Network‐initiated simultaneous mobility in voice over 3GPP‐WLAN

VoIP over WLAN (VoWLAN) gradually has become a popular application with the fast maturing of both WLAN and Voice over IP (VoIP) technology. However there exists one problem that heavily affects the satisfaction of the users which is that the mobility of the mobile host (MH) can disrupt or even intermittently disconnect an ongoing real‐time session. Therefore the issue of how to reduce the handover delay gets more and more important. This paper proposes a Network‐Initiated SimUltaneouS mobility (NISUS) mechanism to facilitate terminal mobility with the session initiation protocol (SIP) in Voice over 3GPP‐WLAN. We design the E2E tunnel state model running on the packet data gateway (PDG) referring to the CAMEL concept. The NISUS is triggered at the PDG by detecting the state transition of the E2E tunnel state model that represents the occurrence of a handover. Then the PDG sends the handover request to notify the Mobility Server (MS) to perform a third party call control (3PCC) and a third party registration on behalf of the MH in parallel for session re‐establishment. With the help of the MS we ensure the lost signaling messages could be correctly re‐sent to moving hosts. Moreover the Master‐Slave Determination procedures derived from H.245 are proposed for the MS in order to handle the racing conditions fairly when two MSs involved in a simultaneous mobility issue 3PCC calls respectively at about the same time. We demonstrate the NISUS works well in the simultaneous and non‐simultaneous movement cases. Analytical results show that the handover delay can be improved significantly by using the NISUS compared with the mobile‐initiated simultaneous/non‐simultaneous mobility. Copyright © 2010 John Wiley & Sons, Ltd.     

Mechanisms and hierarchical topology for fast handover in wireless IP networks

We propose a mechanism to perform fast handover in IP-based wireless networks for real-time applications such as Internet telephony and videoconferencing. Our proposal is designed to reestablish the communication session traffic flow quickly and to minimize the service disruption delay that occurs during mobile IP handover. In this scheme, we propose two different mechanisms to handle micromobility and inter-subdomain mobility, respectively. Micromobility handover handles movements within the same subdomain. Inter-subdomain handover supports handovers between two adjacent subdomains. The reason for having several subdomains is to deploy the network over a wider area to keep the mobile user in the same network for as long as possible. The novelty of the scheme is to retransmit the buffered packets during micromobility handover and to use multicasting to reestablish traffic flow during inter-subdomain movement. The entire scheme is performed within a hierarchical topology based on next-generation IP networks. We analyze both micromobility and inter-subdomain mobility handovers, and display simulation results for both voice and video over IP for micromobility handover.     

IMS-Based Centralized Service Continuity

The IP Multimedia Subsystem (IMS) has been selected as a telecommunication industrial standard for the signal processing in the heterogeneous access networks. It is also brought up to handle the mobility management. However, the mobility of the user equipment (UE) may disrupt or even intermittently disconnect an ongoing real-time session, which heavily affects the satisfaction of the users. Therefore, how to reduce the service disruption time gets more and more important. This paper first proposes a centralized service continuity scheme, abbreviated as CSC, in IMS-based networks. The CSC treats handover as a service in the IMS network. Its architecture and operation are based on service invocation. The service continuity procedure is performed by an application server called CSC AS. The CSC AS can carry out the third-party call control for fast session re-establishment by initiating two INVITE requests concurrently. In addition, a variant of the CSC, denoted by CSC*, is derived by adopting the E-IMS AKA with one-pass authentication for achieving the acceleration of IMS registration during the handover. Analytical results show that both schemes could shorten the handover latency significantly, as compared with the standard IMS-based service continuity.     

A scalable network-based mobility management framework in heterogeneous IP-based networks

This paper proposes a mobility management scheme to provide a mobile node with high-quality handovers among heterogeneous wireless access networks. The proposed scheme employs a signaling architecture to support fast and reliable delivery of control messages by separating a control plane from a data transport plane in the core network. The proposed scheme is based on the network-based mobility management framework which requires the minimum modifications on terminal devices. With interaction between Layers 2 and 3, the proposed scheme accelerates the handover control procedures. It also enables a mobile subscriber to select a target network for a vertical handover with consideration of not only wireless signal strength but also user preference and quality-of-service status. The proposed scheme addresses the well-known problems of the Mobile IP-based approaches, triangular routing and bottleneck at the home agent, since it establishes a data tunnel for a mobile node along the shortest path between two different access networks. The simulation and experimental results indicate that our scheme provisions more efficient performance than the existing approaches in terms of handover latency, data packet loss, data delivery latency and load balancing.     

