Adaptive coding and modulation for satellite broadband networks: From theory to practice

This paper presents the detailed design and the key system performance results of a comprehensive laboratory demonstrator for a broadband Ka‐band multi‐beam satellite system exploiting the new DVB‐S2 standard with adaptive coding and modulation (ACM). This complete demonstrator allows in‐depth verification and optimization of the ACM techniques applied to large satellite broadband networks, as well as complementing and confirming the more theoretical or simulation‐based findings published so far. It is demonstrated that few ACM configurations (in terms of modulation and coding) are able to efficiently cope with a typical Ka‐band multi‐beam satellite system with negligible capacity loss. It is also demonstrated that the exploitation of ACM thresholds with hysteresis represents the most reliable way to adapt the physical layer configuration to the spatial and time variability of the channel conditions while avoiding too many physical layer configuration changes. Simple ACM adaptation techniques, readily implementable over large‐scale networks, are shown to perform very well, fulfilling the target packet‐error rate requirements even in the presence of deep fading conditions. The impact of carrier phase noise and satellite nonlinearity has also been measured. Copyright © 2009 John Wiley & Sons, Ltd.     

Evolution of satellite communications: Integration of ETSI BSM and DVB‐RCS for future satellite terminals

The main added value of the European Telecommunications Standards Institute broadband satellite multimedia (ETSI BSM) architecture is the definition of the Satellite Independent‐Service Access Point (SI‐SAP) protocol interface, which formally separates Satellite Dependent (SD) from SI layers, thus enabling the implementation of powerful vertical QoS mapping strategies. On the other hand, DVB‐S2/RCS satellite standard is considered the driving technology to integrate satellite with terrestrial infrastructure and provide up‐to‐date services. This paper focuses on the integration of ETSI BSM architecture and DVB‐RCS technology, by analysing the adaptations needed on real DVB‐RCS terminals to be interoperable with the SI‐SAP interface. To this end, the detailed design of an underlying architecture taking into account required adaptations and new functionalities is proposed. The possible further evolutions of the BSM specification are also highlighted, showing the potential for the development of future devices integrating both DVB‐RCS and ETSI BSM architectures also in view of the recent upgrade to the DVB‐RCS2 standard. The paper also validates the SI‐SAP QoS functionalities and proves the performance benefits in terms of QoS and quality of experience of Web‐browsing by means of a satellite emulator developed fors this aim. Copyright © 2015 John Wiley & Sons, Ltd.     

Performance evaluation of selected Transmission Control Protocol variants over a digital video broadcasting‐second generation broadband satellite multimedia system with QoS

This paper presents an analysis of several Transmission Control Protocol (TCP) variants working over a digital video broadcasting‐second generation (DVB‐S2) satellite link with the support of the Differentiated Services (DiffServ) architecture to provide quality of service (QoS). This analysis is carried out using the NS‐2 simulator tool. Three TCP variants are considered: SACK TCP, Hybla TCP, and CUBIC TCP. These TCP variants are taken as a starting point because they have proven to be the most suitable variants to deal with long delays present in satellite links. The DVB‐S2 link also introduces the challenge of dealing with variable bandwidth, whereas the DiffServ architecture introduces the challenge of dealing with different priorities. In this paper, we propose a DiffServ model that includes a modified queuing mechanism to enhance the goodput of the assured forwarding traffic class. This modified DiffServ model is simulated and tested, considering the interaction of the selected TCP variants. In addition, we present evaluation metrics, significant simulations results, and conclusions about the performance of these TCP variants evaluated over the proposed scenario. As a general conclusion, we show that CUBIC TCP is the TCP variant that shows the best performance in terms of goodput, latency, and friendliness. Copyright © 2012 John Wiley & Sons, Ltd.     

