Software‐defined networking to improve handover in mobile edge networks

Mobility management and handover for a seamless connection are among all‐time challenges of wireless networks. Software‐defined networking (SDN) has opened new horizons toward research by adding intelligence in edge networks while decoupling the control and data planes. The flexibility and centralized nature of SDN further improve the handover decision algorithms. In this paper, we have improved the network performance with respect to the number of handovers and the handover delay by applying an LTE‐SDN architecture and a novel handover decision algorithm based on predicting the future locations of a moving vehicle. The proposed algorithm decouples the handover procedure into two phases of preparation and execution. In the preparation phase, which occurs in the control plane, the handover decision and resource allocation take place, and in the execution phase, handover gets executed similar to the LTE architecture. The results of our research indicate that our proposed LTE‐SDN performance is improved with respect to the number of handovers, handover delay, and signaling overhead by 24%, 16%, and 20%, respectively. On the other hand, average Reference Signal Received Quality (RSRQ) value is decreased by 4% as a tradeoff for the improvements gained.     

Software‐defined networking approach for enhanced evolved packet core network

The evolved packet core (EPC) network is the mobile network standardized by the 3rd Generation Partnership Project and represents the recent evolution of mobile networks providing high‐speed data rates and on‐demand connectivity services. Software‐defined networking (SDN) is recently gaining momentum in network research as a new generation networking technique. An SDN‐based EPC is expected to introduce gains to the EPC control plane architecture in terms of simplified, and perhaps even software‐based, vendor independent infrastructure nodes. In this paper, we propose a novel SDN‐based EPC architecture along with the protocol‐level detailed implementation and provide a mechanism for identifying information fields exchanged between SDN‐EPC entities that maintains correct functionality with minimal impact on the conventional design. Furthermore, we present the first comprehensive network performance evaluation for the SDN‐based EPC versus the conventional EPC and provide a comparative analysis of 2 networks performances identifying potential bottlenecks and performance issues. The evaluation focuses on 2 network control operations, namely, the S1‐handover and registration operations, taking into account several factors, and assessing performance metrics such as end‐to‐end delay (E2ED) for completion of the respective control operation, and EPC nodes utilization figures.     

Performance analysis of handover delay and buffer capacity in mobile OpenFlow‐based networks

Software‐defined networking (SDN) is a network concept that brings significant benefits for the mobile cellular operators. In an SDN‐based core network, the average service time of an OpenFlow switch is highly influenced by the total capacity and type of the output buffer, which is used for temporary storage of the incoming packets. In this work, the main goal is to model the handover delay due to the exchange of OpenFlow‐related messages in mobile SDN networks. The handover delay is defined as the overall delay experienced by the mobile node within the handover procedure, when reestablishing an ongoing session from the switch in the source eNodeB to the switch in the destination eNodeB. We propose a new analytical model, and we compare two systems with different SDN switch designs that model a continuous time Markov process by using quasi‐birth–death processes: (1) single shared buffer without priority (model SFB), used for all output ports for both control and user traffic, and (2) two isolated buffers with priority (model priority finite buffering [PFB]), one for control and the other for user plane traffic, where the control traffic is always prioritized. The two proposed systems are compared in terms of total handover delay and minimal buffer capacity needed to satisfy a certain packet error ratio imposed by the link. The mathematical modeling is verified via extensive simulations. In terms of handover delay, the results show that the model PFB outperforms the model SFB, especially for networks with high number of users and high probability of packet‐in messages. As for the buffer dimensioning analysis, for lower arrival rates, low number of users, and low probability of packet‐in messages, the model SFB has the advantage of requiring a smaller buffer size.     

