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It is a challenge to accelerate the acquisition speed of the three-frequency heterodyne due to the property of multi- frame. In this paper, we propose a composite three-frequency heterodyne technique. Specifically, the frequency division multiplexing (FDM) technique is applied to combine three phase- shifting patterns of each frequency into a composite pattern by modulating each phase-shifting pattern onto the carrier pattern and summing them. This multiplexing technique reduces 9 projection images in the three-frequency heterodyne method to 3 images. Experimental results show that the average plane fitting error of the reconstructed white plate is approximately 0.58mm, which is comparable to other commonly used methods while accelerating the acquisition speed.

In this paper, the problem of caching at small base stations (SBSs) is investigated, where the SBSs are allowed to communicate with each other through a fixed communication topology. Assume that the central controller can only serve a subset of SBSs due to its limited capacity, when the cellular users request files. A problem rises in selecting which SBSs to cache the files requested in order to minimize the delay of file transmission from the SBS to the user. Moreover, the delay associated with all the user in the wireless network depends on the number of requirements. Motivated by this, the problem of selecting which SBSs to cache which file for minimizing the delay experienced by the cellular users is studied. We formulate the problem of minimizing the latency experienced by the cellular users as an integer programming problem and then propose a corresponding algorithm to obtain the optimal caching strategy. The numerical simulations show the validity of the proposed algorithm.es, or Math in Paper Title or Abstract.

Caching contents in the small base station (SBS) is expected as a class of promising techniques in an effort to mitigate the congestion problem for future cellular networks. In this paper, we consider a heterogeneous cellular network with storage capable SBSs, and focus our attention on the SBS selection problem, in order to achieve balanced cost including incurred serving cost and users' experienced delay. The numerical results show that the location of SBS has an impact on the delay and servicing cost, which should be carefully decided in system design.