A novel media independent handover‐based approach for vertical handover over heterogeneous wireless networks

The key purpose for seamless mobility and service continuity between heterogeneous wireless networks is the handover. Vertical handover management is one of key challenges in such environment. To deal with some of these challenges, an IEEE 802.21 media independent handover (MIH) framework has been standardized. The main purpose of this standard is to offer a general interface for the handover by abstracting the link layer intelligence to higher layers. However, there still exist a number of limitations in MIH architecture. In this paper, a new architecture of improved MIH is presented to perform vertical handover between wireless heterogeneous networks. We focused on interworking architecture between wireless local area network and long term evolution advanced network with the use of MIH signaling to define an efficient vertical handover. A performance analysis model for the proposed MIH‐based vertical handover is derived. Analysis results show that the proposed method can be easily deployed in present multimedia service networks. Copyright © 2013 John Wiley & Sons, Ltd.     

Admission control and handover management for high‐speed trains in vehicular geostationary satellite networks with terrestrial gap‐filling

Following a recent upgrade, the Digital Video Broadcasting—Return Channel Satellite (DVB‐RCS) standard sets up to support terminal mobility. In this scenario, integration with terrestrial systems becomes a primary concern to ensure network connectivity in urban areas. This article proposes an integrated satellite–terrestrial architecture for the provision of broadband services onboard high‐speed trains, in which terrestrial cellular networks are seen as viable gap‐fillers for discontinuous satellite coverage. We derive an analytical model of the hybrid DVB‐RCS‐cellular system by exploiting analogies between the mobility pattern predictability of LEO constellations and that of high‐speed trains. Terminals whose QoS cannot be guaranteed by the satellite segment are proposed to temporarily divert the connections towards the terrestrial infrastructure, where available. Using an iterative approach based on the Erlang fixed‐point approximation, we show performance improvements with respect to stand‐alone satellite systems in terms of handover failure probability and overall resource utilization. The analytical model is also validated via our ns2‐based DVB‐RCS packet‐level simulator. Detailed modelling of synchronization and signalling mechanisms confirms the accuracy of the analytical results, and shows that topology and mobility information can contribute to refine radio resource utilization optimality when used jointly. Copyright © 2009 John Wiley & Sons, Ltd.     

A seamless soft handover management scheme in NGEO satellite networks

Satellite networks can provide extensive geographic coverage to diverse user population, but handovers of active communications should be controlled considering the satellites' high speed. Mobile IP and many other handover algorithms have been proposed for terrestrial wireless networks. However, the satellite network exhibits several unique features compared with the terrestrial wireless networks, such as the long delay. This paper proposes a seamless soft handover scheme (S2H) for satellite networks. S2H designs an identity locator split addressing to solve the multihoming problem and applies the network coding scheme during handover. This manner is able to reduce the interference opportunity, save transmissions, and achieve low handover delay, short queue length, and high throughput. Relying on the simulation results, S2H is able to achieve better performance compared with the proposed handover algorithms in the satellite environment when there are multiple traffic flows. Copyright © 2013 John Wiley & Sons, Ltd.     

SDN/NFV‐based handover management approach for ultradense 5G mobile networks

With the great increase of connected devices and new types of applications, mobile networks are witnessing exponential growth of traffic volume. To meet emerging requirements, it is widely agreed that the fifth‐generation mobile network will be ultradense and heterogeneous. However, the deployment of a high number of small cells in such networks poses challenges for the mobility management, including frequent, undesired, and ping‐pong handovers, not to mention issues related to increased delay and failure of the handover process. The adoption of software‐defined networking (SDN) and network function virtualization (NFV) technologies into 5G networks offers a new way to address the above‐mentioned challenges. These technologies offer tools and mechanisms to make networks flexible, programmable, and more manageable. The SDN has global network control ability so that various functions such as the handover control can be implemented in the SDN architecture to manage the handover efficiently. In this article, we propose a Software‐Defined Handover (SDHO) solution to optimize the handover in future 5G networks. In particular, we design a Software‐Defined Handover Management Engine (SDHME) to handle the handover control mechanism in 5G ultradense networks. The SDHME is defined in the application plane of the SDN architecture, executed by the control plane to orchestrate the data plane. Simulation results demonstrate that, compared with the conventional LTE handover strategy, the proposed approach significantly reduces the handover failure ratio and handover delay.     

