Performance evaluation of digital beamforming strategies for satellite communications

Abstract

Smart antennas are becoming one of the promising technologies to meet the rapidly increasing demands for more capacity of satellite communication systems. A main component in a smart antenna system is beamforming. Because of the limitations of analog beamforming, digital beamforming will be employed in future satellite communication systems. We evaluate the performance of various digital beamforming strategies proposed in the literature for satellite communications: 1) single fixed beam/single user, 2) single fixed beam/multiple users, 3) single adaptive beam/single user, and 4) single Chebyshev dynamic beam/multiple users. Multiple criteria including coverage, system capacity, signal-to-interference-plus-noise ratio (SINR), and computation complexity are used to evaluate these satellite communication beamforming strategies. In particular, a Ka-band satellite communication system is used to address the various issues of these beamforming strategies. For the adaptive beamforming approach, subarray structure is used to obtain the weights of a large 2D antenna array, and a globally convergent recurrent neural network (RNN) is proposed to realize the adaptive beamforming algorithm in parallel. The new subarray-based neural beamforming algorithm can reduce the computation complexity greatly, and is more effective than the conventional least mean square (LMS) beamforming approach. It is shown that the single adaptive beam/single user approach has the highest system capacity.

Effect of Antenna Power Roll-Off on the Performance of 3G Cellular Systems from High Altitude Platforms

“…Studies into the impact of limited antenna stabilization on HAP broadband systems can be found in [4], but as this paper discusses the effect of antenna beam shapes, we have decided not to repeat this analysis for 3G systems here. More details about antennas suitable for HAP can be found in [18] and [19].…”

Satellite-Based Spectrum Sensing for Dynamic Spectrum Sharing in Ground-Located CRNs

“…Various digital beamforming strategies for satellite communications are discussed in [10] and [11]. Here, in order to examine the sensing scheme in 2-dimonsion covered ground areas, the planar antenna array with a specific geometry is applied in the satellite to receive the K cells' signals through antenna elements, producing approximately circular beams.…”

Modelling and Design of Circularly Masked Two-Dimensional Antenna Arrays

“…For microstrip antenna arrays, the CCA provides difficulties in the feeding and alignment for each antenna element in the array. Another important and practical antenna array configuration is the twodimensional planar array where the elements are aligned in a two-dimensional plane with regular antenna locations and separations [3,[6][7][8]. This last configuration makes it easy to fabricate the array with any antenna type.…”