SDN‐DMM for intelligent mobility management in heterogeneous mobile IP networks

Mobility management applied to the traditional architecture of the Internet has become a great challenge because of the exponential growth in the number of devices that can connect to the network. This article proposes a Software‐Defined Networking (SDN)‐based architecture, called SDN‐DMM (SDN‐Distributed Mobility Management), that deals with the distributed mode of mobility management in heterogeneous access networks in a simplified and efficient way, ensuring mainly the continuity of IP sessions. Intent‐based mobility management with an IP mapping schema for mobile node identification offers optimized routing without tunneling techniques, hence, an efficient use of the network infrastructure. The simplified mobility control API reduces both signaling and handover latency costs and provides a better scalability and performance in comparison with traditional and SDN‐based DMM approaches. An analytical evaluation of such costs demonstrated the better performance of SDN‐DMM, and a proof of concept of the proposal was implemented in a real environment.     

Dynamic handover algorithm with interference cancellation in 5G networks for emergency communication

The integration of 5G networks with cognitive radio (CR) technology enables the software‐defined networking (SDN) infrastructure to support emergency applications. In future, CR can be integrated with 5G and many wireless networks like Wi‐Fi, WSN, and MANET for efficient spectrum utilization with higher data rate and lower latency. This CR technology allows unlicensed users to access the licensed spectrum, whenever it is free. In this paper, an efficient SDN architecture with cognitive ability for emergency network is proposed in which the SDN controller prolong communication between disaster victims and first responders and so the first responders can arrive at the spot directly and rescue the victims. The SDN controller has cognitive ability so that the victims can utilize the vacant licensed band to communicate with the first responders, thereby improving the spectrum utilization of the network. Another two main challenges during emergency are the occurrence of interference and link failure. The proposed dynamic handover algorithm with interference cancellation (DHAIC) cancels the interference between the nodes inside the network and performs dynamic handoff, whenever link failure occurs between the cluster head (CH) and the controller. An optimum throughput and minimal delay is achieved to ensure the network performance.     

Modeling of OpenFlow-related handover messages in mobile networks

Software defined networking (SDN) and its most popular southbound implementation OpenFlow (OF) are already greatly exploited in the existing mobile cellular networks as part of data centers and mobile core networks. Due to user’s mobility, it is of upmost importance for the operators to provide the shortest possible interruption when the mobile users are performing the procedure of handover. In this work, we proposed a novel analytical approach to model the OF-related handover messages exchanged between the OF-switches and the SDN controller. We modeled two different OF-switch implementations and we compared the results: (1) single shared buffer used for the control and data plane; (2) two priority buffers, where the data plane packets are served only when there are no packets to be processed in the control plane. We numerically evaluated the two systems and we validated the model by using simulations. The obtained results clearly point that although the priority buffering increased the complexity, it effectively provided the shortest handover delay. Therefore, the priority buffering should be the preferred mechanism for mobile networks.

     

一种基于Viterbi算法的虚拟网络功能自适应部署方法

为了应对移动数据流量的爆炸性增长,5G移动通信网将引入新型的架构设计。软件定义网络和网络功能虚拟化是网络转型的关键技术,将驱动移动通信网络架构的创新,服务链虚拟网络功能的部署是网络虚拟化研究中亟待解决的问题。该文针对已有部署方法未考虑服务链中虚拟网络功能间顺序约束和移动业务特点的问题,提出一种基于Viterbi算法的虚拟网络功能自适应部署方法。该方法实时感知底层节点的资源变化并动态调整拓扑结构,采用隐马尔科夫模型描述满足资源约束的可用的底层网络节点拓扑信息,基于Viterbi算法在候选节点中选择时延最短的服务路径。实验表明,与其它的虚拟网络功能部署方法相比,该方法降低了服务链的服务处理时间,并提高了服务链的请求接受率和底层资源的成本效率。     

Service‐oriented 5G network architecture: an end‐to‐end software defining approach

