Network technologies

ABSTRACT
This paper analyzes different techniques to implement Quality of service (QoS) on multi-tenant 5G networks. Describes the architecture of the next generation mobile network based on cloud-enabled small cell deployments and also proposes an hybrid-cloud solution coexisting with centralized cloud RAN (C-RAN), in order to achieve a gradual implementation of the technology. In this context, the work here presented deals with the challenges of preserving the quality of experience in a multi-tenant cloud enable RAN bearing in mind the Key Performance Indicator (KPI) agreed in the Service Level Agreement (SLA). To achieve this goal, QoS should be managed at different levels of the architecture. Feedback should be given between learning modules in order to analyze the results and infer enhanced decision rules which may conclude in an architecture replacement.

ABSTRACT
This paper focuses on multi-tenant 5G networks with virtualization and mobile edge computing capabilities, in the scope of cloud-enabled small cell deployments. In this context, the work here presented deals with the service management and orchestration challenges that arise when handling service mapping on the multi-tenant distributed cloud-enabled radio access network architecture. For that aim, once analysed cloud edge services management and 5G network instantiation in the OpenStack platform, we modify the provided virtual infrastructure manager so as to incorporate virtual network function placement features of the SESAME environment. As main contributions, we adapt the OpenStack application instances to 5G Network Service instantiation, and we include an energy-aware and latency-constrained placement solution.

ABSTRACT
The SESAME 5G-PPP project targets innovations in three fundamental 5G areas such as the “placement” of network intelligence and applications in the network edge through NFV and cloud computing, the substantial evolution of the Small Cell concept and the consolidation of multitenancy in modern communications infrastructure. A dedicated architecture has been proposed for that purpose. In the present work and taking onto account recent challenges, we discuss latest innovations and/or potential updates of the corresponding architecture, in specific areas covering the SC-Common VNF as fun-in/fun-out module, the progress in SESAME Small Cell functional splits, the placement of “Self-x” features and wireless backhauling. Moreover, we proceed further and analyse the functional description of the related architectural components, in order to promote future improvements.

ABSTRACT
This paper aims at increasing our understanding of the behaviour of some of the major TCP variants in LTE networks. A simulation study on the behaviour of seven TCP variants is performed. The evolution of the throughput, congestion window and queuing delay are studied for four scenarios with different network loads and flow types. Our measurements show that, in average radio conditions, most variants are able to quickly reach full link utilisation. However, to achieve the same throughput, they create different amounts of queuing delay. On the one hand, loss-based algorithms tend to completely fill the queue, creating huge queuing delays and inducing packet losses. On the other hand, delay-based variants manage to limit the queue size and decrease the amount of packets dropped by the eNodeB, but struggle to reach the maximum throughput in some circumstances.

ABSTRACT
The proper execution of performance tests is of utmost importance for the analysis and evaluation of Internet-related technologies, protocols and deployment strategies. Nowadays, there are plenty of tools available to experimenters ranging from simulation tools, emulation equipment, to small and large scale experimentation testbeds. Each of these performance evaluation frameworks introduces a series of capabilities and drawbacks. Additionally, there is a need for using a common methodology to perform different performance tests and to create comparable outcomes. Seeking for the standardization of reliable and comparable Internet speed measurements and trying to provide end-users with trustworthy measurement tools, different SDOs have standardized both TCP-based and IP-based measurement methodologies. This paper focuses on the applicability of the different measurement frameworks and methodologies in the field of mobile Internet, with special focus on the impact of using TCP over mobile broadband connections. The paper describes a series of experiments over different frameworks and, based on the obtained results, identifies the implications of the different types of performance tests into the evaluation outcomes and states the need for large scale measurements.

ABSTRACT
The Cloud Enabled Small Cell (CESC) concept proposed in EU funded project SESAME has emerged as a promising solution to form a multi-tenant, multi-service architecture at the network edge according to 5G needs. It allows several operators/service providers to engage in a sharing model of both radio access capacity and Mobile Edge Computing (MEC) capabilities. From a business perspective, the shared ecosystem guarantees benefits such as easy system upgrades and CAPEX/OPEX reduction. However, depending on the adapted model which is reflected at Service Level Agreement (SLA) between involved stakeholders, cost and benefit of each party are subject to change. This paper is an effort to identify and analyse different radio and cloud models and pricing schemes for the joint provisioning of radio access capacity and MEC services in a multi-tenant Radio Access Network (RAN).