Measurement‐based admission control scheme with priority and service classes for application in wireless IP networks

Wireless IP networks will provide voice and data services using IP protocols over the wireless channel. But current IP is unsuitable to provide delay or loss bounds and insufficient to support diverse quality of service, both required by real‐time applications. In order to support real‐time applications in wireless IP networks, in this paper a measurement‐based admission control (MBAC) with priority criteria and service classes is considered. First we have shown the suitability of MBAC in wireless IP networks by comparing its performance with a parameter‐based scheme. Next, we have investigated the performance of strictly policy‐based MBAC and policy plus traffic characteristic‐based MBAC schemes in terms of (1) increasing the user mobility, (2) changing traffic parameters and (3) the presence of greedy users. The efficiency and fairness of each scheme are measured in terms of lower class new and handoff traffic performance. Copyright © 2003 John Wiley & Sons, Ltd.     

Railway satellite channel at Ku band and above: Composite dynamic modeling for the design of fade mitigation techniques

Past studies on the railway satellite channel (RSC) at Ku band and above consider exclusively the attenuation coming from the metal power arches (PAs) along the railway route, producing significant though deterministic periodical fast fading. Nevertheless, limited attention has been given to model tropospheric effects on the RSC. The present paper takes a more comprehensive view of the RSC by introducing a novel stochastic dynamic model of rain fading in mobile satellite systems on top of the diffraction because of PAs. The proposed approach builds upon well‐established research on rain attenuation time series synthesizers employing stochastic differential equations. It is shown that this propagation tool may provide significant aid, in general, in mobile satellite system simulations and in the design of fade mitigation techniques (FMTs), particularly aiming at the railway scenario. The tool enables the generation of fade events, fade duration statistics, rain attenuation power spectrum and predicting the necessary FMT control loop margin. This is particularly useful for the RSC because most of the proposed FMTs focusing on PAs are not appropriate for compensating atmospheric fading. Copyright © 2011 John Wiley & Sons, Ltd.     

Architecture,mobility management,and quality of service for integrated 3G and WLAN networks

Integration of 3G and wireless LAN (WLAN) becomes a trend in current and future wireless networks, and brings many benefits to both end users and service providers. In this paper, we provide a comprehensive survey on integration of 3G and WLAN. We discuss issues such as underline network architectures, integrated architectures, mobility management, and quality of service (QoS). We particularly study handoff QoS mapping and guarantee between 3G and WLAN, as well as how seamless voice/multimedia/data handoff becomes possible. Copyright © 2005 John Wiley & Sons, Ltd.     

New Framework and Mechanisms of Context‐Aware Service Composition in the Future Internet

The ongoing proliferation of new services, applications, and contents is leading the Internet to an architectural crisis owing to its inability to provide efficient solutions to new requirements. Clean‐slate architectures for the future Internet offer a new approach to tackle current and future challenges. This proposal introduces a novel clean‐slate architecture in which the TCP/IP protocol stack is decoupled in basic functionalities, that is, atomic services (ASs). A negotiation protocol, which enables context‐aware service discovery for providing adapted communications, is also specified. Then, we present how ASs can be discovered and composed according to requesters' requirements. In addition, a media service provisioning use case shows the benefits of our framework. Finally, a proof‐of‐concept implementation of the framework is described and analyzed. This paper describes the first clean‐slate architecture aligned with the work done within the ISO/IEC Future Network working group.     

Comparison of VBR and CBR service classes for MPEG‐2 video multiplexing—Is statistical multiplexing really useful for bursty video transmission?

It has been believed that a statistical multiplexing technique can bring an effective bandwidth usage. When it is applied to MPEG‐2 video, it has been pointed out that two to several times multiplexing gain can be attained due to the highly bursty nature of video traffic. However, most of the past researches do not take into account the implementation aspects of this technique. In this paper, we thoroughly investigate the actual multiplexing gain by comparing ATM CBR and VBR service classes (deterministic and statistical service classes), and point out that the statistical multiplexing gain is far from what one might expect. Copyright © 2001 John Wiley & Sons, Ltd.     

