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The rapid development of broadband satellite internet has brought satellite communication into a new era.The establishment of large-scale low-orbit satellite constellations has gradually saturated spectrum resources, and the high overlap in frequency use has led to serious interference problems between satellite communication systems.Satellite payloads typically communicate using phased-array antennas, which reduce interference by beamforming at the receiving and transmitting ends.The adaptive beamforming algorithm was used at the receiving end to suppressed interference by adaptive zeroing; The low sidelobe beamforming algorithm was used at the transmitting end, which reduced the interference by imposing specifi c constraints on the sidelobes to suppressed the sidelobe level.Three anti-jamming beamforming algorithms were introduced for the ground receiving end and the satellite sending end respectively, which provided a beamlevel method for reduced the interference between satellite communication systems.

Copyright of Space-Integrated-Ground Information Networks is the property of Beijing Xintong Media Co., Ltd. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The cognitive radio which could utilize spectrum holes to boost spectrum efficiency has garnered significant attention over the last few years. The cognitive radio network equipped with smart antennas further improved the spectrum efficiency in the spatial domain vertical to the schemes improving spectrum efficiency in the time domain. This paper argued that the cognitive users equipped with smart antennas could greatly improve spectrum efficiency by exploring spatial spectrum opportunities. With a smart antenna, a cognitive user could change the antenna pattern to avoid interference to primary users and maintain its communication without performing spectrum switching immediately. The paper investigated the statistical probability of the cognitive user utilizing the licensed channel with primary users concurrently. Both analytical and experimental results indicate that using smart antennas can greatly reduce the probability of spectrum switch and increase the spectrum efficiency in the spatial domain. [ABSTRACT FROM AUTHOR]

In view of problems that current underground positioning system is sensitive to environmental change and has low positioning accuracy, the paper introduced an underground positioning algorithm based on DOA and TDOA. The algorithm takes advantages of high accuracy of TDOA and high angular resolution of DOA, uses weighted average of respective direction angle of DOA and TDOA as signal angle, and combined with radius got by TDOA algorithm to calculate coordinates of mobile terminal. The simulation results show that the algorithm can achieve stable performance and high positioning accuracy in complex environment.

An energy-efficient and energy-consumption-balanced routing,named SaDVC-Routing,was put forward for WSN.The algorithm constructs virtual clusters based on assistant relays in the area of smart antenna beams,and then selects the node with maximum relay weight from the cluster to act as routing relay.With the help of energy consumption and nodes distance information,SaDVC-Routing can dynamically update the virtual clusters with beam expanding.If the beam width exceeds the threshold,a routing request is re-broadcasted based on weighted distance matrix.According to the simulation,it was found that this algorithm could not only decrease the energy consumption,but also get consumption balance between nodes in the local and global area.

The uplink user capacity for a TDD-CDMA system with a single traffic was analyzed.The analysis results have a great academic significance.By taking account of the effects by the smart antenna,the joint detection,the imperfect power control,the user distribution density and timeslot allocation,a SIR model for a TDD-CDMA system,and presents a calculation method of uplink user capacity with this model and the Gaussian approximation method.Compared with the existing methods,the factors considered are more complete,so the proposed method can be used for the analysis of uplink capacity in a TDD-CDMA system under all kinds of complicated network situations.

As one of the key technology in the third generation mobile communication, the smart antenna can effectively increase the capacity and reduce the co-channel interference. Since the circular arrays are commonly used in TD-SCDMA system, this paper studies a DOA estimation method by using an advanced ESPRIT algorithm, which is applicable to circular ring arrays, and the corresponding beamforming algorithm. At the last of the paper, we pay attention to the performance of aforementioned algorithm and analysis it from different aspects according to the simulation results in uplink fading channel mode.

The smart antenna sound array adaptive beamforming algorithm model based on quantum particle swarm optimization ( QPSO) algorithm was presented, which applied QPSO to adjust array antenna radius and the initial phase of array element, and then controlled the forming of the sound smart antenna array bam, so that the main lobe of the antenna beam aligned direction desired sound source signals, nulling alignment direction to interference signal, and forming the optimal gain main lobe and side lobes peak ratio. Matlab simulation results showed that the model could enhance the direction of the main lobe gain by about 10 dB, reducing noise directional gain by about 3.75 dB, effectively increasing the system communication capability and anti-jamming capability, and presented a universal scanning angle. [ABSTRACT FROM AUTHOR]

Copyright of Telecommunication Engineering is the property of Telecommunication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Journal of Applied Sciences - Electronics & Information Engineering is the property of Shanghai Scientific & Technical Publishers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

An improved amplitude approach algorithm for the pattern synthesis of arbitrary arrays was presented. Newton downhill method was used to amend the amplitude approach method, so that the process of the pattern synthesis is stable. The simulation results show that not only both the main lobe and side lobe shape can be controlled efficiently, but also the pattern is approaching the expected shape more quickly and steadily. [ABSTRACT FROM AUTHOR]