Cellular networks are reaching their physical limits providing capacity that is almost near the Shannon theory. However, cellular usage is still increasing exponentially with hungry applications demanding higher data rates. As a result, designers are facing significant challenge in meeting the required demands. One promising solutions, being fostered by the 3GPP, is to increase the spectral efficiency through higher frequency reuse using smaller and denser network cells such as femto, pico and nano cells. One of the main challenges behind using smaller cells is managing interference. In this paper, we propose two novel solutions that alleviate the interference of femto-cells on macro-cell user equipment (MUEs). The solutions do not rely on any additional information exchange or signaling, nor do they rely on the backhaul and it's delay. The first proposal is Femto-cell Power Control Scheme (FPCS) that utilizes an analytical approach to adapt the femto base station's transmit power based on Channel Quality Indicator (CQI) reports from affected MUEs. The second method is Random Physical Resource Block Selection Scheme (RPSS) that allocates the femto-cell's resources from a random subset of Physical Resource Blocks (PRBs) so that theMUEs benefit from a reduced interference level. Our evaluations have shown that the two proposals do alleviate the femtocell interference significantly, increasing the SINR and enhancing the end performance. To the best of our knowledge, no similar work exist in literature that addresses the femto-cell's interference without information exchange.

FELIX federates existing Future Internet (FI) experimental facilities across continents to build a test environment for large-scale SDN experiments. The management framework developed by FELIX allows the execution of experimental network services in a distributed environment comprised of heterogeneous resources. The demonstration described in this paper showcases the implementation of the FELIX architecture over the federated experimental facilities across Japan and Europe leveraging on both the infrastructure resources and the FELIX management stack. The presented use-case also provides an important experimental scenario for data center operators who are developing Business Continuity Planning for IT services.

Recent work in software-defined networking experimental facilities has been shifting towards large scale deployments through federation of resources that span across continents and make it possible to perform experiments at a global scale. The success of such deployments very much depends on the design and implementation of essential, secure mechanisms for authentication, authorization, and accounting (AAA) that not only ensure the robustness of such facilities against intrusions and unauthorized use but also ease experimentation and system administration in such complex environments. C-BAS is an initiative in this direction that uses a secure and flexible certificate-based AAA architecture for SDN experimental facilities. Advanced certificate-based authentication and authorization makes C-BAS inherently resilient against attacks specific to traditional AAA mechanisms, increases flexibility and autonomy in experimental facility system administration, and facilitates federation. This article introduces the implementation details of C-BAS, explains its features through use cases, and evaluates its computational performance.

Programmable networks are a substantial part of current R&D on future internet (FI) in Europe and worldwide, with considerable impact generated by large-scale test bed infrastructures. In such test beds, researchers validate proof-of-concept prototypes for new algorithms and mechanisms for efficiently controlling and managing network resources. One of the key domains for FI research is software-defined networking (SDN), which creates innovations in existing Internet architectures by shifting the control and logic outside the network equipment to Data Centres. International cooperation among leading research centres in Europe, Americas and Asia is key to validate SDN foundations and tools. EU and Japan have jointly funded the FELIX project (federated test-beds for large-scale infrastructure experiments), which defines a common control and orchestration framework to manage federated FI test beds across continents. This framework enables an experimenter to (i) request and obtain resources across different test bed infrastructures dynamically; (ii) manage and control the network paths connecting the federated SDN test beds; (iii) monitor the underlying resources and (iv) use distributed applications executed on the federated infrastructures. This paper describes the high-level architecture of the FELIX framework and details six use cases that will be employed for validation. We present our analysis and end-user considerations, highlighting the necessity for resource accessibility and coherent use of physical connections over a large-scale test bed where different control technologies such as OpenFlow and the network service interface (NSI) are simultaneously used.

FELIX, the EU-Japan jointly-funded project, establishes a software defined networking (SDN) experimental facility which spans two continents and several administrative domains via dynamic transit network connections. The FELIX architectural blueprint provides an excellent example where key topics such as policy-based software-defined infrastructure instantiation is supported by resource orchestrators which manage multidomain distributed compute and network resources including ondemand provisioning of transit network resources. In this context, FELIX implements a modern approach for authentication and authorization in SDN experimental facilities which enables fine-grained control and avoids single points of failure. This paper details the underlying mechanisms for user and transit network resource authentication and authorization in FELIX.