Cost‐efficient vertical handover between cellular networks and WLAN based on HMIPv6 and IEEE 802.21 MIH

In order to increase the capacity of wireless communication networks with minor changes and low cost, internetworking between cellular networks and wireless local area networks (WLANs) is considered as an attractive solution. In the internetworking of cellular networks and WLANs, a cost‐efficient vertical handover mechanism is required for seamless service provision. In this paper, we propose a cost‐efficient vertical handover mechanism for the packet‐based cellular networks and WLAN internetworking, where HMIPv6 and IEEE 802.21 are complementarily integrated to optimize the handover procedures. To design the mechanism, we introduce pre‐binding update and hierarchical packet forwarding concepts which can reduce handover signaling cost and delay. A mathematical model for handover rates and costs is proposed in order to analyze the proposed mechanism. In performance evaluation, we investigate how various factors affect handover rates and costs, and compare the proposed mechanism against the conventional mechanism. Copyright © 2013 John Wiley & Sons, Ltd.     

Self‐optimization of handover parameters for dynamic small‐cell networks

Seamless handover is an essential feature of cellular networks. For small‐cell networks, effective handover becomes particularly challenging. If some cells may be activated and deactivated dynamically, effective handover handling will become even more difficult. A key factor of good handover performance is “handover timing,” that is, making handover decision at a right time. If handover is executed too early or too late, users will experience temporary link disconnection, called radio link failure (RLF). Handover timing is controlled by handover parameters, which are set by the network. RLF prevention is directly related to the proper configuration of these parameters. In this paper, we propose a self‐optimization scheme that adjusts the handover parameters to minimize RLFs for dynamic small‐cell networks. Our scheme first detects the types of RLF and then adjusts the handover parameters according to the types of RLF. Unlike most existing schemes, our scheme adjusts both system common parameters and cell‐specific parameters together. In certain situations, such as when two adjacent cells do not have sufficient coverage overlap, RLFs may not be reduced to a satisfactory level by the handover parameter adjustment alone. To deal with such a case, our scheme adjusts the cell coverage in conjunction with the handover parameter optimization. The simulation results show that the proposed scheme can virtually eliminate RLFs. Copyright © 2013 John Wiley & Sons, Ltd.     

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.     

A terminal‐controlled vertical handover decision scheme in IEEE 802.21‐enabled heterogeneous wireless networks

The seamless internetworking among heterogeneous networks is in great demand to provide ‘always‐on’ connectivity services with quality of service (QoS) provision, anywhere at anytime. The integration of wireless‐fidelity (Wi‐Fi) and wireless metropolitan area networks (WiMAX) networks can combine their best features to provide ubiquitous access, while mediating the weakness of both networks. While it is challenging to obtain optimized handover decision‐based dynamic QoS information, users can improve their perceived QoS by using the terminal‐controlled handover decision in a single device equipped with multiple radio interfaces. The IEEE 802.21 aims at providing a framework that defines media‐independent handover (MIH) mechanism that supports seamless handover across heterogeneous networks. In this paper, an multiple attributes decision making‐based terminal‐controlled vertical handover decision scheme using MIH services is proposed in the integrated Wi‐Fi and WiMAX networks to provide ‘always‐on’ connectivity QoS services. The simulation results show that the proposed scheme provides smaller handover times and lower dropping rate than the RSS‐based and cost function‐based vertical handover schemes. Copyright © 2009 John Wiley & Sons, Ltd.     