ABSTRACT
Adding cognitive capabilities to the wireless networks makes it possible to leverage the control and management information used in the network operation to infer information about the local state and exploit it to improve the overall performance. This paper deals with the combined use of centralized and distributed cognitive cycles integrated at different planes in 5G networks: an integrated data plane, a unified control plane and a cross-layer management plane. This context-aware cognitive schema acts on the decision making modules depending on the monitored environment to prevent failures, balance the virtualized execution and get a global enhancement in the provision of mobile services. The multi-level cognitive cycle supports the interaction between the edge and the cloud blurring the line that separates two paradigms: centralized radio operation and mobile edge services.

ABSTRACT
In this manuscript, we will present the main concepts of the 5G-PPP SESAME project dedicated to the implementation of Cloud-Enabled Small Cells (CESCs), able to support edge cloud computing in a multi-tenant, multi-service ecosystem. More particularly, we will present a preview of the SESAME concept at the component/sub-system, system and operation level. At the component/sub-system level, we will detail our plan to deploy multi-operator enabled small cells, enhanced with a virtualised execution platform for 5G. At the system level, we will present the envisaged architecture to manage and control the cloud-enabled small cell infrastructure. Finally, at the operation level, we will explain the potential advantages of adopting the SESAME concept on the 5G access networks.

ABSTRACT
Mobile internet has been widely adopted and it is expected to rise to almost 4 billion users by 2020. Despite the research effort dedicated to the enhancement of its performance, there still exists a gap in the understanding of how TCP and its many variants work over LTE. To this end, this paper evaluates the extent to which five common TCP variants, CUBIC, NewReno, Westwood+, Illinois, and CAIA Delay Gradient (CDG), are able to utilise available radio resources under hard conditions, such as during start-up and in mobile scenarios at different speeds. The paper suggests that CUBIC, due to its Hybrid Slow-Start mechanism, enters congestion avoidance prematurely, and thus experiences a prolonged start-up phase. As a result, it is unable to efficiently utilise radio resources during shorter transmission sessions. Besides, CUBIC, Illinois and NewReno, i.e., the loss-based TCP implementations, offer better throughput, and are able to better utilise available resources during mobility than Westwood+ and CDG – the delay-based variants do.

ABSTRACT
The surge of the Internet traffic with exabytes of data flowing over operators’ mobile networks has created the need to rethink the paradigms behind the design of the mobile network architecture. The inadequacy of the 4G UMTS Long term Evolution (LTE) and even of its advanced version LTE-A is evident, considering that the traffic will be extremely heterogeneous in the near future and ranging from 4K resolution TV to machine-type communications. To keep up with these changes, academia, industries and EU institutions have now engaged in the quest for new 5G technology. In this paper we present the innovative system design, concepts and visions developed by the 5G PPP H2020 project SESAME (Small cEllS coordinAtion for Multi-tenancy and Edge services). The innovation of SESAME is manifold: i) combine the key 5G small cells with cloud technology, ii) promote and develop the concept of Small Cells-as-a-Service (SCaaS), iii) bring computing and storage power at the mobile network edge through the development of non-x86 ARM technology enabled micro-servers, and iv) address a large number of scenarios and use cases applying mobile edge computing.

ABSTRACT
One of the most challenging problems in mobile broadband networks is how to assign the available radio resources among the different mobile users. Traditionally, research proposals are either specific to some type of traffic or deal with computationally intensive algorithms aimed at optimizing the delivery of general purpose traffic. Consequently, commercial networks do not incorporate these mechanisms due to the limited hardware resources at the mobile edge. Emerging 5G architectures introduce cloud computing principles to add flexible computational resources to Radio Access Networks. This paper makes use of the Mobile Edge Computing concepts to introduce a new element, denoted as Mobile Edge Scheduler, aimed at minimizing the mean delay of general traffic flows in the LTE downlink. This element runs close to the eNodeB element and implements a novel flow-aware and channel-aware scheduling policy in order to accommodate the transmissions to the available channel quality of end users.

