Real-time wireless analog video transmission solution

The technical application of 1.2G is increasingly accepted by all walks of life. Wireless monitoring as a special use mode is also gradually optimistic about the majority of users. Its simple installation, strong maneuverability, no delay in real-time images, and high cost-effectiveness make it possible for surveillance systems in more industries to adopt wireless monitoring methods to establish connections between monitored points and monitoring centers. Wireless monitoring technology has been widely used in modern communities, transportation, transportation, water conservancy, shipping, security, firefighting and other fields. Compared with traditional monitoring solutions, wireless monitoring has the following three advantages of wireless analog microwave video transmission: low cost, one-time investment, no need to dig trenches, suitable for outdoor distances and well-repaired occasions; in many cases, Users are often limited by the geographical environment and work content. For example, mountainous areas, ports, and open areas, and other special geographical environments, bring great inconvenience to the wired network and wired transmission wiring projects. The construction period using cable will be very long, even fundamental. can not achieve. At this time, the use of wireless monitoring can get rid of the shackles of cables, and has the advantages of short installation cycle, easy maintenance, strong capacity expansion, and rapid cost recovery.

2. The maintenance cost is low. The wireless monitoring maintenance is maintained by the network provider. The front-end equipment is a plug-and-play, maintenance-free system. The wireless monitoring system is a combination of monitoring and wireless transmission technology. It can transmit the site information in different locations to the monitoring center in real time. In the wireless monitoring system, the wireless monitoring center needs to obtain the video information of the monitored point in real time, and the video Information must be continuous and clear. At the wireless monitoring point, cameras are usually used to collect real-time conditions on the site. The cameras are connected through video wireless transmission devices and send data signals to the monitoring center through radio waves. The device can be widely used in a wide range of distributed safety monitoring, traffic monitoring, industrial monitoring, home monitoring and other fields. Such as: · ATMs, bank tellers, supermarkets, factories and other wireless monitoring and nursing homes, kindergartens, schools to provide remote wireless monitoring services, power station, telecom base station unattended systems, oil, drilling, exploration and other wireless monitoring systems With the rapid economic development of intelligent buildings, and the expansion of large-scale security projects in safe cities, the demand for security products has been increasing, and the security industry has grown explosively. As the largest product area, security video surveillance will continue to play a leading role in the rapid development of the security industry. Transport Infrastructure Promotes Regional Economic Growth, Job Creation, and Poverty Reduction The rapid development of the security industry has attracted many companies in other industries to start paying attention and even extend the business to related fields in security, strengthen the capital operation of mergers and acquisitions, attract talents, and rapidly increase the core The level of technology, production and system integration capabilities, and the enhancement of competitive strengths will make M&A as one of the important development strategies in the security field in the future. We hope to enter into new target markets and improve business layout through acquisitions. For the non-security industry, M&A has also become the most convenient way to enter the security industry.

Security monitoring and remote microwave image transmission is one of the best effective choices for wireless real-time video surveillance. It is mainly used in city surveillance, border defense border monitoring, forest fire prevention monitoring, water conservancy monitoring, dock monitoring, etc. It is not easy to pull the cable and there is no transmission network. Remote microwave image monitoring is popular because of its rapid construction and low cost. With the development of wireless modulation technology in recent years, remote microwave image transmission systems are also particularly suitable for emergency prevention and control and deployment control systems for emergencies. Emergency command and other applications.

Wireless analog transmission: low cost, no need to dig trenches, suitable for outdoor distances and has been renovated, and transmit field information from different locations to the monitoring room in real time. With the development of multimedia processing technologies and communication technologies, people’s Communication methods and content are also undergoing tremendous changes. Especially in recent years, with the gradual establishment of third-generation and later-generation mobile communication systems, the transmission of multimedia data based on video information on the wireless network has become a common focus in the field of communications and multimedia. This article focuses on the major contradictions in the video transmission of wireless networks (mainly referred to as mobile communication networks), carries out research on several key issues, and has obtained some research results in the following aspects:

