Oscar del Rio Herrero

Advances in Random Access protocols for satellite networks

In this paper we review key properties of recently proposed high performance protocols for Random Access (RA) satellite channels for both Time Division and Code Division Multiple Access (TDMA/CDMA) techniques. The proposed protocols by far outperform traditional satellite random access techniques without the need for quick feedback from the gateway. This makes possible to avoid the utilization of demand assigned capacity for the transmission of small/medium size bursts of packets. A fair comparative performance of state-of-the-art TDMA and CDMA RA schemes is provided together with a summary of their key performance results. It is shown that the proposed enhanced RA protocols, although different between TDMA and CDMA, share commonalities as they exploit iterative interference cancellation at the demodulator side and demonstrate to provide even better performance in the presence of received carrier power unbalance. Typical application scenarios of these enhanced random access protocols are then illustrated, as well as possible ways to combine random access and demand assigned protocols.

Spread-spectrum techniques for the provision of packet access on the reverse link of next-generation broadband multimedia satellite systems

This paper will examine the potential performances of spread-spectrum-based access techniques via the interaction channel of an Internet protocol (IP)-based multimedia satellite system. In particular, a theoretical analysis of the spread-Aloha technique will be given for the case of forward error correction coded systems. Then, the performance of spread-Aloha access will be confirmed by simulation and compared with that of a conventional time-division multiple-access (TDMA)-based combined free/demand assignment multiple-access system. It appears that spread-Aloha-based techniques, although achieving a lower maximum throughput than the TDMA-based access scheme, may provide a better experience to the user due to the lower transmission latency. Finally, the prospect of a spread-spectrum-based access scheme combining Aloha and reservation mechanisms will be briefly overviewed.

Generalized Analytical Framework for the Performance Assessment of Slotted Random Access Protocols

This manuscript provides a general analytical framework to accurately predict the performance of several slotted Random Access (RA) schemes such as Slotted Aloha and Diversity Slotted Aloha. Compared to past literature the proposed analytical framework allows to perform accurate performance estimation of these RA schemes exploiting state-of-the-art forward error correction schemes in the presence of packet power unbalance as it is the case in many practical systems. Furthermore, the analytical framework is also capable to accurately approximate the performance of more recent RA schemes particularly suitable for satellite communications such as Contention Resolution Diversity Slotted Aloha exploiting iterative interference cancellation techniques on top of packet repetition within the frame to further improve the RA scheme performance. The analytical results have been successfully verified against a comprehensive set of simulations covering cases of practical interest.

S-MIM: A novel radio interface for efficient messaging services over satellite

This article presents a radio interface recently standardized by ETSI under the name of S-band Mobile Interactive Multimedia (S-MIM) and especially designed to provide ubiquitous messaging services over S-band GEO satellites using low-power terminals. Thanks to low terminal cost and high bandwidth efficiency, this standard allows the development of new satellite services, particularly for vehicular and machine-to machine applications. The S-MIM standard relies on a broadcasting radio interface such as DVB-SH or ETSI SDR in the forward link, and reuses 3GPP W-CDMA technology properly adapted to the scope in the return link. Thanks to the use of spread spectrum ALOHA, terminals can access the channel in a totally asynchronous manner. The use of a packet-optimized iterative successive interference cancellation (i- SIC) algorithm at the receiver allows exploiting the inherent power imbalance among terminals in order to boost the throughput with respect to conventional SSA systems. In addition, advanced packet transmission control techniques have been adopted to maximize the probability of successful packet reception in the challenging land mobile satellite channel. Finally, the S-MIM link layer provides efficient and reliable transport of IP datagrams over the forward and return link radio interfaces.

Combining mobility and heterogeneous networking for emergency management: a PMIPv6 and HIP-based approach

Emergency Management is an important topic for research community worldwide, especially after recent major disasters. The problem of supporting mobility at the disaster site to rescue teams equipped with different heterogeneous access technologies and providing interoperability between different agencies and jurisdictions is still under investigation. In this work we propose to merge the advantages of IPv6 micro-mobility management of Proxy Mobile IPv6 (PMIPv6) with macro-mobility management, security, inter-technology handover and multi-homing features of Host Identity Protocol (HIP). This new approach applied to our proposed ad-hoc satellite and wireless mesh system architecture for emergency mobile communications can improve mobility, security, reliability and interoperability in Emergency Management domain.

