Adaptive beamforming for OFDM based hybrid mobile satellite system

Abstract

Global connectivity cannot be guaranteed by terrestrial networks due to the lack of infrastructure in rural areas. Neither can satellite networks assure this due to lack of signal penetration and capacity coverage issues in densely populated areas. To bridge this gap, we propose an Orthogonal Frequency Domain (OFDM) based hybrid architecture where users are provided service by existing mobile networks in urban areas and are served by satellite in the rural areas. In such a system terrestrial and satellite networks can reuse the portion of spectrum dedicated to each of these systems resulting in significant increase in overall capacity, wider coverage and reduced cost. This frequency reuse induces severe Co-Channel Interference (CCI) at the satellite end and our work focuses on its mitigation using OFDM based adaptive beamforming.

Overview and comparison of on‐ground and on‐board beamforming techniques in mobile satellite service applications

“…Several works have already addressed improving the beamforming in OBB systems. For example, several on‐board adaptive beamforming schemes have been proposed to mitigate co‐channel interferences in a hybrid terrestrial‐satellite system in , however, the adaptive beamforming schemes are still challenging for on‐board applications, because they have to be achieved at the expense of a high complexity and increased mass/power for the satellite. On the contrary, the OGB, which promises a high flexibility and alleviates the on‐board complexity, may appear more attractive when applying adaptive or dynamic beamforming.…”

Semi-Adaptive Beamforming for OFDM Based Hybrid Terrestrial-Satellite Mobile System

“…In conjunction with high capacity, networks must also offer ubiquitous service. Following this objective, we proposed an OFDM based Hybrid Terrestrial-Satellite Mobile System (HTSMS) [1].…”

“…Hence to mitigate uplink CCI in [1], we employ Least Mean Squares (LMS) based adaptive Beamforming (BF) at the satellite. BF has been studied in detail with reference to OFDM [3]- [5].…”

Iterative turbo beamforming for orthogonal frequency division multiplexing-based hybrid terrestrial-satellite mobile system

“…Along with provisioning of high data rates, future network services will also need to have global presence to ensure success. In the light of this, we proposed an OFDM based Hybrid Terrestrial-Satellite Mobile System (HTSMS) [1] where users in urban and rural areas are served by satellite and terrestrial cellular Base Stations (BTSs) in an integrated and transparent fashion. This is hybrid in the sense that the BTSs provide service to mobile customers in urban areas while the satellite network serves users in rural areas.…”

“…To mitigate this CCI, we employ Least Mean Squares (LMS) adaptive BF at the satellite [1]. Other variants of LMS can also be adopted such as NLMS [2,3] and VSS-LMS [4] which provide better convergence.…”