ABSTRACT
This work deals with the problem of scheduling traffic flows in emerging wireless networks. In actual mobile implementations the channel state feedback from the users to the radio schedulers may be deployed based on periodic reports in order to avoid uplink signaling overhead. In this work, we study how to design schedulers under partially observable channels. For that aim, we employ the Whittle index approach using a Partially Observable Markov Decision Process. We further analyze the performance of the derived scheduling solution, both in single-class and multi-class scenarios. Real-world channel quality traces are employed in experiments. Finally, we conclude that the proposed scheduling index rule outperforms well-known channelaware disciplines.

ABSTRACT
This paper deals with the classical problem of radio resource management in LTE MIMO, with special focus to the specific radio channel characteristics in commercial LTE networks. First, we provide some conclusions about the Channel Quality Information traces obtained through field testing. From this analysis, we perform a series of experiments by means of an LTE emulator in order to evaluate the accuracy of different fading models used in the 3GPP. As a first outcome of the paper, we infer several fine-grain channel characteristics useful to feed further research work in the area of LTE MIMO. As a second contribution of the paper, we analyze the performance of classical schedulers (i.e., Round Robin, Best CQI and Proportional Fair) under the obtained LTE MIMO channel conditions. Specifically, we analyze the impact of the channel feedback reporting rate in scenarios with multiple greedy sources.

ABSTRACT
In this paper we study how to design a scheduling strategy aimed at minimizing the average holding cost for flows with general size distribution when the feasible transmission rate of each user varies randomly over time. We employ a Whittle-index-based approach in order to achieve an opportunistic and non-anticipating size-aware scheduling index rule proposal. When the flow size distribution belongs to the Decreasing Hazard Rate class, we propose the so-called Attained Service Potential Improvement index rule, which consists in giving priority to the flows with the highest ratio between the current attained service- dependent completion probability and the expected potential improvement of this completion probability. We further analyze the performance of the proposed scheduler, concluding that it outperforms well-known opportunistic disciplines.

ABSTRACT
In this paper we study how to design an opportunistic scheduler when flow sizes have a general service time distribution with the objective of minimizing the expected holding cost. We allow the channel condition to have two states which in particular covers the important special case of ON/OFF channels. We formulate the problem as a multi-armed restless bandit problem, a particular class of Markov decision processes. Since an exact solution is out of reach, we characterize in closed-form the Whittle index, which allows us to define a heuristic scheduling rule for the problem. We then particularize the index to the important subclass of distributions with a decreasing hazard rate. We finally evaluate the performance of the proposed Whittleindex based scheduler by simulation of a wireless network. The numerical results show that the performance of the proposed scheduler is very satisfactory.

ABSTRACT
Nowadays there is a growing uncertainty about the near future evolution of classical PMR solutions due to spectrum scarcity, digital dividend issues and economic crisis. This paper aims at facing this situation by seizing the existing window of opportunity due to the convergence of the IMS as a predominant enabler for future multimedia networks and the deployment of commercial LTE networks. The paper details an innovative emergency inter-networking system capable of connecting existing first responder communication systems and enabling the integration of next generation mobile networks by defining technology independent standardized interfaces under the umbrella of IMS. Concerning the experimental outcomes, the paper focuses on the reference implementation to interface with the proposed system.

ABSTRACT
Nowadays, the Critical Communications networks are experiencing the transformation that will lay the foundations for next decades of emergency communications. Although different forums claim for the benefits of different technological solutions, this evolution seems to be driven towards the adoption of commercial radio technologies and mass market devices. Although new standards are being developed by different standardization organizations, the concept of interoperability between Public Safety organizations as a holistic standpoint is still an open issue standards should address in the near future. This paper analyzes the current trends in next generation Critical Communications, and reviews the different efforts carried out by different standardization organizations. It is shown that, although different aspects of interoperability are addressed, an integral interoperability framework is needed. Additionally, the specific area of Operation and Management is discussed as one of the missing pieces. A series of system requirements and design principles are finally provided.

