In the current global chip market, many well-known foreign companies are adopting diversification strategies. These companies have not only launched ZigBee chips based on the 2.4GHz frequency band, but are also actively developing radio frequency chip technology in the Sub-1GHz frequency band. As an important part of the industry, ZigBee technology is still limited to the 2.4GHz frequency band despite continuous development and improvement. In addition, although its protocol stack technology system has undergone evolution, it has not undergone fundamental changes. At the user interface level, ZigBee is gradually shifting from the initial profile solution to a more open and standardized IPv6 technology.
ZigBee technology has shown its application potential in some specific fields due to its low speed and low cost. However, in application scenarios that require high transmission characteristics, it is often excluded at the planning stage. Its main problems include: first, poor penetration and diffraction performance, which limits the gain improvement of power amplifiers (PA) and low noise amplifiers (LNA); second, they are very sensitive to noise, especially digital noise, resulting in products that The stability and noise immunity are poor; third, the ability to transmit large data such as voice, pictures and videos is insufficient; fourth, under the multi-hop model, it is almost impossible to transmit medium-sized data blocks; fifth, the network topology changes rapidly When, the adaptive adjustment capability is insufficient.
Domestic manufacturers are also actively exploring self-organizing network technology based on 433MHz. However, these manufacturers mainly apply it to specific engineering projects, such as power meter reading. This kind of protocol stack design targeting specific markets has limitations in versatility, so they are more of a complement to ZigBee technology rather than a replacement.
A common problem faced by current wireless ad hoc network protocol stack products is that most of them are only suitable for WAN applications. These products usually use time slot expansion to arrange the access time of each node, resulting in low communication efficiency. Even in a network with only a few nodes, data collection takes a long time.
However, the real-time and efficiency of communication are crucial for users. Although adding relay nodes may cause a certain delay, users are usually able to accept it, provided that this delay increases linearly. This is a key difference between LAN and WAN. In our research, we use distributed computing and asynchronous variable frequency communication technology, combining time division multiple access (TDMA) and frequency division multiple access (FDMA) technology to provide high bandwidth, low latency and large capacity network characteristics . This design not only optimizes the integration of LAN and WAN, but also overcomes the heterogeneous problem between sensor network and transmission network, realizes the smooth extension of network coverage in an intuitive way, and demonstrates the wireless ad hoc network. The future direction of technology.