Spectrally Efficient Waveforms for the Return Link in Satellite Communication Systems

In this paper, we study the applicability of terrestrial mobile waveforms in the return link of a high throughput satellite (HTS) communication system. These include orthogonal frequency division multiple access (OFDMA), single-carrier frequency division multiple access (SC-FDMA) and filter bank multi-carrier (FBMC). Key solutions to the challenges in a geostationary orbit (GEO) satellite channel, such as synchronization and non-linear distortion, are presented. A global-positioning-system-(GPS)-based approach for synchronization acquisition is proposed, while suitable algorithms are studied for timing/frequency offset estimation and synchronization tracking. The spectral and power efficiencies of the schemes are optimized by means of an intermodulation interference (IMI) cancelling receiver, and these are compared to state-of-the-art time division multiple access (TDMA). Finally, end-to-end simulations validate the system performance

BEAMFORMING FOR SMALL CELL DEPLOYMENT IN LTE-ADVANCED AND BEYOND

Integrating the standard coverage of traditional macrocells with cells of reduced dimensions (i.e., small cells) is considered one of the main enhancements for Long Term Evolution systems. Small cells will be overlapped with macrocells and possibly also with each other in areas where wider coverage capability and higher throughput are needed. Such heterogeneous network deployment presents many potential benefits but also some challenges that need to be resolved. In particular, multi-antenna techniques and processing in the spatial domain will be key enabling factors to mitigate these issues. This article presents different small cell deployment approaches: sharing the same frequency bands with the macrocell, or using separated higher frequency bands. For each approach, the benefits of beamforming are discussed

Capacity Enhancing Techniques for High Throughput Satellite Communications

In this paper, we present physical layer and system level techniques that can increase the capacity of a multi-beam high throughput satellite (HTS) communication system. These include advanced predistortion and equalization techniques for the forward link, synchronization and non-linear distortion minimization techniques for the return link waveforms. Interference management techniques such as precoding, multi-user detection (MUD), interference cancellation and coordination are evaluated under realistic co-channel interference (CCI) conditions. Interference-aware radio resource management (RRM) algorithms are presented for the forward and return links with full frequency reuse. These include satellite-switched smart gateway diversity, interference aware scheduling (IAS) for the forward link and scheduling based on multi-partite graph matching for the return link. The capacity enhancing techniques are evaluated in the Broadband Access via Integrated Terrestrial and Satellite Systems (BATS) framework