With the continuous development of communication and information technology, the application of short-range wireless communication technology is accelerating and becoming increasingly mature. In a general sense, as long as both the sender and receiver of communication transmit information through radio waves and the transmission distance is limited to a short range (tens of meters), it can be called short-range wireless communication. The short-range wireless technologies we have seen at present have their own characteristics, or special requirements based on transmission speed, distance, and power consumption; or focus on the scalability of functions; or meet the special requirements of certain single applications; or Establishing the differentiation of competing technologies, but no one technology can be perfect enough to meet all needs. Let’s review the current short-range wireless technologies:
The bluetooth technology is a short-range wireless connection technology that has received widespread industry attention. It is an open global specification for wireless data and voice communication. It is based on low-cost short-distance wireless connections and can provide low-cost access services for fixed or mobile terminal devices. Bluetooth technology is an open global specification for wireless data and voice communication. Its essence is to establish a universal short-range wireless interface for the communication environment between fixed or mobile devices, and further combine communication technology with computer technology to enable Various devices can communicate or operate within a short distance without wires or cables connected to each other. Its transmission frequency band is the 2.4GHz ISM frequency band commonly used by the global public, providing a transmission rate of 1Mbps and a transmission distance of 10m.
But the biggest obstacle that Bluetooth technology has encountered is being too expensive. The outstanding performance is that the chip size and price are difficult to reduce, the anti-interference ability is not strong, the transmission distance is too short, and the information security issues. This makes many users unwilling to spend a lot of money to buy such wireless devices. Therefore, industry experts believe that the market prospect of Bluetooth depends on the price of Bluetooth and whether Bluetooth-based applications can reach a certain scale.
Wi-Fi is a wireless extension of Ethernet. In theory, as long as the user is located in a certain area around an access point. But in fact, if multiple users access through one point at the same time, and the bandwidth is shared by multiple users, the Wi-Fi connection speed will generally be only a few hundred kb/s. The signal is not blocked by the wall, but in the building The effective transmission distance is smaller than outdoors.
The most potential applications of WLAN in the future will be mainly in SOHO, home wireless networks, and buildings or places where it is inconvenient to install cables. Currently, users of this technology mainly come from public hot spots such as airports, hotels, and shopping malls. Wi-Fi technology can integrate Wi-Fi with XML or Java-based Web services, which can greatly reduce the cost of enterprises. For example, companies choose to equip each floor or each department with 802.11b access points instead of connecting the entire building with cables. In this way, you can save a lot of money needed to lay cables.
IrDA is a technology that uses infrared for point-to-point communication, and is the first technology to implement wireless personal area network (PAN). At present, its software and hardware technologies are mature and widely used in small mobile devices such as PDAs and mobile phones. In fact, every PDA and many mobile phones, laptops, printers and other products that leave the factory today support IrDA.
The main advantage of IrDA is that there is no need to apply for the right to use the frequency, so the cost of infrared communication is low. And it also has the characteristics of small size, low power consumption, convenient connection, and easy use required for mobile communication. In addition, the infrared emission angle is small, and the transmission safety is high. The disadvantage of IrDA is that it is a line-of-sight transmission. Two devices that communicate with each other must be aligned and cannot be blocked by other objects. Therefore, this technology can only be used for the connection between two (not multiple) devices. . Bluetooth does not have this restriction and is not blocked by walls. IrDA's current research direction is how to solve the line-of-sight transmission problem and improve the data transmission rate.
NFC is a short-range wireless communication technology standard similar to RFID (non-contact radio frequency identification) promoted by Philips, NOKIA and Sony. Unlike RFID, NFC uses two-way identification and connection. Work in the 13.56MHz frequency range within a distance of 20cm. NFC was originally just a combination of remote control identification and network technology, but it has now developed into a wireless connection technology. It can quickly and automatically establish a wireless network, providing a "virtual connection" for cellular devices, Bluetooth devices, and Wi-Fi devices, so that electronic devices can communicate in short distances. The short-distance interaction of NFC greatly simplifies the entire authentication and identification process, and makes mutual access between electronic devices more direct, safer and clearer, without having to hear various electronic noises.
NFC helps solve the trouble of remembering multiple passwords by combining all the identification applications and services on a single device, while also ensuring the security of data. With NFC, wireless interconnection between multiple devices such as digital cameras, PDAs, set-top boxes, computers, mobile phones, etc., will be possible to exchange data or services with each other. Similarly, building a Wi-Fi family wireless network requires multiple computers, printers and other devices with wireless network cards. In addition, a certain technical professional is required to be competent for this job. After NFC is placed in the access point, you can communicate with only two of them close together, which is much easier than configuring Wi-Fi connections.
ZigBee is mainly used between various electronic devices within a short distance and the data transmission rate is not high. The name ZigBee comes from the communication method used by the bee colony for survival and development. The bees dance in the shape of ZigZag to share information such as the location, distance and direction of the newly discovered food source.
ZigBee can be said to be the sibling of Bluetooth. It uses the 2.4 GHz band and uses frequency hopping technology. Compared with Bluetooth, ZigBee is simpler, slower, lower power and cost. Its basic rate is 250kb/s. When it is reduced to 28kb/s, the transmission range can be expanded to 134m and higher reliability can be obtained. In addition, it can be networked with 254 nodes. It can support games, consumer electronics, instruments and home automation applications better than Bluetooth. People expect to expand the application of ZigBee in areas such as industrial monitoring, sensor networks, home monitoring, security systems and toys.
Ultra-wideband technology UWB is a wireless carrier communication technology. It does not use a sinusoidal carrier, but uses nanosecond non-sine wave narrow pulses to transmit data, so it occupies a wide spectrum. UWB can transmit signals over a very wide bandwidth. The US FCC's regulations on UWB are: occupies a bandwidth of more than 500MHz in the 3.1-10.6GHz frequency band. Because UWB can use low power consumption and low complexity transmitter/receiver to realize high-speed data transmission, it has developed rapidly in recent years. It uses low-power pulses to transmit data in a very wide frequency spectrum without causing major interference to conventional narrowband wireless communication systems, and can make full use of spectrum resources. The high-speed data transceiver based on UWB technology has a wide range of uses.
UWB technology has the advantages of low system complexity, low power spectral density of transmitted signals, insensitive to channel fading, low interception capability, and high positioning accuracy. It is especially suitable for high-speed wireless access in dense multipath places such as indoors, and is very suitable for establishing a Efficient wireless local area network or wireless personal area network (WPAN). UWB is mainly used in small-scale, high-resolution radar and image systems that can penetrate walls, ground and bodies. In addition, this new technology is suitable for LANs or PANs with very high speed requirements (greater than 100 Mb/s).
With certain compatibility, high speed, low cost, and low power consumption, UWB is more suitable for the needs of the home wireless consumer market: UWB is especially suitable for high-speed transmission of large amounts of multimedia data in short distances and the outstanding advantages of being able to penetrate obstacles. Commercial companies see it as a promising wireless communication technology for home applications such as wireless transmission of video signals from set-top boxes to digital TVs. Of course, the future of UWB depends on many factors such as the technological development, cost, user habits, and market maturity of various wireless solutions.