IPTV QoS adaptation for multi-homed mobile terminals in a new IMS based architecture

With the emergence of multimedia applications that have real constraints, ensuring a satisfying quality of service to mobile users presents a big challenge in heterogeneous wireless networks. In such environment, the asymmetry of the available resources as well as user’s mobility can cause offered QoS degradation. In this paper, we propose the use of the Stream Control Transmission Protocol (SCTP) within a QoS adaptive IPTV services in a novel IMS architecture. The multi-homing feature and the partial reliability extension allow improving the network performance and increasing the user satisfaction. In addition, we have proposed an mSCTP based mobility scheme to guarantee service continuity during handover to IPTV users over IMS. The handover decision includes Perceived QoS (PQoS) measurement reflecting the user satisfaction and Media Independent Handover (MIH) information. An analytical study of the time required to perform IPTV adaptation, show that our approach improves the performance by minimizing the delay and maximizing the user satisfaction.     

Weighted Graph Based Clustering and Local Mobility Management for Dense Small Cell Network with X2 Interface

Along with the surge in mobile data, dense small cell network has become an effective method to improve system capacity and spectrum efficiency. However, because more small cells are deployed, the interference among dense small cells exacerbates. It also makes frequent handover for mobile users (UEs), which brings a great deal of signaling overhead to the core network. In order to solve the problems of interference and frequent handover, a novel clustering scheme for dense small cell network is proposed in this paper. The scheme is based on the weighted graph. First, we present a dense small cell clustering model based on X2 interface to minimize core network signaling overhead. To improve the usability of the model, we model the system as an undirected weighted graph. Then we propose the maximum benefit merging algorithm to reduce the complexity. This method enables adjacent small cells to cooperate and form virtual cellular cluster according to handover statistics information. Then we select cluster head (CH) according to certain rule in each cluster. Cluster head acts as the mobility anchor, managing the handovers between cluster members. This can reduce core network signaling overhead and the interference among small cells effectively. Compared with the 3GPP handover algorithm, the proposed clustering model in this paper can reduce the signaling overhead more than 70%. The simulation results show that the proposed clustering model can effectively cluster the dense small cell.     

An efficient EAP‐based proxy signature handover authentication scheme for WRANs over TV white space

The wireless regional area networks (WRANs) operates in the very high frequency and ultra high frequency television white space bands regulated by the IEEE 802.22 standard. The IEEE 802.22 standard supports Extensible Authentication Protocol (EAP)‐based authentication scheme. Due to the participation of a server and the information exchanged between a customer primes equipment and the secondary user base station, it takes around 50 ms to complete a complete EAP authentication that cannot be accepted in a handover procedure in WRANs. In this paper, we propose an EAP‐based proxy signature (EPS) handover authentication scheme for WRANs. The customer primes equipment and secondary user base station accomplish a handover authentication without entailing the server by using the proxy signature. Approved by the logic derivation by Burrows, Abadi, and Needham logic and formal verification by Automated Validation of Internet Security Protocols and Applications, we can conclude that the proposed EPS scheme can obtain mutual authentication and hold the key secrecy with a strong antiattack ability. Additionally, the performance of the EPS scheme in terms of the authentication delay has been investigated by simulation experiments with the results showing that the EPS scheme is much more efficient in terms of low computation delay and less communication resources required than the security scheme regulated in IEEE 802.22 standard.     

Hybrid coupling scheme for UMTS and wireless LAN interworking

We propose a hybrid coupling scheme to support interworking between UMTS and WLAN networks. Under the Tight-coupled system, it is expected that WLAN users can also use UMTS services with guaranteed QoS and seamless mobility. However, the interworking is problematic. The capacity of UMTS core network nodes cannot accommodate the bulky data traffic from WLAN, since the core network nodes are designed to handle the small-sized data of circuit voice calls or short packets. The proposed coupling scheme differentiates the data paths according to the type of the traffic and can accommodate traffic from WLAN efficiently, with guaranteed QoS and seamless mobility. We compare the handover procedures of the proposed coupling strategy with those of the loose and tight coupled schemes. In addition, we analyze the delay based on signaling costs during vertical handover. It is shown that the handover latency decreases when the UMTS and WLAN are coupled in the proposed way.     