With the ever‐increasing mobile demands and proliferation of mobile services, mobile Internet has penetrated into every aspect of human life. Although the 4G mobile communication system is now being deployed worldwide, simply evolving or incrementally improving the current mobile networks can no longer keep the pace with the proliferation of mobile services. Against this background, aiming to achieve service‐oriented 5G mobile networks, this article proposes an end‐to‐end software defining architecture, which introduces a logically centralized control plane and dramatically simplifies the data‐plane. The control plane decomposes the diversified mobile service requirements and, correspondingly, controls the functions and behaviors of data‐plane devices. Consequently, the network directly orients towards services, and the devices are dynamically operated according to the service requirements. Therefore, the proposed architecture efficiently guarantees the end‐to‐end QoS and quality of experience. The challenges and key technologies of our architecture are also discussed in this article. Real traces‐based simulations validate the performance advantages of proposed architecture, including energy efficiency and the whole performance. Copyright © 2015 John Wiley & Sons, Ltd.     

Trust-Assisted Handover Approach in Hybrid Wireless Networks

In Next-Generation (NG) hybrid wireless networks, Mobile-Controlled Handover (MCHO) is expected to be employed as the handover control mechanism, in contrast to Network-Controlled Handover (NCHO) used in homogeneous wireless networks. As more independent network operators get involved in providing Internet access, roaming mobile users would have to deal with complex trust relationships between heterogeneous network domains. The state-of-the-art handover approaches just take into account Quality of Service (QoS), but ignore the complexities arising from the coexistence of multiple network operators in the NG networks. The existence of a complex trust relationship between networks may lead to unnecessary handover attempts in service roaming. In this regard, this paper introduces a novel approach of dynamically retrieving network trust information, and using it in MCHO. We show how network trust information can be utilised to obtain a 35% reduction in handover delay, meanwhile retain QoS in a handover. The proposed scheme does not need bulk storage in mobile handsets, and can react to changes to network topology and trust relationships dynamically. Analytical results are provided to demonstrate how roaming mobile users make more intelligent and reliable handover if implementing the proposed handover approach in a multi-operator and multi-technology environment.     

Software-Defined Mobile Networks Security

The future 5G wireless is triggered by the higher demand on wireless capacity. With Software Defined Network (SDN), the data layer can be separated from the control layer. The development of relevant studies about Network Function Virtualization (NFV) and cloud computing has the potential of offering a quicker and more reliable network access for growing data traffic. Under such circumstances, Software Defined Mobile Network (SDMN) is presented as a promising solution for meeting the wireless data demands. This paper provides a survey of SDMN and its related security problems. As SDMN integrates cloud computing, SDN, and NFV, and works on improving network functions, performance, flexibility, energy efficiency, and scalability, it is an important component of the next generation telecommunication networks. However, the SDMN concept also raises new security concerns. We explore relevant security threats and their corresponding countermeasures with respect to the data layer, control layer, application layer, and communication protocols. We also adopt the STRIDE method to classify various security threats to better reveal them in the context of SDMN. This survey is concluded with a list of open security challenges in SDMN.     

软件定义网络安全研究

软件定义网络（SDN）采用控制和转发的分离架构,使研究者可以通过软件实现任意的网络控制逻辑,而不需对网络设备本身进行修改,具备极强的灵活性,已经在路由决策、网络虚拟化、无线接入、云计算数据中心网络等领域得到研究和应用,成为一项热点技术。但SDN在蓬勃发展的同时,也引入了新的安全风险,带来新的安全问题。另一方面,SDN也给传统安全技术以冲击,带来创新的网络安全应用发展的机会。鉴于此,结合SDN网络架构的特点综述了SDN安全的研究现状,包括SDN安全风险分析和安全技术及应用,并思考了SDN对信息安全的意义。     

SDI: a multi-domain SDN mechanism for fine-grained inter-domain routing

Software-defined networking (SDN) scheme decouples network control plane and data plane, which can improve the flexibility of traffic management in networks. OpenFlow is a promising implementation instance of SDN scheme and has been applied to enterprise networks and data center networks in practice. However, it has less effort to spread SDN control scheme over the Internet to conquer the ossification of inter-domain routing. In this paper, we further innovate to the SDN inter-domain routing inspired by the OpenFlow protocol. We apply SDN flow-based routing control to inter-domain routing and propose a fine-granularity inter-domain routing mechanism, named SDI (Software Defined Inter-domain routing). It enables inter-domain routing to support the flexible routing policy by matching multiple fields of IP packet header. We also propose a method to reduce redundant flow entries for inter-domain settings. And, we implement a prototype and deploy it on a multi-domain testbed.     

