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With the burst of mobile data, it is necessary to make use of idle mobile equipment for caching space. Caching in the femto-cells is proposed for reducing transmission latency between the WiFi points and its mobile users (MU) and better user service. In this paper, we firstly take the copyright of the files as the allocation resource and the WiFi points with caching space want to rent these copyrights. We propose a multi-rounds double auction mechanism for this problem and take the popularity parameter of the files as the quality weight. This game can help multiple content providers (CP) lease copyrights of the files to multiple WiFi points effectively. Different from traditional double auctions, it will take the failed buyers and sellers into consideration and they are allowed to change their requests in the next auction process. This mechanism can largely improve efficiency of the game and is budget balanced. We also prove that the allocation process is monotone and with the set of the critical payment rule, we prove the truthfulness of the mechanism. Additionally, we prove that the mechanism can form a conditional equilibrium. Simulation results verify the effectiveness of the proposed mechanism and compare with the traditional one-round double auction.

In the conventional directional modulation (DM) system without relay aiding, when the eavesdropper locates within the main-beam of the desired direction, it can intercept the confidential message from source Alice. In this paper, we propose a strategy to enhance physical-layer security of direction modulation in wireless transmission with the help of multi-relay cooperation. In this scenario, the confidential messages are forwarded to the desired destination receiver, and the artificial noise (AN) is enforced to the eavesdroppers with the aid of multi-relays and direction modulation such that the eavesdropper can not successfully recover the useful information from its received signals. The simulation results show that the proposed method achieves a significantly higher signal-to-interference-plus-noise ratio (SINR) peak at the destination position than at other positions outside the main-beam of the desired position and its secrecy rate performance at undesired position is so poor that the secure transmission is guaranteed.

Point Spread Function (PSF) estimation, a method established on the basis of joint transform correlation, is put forward to resolve the deterioration of the star map imaging caused by missile vibration. This method involves three steps. Firstly, within low frame rate charge coupled device (CCD) camera exposure time, a high frame rate CCD camera is used to obtain a continuous translation star map sequence under missile vibration and then the adjacent frames of star map sequence are put together into a joint input star map. Secondly, optical joint transform correlator is used as the processor and introduced into coordinate transformation to obtain the relative displacement vector of joint input star map, and then consecutive PSF of fuzzy star map is estimated after an interpolation process. Finally, the effectiveness of the algorithm is simulated and verified.

In this paper, a novel method for the spatial-temporal spectral estimation of multiple narrowband plane waves is developed based on the multistage Wiener filter (MSWF). The proposed method does not apply the estimation of covariance matrix and its eigendecomposition, therefore, its computational complexity is low. The numerical examples are used to demonstrate the performance of proposed method