| It is well known that the design of digital transmission for wireless video multicast will produce cliff effect.In order to serve multiple receivers who have different channel characteristics,a pseudo analog transmission system,named Soft Cast,is proposed.To address the bandwidth challenges brought by the increasing mobile video traffic,the multiple-input multiple-output(MIMO)technology is able to solve this problem through spatial multiplexing.Therefore,it is more and more meaningful to explore wireless video transmission with multiple antennas.However,the core idea in MIMO system is space-time signals processing.One of the most commonly used channel coding techniques is spacetime block coding(STBC).Space-time block coding is divided into orthogonal space-time block coding(OSTBC)and quasi-orthogonal space-time block coding(QSTBC).However,only one form of space-time block coding is used in the current soft video transmission with multiple antennas.Only orthogonal spacetime block coding can greatly improve the reconstructed video quality of the receiver,but for the transmitted complex signal,orthogonal space-time block coding cannot achieve the maximum transmission rate in the scene where the transmitter is more than two antennas.Although the maximum transmission rate can be realized by using only quasi-orthogonal space-time block coding technology,the reconstructed video quality of the receiver is lower than that of the video transmission scheme using orthogonal space-time block coding technology.Therefore,so this paper mainly solves the problem of bandwidth resource allocation caused by channel coding for wireless soft video transmission with multiple antennas.The main work and innovations are as follows:Firstly,a wireless soft video transmission scheme based on ASTBC based on MISO is proposed.In this scheme,a frame image of the transmitted video is typed into 64 packets under given bandwidth and channel conditions,the packets are reorganized according to the importance,the high importance packets are transmitted using OSTBC coding,and the generally important packets are transmitted by QSTBC coding,and the unimportant packets are discarded.Deduce the optimization formula to describe the reorganization problem of the packets.Here the transmission rate of OSTBC is 1/2,that is,the number of lost packets is the same as the number of packets using OSTBC.The simulation results describe the PSNR performance of different sequences transmitted by OSTBC under different channel conditions,and the comparison of PSNR performance of this scheme with pure OSTBC coding technology and QSTBC coding technology under different channel conditions.It shows the advantage of this scheme in the effective allocation of bandwidth under the condition of channel coding.Secondly,an ASTBC wireless video soft broadcast transmission based on MIMO is proposed.Based on the wireless soft video transmission scheme of ASTBC based on MISO,the problem of antenna heterogeneity is further considered,so as to further improve the reconstructed video quality of the receiver.In this scheme,the receiving diversity gain obtained by carrying multiple antennas at the receiving end further improves the reconstructed video quality received by the user.The experimental results show that the proposed scheme can obtain better reconstructed video quality than the wireless soft video transmission scheme of ASTBC based on MISO under the same bandwidth and different channel conditions. |
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