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Mathematical analysis and optimization of a carrier tracking loop are presented. Due to fast changing of the carrier frequency in some satellite systems, such as Low Earth Orbit (LEO) or Global Positioning System (GPS), or some planes like Unmanned Aerial Vehicles (UAVs), high dynamic tracking loops play a very important role. In this paper an optimized tracking loop consisting of a third-order Phase Locked Loop (PLL) assisted by a second-order Frequency Locked Loop (FLL) for UAVs is proposed and discussed. Based on this structure an optimal loop has been designed. The main advantages of this approach are the reduction of the computation complexity and smaller phase error. The paper shows the simulation results, comparing them with a previous work.

Dynamic Channel Allocation (DCA) technology is an effective ways to solve the contradiction between limited spectrum resources and increasing user demand in TD-SCDMA system. Aiming at the limitation of conventional DCA algorithm, an improved dynamic channel allocation algorithm based on carrier priority is proposed in this paper to solve tidal phenomenon caused by regional traffic migration and shows channel model. The simulation results show that the proposed algorithm can effectively increase resource utilization and improve access success rate with less changing in channel model.

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