GPRS, 3G and WiFi transmission technology Competition

      Currently optional wireless transmission technology are mainly GPRS ,3G,WiFi, The difference between the following three techniques outlined at.

      GPRS: The Packet(Packet)Type to transfer, it is different from continuous transmission style in the past, the transmission rate can be increased to56-114Kbps. This transmission occurs early, and therefore use the longest.

      3G: For the current 3 kind of  3G Technology, China Mobile TD-SCDMA Bandwidth is small, this technique is rarely used Standard; & Nbsp; 3G Emerged in recent years, has developed rapidly, the current use is very common.

      WiFi: According to the old speed and technology can be divided into802.11a,802.11b,802.11g,802.11n; The last two years with the rapid development of mobile terminals,WiFi The rapid spread of the use of the range, and thus also for monitoring WIFI The product provides a convenient transport.

These three techniques are commonly used in the existing wireless transmission technology, wherein 3G Network is the most common, but also real-time transmission of the main carrier;After vigorously support the country in recent years, China's 3G Network coverage more widely, & nbsp; both cloth built in cities and surrounding areas, the theoretical bandwidth 2Mbps Above, can meet the needs of real-time transmission bus standard definition video streams.WiFi Network bandwidth is much larger than 3G Bandwidth, but the narrow construction of the surface, even in Beijing and other cities, but also failed to achieve full coverage of its network, and is not conducive to public transportation 3G Mobile DVR  The Monitoring And Real-time data transmission applications;To compensate for 3G Wireless bandwidth is insufficient, the bus company will generally be present station was built fabric WiFi Network, & nbsp; When the bus comes into play, which began automatically switch to high bandwidth WiFi Network for data transmission of high flow. GPRS Bandwidth of the wireless transmission technology is that the transmission efficiency is the lowest among the three one network to the next well of tens case100 Multi-KbpsIs not conducive to real-time transmission of video streams, generally used for frame transmission or alarm information release;Network bad situation, the server will automatically select the car GPRS Priority transmission network alarm information. & Nbsp; addition 2 Generation networks GSM Transmission technology, since the bandwidth of the technology is extremely small, usually only a few Kbps, But its network coverage is very broad, is still the mainstream of wireless transmission technology, in remote areas,3G Network can not cover, this technique can be used to intermittent or continuous transmission vehicle condition.

& Nbsp; although the type of wireless network transmission technology more, but coverage, network bandwidth, etc., but not the same,3G Although you can achieve real-time transmission, but for now general,3G The actual application of the maximum bandwidth of the network bandwidth is 300Multi- Kbps, And real-time transmission 1 Channel  D1 Quality must be at least 1 Mbps Bandwidth, therefore the current 3G Only real-time transmission bandwidth 1 Channel CIF Or 4 Channel QCIF Video stream. So how to solve 3G Insufficient bandwidth problem? Fortunately, the problem-solving method always emerged as the cause of the problem, then some domestic manufacturers have proposed specific solutions, have adopted dual-stream transmission technology: Car D1 Storage, use CIF Format resolution real-time transmission. It may also be the self-selection function by optimizing the network to improve transmission performance, generally considered: the future trend is the bus monitor program 3G And WiFi Two kinds of wireless transmission technology, the image transfer process Car DVR Stand by 3G,WiFi Automatic switching equipment precedence WiFi Network, not when the vehicle enters WiFi Area of ​​the device automatically switches to the network 3G Network and automatically adjust the resolution, when the vehicle enters there WiFi Regional network Mobile DVR Automatically switch to WiFi Network;And self-built bus terminal WiFi Network, through WiFi Network video data stored in the car automatically imported bus station storage server.