Looking at the research status of personal area network (PAN) at home and abroad, PAN implementation technology is nothing more than four kinds: IrDA, 802.11, HomeRF and Bluetooth. Below, the four technologies are analyzed and compared.
IrDA is a technology that uses infrared rays for point-to-point communication. It is technically required to have small size, low power, and low power consumption. The transmission rate is the highest among the four technologies. Due to the point-to-point connection, the data transmission is less subject to interference and the rate can reach 16 Mb/s. However, IrDA is a line-of-sight transmission technology, that is, if two devices with IrDA ports transmit data, there is no barrier in the middle, which is easy to implement between the two devices, but in multiple In the electronic equipment room, it is necessary to adjust the position and angle of each other. In addition, the core component of the IrDA device, an infrared LED, is not durable. If the mobile phone equipped with the IrDA port is frequently used, it may soon be overwhelmed.
The working frequency bands of 802.11, HomeRF and Bluetooth are all unlicensed industrial, medical and scientific frequency bands (2.4 GHz ISM band), thus ensuring that they can be used directly without application on a global scale. IEEE 802.1l works in the physical layer and MAC layer of the Open Systems Interconnection Reference Model (OSI/RM). The MAC layer uses Carrier Sense Multiple Access, Collision Avoidance (CSMA/CA) protocol. At the physical layer, IEEE 802.1l defines three different physical media: infrared, frequency hopping spread spectrum (F}I), and direct expansion. Mode (Ds). IEEE 802.11 supports a higher data rate of 1.11 Mb/s, but it is rarely used in the implementation of PAN because of its high cost and high power consumption.
HomeRF is designed for home users. HomeRF uses frequency hopping spread spectrum to communicate between mobile data and voice devices through a host in the home. It can support voice communication through time division multiplexing and data communication through carrier sense multiple access/collision avoidance protocol. service.
Bluetooth technology is a short-range wireless communication technology that supports point-to-point, point-to-multipoint voice and data services. The development of Bluetooth technology has greatly promoted the development of PAN technology. The original intention of Bluetooth is to use a small, low-cost and low-power wireless communication technology to form a network around the individual, making it cover a variety of areas. Informatized mobile or fixed devices can achieve resource sharing "seamlessly". The essence of this is to establish a common standard for the radio air interface and its control software, so that the communication and the computer can be further combined, so that the devices produced by different manufacturers can be in close proximity without wires or cables connected to each other. Interoperability and interoperability in the scope. Because Bluetooth technology can be easily embedded in a single CMOS chip, it is especially suitable for small mobile communication devices.
In general, IrDA is suitable for devices that require high transmission rate, low number of uses, small moving range, and relatively low price, such as printers, scanners, and digital cameras. IEEE802.11 has a long transmission distance and is fast. Suitable for wireless networks with large distances in corporate companies. HomeRF technology is more suitable for communication in the home environment because the radius of activity of this environment is greater than the range of motion specified by Bluetooth technology, and is generally smaller than the radius of IEEE 802.1l. Bluetooth technology hops fast. Low power consumption and flexibility make it more advantageous for mobile device interconnection, especially for devices that require a wide range of activities and require quick interconnection of multiple devices, such as laptops, digital cordless phones, PDAs. Mobile phones, etc., are also more attractive and competitive in the emerging personal area network.
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