can provide low-power MCUs to run its software protocol stack.

When the number of nodes in the Internet of Things reaches an astonishing level, security issues will inevitably become a key link. To solve the security problem, we must consider it comprehensively from many aspects, such as adding security authentication chips, introducing anti-disassembly technology, increasing secure startup, and encrypting communications.

The future world must be a fully interconnected one, and humans can access it seamlessly through a variety of devices. Sensor nodes need to be low-power, mesh network, secure, IP addressable, and have certain node computing capabilities to achieve edge computing, while the cloud needs to be based on artificial intelligence to achieve data modeling and analysis, and ultimately make decisions and execute.

As far as low-power wireless networks are concerned, the complexity of application scenarios means that no single network can be applied to all scenarios. For a long time in the future, the various standards mentioned in this article will coexist. (Author: Yi Fang, Marketing Manager of Microcontroller Division, Greater China, NXP Semiconductors, the article was originally published in Smart Electronic Integration)