Innovative hybrid optical/digital ultra-fast packet-switched processor for meshed satellite networks

This paper describes the architectural study of an innovative ultra-fast packet-switched transparent processor dealing efficiently with unicast and multicast applications. The proposed architecture aims at outperforming current packet processor architectures in terms of total throughput and efficiency. In order to cope with the limitations of todays on board processors, three new concepts are introduced: transparent burst switching, channel multiplexing, and bandwidth asymmetry . Some of these concepts are already well known in the field of optical terrestrial networks but need further improvements and adaptations to cope with the requirements of satellite processors and systems. Transparent burst switching is used to enhance the transparency of the processor: the packet payload is processed transparently and only the header is demodulated onboard. The channel multiplexing and bandwidth asymmetry techniques are used to consolidate bufferless switch architectures, which appear to be very attractive for increasing the overall throughput of switches. Finally, the paper introduces an innovative efficient and scalable hybrid optical/digital implementation of this processor. The focus here is on a satellite-switched code/time-division multiple-access type of system but the results and concepts provided in this paper can apply to other satellite-switched systems.

Random access schemes for satellite networks, from VSAT to M2M: a survey

Summary In this survey paper, we review the random access (RA) techniques with particular emphasis on the issues and the possible solutions applicable to satellite networks. RA dates back to the 1970s when the ALOHA protocol was developed to solve the problem of interconnecting university computers located in different Hawaiian islands. Since then, several evolutions of the ALOHA protocol have been developed. In particular, solutions were devised to mitigate the problem of packet collisions severely degrading the RA protocols performance. The approach followed for many years has been to avoid the occurrence of collisions rather than solving them. More recently, techniques tackling the RA packet collision problem have appeared triggered by the need of improving RA performance in satellite and terrestrial wireless networks. In particular, satellite networks large propagation delay does not allow the adoption of enhanced terrestrial RA techniques based on channel sensing. Adopting conventional demand assignment multiple access protocols is not suitable for supporting a large number of sensors or devices transmitting small-size low duty cycle packets as required for machine-to-machine communications. This provided the stimulus to exploit successive interference cancelation schemes to solve packet collision issues. The use of successive interference cancelation in RA is relatively new and has opened up a promising research area. We provide an extensive review of recent high-performance RA techniques achieving more than three orders of magnitude throughput increase compared with the original ALOHA at low packet loss rate. In this survey, we cover both slotted and unslotted techniques. Finally, we review the use of RA in satellite systems and related standards including recent proposals for machine-to-machine applications. Copyright

Enhanced spread spectrum ALOHA system level performance assessment

SUMMARY This paper describes the simulated system performances of the enhanced spread spectrum ALOHA (E-SSA) random access scheme in a realistic mobile satellite multibeam scenario operating in S-band. The E-SSA random access scheme has been selected for supporting messaging services in the ETSI S-band Mobile Interactive Multimedia (S-MIM) standard. Finally, the operation and the performance of E-SSA is elaborated in the context of a terrestrial gap-filler component complementing the satellite coverage in densely populated areas. It is shown that the terrestrial network is able to off-load traffic from the satellite component while ensuring continuity of service in areas that cannot be covered by a satellite only system. Copyright

A dynamic cross-layer architecture for QoS provisioning of multimedia services on all-IP based adaptive satellite networks

This paper identifies a dynamic cross-layer architecture for QoS provisioning of multimedia services on an all-IP-based DVB-RCS/S2 satellite network. The proposed dynamic QoS architecture presents three cross-layer interfaces: one between the application and network layers on the satellite terminals (ST), which allows the provision of dynamic guaranteed QoS for multimedia applications and the user of adaptive codecs or multi-codec applications on the user side. A second cross-layer interface is proposed, between the IP and MAC layers in the Network Control Centre (NCC), which increases the efficiency of the satellite resource utilization. Finally, a third interface is introduced, between the physical layer of the gateway and the QoS manager of the NCC, which helps to minimize the connection blocking and dropping probabilities by implementing on the QoS manager a prediction algorithm (Bandwidth Estimator - BWE) for the physical channel variations. In addition, the system also implements in-band signaling to compensate for the management and control traffic overhead introduced by the highly dynamic architecture.

Random Access Versus Multiple Access

The support of Internet of Things (IoT) calls for physical and media access control (MAC) solutions capable to support a very large number of wireless devices transmitting short packets with low duty cycle. This chapter provides a survey of random access (RA) schemes devised for terrestrial and satellite applications which are suited to support IoT. The RA schemes presented are typically based on multiple access techniques described in the previous chapters. In particular, RA is exploiting time-, frequency-, and code-division multiple access techniques or combinations thereof. Various flavors of non-orthogonal multiple access (NOMA) are also adopted to increase the RA scheme spectral and power efficiency. The chapter is organized as follows: Sect. 17.1 summarizes the main terrestrial RA techniques and their suitability for 5G IoT applications; Sect. 17.2 provides a survey of 5G NOMA-based RA proposals for IoT; finally, Sect. 17.3 illustrates the most promising NOMA-based RA schemes proposed or adopted for satellite networks which are also of interest to the more general terrestrial wireless applications.