The development of test environments as close as possible to the real world scenarios is becoming a fundamental requirement in designing innovative network applications. This environment must be fully configurable and reliable enough to provide similar results in multiple experiment runs. The federation of existing Future Internet (FI) test beds is an initiative tofu fill these strict requirements. The FELIX project aims to define, implement, and deploy a control and monitoring framework which allows experimenters to execute their network services in a distributed environment spread across two continents, i.e. Europe and Asia. This paper describes the architecture of the software components developed to manage heterogeneous resources that constitute the FELIX infrastructure, i.e. Computing, SDN and transport resources. This article introduces the components of a modular architecture with particular emphasis on the provided functionalities, the exported interfaces, the dependencies and the relationship between the internal building blocks. Details of the implementation choices and the workflows to realize user requests are also presented.

OpenFlow is a leading standard for Software-Defined Networking (SDN) and has already played a significant role in reshaping network infrastructures. However, a wide range of existing provider domains is still not equipped with a framework that supports wider deployment of an OpenFlow-based control plane beyond Ethernet-dominated networks. We address this gap by introducing a Hardware Abstraction Layer (HAL) which can transform legacy network elements into OpenFlow capable devices. This paper details the functional architecture of HAL, discusses the key design aspects and explains how HAL can support a number of network device classes. In addition, this paper presents the implementation details of HAL for hardware platforms such as DOCSIS (Data over Cable Service Interface Specification) and DWDM (Dense Wavelength Division Multiplexing) which have so far received little attention by the OpenFlow research community despite their wide real-world deployment.

OpenFlow is catalyzing the deployment of software defined networking (SDN) technologies around the globe. In practice, however, compatibility issues hinder the deployment of an OpenFlow control plane on a number of network platforms. The FP7 ALIEN project addresses this problem by introducing a Hardware Abstraction Layer (HAL) which enables OpenFlow capabilities on legacy network elements. This paper presents the implementation of a HAL on programmable network platforms with multi-core CPUs and summarizes the implementation experience gained in the process.

This paper describes a viable and experimentally-tested way forward for augmenting legacy network elements with software-defined networking control. Following and implementation-driven approach we have explored the possibilities for adding SDN-based interfaces to devices which are not compatible with OpenFlow. OpenFlow is arguably a leading control-place protocol for the upcoming generation of operator networks. Yet not all domains will be equipped from the very beginning with compatible supporting frameworks. To address this gap, we introduce the Hardware Abstraction Layer (HAL) for non-OpenFlow capable devices which tackles this problem. We discuss the advantages of the proposed approach and explain how a HAL-based architecture can support different classes of network devices.

Long Term Evolution (LTE) promises substantially higher radio interface throughput compared to 3G access technologies. Sometimes, the bandwidth demands of a time varying LTE user traffic cannot be fulfilled by the existing transport network either due to the limited capacity or because of the inaccuracies involved in the transport link bandwidth dimensioning. This often results in a congestion situation in the transport network. In this study a novel congestion control scheme is introduced for the LTE uplink which works based on the coordination between the limited transport network capacity and the time varying radio interface capacity. The proposed mechanism operates at the eNB where the two network interfaces can be monitored in order to efficiently minimize the congestion situations. The coordination based congestion control algorithm is implemented in an LTE network simulator and its performance is studied for various system load configurations. The simulation results confirm that the proposed algorithm effectively mitigates the congestion and helps achieve an improved uplink application performance. Furthermore, a significant application performance gain is also observed for the downlink applications when the congestion in the uplink is controlled.

Modern mobile devices comprise multiple interfaces for heterogeneous network technologies. However, currently implemented mechanisms to decide which one(s) to use and distribute application flows accordingly (i.e., solving the multihomed flow management problem, MFM) are rather coarse and do not leverage the opportunities. A user-centric quality-aware (QA) MFM has been proposed which optimises network use based on user-perceivable metrics such as application quality as well as energy and monetary costs. This paper refines this approach by providing a single method for both real-time and elastic (i.e., TCP-based) traffic, and uses realistic available capacity estimation. We evaluate this method in OPNET-simulated LTE and WLAN mobile networks. We study the impact of methods used to trigger the decision algorithm, and investigate the influence of an increasing number of users employing the QA-MFM technique on both the user-perceivable metrics and the global network performance. We find that on-demand triggering performs better than a static periodic method. We also demonstrate that the proposed approach out-performs classical network selection techniques in terms of application quality. We also show that the QA-MFM is not too greedy as to not scale with a number of users, and has a positive effect on the network loads, by preemptively adapting applications parameters to match network conditions.