1. Bit rate control technology based on the statistical characteristics of the original sequence of the video: Large amount of video data but low bandwidth of the wireless channel. In order to obtain better end-to-end video transmission performance under low bandwidth conditions, an optimized low bit rate rate control technique essential. To this end, we have conducted an in-depth analysis of existing bit rate control techniques and found that existing techniques assume that the time jitter of the video stream can be simulated by a random process with certain parameters, and then use forward prediction to predict The code rate control parameter of the current frame/coding unit. Due to the non-stationary randomness of video sequence content (such as object motion, etc.), such assumptions do not describe the jitter of its code rate well. Especially in the wireless transmission environment, the video transmission code rate is low, and the main proportion of the code stream is the motion feature data. The forward prediction mechanism of existing rate control techniques cannot effectively track changes in the motion of objects in a video sequence. For this reason, we propose a mechanism for allocating the code rate using the statistical characteristics of the original image as a parameter. On this basis, a quantization parameter adjustment algorithm based on the basic unit coding complexity prediction is further proposed, thereby avoiding the analytical model having low adjustment performance but high computational complexity under low bit rate applications (need to update parameters in the model in real time ) This defect. In addition, for the intra-coded frames in the codestream, we have also proposed a new rate-distortion-optimized code rate allocation scheme, which effectively improves the rate-control-rate distortion performance under the condition of bandwidth constrained.

2. Optimized fault-tolerant transmission mechanism based on bandwidth-distortion cost: In this study, the concept of bandwidth-distortion cost function was first proposed to evaluate the wireless video transmission system. Based on this, the bandwidth-distortion cost minimization criterion was further given. Part of the retransmission error control mechanism. One of the most important limitations in wireless transmission is still the limited bandwidth resources. This limitation is particularly evident in the massive video data transmission. If there is a reverse channel (such as a wireless streaming media application), in the case that the delay is satisfied, after receiving an error, a retransmission request may be sent through the reverse channel to correct the erroneous data. The current mainstream composite ARQ error control mechanism (forward error correction coding and ARQ combination) uses ARQ to retransmit the forward error correction code or error data of the error data after the forward error correction fails. If the error data cannot be corrected after the delay limit is exceeded, the error data will be discarded. In this way, the receiver application layer must use the spatio-temporal correlation characteristics of the video sequence to perform error concealment and recovery. In fact, because of the strong spatio-temporal correlation of video sequences, certain strong correlation parts can be well restored by adopting certain error recovery mechanisms. If these parts first use the retransmission mechanism to correct errors after an error, there is obviously a waste of bandwidth resources. In response to this problem, we proposed a partial retransmission error control mechanism based on minimizing the bandwidth-distortion cost for video transmission on the wireless channel, and effectively prevented retransmissions from occurring on the premise of ensuring terminal receiving quality. Bandwidth resources are wasted.

3. Efficient joint source channel coding based on arithmetic codewords: Fault-tolerant coding is one of the key technologies in wireless video transmission. A research hotspot of current fault-tolerant coding and joint source channel coding based on arithmetic codewords are studied. The concept of distance-weighted posterior probability and local maximum posterior probability is proposed. Based on this, a joint coding and decoding algorithm for the maximum distance weighted posterior probability source of arithmetic codewords is further presented. For fault-tolerant coding, the traditional design concept is to separate source coding/decoding and channel coding/decoding. In the wireless transmission environment with limited delay and complexity, such a design makes the transmission fault tolerance performance greatly limited. Source. The one-channel joint coding technique can eliminate this limitation and thus provide better fault tolerance performance at the same bandwidth. Arithmetic coding has been widely used as a kind of effective entropy coding in video source coding. At the same time, it can also be applied to fault-tolerant coding as a code with error detection performance. However, existing source-channel joint coding schemes that use arithmetic coding are either too complex or have poor error correction performance. For this reason, we propose a local maximum a posteriori decoding algorithm for the disadvantage of the high complexity of the current MAP decoding algorithm, which can take into account both the complexity and the error correction performance. On this basis, we further propose an arithmetic decoding algorithm based on the maximum distance weighted posterior probability. This algorithm can provide better error correction performance than MAP while maintaining moderate algorithm complexity. Based on the analysis of existing technologies, this paper proposes new models or evaluation criteria to further improve the end-to-end performance of wireless video transmission. In the model, for the low-bit applications, an I-frame quantization parameter estimation, code rate allocation, and quantization parameter adjustment parameter model based on video statistical features are proposed. In terms of evaluation criteria, a bandwidth distortion cost criterion is proposed for fault-tolerant transmission. For fault-tolerant coding, a local maximum posterior probability and a distance-weighted posterior probability criterion are proposed. The research results of this paper effectively improve the end-to-end quality of wireless video transmission, reduce the complexity of terminal processing, and to a certain extent ease the inherent contradiction in wireless video transmission.

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