The perfect choice of one-stop service for diversification of architecture.

Wireless Video Communication Scheme Based on MIMO Technology and H.264 Code

Aiming at the problem of low reconstructed image quality in traditional video transmission, a new scheme of H.264 bitstream transmission is proposed. At the source end, according to the importance difference of H.264 code stream, it is divided into two parts. MIMO channel is used to transmit video signal. Under the condition of keeping the total transmission power constant, the transmission power is dynamically distributed on two antennas. Simulation results show that the proposed scheme effectively improves the reconstructed image quality at the receiver under the same channel conditions.

0 Introduction

In recent years, with the development and application of high-speed broadband wireless technology, wireless video communication is becoming a field of widespread concern. How to significantly improve the spectrum efficiency in wireless communication system to meet the increasing demand of communication capacity has become a widespread concern and urgent problem to be solved all over the world. Multiple input multiple output (MIMO) technology can effectively alleviate the above contradiction by increasing the number of antennas at the transmitter and receiver. The system uses multiple antenna arrays at the transmitter and receiver to obtain spatial multiplexing and diversity gain, and space-time code (STC) fully exploits the MIMO system capacity, which is an effective means to improve the bit error performance of the whole system. On the other hand, as a new generation of video compression coding standard, h.264/avc has high coding efficiency and good network performance

Complex affinity has been widely valued by scholars at home and abroad. The combination of MIMO technology and h.264/avc will greatly improve the reliability of wireless video communication.

1. Bitstream segmentation of H.264

H. The code stream of 264 is encapsulated by network abstraction layer (NAL unit). Each nal unit has a specific data type. It contains a byte nal unit header and an original byte sequence load. The importance of the current nal unit is indicated by the NRI in the nal unit header information. The higher its value, the more important the nal unit is. In the semantics of H.264 nal layer, nal is used_ ref_ IDC to indicate the priority of the current nal.

Based on this idea, for the H.264 code stream in annexb data format, the nal of I frame or IDR frame (immediate refresh frame), SPS (sequence parameter set) and PPS (image parameter set) in the sequence_ ref_ The IDE value of 3 indicates that the nal unit in which it is located has a high importance level. Once this kind of data is lost, it will have a fatal impact on video reconstruction. Because I frame is the intra coding mode and it is used as the reference frame of P frame, only its accurate transmission can ensure the complete decoding of the image. SPS and PPS are necessary parameters for decoding, and its loss is bound to have a fatal impact on the image. Based on the above considerations, the bitstream segmentation method in this paper is as follows: the data of I frame (or IDR frame), SPS and PPS which play an important role in video image reconstruction are regarded as a kind of data, and the high-level protection is adopted for this kind of data; The rest is class II data, which adopts low-level protection, and on this basis, unequal error protection scheme is designed to improve the quality of reconstructed image.

2 space time block coding (STBC)

Space-time code is a high reliability channel coding proposed to realize the channel capacity of MIMO system. According to the channel characteristics, it effectively integrates the technologies of transmit diversity, receive diversity, error correction coding and modulation. It can achieve high spectral efficiency communication with low transmission power and approach the performance of MIMO channel capacity. Compared with the system without space-time coding, space-time code can obtain better anti error performance under the same spectrum resources.

Space-time coding system not only provides full diversity gain, but also provides coding gain, and has linear detection complexity. For simplicity and generality, this paper adopts a STBC system with two transmitters and one receiver. This system is also the most classical space-time code at present. It not only provides full diversity gain, but also provides coding gain, and has linear detection complexity. This scheme is also the most classical space-time code, and its coding structure is

The received signal corresponding to two consecutive time slots on the receiving antenna can be expressed as

Where H1 and H2 are the channel fading coefficients from the two transmitting antennas to the receiving antenna respectively, W1 and W2 are the complex Gaussian white noise added to the receiving antenna, the mean value is 0 and the variance is N0. The detection can be completed by the maximum likelihood decoding criterion.

3 H.264 space-time coding scheme based on power allocation

3.1 power allocation strategy

Assuming that the total transmission power of the system is p, there are n transmission antennas, and the transmission power on each antenna is P0, so there is

In order to realize unequal error protection, for the STBC system with two transmitters and one receiver, it is assumed that antenna 1 transmits a high priority code stream and allocates a large transmission power to it, and the allocation coefficient is K1, (K1 > 1); Antenna 2 transmits low priority code stream and allocates small transmission power to it. Set the allocation coefficient as K2, (K2

