Bluetooth topology networking

Bluetooth topology networking technology solution

Deepening teaching reform and making teaching more interactive is one of the important goals of the development of educational technology, and it is also the embodiment of the value of modern technology in educational reform. On the one hand, in the traditional teaching, the class teaching system is used to divide students, and there are differences in the level of students, so it is difficult to meet the requirements of teaching students in accordance with their aptitude.

On the other hand, the traditional teaching mode separates the knowledge content from the real and rich situational relationship it produces, resulting in subjective passive learning and stagnant knowledge, which is not conducive to effectively building a complete knowledge system and innovation. Traditional education adopts the cramming education method, and students cannot obtain perceptual and diversified learning modes, and the interaction between teachers and students, and between students and students is very poor. Therefore, attention should be paid to the improvement of experimental methods and technologies, and new educational models such as interactive education, independent choice of courses and learning environments should be widely adopted and accepted. The combination of wireless network education and traditional campus network shows people a brand-new and broad learning level, breaking through the shackles of traditional education methods, as long as there is a digital terminal and equipment connected to the network, learning can be carried out anytime and anywhere and training. The bluetooth technology that appears in the field of wireless communication can transmit data such as voice, image and text synchronously, and is an effective technology for realizing wireless network education.

Bluetooth (Bluetooth) is a short-range wireless communication technology standard jointly formulated by five companies including Ericsson, IBM, Intel, Nokia, and Toshiba in 1995. Its purpose is to achieve a maximum data transmission rate of 1Mb/s and a maximum transmission distance of 10m. Wireless communication. The Bluetooth operating frequency is the 2.4GHz ISM (Industrial, Scientific, Medical) frequency band commonly used in the world, so there is no need to apply for an applicable license from the Federal Communications Commission (Federal Communication Commission) or any international regulatory agency. Bluetooth products communicate with the Internet, so that devices between classrooms and offices, and between student data terminals and campus networks can be interconnected without cables, greatly improving office and communication efficiency.

1. Introduction to Bluetooth Technology

Bluetooth is an open low-cost, short-range wireless connection technology specification for transmitting voice, image and text data between different devices. As a standard for short-range wireless interconnection between fixed electronic devices and portable electronic devices, Bluetooth replaces cable connections. Its main features are stable work, simple equipment, low power, little harm to the human body, and low price. Bluetooth technology is mainly oriented to various voice and data devices in wireless networks. It connects them into a piconet by means of wireless communication, and multiple piconets can also be interconnected into a distributed network, so that various devices can be realized conveniently and quickly. communication between. A communication device with Bluetooth function can establish a connection within a certain distance, thereby establishing a temporary personal wireless network. The Bluetooth technology wireless transceiver is a very small chip, about 9mm×9mm, which can be easily embedded into any fixed or portable device, easy to install, does not affect the appearance of the device, and has high practicability and operability. Bluetooth technology supports point-to-point and point-to-multiple communications. The principle of implementation is that a Bluetooth device relies on a dedicated Bluetooth chip to send radio signals within a short distance to find another Bluetooth device. Once found, the device starts to communicate.

The characteristics of Bluetooth technology mainly include: ①The short-range Bluetooth wireless communication distance is 10m, which saves battery power; ②The wireless transceiver chip with low power, small size and low cost is only 0.5 square inches; ③Use simple link layer protocol and binary The frequency hopping technology further reduces the complexity and cost of the radio frequency chip; ④Bluetooth technology provides a standard rate of 1Mbit/s for the piconet; ⑤Using an additional power amplifier can extend the wireless communication distance to 100m. Within a Bluetooth range, multiple independent piconets can exist. These piconets form a distributed network so that more Bluetooth devices can be activated and combine to provide higher bandwidth.

2.The structural characteristics of the Bluetooth technology system

Like OSI (Open System Interconnection), a layered approach is used in the protocol architecture of the Bluetooth technology standard, and its purpose is also to make applications interoperable. If the application programs of the remote device run on the same protocol stack, they can communicate with each other, and different application programs can use different protocol stacks. The Bluetooth protocol stack uses the common Bluetooth data link layer and physical layer protocols.

The Bluetooth core protocol is a protocol unique to the Bluetooth technology standard, developed by the SIG (Bluetooth Special Interest Group). Bluetooth devices must support the Bluetooth wireless interface and core protocol, while other protocols can be selected according to specific circumstances, mainly including Logical Link Control and Adaptation Protocol (L2CAP), Service Discovery Protocol (SDP), and baseband protocol and link Management Protocol (LMP).

