This paper presents a method to suppress narrowband interference in the direct sequence spread spectrum communication based frequency domain adaptive algorithm. The method determines the interference threshold by N-sigma algorithm and calculates the cut-off condition by separating the signal. The method suppresses the narrowband interference by frequency domain batch algorithm. This paper gives a detailed design method and simulation results, and makes a performance comparison with other methods. The results show that, the method in this paper has better performance than other methods. It is suitable for narrowband interference suppression in broadband systems.
A flexible hemispherical coverage array antenna based on multi-planar arrays is proposed to meet the growing demands for multi-target TT&C. The advantages and disadvantages of multi-planar arrays and dome phased in engineering implement are compared. Meanwhile, the influence of different number of plane arrays on antenna pattern is analyzed. For the purpose of interference suppression a novel beamforming method by adding constraint conditions is analyzed to enhance the performance of antenna for TT&C system. Considering the influence of occultation effect on the antenna performance, an effective occultation algorithm is presented. Firstly, the faces in bright area are projected on the plane that is perpendicular with the direction of receiving wave. Secondly, adopting the principle of line segment intersection, the intersect relationship of projective planes is determined. Finally, the facets shadowing relationship is judged by the overlapping and depth-of-view of facets along the receiving wave direction. Theoretical analyses and simulation results show that the antenna has approximate uniform gain beampattern in different steered angle and the occultation algorithm is feasible and effective.
Abstract. The large changing of link capacity and number of users caused by the movement of both platform and users in communication system based on high altitude platform station (HAPS) will resulting in high dropping rate of handover and reduce resource utilization. In order to solve these problems, this paper proposes an adaptive call admission control strategy based on reinforcement learning approach. The goal of this strategy is to maximize long-term gains of system, with the introduction of cross-layer interaction and the service downgraded. In order to access different traffics adaptively, the access utility of handover traffics and new call traffics is designed in different state of communication system. Numerical simulation result shows that the proposed call admission control strategy can enhance bandwidth resource utilization and the performances of handover traffics.
A flexible hemispherical coverage array antenna based on multi-planar arrays is proposed to meet the growing demands for multi-target TT&C. The advantages and disadvantages of multi-planar arrays and dome phased in engineering implement are compared. Meanwhile, the influence of different number of plane arrays on antenna pattern is analyzed. For the purpose of interference suppression a novel beamforming method by adding constraint conditions is analyzed to enhance the performance of antenna for TT&C system. System simulation is done based on the multi-planar arrays antenna. The feasibility of hemispherical coverage and the performance of anti-jamming are verified. Finally, a comprehensive summary is given.
To decrease the computational complexity and improve the performance of channel estimation for underwater acoustic (UWA) sparse multipath channels, a sparse least square (SLS) channel estimation algorithm is proposed. The proposed algorithm combines advantages of both generalized akaike information criterion (GAIC) estimation and estimation using effective order of channel impulse response (CIR). Known pilot data is used to estimate effective order of CIR and then the position of taps of CIR is estimated. In order to adapt to the environment with low SNR and reduce the dimension of signal space, adaptive threshold is also used. Simulation results indicate that the proposed method has good performance of channel estimation and low complexity.
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