Wireless Video Communication Scheme Based on MIMO Technology and H.264 Code 1

get in touch with us
مقالات مقترحة
Problems of Phased Array Ground Penetrating Radar Detection System
Although GPR has been widely used in hydrology, engineering, environment and other fields, many basic theoretical and technical problems have not been fundamentally solved, so the real advantages of GPR have not been brought into full play.The main problems existing in GPR technology include:1) The detection depth is shallow, and the contradiction between detection depth and resolution cannot be overcome. Increasing detection depth means sacrificing detection resolution;2) Multiple spread and other clutter jamming are serious, and there has been no good elimination method, which exists in radars at home and abroad;3) The influence of medium unevenness is great and can not be eliminated, resulting in difficulty in obtaining necessary velocity data;4) The data collection method of single sending and single receiving can provide limited information for post-processing and interpretation.The above problems are fatal defects for GPR. Although many geophysicists, electromagnetic experts and geophysical workers have done a lot of research and improvement on radar antenna design, signal processing and underground target imaging, these works are only partial modifications to the existing GPR system. In order to develop GPR technology, we must update our ideas and solve the problems from the fundamental principle.In view of this situation, experts proposed to develop a new GPR system - phased array GPR detection system in 1999.The basic research idea is to replace the current monopole radar antenna with the phased array radar antenna by using the relatively mature military phased array radar technology. Its purpose is to gather the electromagnetic wave into a narrow beam to transmit underground (or detection object) through the phased array technology, and receive the radar echo signal reflected by the target by using the multi-channel acquisition technology, The advanced data processing is carried out, and finally the three-dimensional image of the internal structure of the detection object is given.Development prospect of ground penetrating radar technologyIt is worth noting that at present, similar products have appeared in the market, such as RIS antenna array series of a company, but these products simply combine multiple monopole antennas into array antennas, which is essentially different from the idea of phased array ground penetrating radar.Because the phased array radar converges the electromagnetic wave into a narrow beam by controlling the phase delay of each channel, the energy is concentrated and the wave front diffusion is small. Therefore, the detection depth of the phased array radar is much larger under the condition of the same frequency and transmission power; On the contrary, under the same detection depth, phased array radar can improve the transmission power, so its resolution is much higher than the existing radar. In addition, since the spherical wave transmission is changed to beam transmission, the influence of medium heterogeneity is much smaller.Secondly, the phased array radar works in a continuous scanning mode and can scan in multiple directions. Therefore, the amount of information is much larger than that of the existing ground penetrating radar. For some special detection work, such as the quality detection of embankment cut-off wall, its role is unmatched by the existing ground penetrating radar (monopole antenna radar can not detect the joints, forks and other defects of embankment cut-off wall at all).Because phased array radar is a multi-channel received signal, multi-channel superposition can be carried out, just like the multiple coverage technology of reflection seismic exploration. Therefore, multiple interference can be greatly eliminated, which is difficult for existing radars. The antenna of high frequency (600mhz-1ghz) phased array ground penetrating radar can be made smaller, and its advantages are unmatched by the existing ground penetrating radar in shallow detection.At present, the system prototype has been completed. The carrier free pulse working system with center frequency of 900MHz is adopted, and the transmitting and receiving antennas are separated. 16 (4 × 4) Transmit channel forming, beam aggregation and scanning 16 (4) × 4) The channel receives the echo, and the optional scanning angles are - 36 °, - 24 °, - 12 °, 0 °, 12 °, 24 ° and 36 °.The software part of the system has rich data processing functions. The main conventional processing includes filtering, gain adjustment, static and dynamic correction, deconvolution, complex signal analysis, time-frequency analysis, etc., and multi-channel data processing, such as velocity analysis, superposition technology, coherence analysis technology, array signal processing, etc. And weak signal extraction, target automatic recognition and inversion interpretation under various clutter interference. A large number of field experiments on concrete detection in Yichang Three Gorges dam are carried out. The experimental results show that the spotlight scanning function of phased array radar has been realized, the penetration depth is greater than 1.5m and the resolution is higher than that of ordinary radar.Editing: hfy
Suggestions for Journaling, Bullet Notes, Activity, Wiki Like Application
How Many NCAA Football Bowls Are There?
What Is the Name of a Horror Movie with an Eye Falling in a Cocktail Glass?
Automotive Backup Camera Systems, Backup Hub
Blockchain Technology Explained: Powering Bitcoin
The National Key R & D Plan Launched the Key Project of "key Technologies and Demonstration of Inter
Alibaba Goes to War! Smart Home Battlefield Adds Another Giant
Looking for Software to Monitor Installations
عمليات البحث ذات الصلة
The Development of Intelligent Security Is Accelerating, and the Scale of Video Surveillance Market
Fingerprint Humidity Control Mechanism Is Conducive to the Development of Better Robots and Other Eq
Problems of Phased Array Ground Penetrating Radar Detection System
Suggestions for Journaling, Bullet Notes, Activity, Wiki Like Application
How Many NCAA Football Bowls Are There?
What Is the Name of a Horror Movie with an Eye Falling in a Cocktail Glass?
Automotive Backup Camera Systems, Backup Hub
Blockchain Technology Explained: Powering Bitcoin
House Empire Construction&Furnishing Co.,Ltd
لايوجد بيانات
Sign Up For The Newsletterus
Copyright © 2018 Guangzhou House Empire Construction&Furnishing Co.,Ltd. | All Rights Reserved Design by |Sitemap