LTE‐based satellite communications in LEO mega‐constellations

The integration of satellite and terrestrial networks is a promising solution for extending broadband coverage to areas not connected to a terrestrial infrastructure, as also demonstrated by recent commercial and standardisation endeavours. However, the large delays and Doppler shifts over the satellite channel pose severe technical challenges to traditional terrestrial systems, as long‐term evolution (LTE) or 5G. In this paper, 2 architectures are proposed for a low Earth orbit mega‐constellation realising a satellite‐enabled LTE system, in which the on‐ground LTE entity is either an eNB (Sat‐eNB) or a relay node (Sat‐RN). The impact of satellite channel impairments as large delays and Doppler shifts on LTE PHY/MAC procedures is discussed and assessed. The proposed analysis shows that, while carrier spacings, random access and RN attach procedures do not pose specific issues and hybrid automatic repeat request requires substantial modifications. Moreover, advanced handover procedures will be also required due to the satellites' movement.     

QoS handover management for multimedia LEO satellite networks

Low earth orbit (LEO) satellite systems gained considerable interest towards the end of the previous decade by virtue of some of the appealing features that are endowed with, such as low propagation delay and the ability to communicate with handheld terminals. However, after the limited commercial success of the first networks of this kind, future satellite networks are now conceived as complementary rather than competitive to terrestrial networks. In this paper, we focus on one of the most influential factors in system performance, that is, the handover of a call. First, we provide a succinct review of the handover strategies that have been proposed in the literature. Then we propose two different satellite handover techniques for broadband LEO satellite systems that capitalize upon the satellite diversity that a system may provide. The proposed schemes cater for multimedia traffic and are based on the queuing of handover requests. Moreover, a deallocation scheme is also proposed according to which capacity reservation requests are countermanded when the capacity that they strive to reserve is unlikely to be used. Simulation studies further document and confirm the positive characteristics of the proposed handover schemes.     

An agent‐based perspective to handover management in 4G networks

In 3G or earlier generation networks handovers are usually initiated and decided by the base station, on the basis of measurements of RSS or SNR received by the terminal, cell congestion, terminal speed etc. In 4G, due to the diversity of available radio access services, additional factors, for example user profile, application requirements, and terminal device capabilities, need also to be taken into account. We propose an agent‐based architecture that determines the timing and target network for handovers in a 4G network setting. The capabilities of the architecture are provided as a value‐added service on top of network operators' wireless access infrastructure. Network selection spans both wireless access and core routing services and is performed by user agents executing in the network side. In order to deal with trust issues we study the integration of the regulatory authority in the architecture. A performance study of the architecture's impact on handover latency is provided through a simulation system. Copyright © 2007 John Wiley & Sons, Ltd.     

基于环境感知与MIH的无缝切换优化研究

网络多样化已经是当今接入网的一大特点,完成各种网络的准确切换和会话连续性保障是其中关键的两项。IEEE802.21框架能够保证移动终端(Mobile Node,MN)在多网络中自由移动,然而保证切换过程中QoS连续性仍是需要解决的问题。针对切换过程中的这两个要求,提出动态阈值和被动资源预留方法保证准时切换和会话连续性,通过仿真可以看到相对传统的固定阈值和无资源预留方法的情况,该方法对切换连续性有一定的改善。     

Experimental proof of concept of an SDN‐based traffic engineering solution for hybrid satellite‐terrestrial mobile backhauling