Pluggable SDN framework for managing heterogeneous SDN networks

Software‐defined networking (SDN) is a new network paradigm that is separating the data plane and the control plane of the network, making one or more centralized controllers to supervise the behaviour of the entire network. Different types of SDN controller software exist, and research dealing with the difficulties of consistently integrating these different controller types has mostly been declared future work. In this paper, the Domino framework is proposed, a pluggable SDN framework for managing heterogeneous SDN networks. In contrast to related work, the proposed framework allows research into SDN networks controlled by different types of SDN controllers attempting to standardize the northbound API of them. Domino implements a microservice plugin architecture where users can link different SDN networks to a processing algorithm. Such an algorithm allows for, eg, adapting the flows by building a pipeline using plugins that either invoke other SDN operations or generic data processing algorithms. The Domino framework is evaluated by implementing a proof‐of‐concept implementation, which is tested on the initial requirements. It achieves the modifiability and the interoperability with an average successful exchange ratio of 99.99%. The performance requirements are met for the frequently used commands with an average response time of 0.26 seconds, and the framework can handle at least 72 plugins simultaneously depending on the available amount of RAM. The proposed framework is evaluated by means of the implementation of a shortest path routing algorithm between heterogeneous SDN networks.     

Software defined vehicular networks: A comprehensive review

The recent breakthroughs in the automobile industries and telecommunication technologies along with the exceptional multimodal mobility services brought focus on intelligent transportation system (ITS), of which vehicular ad hoc networks (VANETs) gain much more attention. The distinctive features of software‐defined networking (SDN) leverages the vehicular networks by its state of the centralized art having a comprehensive view of the network. Its potential to bring the flexibility, programmability and other extensive advancements to vehicular networks has set the stage for a novel networking paradigm termed as software‐defined vehicular networks (SDVNs). Many researchers have demonstrated the SDN‐based VANETs with the various configuration of the SDN components in VANET architecture. However, a compilation of the work on the SDN‐based VANET system as a whole, incorporating its architecture, use‐cases, and opportunities, is still inadequate. We start with the summary of the recent studies that exist on the SDVNs, followed by the comprehensive explanation of its components. Next, we present the taxonomy of SDVN based on the architecture modes, protocols, access technologies, and opportunities with trending technologies. Finally, we highlight the challenges, open research issues, and future research directions.     

Mobility management approaches for SDN-enabled mobile networks

The evolving network technologies aim at meeting the envisioned communication demands of future smart cities and applications. Although software-defined networking (SDN) enables flexible network control, its applicability to mobile networks is still in its infancy. When it comes to introducing the SDN vision to mobile networks, handling of wireless events and mobility management operations stand out as major challenges. In this paper, we study the scalability issues of SDNized wireless networks, specifically those relevant to mobility management. We design and implement different mobility management approaches in SDNized wireless networks and investigate the impact of various system variables on the overall handover delays. We also study the improvements in handover delays: (i) when a proposed proactive mobility management algorithm is implemented; (ii) when the controller delegates partial control of mobility management to the forwarding entities. For the implementation of the proposed approaches on the OpenFlow network, the paper also suggests potential extensions to the OpenFlow protocol. The contributed approaches are validated on a full-scale demonstrator, with results showing that proactive outperforms reactive and that the delegated control approach performs better than proactive for smaller topology sizes. Furthermore, a proposal for LTE X2-specific control delegation is discussed as a use case.     