ABSTRACT
This paper analyzes the scenario where multiple users are trying to transmit the same or related content to a common destination through a shared radio access network. A specific aspect of this study is that all users work for a common objective, as it would be the transmission of critical emergency-related media contents to a central operator. We analyze the performance achievable using an LTE cell, with different client-driven autonomous adaptation strategies that take both the network performance and the battery status as input parameters. Remarkable performance results are achieved in terms of number of acceptable uplink video streams in different simulation scenarios. The work would help for designing context- and network-aware adaptation schemes for emergency mobile applications.

ABSTRACT
This paper deals with the performance evaluation of deploying an IMS-based media plane interoperability framework. The 3GPP standards describe two possible operating modes based on either a reactive or a proactive approach. We show that both approaches entail some advantages and drawbacks in terms of signaling overhead and call setup times. In order to use experimental individual delay contributions, a prototype implementation of the required elements was carried out for which transmission and processing times and the average ratio of incompatible calls where evaluated. Additionally, the evaluation focuses on the impact of deploying the interoperability solutions over current UMTS and LTE radio access networks.

ABSTRACT
Currently, the critical communications sector is aware of the need for evolving the portfolio of service capabilities to support advanced multimedia communications in their daily emergency operations. However, there is a discussion about the evolving the private communication networks or adopting commercial network technologies, which have evolved significantly during the last years. This paper presents a process of interaction with critical communication professionals belonging in different professional sectors, different countries and different user profiles. This paper gathers the main findings of this interaction in terms of captured users’ requirements for novel services to be adopted and types of networks which shall support them.

ABSTRACT
Emergency telecommunication systems play an important role in people’s daily life, supporting communication for the public and first responders during emergency related incidents. Nonetheless, the majority of existing emergency communications are limited to traditional voice and text message services due to the data bandwidth constraint of current networks. It is well known that emerging 4G broadband communication technologies have the ability to provide a range of multimedia services (e.g. picture transmission) that could be utilised by the emergency services to save lives. However, a secured emergency conversation cannot be established between incompatible mobile/end devices without the assistance of a security gateway. Therefore, this paper proposes a technology independent security gateway that provides security support for future emergency telecommunication systems. The proposed security gateway works in three modes to cover all the situations in which its assistance is required to establish a secured emergency conversation. In addition, the development process of the security gateway will also be fully discussed in this paper.

ABSTRACT
The great technological evolution achieved in the field of public communication networks in comparison to the slower pace of the critical communications sector has raised discussions regarding the next evolutionary steps of PMR technologies and the integration of mission critical aspects into public wideband networks. This paper analyses a converged scenario of the public and private mobile network technologies which will enable those professionals to make the most of both worlds, while assuring efficient use of critical resources. This paper provides a short overview of the principles that derive from end-user requirements along with a system applicability analysis in a number of complete use cases.

ABSTRACT
This paper presents a novel open-source implementation of a call center, which is compatible with the IP Multimedia Subsystem (IMS) platform, supporting call forwarding and dispatching services, along with video call and chat with file transfer. The proposed solution is called Call Center for IMS (CC4IMS) and following a requirement analysis, the paper discusses the overall architecture and design of the proposed Call Center, focusing on the IMS compatibility and mobility of the implementation. Then, an open-source prototype implementation is presented, which was designed for mobile devices in order to be suitable for distributed and ad-hoc launch at emergency situations by first responder teams near to the location of the emergency incident. Finally, a protocol and message illustration between the CC4IMS and the IMS modules is presented, based on messages that have been actually captured by the CC4IMS prototype and the Open IMS Core, showing that the proposed Call Center confronts with the IMS signaling.

ABSTRACT
This paper deals with the analysis of the impact of different scheduling algorithms on flow level mean delay performance of elastic traffic in a single cell wireless downlink data channel paradigm. An enhanced size-based and channelaware discipline is proposed, which is based on the sized-aware Gittins index approach applied to a time-varying channel context. In order to compare the proposed Opportunistic Gittins rule performance with well-known scheduling algorithms, several simulations have been performed for stochastically arriving flows with Pareto sizes under fading conditions, for different network loads and channel quality indicator reporting rates. As concluded, an approach that combines both flow size-awareness and channel awareness is the best option, which guarantees a trade–off between minimizing uplink overhead due to channel quality reports and improving scheduling performance aimed at reducing overall flow mean delay.