Satellite networks are expected to be an integral part of 5G service deployment. One compelling use case is mobile backhauling, where the exploitation of a satellite component can improve the reach, robustness, and economics of 5G rollout. The envisaged availability of new satellite capacity, together with the development of better integration approaches for the provisioning and operation of the satellite component in a more flexible, agile, and cost‐effective manner than done today, are expected to revamp such use case within the 5G ecosystem. In this context, sustained in the architectural designs proposed within H2020 VITAL research project, this paper presents an experimental proof of concept (PoC) of a satellite‐terrestrial integration solution that builds upon software‐defined networking (SDN) technologies for the realization of end‐to‐end traffic engineering (E2E TE) in mobile backhauling networks with a satellite component. A laboratory test bed has been developed and validated, consisting of a small‐scale private mobile network with a backhaul setting that combines Ethernet‐wired links, a satellite link emulator (OpenSAND), OpenFlow switches, and an OpenFlow controller running the network application for E2E TE. Provided results show the operation of a E2E TE application able to enforce different traffic routing and path failure restoration policies as well as the performance impact that it has on the mobile network connectivity services.     

SIP-based IEEE802.21 media independent handover — a BT Intel collaboration

In this paper, we look at various mobility management protocols and handover frameworks in use in BT. We also report on the results from a collaborative proof of concept mixed network prototype for a seamless handover system using Intel’s early implementation of the IEEE802.21 media-independent handover standard. The paper reports the design, implementation and deployment issues/options of a handover mechanism using the Intel framework which includes a connection manager and mixed network IEEE802.21 adaptation layer together with BT’s SIP-based audio/video application in a heterogeneous Wi-Fi, WiMAX and Ethernet network environment.     

IEEE 802.21: Media independent handover: Features, applicability, and realization

Providing users of multi-interface devices the ability to roam between different access networks is becoming a key requirement for service providers. The availability of multiple mobile broadband access technologies, together with the increasing use of real-time multimedia applications, is creating strong demand for handover solutions that can seamlessly and securely transition user sessions across different access technologies. A key challenge to meeting this growing demand is to ensure handover performance, measured in terms of latency and loss. In addition, handover solutions must allow service providers, application providers, and other entities to implement handover policies based on a variety of operational and business requirements. Therefore, standards are required that can facilitate seamless handover between such heterogeneous access networks and that can work with multiple mobility management mechanisms. The IEEE 802.21 standard addresses this problem space by providing a media-independent framework and associated services to enable seamless handover between heterogeneous access technologies. In this article, we discuss how the IEEE 802.21 standard framework and services are addressing the challenges of seamless mobility for multi-interface devices. In addition, we describe and discuss design considerations for a proof-of-concept IEEE 802.21 implementation and share practical insights into how this standard can optimize handover performance.     

Seamless proactive handover across heterogeneous access networks

Dual-mode handsets and multimode terminals are generating demand for solutions that enable convergence and seamless handover across heterogeneous access networks. The IEEE 802.21 working group is creating a framework that defines a Media Independent Handover Function (MIHF), facilitates handover across heterogeneous access networks, and helps mobile users experience better performance during mobility events. In this paper, we describe this 802.21 framework and also summarize a Media-independent Pre-Authentication (MPA) mechanism currently under discussion within the IRTF that can further optimize handover performance. We discuss how the 802.21 framework and the MPA technique can be integrated to improve handover performance. Finally, we describe a test-bed implementation and validate experimental performance results of the combined mobility technique.     

Dynamic inter-domain MDS approach with secure seamless handover based on IEEE 802.21 MIH

The accessibility of available wireless access technologies with increasing demand for real time multimedia application becomes an essential part for mobile communication. Mobile users resourcefully utilize the heterogeneous environment for best quality of service (Qos) anywhere and anytime. Efficient handover optimization and intelligent mobility management is a key requirement for designing next generation wireless networks. Therefore, a novel IEEE 802.21 media independent handover (MIH) standard is adopted to provide an associated service for intelligent handover procedures. In addition, dynamic mobility management decision server (MDS) and IEEE 802.21a security extension for MIH services are also integrated in the proposed architectures to support fast, seamless and secure handover optimization in inter-domain mobility. Simulation results prove that the presented work resourcefully minimizes the packet loss, unnecessary handover probability and vertical handover delay by avoiding time consuming scanning process for target network discovery. The system thus achieves Qos guarantee by balancing the network load and throughput improvement for different applications with Proxy MIPv6 mobility management protocol.     