A New Enhanced Fast Handover Algorithm in Hierarchical Mobile IPv6 Network

1　Introduction　MobileIPv6requirestheMobileNode (MN)toregisterwiththeHomeAgent (HA)andtheCorre spondentNode (CN)whenitchangesitspointofattachmentintheInternet[1～ 3] .Therefore ,thiscauseMobileIPv6toincurlongdelayintheregis tration process,andaddsignalingtraffictothebackbonenetworkespeciallywhentheHAandCNarefarawayfromtheMN .Inordertominimizethisdelay ,andthesignalingoverhead presentinMobileIPv6,literatures[4～7] proposeHierarchicalMobileIPv6(HMIPv6)architectureandafasthan dover…     

Local and Global Handovers Based on In-Band Signaling in Wireless ATM Networks

This paper presents a handover protocol for wireless ATM networks, which makes use of in-band signaling, i.e., of ATM resource management cells, to process network handovers and guarantee the in-sequence and loss-free delivery of the ATM cells containing user data. The goal of the proposed approach is to minimize the modifications of the ATM signaling standard required to overlay user mobility onto the fixed network infrastructure, and provide for a gradual upgrade of the fixed network to handle mobility. The proposed protocol handles both local handovers, in which the connection access point needs not migrate to a new ATM local exchange, and global handovers, in which the connection access point must migrate to a new local exchange. The handover scheme is devised so as to grant in-sequence delivery of cells. The performance of the network during handover is analyzed in case of connections requiring loss-free operation. The considered performance figures are the cell transmission delay introduced by the handover and the cell buffering requirements posed to the network. The behavior of the proposed protocol in presence of multiple handovers is studied via simulation, while a simple analytical method is derived for the performance evaluation of a single handover in isolation.     

Seamless handover support over heterogeneous networks using FMIPv6 with definitive L2 triggers

Various wireless communication systems have been developed and will be integrated into an IP-based network to offer end users the Internet access anytime and anywhere. In heterogeneous multi-access networks, one of main issues is to manage nodes’ mobility with session continuity and minimal handover latency. In order to support the mobility of mobile nodes, MIPv6 has been proposed by IETF. Even though MIPv6 provides a solution to handling nodes’ mobility in IPv6 networks, there is a significant problem due to its inability to support a seamless handover caused by long latency and high packet losses during a handover. FMIPv6 has been proposed to reduce MIPv6 handover latency by using an address pre- configuration method with the aid of L2 triggers. Current research defines a general L2 trigger model for seamless handover operation, but it does not address the exact timing and definitive criteria of L2 triggers which causes a significant effect on the handover performance of FMIPv6. This paper considers the available timing and accurate criteria of L2 triggers. With the definitive L2 triggers, we present a practical handover scenario to integrate L2 and L3 layers for low handover latency and low number of packet losses during a handover. We also study the impact of definitive L2 triggers on the handover performance of the FMIPv6 protocol in real testbeds and prove that the FMIPv6 protocol performs its handover operation prior to the L2 handover and obtains a seamless handover.     

A pairing‐free identity‐based handover AKE protocol with anonymity in the heterogeneous wireless networks

Nowadays, seamless roaming service in heterogeneous wireless networks attracts more and more attention. When a mobile user roams into a foreign domain, the process of secure handover authentication and key exchange (AKE) plays an important role to verify the authenticity and establish a secure communication between the user and the access point. Meanwhile, to prevent the user's current location and moving history information from being tracked, privacy preservation should be also considered. However, existing handover AKE schemes have more or less defects in security aspects or efficiency. In this paper, a secure pairing‐free identity‐based handover AKE protocol with privacy preservation is proposed. In our scheme, users' temporary identities will be used to conceal their real identities during the handover process, and the foreign server can verify the legitimacy of the user with the home server's assistance. Besides, to resist ephemeral private key leakage attack, the session key is generated from the static private keys and the ephemeral private keys together. Security analysis shows that our protocol is provably secure in extended Canetti‐Krawczyk (eCK) model under the computational Diffie‐Hellman (CDH) assumption and can capture desirable security properties including key‐compromise impersonation resistance, ephemeral secrets reveal resistance, strong anonymity, etc. Furthermore, the efficiency of our identity‐based protocol is improved by removing pairings, which not only simplifies the complex management of public key infrastructure (PKI) but also reduces the computation overhead of ID‐based cryptosystem with pairings. It is shown that our proposed handover AKE protocol provides better security assurance and higher computational efficiency for roaming authentication in heterogeneous wireless networks.     

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.     

Mobility Management in WLAN-Based Virtualized Networks

Traditional network architectures are about to reach the limits of sustainable development for future service innovation and growth. To overcome the limitation of current architectures and efficiently redesign the future network architecture, a new technology called “network virtualization” is under development. In particular, wireless network virtualization is expected to become an emerging architectural choice to support concurrent heterogeneous services with finer controls over quality of service (QoS) features on the shared wireless network. We note that mobility management has a great influence on user-perceived QoS due to the service disruption during a handover process, and one of the main advantages of wireless network virtualization is to allow for finer-grained control of mobility policy. Although there have been several studies on wireless network virtualization, they focus on virtualizing the radio resources and the network devices. Therefore, in this paper, we propose a detailed protocol to support seamless mobility using the virtualization approach in the IEEE 802.11 wireless networks. We analyze the performance of the proposed mobility management scheme in terms of the handover latency and the signaling overhead. Analytical and simulation results demonstrate that the proposed scheme can significantly reduce handover latency with reasonable signaling cost compared to proxy mobile IP (PMIP) and fast handover for PMIP (FPMIP) in the traditional network.     