Performance analysis of a channel allocation scheme for multi‐service mobile cellular networks

This paper presents a new channel allocation scheme, namely the dynamic partition with pre‐emptive priority (DPPP) scheme, for multi‐service mobile cellular networks. The system is modelled by a two‐dimensional Markov process and analysed by the matrix‐analytic method. A pre‐emptive priority (PP) mechanism is employed to guarantee the quality of service (QoS) requirement of the real‐time (RT) traffic at the expense of some degradation of non‐real‐time (NRT) traffic, while the victim buffer compensates the degradation and has no negative impact on the RT traffic. The complete service differentiation between new calls and handoff calls from different traffic classes is achieved by using the dynamic partition (DP) concept with the help of related design parameters. The performance analysis and numerical results show that the DPPP scheme, compared with the existing schemes, is effective and practical in multi‐service environments. Copyright © 2006 John Wiley & Sons, Ltd.     

Use cases and scenarios of 5G integrated satellite‐terrestrial networks for enhanced mobile broadband: The SaT5G approach

This paper presents initial results available from the European Commission Horizon 2020 5G Public Private Partnership Phase 2 project “SaT5G” (Satellite and Terrestrial Network for 5G). 1 After describing the concept, objectives, challenges, and research pillars addressed by the SaT5G project, this paper elaborates on the selected use cases and scenarios for satellite communications positioning in the 5G usage scenario of enhanced mobile broadband.     

The effects of shadow‐fading on QoS‐aware routing and admission control protocols designed for multi‐hop MANETs

Providing quality‐of‐service (QoS) assurances in a mobile ad hoc network (MANET) is difficult due to node mobility, contention for channel access, a lack of centralised coordination, and the unreliable nature of the wireless channel. QoS‐aware routing (QAR) and admission control (AC) protocols comprise two of the most important components of a system attempting to provide QoS guarantees in the face of the above‐mentioned difficulties. This paper presents a comparative study, utilising a realistic shadow fading channel, of the performance of several state‐of‐the‐art amalgamated QAR‐AC protocols, which are designed for providing throughput guarantees to applications. The advantages and drawbacks of their particular features are highlighted. For an environment where link quality varies rapidly, the results of the study highlight the ineffectiveness of previously‐proposed methods of relying merely on the success of route discovery to perform AC, of relying on the exceeding of the MAC layer retransmission count for link failure detection, of existing congestion detection schemes and of careful re‐admission of data sessions rather than fast re‐routing after shadowing‐induced link failures. Based on the lessons learnt, design guidelines for future QAR and AC protocols operating in a mobile shadow‐fading‐afflicted environment are presented. Copyright © 2010 John Wiley & Sons, Ltd.     

Architecture design,performance analysis and VLSI implementation of a reconfigurable shared buffer for high‐speed switch/router

Modern switches and routers require massive storage space to buffer packets. This becomes more significant as link speed increases and switch size grows. From the memory technology perspective, while DRAM is a good choice to meet capacity requirement, the access time causes problems for high‐speed applications. On the other hand, though SRAM is faster, it is more costly and does not have high storage density. The SRAM/DRAM hybrid architecture provides a good solution to meet both capacity and speed requirements. From the switch design and network traffic perspective, to minimize packet loss, the buffering space allocated for each switch port is normally based on the worst‐case scenario, which is usually huge. However, under normal traffic load conditions, the buffer utilization for such configuration is very low. Therefore, we propose a reconfigurable buffer‐sharing scheme that can dynamically adjust the buffering space for each port according to the traffic patterns and buffer saturation status. The target is to achieve high performance and improve buffer utilization, while not posing much constraint on the buffer speed. In this paper, we study the performance of the proposed buffer‐sharing scheme by both a numerical model and extensive simulations under uniform and non‐uniform traffic conditions. We also present the architecture design and VLSI implementation of the proposed reconfigurable shared buffer using the 0.18 µm CMOS technology. Our results manifest that the proposed architecture can always achieve high performance and provide much flexibility for the high‐speed packet switches to adapt to various traffic patterns. Furthermore, it can be easily integrated into the functionality of port controllers of modern switches and routers. Copyright © 2008 John Wiley & Sons, Ltd.