Research On The Equalization Technologies For The Wireless Image Transmission Data Link System Based On The UAV Platform

Currently, the social informatization continuously boosts and the communication structure gradually diversifies. What's more, the existing communication technical methods based on the ground and the satellite communication cannot meet people's growing needs quite well. As a result, airborne communication is gradually becoming an important supplement and support for the three-dimensional information system. With the integration of wireless communication and multimedia technologies into the next generation of unmanned aerial vehicle(UAV) wireless image transmission data link system, the demand for system capacity and service quality is constantly rising. It has become a hot spot in the field of wireless communication about how to improve the effectiveness and reliability of data transmission as well as to lower bit error rate(BER). Both of the combination of multiple-input multiple-output(MIMO) technology and orthogonal frequency division multiplexing(OFDM) technology and the combination of single carrier frequency domain equalization(SC-FDE) technology and serially concatenated continuous phase modulation(SC-CPM) technology are able to greatly satisfy the above requirements. However, the influence upon the system performance by the factors like inter-symbol interference(ISI) and inter-channel interference(ICI), etc. is very serious. Therefore, the effective equalization technologies have become the key to the design of the wireless image transmission data link system based on the UAV platform.Aiming at the defects such as high computation complexity, low power efficiency and poor spectrum efficiency, etc. caused by conventional methods under the hostile communication environment, the new and efficient equalization technology solutions for the wireless image transmission data link system based on the UAV platform are proposed from the two technical routes of MIMO-OFDM and SC-FDE SC-CPM in this paper:Firstly, a kind of internal synergetic optimization solution for sphere equalization technology is proposed after the detailed analysis of the system model of MIMO-OFDM UAV wireless image transmission data link. Besides, the computation complexity of the system is reduced to some degree by multiple optimization upon the aspects such as the initial search radius, detection sequence and enumeration strategy, etc. as well as the support of the configuration of relevant parameters.Secondly, a kind of external collaborative optimization solution for sphere equalization technology is proposed based on the previous foundation. It embeds ? quantum genetic algorithm into sphere equalization technology, and contains both the advantages of quantum computing and genetic algorithm(GA). Moreover, a great many of complex matrix operations are avoided so as to improve the detection efficiency through reducing the multidimensional search into the unidimensional search.Thirdly, a kind of low-complexity SC-FDE SC-CPM technology is proposed, which combines serial concatenated convolutional coding(SCCC) technology with continuous phase modulation(CPM) technology to effectively eliminate ISI and ICI so as to achieve a more excellent performance than Turbo code. Furthermore, the pilot training word sequence is embedded into each data package for channel estimation and the M-ary Laurent decomposition method is introduced for carrying out low-complexity minimum mean square error(MMSE) frequency domain equalization.Fourthly, a kind of collaborative design and optimization scheme for both of hardware and software of low-complexity UAV equalizer based on SC-FDE SC-CPM is proposed by means of having weighed the advantages and disadvantages of the above-mentioned two equalization routes applied to UAV wireless image transmission data link system. It combines SC-FDE technology with SC-CPM technology to increase the utilization ratio of spectrum and power while resisting to the multipath effect. Besides, the computation complexity of the system is greatly reduced and the detection efficiency and the complex environment adaptability are improved by the collaborative design and optimization for the equalizer upon the two aspects of algorithm and architecture.On the whole, the main research work of this paper focuses on the collaborative design and multiple optimization for both of hardware and software of the equalization technologies in UAV wireless image transmission data link system. What's more, it has very important reference significance and application value to the development of the equalization technologies for UAV wireless image transmission data link system in China as well as to the researches in relevant fields at home and abroad.