An enhanced radio resource management based MIH policies in heterogeneous wireless networks

The require of omnipresent wireless access and high data rate services are expected to increase extensively in the near future. In this context, heterogeneous networks, which are a mixture of different wireless technologies (LTE-advanced, LTE-advanced Pro, C-IoT (Cellular Internet of Thing), 5G WiFi, etc) are invited to enable important capabilities, such as high data rates, low latencies and efficient resource utilization in order to provide dedicated capacity to offices, homes, and urban hotspots. Mixing these technologies in the same system, with their complementary characteristics, to afford a complete coverage to users can cause various challenges such as seamless handover, resource management and call admission control. This article proposes a general radio resource management framework which can be supported by future network architectures. A combined call admission control, resource reservation algorithm and bandwidth adaptation based IEEE 802.21 MIH standard approach for heterogeneous wireless network is detailed in this framework. Our aims are to guarantee quality of service (QoS) requirements of all accepted calls, reduce new call blocking probability and handover call dropping probability, and maintain efficient resource utilization. Performance analysis shows that our proposed approach best guarantees QoS requirements.     

On the secrecy performance of integrated satellite‐aerial‐terrestrial networks

This paper investigates secure transmission of an integrated satellite‐aerial‐terrestrial network (ISATN), where multiple eavesdroppers (Eves) attempt to overhear the satellite signals cooperatively. The ISATN adopts an unmanned aerial vehicle (UAV) equipped with multiple antennas as a relay with threshold‐based decode‐and‐forward (DF) protocol. By assuming that perfect instantaneous channel state information (CSI) of the satellite‐UAV link and the statistical CSI of the UAV‐user link are available, we first propose a beamforming (BF) scheme for maximizing the achievable secrecy rate (ASR) of the considered network. Then, we derive the analytical expressions of the secrecy outage probability (SOP) and ergodic secrecy rate (ESR) of the considered system with the BF strategy under an assumption that the satellite‐UAV link undergoes the shadowed‐Rician fading, while the UAV‐user link experiences the correlated Rayleigh fading. Finally, numerical results are given to demonstrate the superiority of the proposed BF scheme against zero forcing (ZF) and maximal ratio transmission (MRT) schemes and the validity of the secrecy performance analysis.     

SRGH: A secure and robust group‐based handover AKA protocol for MTC in LTE‐A networks

Machine‐type communication (MTC) is defined as an automatic aggregation, processing, and exchange of information among intelligent devices without humans intervention. With the development of immense embedded devices, MTC is emerging as the leading communication technology for a wide range of applications and services in the Internet of Things (IoT). For achieving the reliability and to fulfill the security requirements of IoT‐based applications, researchers have proposed some group‐based handover authentication and key agreement (AKA) protocols for mass MTCDs in LTE‐A networks. However, the realization of secure handover authentication for the group of MTCDs in IoT enabled LTE‐A network is an imminent issue. Whenever mass MTCDs enter into the coverage area of target base‐station simultaneously, the protocols incur high signaling congestion. In addition, the existing group‐based handover protocols suffer from the huge network overhead and numerous identified problems such as lack of key forward/backward secrecy, privacy‐preservation. Moreover, the protocols fail to avoid the key escrow problem and vulnerable to malicious attacks. To overcome these issues, we propose a secure and robust group‐based handover (SRGH) AKA protocol for mass MTCDs in LTE‐A network. The protocol establishes the group key update mechanism with forward/backward secrecy. The formal security proof demonstrates that the protocol achieves all the security properties including session key secrecy and data integrity. Furthermore, the formal verification using the AVISPA tool shows the correctness and informal analysis discusses the resistance from various security problems. The performance evaluation illustrates that the proposed protocol obtains substantial efficiency compared with the existing group‐based handover AKA protocols.