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   Comparative Assessment of Orthogonal and Nonorthogonal Multiplexing Techniques for Differentiated Satellite Broadcasting ServicesKayhan, Farbod  ; ; et alScientific Conference (2015) This paper presents a comparative assessment of two multiplexing techniques for providing differentiated classes of services over a realistic broadcasting satellite channel under variable link conditions ... [more ▼] This paper presents a comparative assessment of two multiplexing techniques for providing differentiated classes of services over a realistic broadcasting satellite channel under variable link conditions. A distinctive characteristic of satellite broadcasting channels is the non-linear characteristics of high power amplifier on-board of the satellite. In this scenario, the conventional additive white Gaussian noise (AWGN) channel with average power limitation is no longer an accurate model and nonlinear characteristics have to be taken into account. Orthogonal multiplexing (time sharing) techniques combined with variable coding and modulation are compared with hierarchical modulations with the goal of maximizing the number of broadcast channels over a given transponder while maintaining a target service availability. Hierarchical modulations are shown to provide better performance than orthogonal time division multiplexing (time-sharing) schemes for the AWGN channel. Here we design a practical transmitter scheme based on the hierarchical modulation and maximize the throughput by optimizing the achievable mutual information for finite size constellations. This will provide a lower bound on throughput which can be achieved by non orthogonal multiplexing scheme. We compare the performance of hierarchical modulation (non-orthogonal multiplexing) and time sharing techniques (orthogonal multiplexing) supporting two different service quality and service availability requirements for broadcasting the same content. [less ▲] Detailed reference viewed: 211 (12 UL)Precoding in multibeam satellite communications: present and future challenges; ; et al in jourlib Journal (2015) Whenever multibeam satellite systems target very aggressive frequency reuse in their coverage area, inter-beam interference becomes the major obstacle for increasing the overall system throughput. As a ... [more ▼] Whenever multibeam satellite systems target very aggressive frequency reuse in their coverage area, inter-beam interference becomes the major obstacle for increasing the overall system throughput. As a matter of fact, users located at the beam edges suffer from a very large interference for even a moderately aggressive planning of reuse-2. Although solutions for inter-beam interference management have been investigated at the satellite terminal, it turns out that the performance improvement does not justify the increased terminal complexity and cost. In this article, we pay attention to interference mitigation techniques that take place at the transmitter (i.e. the gateway). Based on this understanding, we provide our vision on advanced precoding techniques and user clustering methods for multibeam broadband fixed satellite communications. We also discuss practical challenges to deploy precoding schemes and the support introduced in the recently published DVB-S2X standard. Future challenges for novel configurations employing precoding are also provided. [less ▲] Detailed reference viewed: 191 (8 UL)Multibeam Joint Precoding: frame based designChristopoulos, Dimitrios ; Chatzinotas, Symeon ; et alin Cooperative and Cognitive Satellite Systems (2015) Detailed reference viewed: 128 (3 UL) |
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