(1) Baseband protocol. It is mainly responsible for establishing the physical radio frequency link between each bluetooth device unit in the micro network, that is, controlling the synchronization and transmission of the frequency hopping sequence. Because the Bluetooth radio frequency system uses frequency hopping spread spectrum technology, that is, frequency hopping is performed at a rate of 1600 hops/second on the 2.4GHz frequency band to realize information transmission and reception. A packet is meant to be sent at a specified time and at a specified frequency. The frequency hopping technology mainly divides the frequency band into several frequency hopping channels. On this layer, the clocks and transmission hopping frequencies of different Bluetooth devices are synchronized through paging and inquiry processes.

(2) Link Management Protocol (LMP). It is mainly responsible for the control and establishment of the link between Bluetooth devices, as well as the negotiation and control of the size of the baseband group. It is mainly responsible for the completion of device link quality management, device power management, data packet management, link control management and link security management, etc. five tasks. It conducts authentication and encryption through connection initiation, exchange and verification, and determines the baseband data packet size through negotiation. The user of the device with Bluetooth function can set and control the link status of the remote Bluetooth device and the local Bluetooth device through the link manager, and then realize the management of the link.

(3) Logical Link Control and Adaptation Protocol (L2CAP). The logical link control and adaptation protocol supports secondary multiplexing of high-level protocols, reassembly and segmentation of packets, and quality of service. It belongs to the underlying Bluetooth transmission protocol, which mainly focuses on the realization of wireless communication of data and voice data on the physical link. It is an adaptation protocol that shields the baseband protocol for the high-level transport layer and application layer protocols. The protocol allows high-level protocols and applications to send and receive data as long as 64K bytes. The Logical Link Control and Adaptation Protocol only supports asynchronous connectionless (ACL) links.

(4) Service Discovery Protocol (SDP). The service discovery protocol plays a very critical role in the Bluetooth technology framework and is the basis of all user models. In the Bluetooth device network environment, the discovery of local devices and the use of services and functions provided by remote devices to provide their own services to other Bluetooth devices are also the main way of network resource sharing and the problem that SDP needs to solve. Device information, service characteristics and service types can be queried through the service discovery protocol. Users can select one of the available proximity services to establish a connection between two or more Bluetooth devices.

Bluetooth supports packet switching and circuit switching technologies, and defines two types of links, namely connectionless asynchronous link (ACL) and connection-oriented synchronous link (SCO). Each link supports 16 different packet types, 4 of which are used for control packets.

3. Application of Bluetooth network topology in modern universities

The modern university network designed based on Bluetooth technology must first solve the division of the network structure, so choosing an appropriate network topology has become the key to setting the network structure. Devices in the network are generally divided into master devices and slave devices. The clock and frequency hopping sequence of the master device are used to synchronize all other devices, namely slave devices. The device that performs paging and establishes a connection is defaulted as the master device connected to the network, and the device in the network that is synchronized with the clock and frequency hopping sequence of the master device is the slave device. Since the Bluetooth standard supports both point-to-point and point-to-multipoint connections, multi-networks can be established as required, and then multi-network connections can be made into a topology map of a scatternet.

Due to the ease of use and high aggregation of the Bluetooth network, the wireless network structure of colleges and universities can be realized according to different network topologies. A typical Bluetooth-based wireless network takes the Internet network management center as the core, and the management center provides a wired network to each functional server. Users can access the corresponding server through the wireless access node of the server through digital terminal devices with Bluetooth functions such as smartphones, laptops, and PDAs. No matter when and where, as long as there is wireless network coverage, they can access the corresponding information.

Summarize

According to different Bluetooth wireless network access methods, different wireless network-based solutions can be constructed. At present, point-to-point applications and wireless access points are mainly used. The construction of Bluetooth wireless network in colleges and universities is developed with the rapid development of computer network technology and modern communication technology. Wireless network is not a ban on wired network, but a functional expansion of it. Although there are problems in some technical details of Bluetooth, the integration of Bluetooth components, and the price, with the continuous development of technology, the application prospects of Bluetooth-based wireless networks in colleges and universities will be broader.

The above are the details of the development of Bluetooth technology introduced by Shenzhen Zuchuang Microelectronics Co., Ltd. for you. If you have Bluetooth product design and development needs, you can trust us. We have rich experience in custom development of smart electronic products. We can evaluate the development cycle and IC price as soon as possible, and can also calculate the PCBA quotation. We are a number of chip agents at home and abroad: Songhan, Yingguang, Jieli, Ankai, Quanzhi, realtek, with MCU, voice IC, BLE Bluetooth IC, dual-mode Bluetooth module, wifi module. We have hardware design and software development capabilities. Covering circuit design, PCB design, single-chip microcomputer development, software custom development, APP custom development, WeChat official account development, voice recognition technology, Bluetooth development, wifi technology, etc. It can also undertake the research and development of smart electronic products, the design of household appliances, the development of beauty equipment, the development of Internet of Things applications, the design of smart home solutions, the development of TWS earphones, the development of Bluetooth earphone speakers, the development of children's toys, and the research and development of electronic education products.