In this paper, we focus on analyzing the impact of human-to-human contact patterns on opportunistic communication in Pocket Switched Networks (PSNs). We take advantage of statistical methods to consider the distributions of two different types of inter-contact time as well as the number of contacts between human-carried mobile devices. Different from the results from recent studies, we present empirical evidence that power law with exponential cutoff characterizes all three distributions of interest better than other possible long-tail distributions. We further show that each of the investigated distributions has a finite mean value. Having a finite mean value is of importance for each distribution, as it facilitates the design of distributed community detection algorithms as well as social-based forwarding algorithms. Finally, we make the recommendation to exploit the average number of contacts as a threshold for each device to determine their friend-set, which is a precondition for some distributed community detection algorithms.

This paper proposes efficient analytical models to dimension the necessary transport bandwidths for the Long Term Evolution (LTE) access network satisfying the QoS targets required by different services. In this paper, we consider two major traffic types: elastic traffic and real time traffic. For each type of traffic, individual dimensioning models are proposed for both the S1 interface and the X2 interface. For elastic traffic the dimensioning models are based on the Processor Sharing models; while for real time traffic the dimensioning models are based on the fundamental queuing models. For validating these analytical dimensioning models, a developed LTE system simulation model is used. Extensive simulations are performed for various traffic and network scenarios. The analytical results derived from the proposed dimensioning models are compared with the simulation results. The presented results demonstrate that the proposed analytical models can appropriately estimate the required performances for different service classes and priorities. Hence they are suitable to be used for dimensioning of the LTE access network with different traffic and network conditions.

Future wireless networks will consist of a mixed heterogeneous 3GPP and non-3GPP access technologies. The 3rd Generation Partnership Project 3GPP has already facilitated the integration of non-3GPP access by standardizing the System Architecture Evolution (SAE) where non-3GPP access technologies can co-exist with 3GPP access networks. In such heterogeneous networks though the seamless vertical handovers can be performed between the available access networks, the question still remains whether the Quality of Service (QoS) demands of user applications can be satisfied from QoS unaware non-3GPP access technologies? Within the context of the Open Connectivity Services (OConS) of the SAIL European project[1], this work investigates the effects of the integration of two network types on user Quality of Experience (QoE) in the uplink direction. In order to realize QoS guaranteed service from non-3GPP access technologies, this paper proposes two novel resource estimation and management algorithms. With the help of simulation it is shown that integration of non-3GPP technologies in the existing 4G networks extends the network capacity without compromising the user QoE when the proposed schemes are deployed.

We implemented approaches to solve the multihomed flow management problem using the OPNET simulator. We formulate a quality-aware decision method as a binary integer problem and use it (with the CPLEX solver) to drive the network selection and flow distribution in the simulated scenarios. We compare the behaviour of application flows with our approach and the most commonly implemented nowadays. This allows us to more accurately evaluate these approaches’ potential when applied to real network scenarios, where adaptation loops in protocols and algorithms in the network stack may alter the expected performance. We show that, even uncalibrated, the quality-aware multihomed flow management allows to make better trade-offs between different user criteria and identify improvement directions.