ABSTRACT
In this paper we present an implementation and validation tests that allow a GNU/Linux node act as a PE router in a BGP/MPLS IP VPN architecture. Precisely, this implementation supports all the mandatory capabilities defined in RFC 4364 with regard to the data forwarding plane, such as VRFs to separate the traffic from different VPNs, MPLS to manage the VPN routes at PE nodes and MPLS tunnels for the communication between PEs. Moreover, this basic implementation is extended to support the operation defined in RFC 4797, which allows other kinds of tunnel technologies to be used between PE nodes. We provide configuration examples for both cases, and finally complete the study with the addition of IPsec options to the PE-PE GRE tunnel communication.

ABSTRACT
This paper presents an implementation of the BGP/MPLS IP VPN functionalities for GNU/Linux. First, we briefly review the operation mode described in the IETF RFC 4364 and show the characteristics that are supported by this implementation. Afterwards, we provide some implementation details of the forwarding plane for the kernel 2.6.18.1. This implementation includes the integration of the MPLS- and VRF-for-Linux projects. Finally, we present some example scenarios to validate our implementation in different cases, and show the corresponding commands for the ingress and egress PE routers. This work establishes a first approach for testing BGP/MPLS IP VPN technology in GNU/Linux testbeds and supports the basic functionalities for a future implementation of the signaling plane.

ABSTRACT
This work focuses on the analysis of Quality of Service (QoS) management in controlled scenarios such as corporate networks. We present a testbed based on BGP/MPLS IP VPN networks and show the QoS configuration implemented in the different nodes. The motivation of this work is to obtain stable QoS monitoring procedures that will allow us to deploy optimized QoS management mechanisms. The results are intended to represent users’ satisfaction for different networked services, so we base our QoS evaluation in perceived-QoS (PQoS) schemes. In this paper we proposed a network scenario made up of a VPN connectivity between two corporate sites. Based on the terms included in the SLA and the characteristics of different traffic profiles, we try to monitor the PQoS in different conditions, so we can obtain valuable information for a better traffic classification.

ABSTRACT
Data network Quality of Service (QoS) measurement and evaluation is a challenge being deeply studied nowadays. Measurement techniques and methodologies are broad available, but they are not connected among them, this is, the evaluation is based on raw parameters. In this paper we present a proposal of an integrating architecture which can evaluate user's perceived QoS, merging results obtained by different measurement tools in order to acquire a better knowledge of the communication link than using a single parameter. Extra effort is made to develop a set of easy to use and understand measurement tools.

ABSTRACT
This paper considers the subject of provisioning services in ad-hoc networks. Service discovery in these networks is challenging due to the lack of central infrastructure, limited resources and high mobility. We propose integrating this mechanism on the proactive OLSR (Optimized Link State Routing) protocol. A new message type, called Service Discovery Message (SDM), is added. This message will announce (servers) and request (clients) for services. Available local services will only be advertised once, with a specific lifetime, in order to avoid increasing the network overhead. These services will be stored in a local service cache that is maintained on each node. When a node wants to make use of a service, it will look on the cache. If it is not yet stored, it will send a query message. Simulation results are presented to demonstrate that the introduced packet overhead is insignificant compared with the standard OLSR protocol.

These mechanisms must be efficient: every node should know the maximum number of services as possible. In networks with few nodes, the percentage of discovered services is around 90%. On the other hand, in bigger networks, was higher than the 80%. We believe that due to the obtained results, the following step consists on proving the protocol here presented in real scenarios using prototypes.

ABSTRACT
This paper deals with the management of QoS as perceived by end users in corporate networks. First, we overview some previous results achieved by the research group in the field of estimating and managing the QoS. In this work we accomplished some validation tasks by means of simulation. Going on with the analysis of applicability of the general model to real-world, we propose here to analyze a network scenario that includes an MPLS IP VPN. In this scenario we can take into account all the agents involved in the provision of Internet services and moreover we can carry out a management of QoS in the network.

