Technology of wireless video monitoring and system are summed up

Be based on wireless local area network subsidiary channels in the human body through which vital energy (WLAN) multimedia information is transmitted, it is to solve the main measure of slick video monitoring inside the building, be based on 802.11 agreements a group of things with common features. The frequency point that IEEE802.11a provides is 5GHz, agree with indoor reach mobile environment, transmission speed is 1 to 2Mbps. IEEE802.11b (Wi-Fi) the job is nodded at 2.4GHz frequency, when when the letter comparing of a confusion of voices is restricted to be worth under a certain, its transmit rate to be able to fall automatically from 11Mb/s to 5.5Mb/s, perhaps fall to reach 1Mb/s rate to the 2Mb/s of technology of frequency of direct alignment enlarge again. IEEE802.11e and IEEE802.11g are next generation wireless LAN standard, be called the patulous standard of IEEE802.11 of way of wireless LAN standard, it is the level that increased QOS function and safe function in the MAC layer of existing 802.11b and 802.11a, transmit for the reliable video information on its laid a foundation.

As WiMAX technology and 3G technology mature with each passing day, the wireless video monitoring that is based on WiMax and 3G also becomes research heat. WiMAX(Worldwide Interoperability For Microwave Access) is a kind of when appear in recent years wireless broadband receives a technology. WiMAX uses technology of modulation of much carrier wave, can provide high-speed data professional work, and have spectrum resource utilization rate tall, cover range big (transmission distance can amount to tens of kilometers) wait for a characteristic. Net of wireless city land with certain boundaries (WMAN) used WiMax technology, the 802.16 agreements that group net uses a group of things with common features. Compare with existing mobile technology photograph, wiMAX technology can offer higher data rate, stronger data professional ability.

Multimedia business is the key of 3G data business, its transmit rate to ask to be: 144kbps can be achieved when high speed is mobile, 384kbps is slow when fast shift, static condition is 2Mbps. The bandwidth of 3G suits the application of wireless video monitoring very much. Believe to be used as the business of 3G, wireless video monitoring is sure to develop flourishingly.

The crucial technology step that CDMA or OFDM arrive many a little bit as the dot or orders information of bit of image, video to transmit, capacity of the multimedia service that high speed of tall, support leads its spectrum utilization rate, system, fight much diameter channel to disturb ability strong. CDMA technology is the modulation that is based on theory of enlarge frequency communication and technology of much location join, OFDM technology attributes skill of modulation of much carrier wave. The mainstream technology that predicts the 3rd acting the following mobile will be OFDM technology.

In supervisory system of video of wireless real time, a lot of and serious problem such as the efficiency that controlled an agreement to decide whole system, compatibility, security, it is the command center that the system runs. Dominate a deliberation especially the control agreement of supervisory system of wireless real time, not only the requirement can establish link steadily quickly, and the requirement has certain control capacity to this join. SIP of the conversational agreement that start (Session Initiation Protocol) the MMUSIC that is IETF (Multiparty Multimedia Session Control) the layer of application of multimedia communication frame that the working group makes believes your agreement, design concept and consultative structure accord with the character of NGN and requirement completely, got the public figure inside increasing course of study approbate, domestic and international the research that a lot of well-known companies begin to be engaged in SIP and development work. Nokia and Ericsson had developed the carries end network multimedia that is based on SIP system, 3GPP and 3GPP2 introduced the IMS that is based on SIP in R5 and Phase2 phase respectively (IP multimedia subsystem) . The multimedia communication that is based on SIP has become new main trend to develop way.
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