Mobile communication technology is evolving with a great pace to offer richer user experience and make an operator’s business more profitable at the same time. The development of the Long Term Evolution (LTE) mobile system by 3GPP is one of the milestones in this direction. 3GPP specifications for LTE mobile systems serve as the high level standards leaving room for improvements by researchers. This work highlights a few of such areas in the LTE radio access network where the proposed innovative mechanisms can substantially improve overall system performance. This includes a novel air interface scheduler design which can coordinate with the core network entities to avoid imminent network congestion. Another proposed air interface scheduling algorithm exhibits an adaptive behavior and reacts to network load conditions in optimizing the scheduler operations. Similarly, packet queue management for buffers of the LTE air interface scheduler is an important subject which has significant impact on user perceived QoE and inter-site handover operations. The thesis discusses all these topics in great detail and proposes practical solutions which are proven to be effective with the help of simulation based analysis. The advent of mobile devices with multiple radio interfaces has increased the opportunity for users to stay connected through any available network type. This makes operators realize that the integration of 3GPP networks (e.g., LTE, HSPA etc.) and non-3GPP networks (e.g., WLAN, WiMAX etc.) is inevitable. This integration would enable operators to offload the select user traffic from 3GPP networks to the integrated WLAN networks with overlapped coverage. However, it comes with the responsibility of the operators to actively manage the bandwidth resources of the two network types in order to get most out of this integration. The thesis addresses this issue in immense detail. For this purpose, a comprehensive system architecture is developed as an overlay of the 3GPP defined SAE architecture. The proposed architecture serves as a framework for implementing network bandwidth resource management mechanisms. In addition, this work also proposes several resource management mechanisms which can operate in conjunction with the purported overlay system architecture. The performance of these mechanisms is evaluated using a heterogeneous network simulator, developed by the

Due to the coexistence of different generations of mobile radio technologies, more and more mobile network operators are keen on deploying multiple radio technologies on a single cell site and carry their traffic over a common transport network. This paper studies such a collocated multiradio system: collocated LTE and HSDPA. Firstly, we investigate the potential gain by using a shared transport network to carry different radio technologies. Furthermore, this paper proposes analytical models to dimension the shared transport network for elastic traffic (TCP-based traffic) from the different radio technologies, by taking traffic characteristics, QoS requirements of each radio technology and the deployed transport QoS function and packet scheduling into considerations. The proposal for modeling the shared transport network is to apply the M/G/R-PS model per QoS class while taking the potential multiplexing gain of bandwidth sharing among the different QoS classes into account. For validating the analytical models, a system simulation model is developed. The analytical results derived from the proposed dimensioning models are validated by comparing with the simulation results for various traffic and network scenarios. Presented results demonstrate that proposed analytical models are well suitable for dimensioning of the shared transport network. With the help of the proposed analytical models, we analyze the potential sharing gain of such a shared transport system under different traffic loads and mix of different radio technologies.

There have been tremendous advances over the past decades when it comes to wireless access technologies. Nowadays, several wireless access technologies are available everywhere. Even mobile devices have evolved to support multiple access technologies (e.g., 3G, 4G or WiFi) in providing the best possible access to the Internet. However, all of these devices can communicate using only one access technology at a time. It is foreseen that an integration of these access technologies to offer users a network access through multiple simultaneous connections would be beneficial for both end users and the mobile network operators. This paper investigates how to tackle the simultaneous usage of multiple wireless access technologies in the downlink. For this purpose, a practical example of heterogeneous network is considered where 3GPP LTE and non-3GPP WLAN access technologies are integrated together. Furthermore, a novel decision mechanism is proposed, that focuses on optimizing the network resource management based on a mathematical formulation of the system. The mathematical model is implemented using the Linear Programming techniques. The paper demonstrates the gains that are achieved from using such innovative decision mechanism as well as the benefits that arise from the simultaneous usage of multiple wireless heterogeneous accesses. Keywords— LTE and WLAN interworking, User QoE optimization, Linear programming, Access link modeling, Heuristic methods

The goal of advanced radio resource management procedures in 4G Long Term Evolution (LTE) is to increase the spectral efficiency beyond an ever achieved level. This objective, however, should be realized by considering an optimal trade-off between system performance and fairness among the users. This work proposes an adaptive packet scheduling mechanism which provides higher spectral efficiency during the times of high system load and a better fairness when enough radio resources are available. The proposed scheme dynamically switches between the well-known Proportional Fair and Blind Equal Throughput scheduling schemes based on the congestion level at the radio interface. Moreover, this work also provides a sophisticated mechanism to estimate the radio interface congestion level to assist the operations of the proposed Adaptive Fair scheduling scheme. The proof of concept is provided with the help of simulation results where the performance of the proposed scheme is evaluated at different radio interface congestion levels.