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.     

LR-AKE-Based AAA for Network Mobility (NEMO) Over Wireless Links

Network mobility introduces far more complexity than host mobility. Therefore, host mobility protocols such as Mobile IPv6 (MIPv6) need to be extended to support this new type of mobility. To address the extensions needed for network mobility, the IETF NEMO working group has recently standardized the network mobility basic support protocol in RFC 3963. However, in this RFC, it is not mentioned how authentication authorization and accounting (AAA) issues are handled in NEMO environment. Also, the use of IPsec to secure NEMO procedures does not provide robustness against leakage of stored secrets. To address this security issue and to achieve AAA with mobility, we propose new handover procedures to be performed by mobile routers and by visiting mobile nodes. This new handover procedure is based on leakage resilient-authenticated key establishment (LR-AKE) protocol. Using analytical models, we evaluate the proposed handover procedure in terms of handover delay which affects the session continuity. Our performance evaluation is based on transmission, queueing and encryption delays over wireless links.     

MSC POOL核心网性能分析

为了减少移动核心网的信令链路负荷,提高资源利用率,提出了一种核心网的组网方案。通过MSC POOL组网实现该方案,并对接入到MSC POOL核心网中的随机移动用户建立概率模型,利用泊松概率分布模型对MSC POOL网络进行理论定性分析和实验。实验结果表明,与传统组网相比,该方案降低了网络负载率,提高了切换成功率和位置更新成功率,对于移动网络结构和性能有着整体的提升。     

An adaptive hierarchical mobile IPv6 using mobility profile

The Hierarchical Mobile IPv6 (HMIPv6), which is based on the Mobile IPv6 (MIPv6), has been proposed by IETF to reduce registration control signaling. It separates micro‐mobility from macro‐mobility with the help of an intermediate mobility agent, called the mobility anchor point (MAP), and exploits a Mobile Node's (MN's) spatial locality. However, all packets from a Correspondent Node (CN) to an MN are delivered through the MAP. That causes delay in packets delivery and the congestion of packets in the MAP so that it results in deterioration of network capability. To alleviate these problems, we propose a Hierarchical Mobile IPv6 protocol using not only spatial locality but also temporal locality. We introduce a profile for management of these locality information. According to the information in the profile, some packets are directly delivered to an MN, if MN seems to reside for a long time in the current subnet. Also, we introduce a handover scheme with the help of an L2 trigger, so that the proposed scheme takes nearly the same handover delay time as HMIPv6. The other contribution of this paper is to suggest a mathematical modeling and analysis of network traffic costs, MAP processing costs and handover latency for both HMIPv6 and the proposed scheme. Copyright © 2004 John Wiley & Sons, Ltd.     

Mobility management incorporating fuzzy logic for heterogeneous aIP environment

The next generation in mobility management will enable different mobile networks to interoperate with each other to ensure terminal and personal mobility and global portability of network services. However, in order to ensure global mobility, the deployment and integration of both satellite and terrestrial components are necessary. This article is focused on issues related to mobility management in a future mobile communications system, in a scenario where a multisegment access network is integrated into an IP core network by exploiting the principles of Mobile IP. In particular, attention is given to the requirements for location, address, and handover management. In a heterogeneous environment, the need to perform handover between access networks imposes particular constraints on the type of information available to the terminal and network. In this case, consideration will need to be given to parameters other than radio characteristics, such as achievable quality of service and user preference. This article proposes a new approach to handover management by applying the fuzzy logic concept to a heterogeneous environment. The article concludes with a presentation of mobility management signaling protocols     

A utility‐based load‐balancing scheme with guarantee of users' rate for LTE self‐organization networks

Mobility load balance is becoming increasingly crucial in the design of self‐organization networks for LTE (long‐term evolution), especially under dynamic scenarios. In this paper, we study the problem of load balance with guarantee of users' rate and formulate a general optimization model, where the weighted sum of the first‐order and second‐order statistics of load distribution (load variance and total load level) are considered directly. We prove the convexity of the model and derive the optimal user‐station association scheme in different weights. Based on analysis of the optimization model, a dynamic admission and handover scheme is proposed. Mobile users with rate requirement select a base station based on the load utility in a distributed way and handover to the selected station (if handover is triggered). Furthermore, a simulation platform with seven cells is developed to evaluate the dynamic admission and handover scheme. It is demonstrated that our proposed scheme outperforms the conventional counterpart. Copyright © 2013 John Wiley & Sons, Ltd.