A low latency service function chain with SR-I/OV in software defined networks

A network flow is required to be processed by multiple network functions such as PGW and SGW in mobile networks as a service function chain (SFC). Compared to hardware-based network functions, virtualized network functions are more flexible for deployment. Software defined network (SDN) provides a centralized network architecture to manage network resources and route the network flow among network functions in sequence and virtual machines are leveraged to deploy the network functions as network function virtualization (NFV). However, currently the performance of NFV suffers from I/O latency because packet processing causes lots of interrupts that decreases CPU utilization. To address the I/O latency issue, SR-I/OV network card is designed to replace OpenvSwitch in host machines to reduce the system interrupts. However, SR-I/OV is not compatible with existing SDN system, which is an important component in future 5G networks. Therefore, we propose an integrated architecture called the low latency service function chain from a wider perspective in system design to overcome main defects described above. We modify appropriate components in SR-I/OV driver and OpenvSwitch to dramatically reduce packet processing latency in SFC composed by several VNFs. Moreover, our design is compatible with SDN environment and benefited by central control.

     

SDN技术和产业分析及运营商应对策略建议

软件定义网络（SDN）提出了一种全新的网络设计理念,强调控制与转发的分离以及网络的可编程,实现网络架构的开放。SDN正和云计算一道重塑互联网网络模型和产业结构。介绍了SDN的基本概念、本质及特征,分析了SDN核心技术体系及其产业发展现状,从运营商视角探讨了SDN对未来网络的影响,并给出了相应的应用建议。     

Design and analysis of an IEEE 802.21-based mobility management architecture: a context-aware approach

Broadband wireless technologies will soon become an integral part of daily life. In this paper we present the design rationale of a context-aware mobility management architecture for seamless handover in heterogeneous networks. Our proposal is a new cross-layer and interactive approach to seamless handover of users and their services. We present a simple though effective analytical model in typical deployment scenarios in heterogeneous networks with the use of the IEEE Media Independent Handover services. Such analytical model is used to evaluate the resulting handover delay when deploying common mobility protocols in our architecture, such as Mobile IP, Hierarchical MIP, and Proxy MIP.     

移动卫星网络中基于最小费用的切换算法

对于移动卫星网络,合理的星地链路切换方案需要在保证最小切换时延的同时,能够最优地使用网络资源。该文通过引入业务的中断概率和费用模型,给出了切换过程中重路由的最优触发条件,提出一种基于最小费用的切换(SMCH)算法。该算法可在保证切换业务通信的连续性和时延等指标不被破坏的基础上,通过适当的触发重路由来降低切换费用。仿真表明该算法在保证切换业务的QoS,降低切换费用以及适应性、灵活性等方面都优于同类切换算法。     

Vehicular HetNet load distribution using centralized control of software‐defined network

Current vehicular communication systems experience from nonflexible and costly devices, complicated control‐plane protocols, and vendor‐specific configuration interfaces. In the next generation vehicular communication, a mobile device (MD) will be installed on a car capable of accessing multiple services from different networks. So heterogeneous networks (HetNets) may play a vital role in vehicular communication. Despite heterogeneity, flawless connectivity between different systems is a basic need of the travellers. The key challenge for seamless connectivity is the design of a vertical handover (VHO) scheme. We claim that software‐defined networking (SDN) can make things easier in the design and supervision of VHO in vehicular HetNet. The proposed method maximizes the HetNet utilization with lesser handover by balancing the load among the HetNets. Simulation results performed in MATLAB justified that this novel architecture with proper VHO technique boosts the performance by balancing the load, reducing unnecessary VHO, etc. Performance is analyzed by considering four studies, ie, handover served ratio (HSR), on board units (OBUs), OBU served ratio (OSR), and total throughput and total capacities of road side units (RSUs) to serve handover demands from OBUs. It is observed that the HSR increases rapidly as the number of OBUs increases, which indicates almost all the handover requested OBUs are allocated resources by a connected RSU. We also studied the served total throughput by considering VHO with SDN, without SDN in the average case and without SDN in the best case, and it is observed that with SDN as a central controller, the total OSR and total throughput is increased.