Wenbin Gong

DEVELOPMENT OF 61-CHANNEL DIGITAL BEAM-FORMING (DBF) TRANSMITTER ARRAY FOR MOBILE SATELLITE COMMUNICATION

An 61-channel digital beamforming transmitter array antenna used in mobile satellite communication is presented in this paper. It can steer 16 beams simultaneously. The interface, architecture and subunits are described in detail. Standard hexagonal array (SHA) and 61-channel RF front ends are designed. Genetic Algorithm is adopted to realize the pattern synthesis with muti- objective optimization. The signal ∞ow and hardware platform of the digital beamforming network are discussed, which can complete the high speed array signal processing with maximum throughput of 34.16Gbps. A novel calibration scheme with high feasibility of project implementation is also proposed. The measurements of array antenna match well with simulation result, which validates the rationality and feasibility of the algorithms.

A SEMI-PHYSICAL SIMULATION SYSTEM FOR DBF TRANSMITTER ARRAY ON LEO SATELLITE

This paper presents a semi-physical simulation system for 61-channel DBF array transmitter antenna on LEO satellite. It consists of a hardware platform for digital beamfoming network (BFN) and a software simulation system for DBF array. The background and wideband input interface are described, and the signal process of digital beamforming network is discussed in detail. General DFT fllter bank, distributed arithmetic (DA) algorithm and Hartley image rejection structure are adopted to design the digital BFN, which make the calculation of BFN reduced by 98.41% and get the multiplier consumption decreased to 7.11%, compared with conventional algorithms. A novel digital BFN hardware platform with distributed structure is designed, which can complete the high speed array signal processing with maximum throughput of 32.025Gbps. Ultimately, the measurements of semi-physical simulation system show good agreement with the ideal simulation result. The derivation of radiation pattern from energy distribution of earths surface demonstrates that the DBF array has good performance on beam coverage with equal ∞ux density and satisfles the application in mobile satellite communication.

Performance analysis of a seven-beam CDMA-based LEO satellite system

To provide a tool for performance analysis of multibeam CDMA-based LEO satellite system, this paper establishes a comprehensive evaluation model of voice and packet communication respectively, and proposes three performance metrics: capacity, throughput and delay. And moreover with a practical seven-beam antenna pattern, we firstly develop a novel simulation algorithm based on geometric relations to performance analysis. It is shown that system capacity is reduced with the increase of two types of Power Control Error (PCE): PCE for shadowed user and PCE for unshadowed user, but the capacity degradation caused by PCE for shadowed user is larger than the others; In addition the method of power overcompensate in power control can improve the system performance only within limits. Finally, the throughput and delay is also affected by PCE, however, the effect of PCE in high traffic is opposite to that in low traffic.

61-channel digital beamforming (DBF) transmitter array

This paper presents a 61-channel digital beamforming transmitter array antenna for the mobile satellite communication application, that can form sixteen beams simultaneously .After the general introduction, the architecture and interconnect design of the array is discussed. Subsequently, two key technologies of DBF system are proposed: 1) rapid array signal processing and distributed digital beamforming network design and 2) calibration methodologies with ease in project implementation. Finally, the measurements and results of the DBF array demonstrate that the exceptional processing capability of digital beamforming network and the feasibility of project implementation.

SPACE-BORNE HEXAGONAL ARRAY ELEMENT FAILURE CORRECTION USING ITERATIVE CONVEX OPTIMIZTION

Element failure distorts the main-lobe pattern and increases side-lobe power level, which is almost impossible to be corrected artiflcially for space-borne array. It might be solved by redistributing the excitations of the left functional elements; however, this is a nonlinear, non-convex, and NP-hard problem. In this paper, two efiective approaches are proposed for failure correction, which is performed for space-borne hexagonal array using digital beamforming (DBF). One method, a modifled real-code genetic algorithm (RCGA), is employed that uses reinsertion and worst-elimination schemes, but it pays the high computation complexity. The other approach based on convex optimization chooses the excitations synthesized by RCGA as the initial points, and transforms the non-convex problem into a sequence of second-order cone programming (SOCP) problem, which can be solved iteratively by e-cient optimization tool. Numerical results conflrm that after the correction based on iterative convex optimization, the average root-mean-square error (RMSE) is reduced by 36%, and the relative side-lobe level (RSLL) is decreased by 6.7dB, with respect to the RCGA-based correction pattern.