Wearable wireless network technology application program
Wearable wireless network technology application program
1. Wearable computers and wearable wireless networks
1.1 Wearable computer  Wearable computer is a new concept of mobile computing system. The concept originated in the 1960s. Since the 1990s, with the rapid development of large-scale and very large-scale integrated circuits, the research on wearable computers has entered a new stage. Currently, there is no exact definition of the concept of wearable computers. Generally speaking, a wearable computer should have the following basic characteristics:? Can be used under exercise? Use it while freeing up hands or doing other things? User can control? Have sustainability? Diversity, that is, different The application of wearable computers should be different in terms of composition and functions. From the above characteristics, it can be seen that compared with traditional computers, wearable computers are more closely integrated with people. This requires wearable computers to adopt new human-computer interaction technology to achieve the harmony and unity of human-computer. This is also a hot issue and difficulty that must be overcome in the current research on wearable computers.
1.2 Wearable wireless network In the wearable computer system introduced above, the hardware devices are mainly connected through communication cables, and the operating platform used is also based on wired devices. Although this system has its applicability in certain occasions, its shortcomings are also obvious: First, it is not flexible enough. Because the "hard" connection method of the communication cable is used, it will inevitably affect the space and amplitude of the user's body, which is necessary in some applications, such as physical exercise.
Secondly, it does not consider the integration with existing personal communication terminals (such as mobile phones, PDAs, MP3, etc.). This will make the existing communication terminal and the wearable computer physically independent and functionally overlapping devices.
In response to this situation, this article proposes the concept of wearable wireless networks. Compared with wearable computers, wearable wireless networks have the following characteristics:
⑴ Better flexibility.
(2) Fully consider the integration with existing personal communication terminals.
⑶ Distributed control can be carried out. This is because each communication terminal has certain arithmetic processing capabilities and storage capacity (and with the development of very large-scale integrated circuits, the performance in this area is bound to be further improved).
⑷ More humane. The user can choose the appropriate main communication device to control the entire network according to different applications, convenience, and personal preferences.
It can be seen that wearable wireless networks should have better applicability and wider application prospects than wearable computers, and it can be developed on the basis of various existing wireless local area network technologies. Since various existing wireless local area network technologies are relatively mature, they have obvious advantages in development difficulty and development cycle compared with wearable computers.
2. System model of wearable wireless network|
2.1 Network model Currently, the technologies suitable for building wearable wireless networks mainly include Bluetooth and ZigBee. Both of these two wireless technologies belong to the IEEE802.15 family and work in the ISM frequency band. The difference between them is shown in Table 1-1 below. Because they are completely consistent in networking, the wearable network models built with them are basically the same.
Table 1-1 Comparison of Bluetooth and ZigBee
⑴ Wearable wireless network structure constructed with Bluetooth and ZigBee technology
The networking modes of Bluetooth and ZigBee can be divided into three forms: star network, peer-to-peer network and hybrid network . The wearable wireless network constructed with Bluetooth and ZigBee technology should adopt a hybrid structure, as shown in Figure 2.1. It is a loose Ad Hoc network that fits the needs of wearing.
Figure 2.1 Wearable Bluetooth network model
The entire network in the above figure is divided into a two-level hierarchy. The master device (Master) of the first-level pickup net is connected to the master device of each second-level pickup net, and the master device of each second-level pickup net acts as a slave (Slave) in the first-class pickup net. The main equipment is responsible for maintenance and management of each level of Picknet. In order to facilitate the maintenance and management of the entire network, the master device of Level I Picknet serves as the LAP connecting to the external network, and the master device is not the master (slave) device of Level II Picknet. Of course, the LAP here is not directly connected to the wired network. There may be more than one device that can play the role of LAP, but no matter which device is used as a gateway device, the above networking principles should be followed.
⑵ Wearable wireless network equipment
In the above two wearable wireless networks, the devices in the entire network can be divided into two basic types according to different roles:
Sensors or other terminal equipment: This type of equipment only needs to transmit the collected data to the Master, and does not undertake any task of managing and maintaining the network. Such equipment mainly includes sensors, detectors, headsets and cameras.
Network interconnection equipment: The network interconnection equipment is not only responsible for forwarding data from the terminal equipment, but also must manage and maintain each level II network. At the same time, a new network must be formed between these interconnected devices. Therefore, network interconnection equipment should have a certain storage capacity and data processing capabilities. In theory, each Master can act as a LAP, but in fact it is not necessary. In this model, the LAP acting as the gateway is only a member of the first-level network, responsible for the management and maintenance of the first-level network, and not as the base station of the second-level network. The purpose of this is to prevent the same device from assuming too many roles, which will increase the complexity of the device. Devices that can serve as network interconnection devices include PDAs, GPS, headsets, MP3s, mobile phones, and PTT (Push To Talk), among which mobile phones can also serve as gateways to the external network.