Security Trends: Video surveillance technology of wireless transmission (1).

<P> Way of video surveillance by the cable into the wireless access is an inevitable trend. .Wireless image transmission to break the traditional coaxial and fiber optic video surveillance hardware connection is subject to the adverse situation, with greater flexibility and convenience, wireless network-based video surveillance system came into being. .Wireless video transmission technology has the structure of wireless mobile networks and protocols have a profound impact, but the wireless channel bandwidth is limited, many confounding factors, and the video signal data volume, real-time requirements of higher problem. .</ P> <P> wireless video transmission technology development status </ P> <P> the development of information society, people are increasingly demanding security monitoring, in addition to a concentration of party and government organs, enterprises and institutions outside ., as in the sea, mountains, mines, basements and other complex environments can not be set up where wired networks. .Are required to implement security video surveillance, which need to use wireless video transmission technology. .</ P> <P> currently on the market for wireless video transmission technology they use GPRS and CDMA technology. .The lack of GPRS transmission bandwidth, transmission of video frames per second, only a few, and appear prone to break when the emergency event and the wireless receiver of the dead. .CDMA transmission also exists for such failure, the downstream bandwidth is 153 kb / s, upstream bandwidth is 70 ~ 80 kb / s, so smooth video transmission is basically impossible. .Because the image is only a few frames to capture the form of transfer, and for the small screen size. .Obviously, such systems can not meet the real-time video surveillance applications. .For the microwave (digital microwave, spread spectrum microwave), wireless local area network (WLAN, 802.11 (ab, g)) and other high technologies such as wireless transmission scheme for video coding in the MPEG-2 / 4, H.264, etc. for the .Lord. .However, most of them common problems exist that can do pass, as the transmission, directional transmission, and difficult to support mobile transmission, thus limiting the application of the video surveillance system. .</ P> <P> transmission control systems are generally low frame rate and ensure the transmission of clarity, because only the CIF MPEG-4 over the image sharpness in order to meet the needs of investigation and evidence collection. .Therefore, the wireless transmission technology to the monitoring system has been an absolute advantage into full play should be met: visualization and in non-blocking environment applications; for high-speed wireless transmission of moving images in real time; for transmission of high bandwidth, high .stream high-definition audio and video; has excellent anti-jamming, anti-fading ability. .In practice, real-time wireless video transmission has two main concepts: First, move the transmission; Second, broadband transmission. .Therefore, the development can be very wide-band high-definition video to an unlimited and stable video transmission systems, data transport mechanism optimization is one of the key issues to be resolved, unlimited bandwidth link resources are limited, this limitation handed down in the massive video .especially reflected. .Here, for wireless video transmission system fault tolerant data transfer mechanism to start the appropriate research to address the wireless video transmission bandwidth is limited resources and large amount of video data, this contradiction, take advantage of temporal correlation of video signal to save the .brought unnecessary retransmission bandwidth waste of resources. .Distortion through the use of the bandwidth of a cost function to evaluate the concept of wireless video transmission system. .On this basis, further consideration is given based on the bandwidth of a distortion minimization part of retransmission error control mechanism, thus improving bandwidth utilization, and the corresponding experimental analysis. .</ P> <P> [1] [2] [3].