ABSTRACT
This paper proposes a service discovery protocol for discovering and advertising services in a proactive ad hoc network. The protocol we have defined is piggybacked into the OLSR (Optimized Link State Routing) protocol. We define a new message type into OLSR called Service Discovery Message (SDM) for both advertisement and discovery of services. The advertisement frequency and advertisement lifetime are usercontrolled parameters, so that they can be modified depending on the user requirements. Each node maintains a service cache to store information about its own services, and the services each device discovers in the network. We also present simulation results of our protocol and show that the service discovery protocol defined here achieves much efficiency in discovering services, while it introduces practically no packet overhead compared to the basis OLSR protocol.

ABSTRACT
This paper considers the problem of provisioning services in proactive ad hoc networks. Our proposal consists in a service discovery mechanism, integrated on the proactive OLSR (Optimized Link State Routing) protocol. We define a new message type into OLSR called Service Discovery Message (SDM) for advertising and discovering services. The advertisement frequency and advertisement lifetime are usercontrolled parameters, so that they can be modified depending on the user requirements. Each node maintains a service cache to store information about services discovered via advertisements. We also present simulation results that demonstrate that the service discovery mechanism defined here, introduces insignificant packet overhead compared to the basis OLSR protocol.

ABSTRACT
In this article, we introduce a tool to analyse quality of service in DiffServ-MPLS networks and we also show its design and implementation issues. We have designed a distributed architecture that allows users to send and receive traffic flows in real-world environments applying several service policies, extracting quality of service parameters from end hosts and core devices, and information about performance in traffic flows treatment at DS-MPLS network core nodes.

ABSTRACT
This paper analyses several issues about security and QoS in corporate networks based on BGP/MPLS IP VPN technology. First, we discuss some security requirements and constraints specified for ‘conventional’ BGP/MPLS IP VPNs, where the provider’s transport infrastructure supports MPLS. Likewise, we describe different alternative mechanisms suitable to provide QoS guarantees in this kind of networks. Afterwards, the paper focuses on a transition scenario, where some of the corporate sites may be attached to an IP backbone with no MPLS support. In order to preserve the basic VPN architecture some alternative tunneling approaches are defined. We study some critical security requirements in this scenario and analyse the potential impact of its implementation over the QoS characteristics. We present a testbed based on Linux boxes and some general implementation issues, and finally some empirical results are shown.

ABSTRACT
This paper presents an overview of the research activities accomplished in the N-QaS (Networking, Quality and Security Group) in the area of quality of service (QoS) in wireless environments and concretely in Ad HOC networks. After studying the different objective parameters that can be used to guarantee a minimum of QoS (such as: bandwidth, delay, jitter and rate of errors), and with the later study of different signalling systems for the reservation of resources (such as INSIGNIA and dRSVP), the possibility has been identified of using the period of discovery of routes from the origin to the destination (in search of the road that better responds to our necessities from the point of view of the QoS) only not thinking of the shortest road (the one that less hops offers from the origin to the destination, habitual operation from the point of view of the most routing protocols, it is not the most effective parameters in the QoS) also keeping in mind that we are allowed to be able to give priority to other parameters of QoS (objective parameters) and that they can be reserved for the whole session of communication in the same way that the route is reserved. And what is more important, this whole process would be made in parallel (at the same time), winning this way in functionality (we are fusing two necessary processes in one).

ABSTRACT
This paper offers an approach to the definition of access speed measurements. An ever growing increase of Internet Service Providers (ISP) and different types of technologies in the Internet access, makes it difficult for users to decide which is the best or most suitable connection to satisfy their needs. From these considerations, the possibility of the Internet users to obtain a real and neutral measurement of the service of their Internet access may help them to decide if it is covering their demands or, on the contrary, the provider is not complying with the terms of the contract. In order to perform this measurement, an Internet speed test through web interface has been defined, as well as the way to obtain a measure which can comply with the objective of giving users a proper idea of how their Internet access is working. This project is included in the Quality of Service (QoS) investigation area in our investigation group.