Handover Mechanism Research Articles

A Network Topology Control and Identity Authentication Protocol with Support for Movable Sensor Nodes.

It is expected that in the near future wireless sensor network (WSNs) will be more widely used in the mobile environment, in applications such as Autonomous Underwater Vehicles (AUVs) for marine monitoring and mobile robots for environmental investigation. The sensor nodes’ mobility can easily cause changes to the structure of a network topology, and lead to the decline in the amount of transmitted data, excessive energy consumption, and lack of security. To solve these problems, a kind of efficient Topology Control algorithm for node Mobility (TCM) is proposed. In the topology construction stage, an efficient clustering algorithm is adopted, which supports sensor node movement. It can ensure the balance of clustering, and reduce the energy consumption. In the topology maintenance stage, the digital signature authentication based on Error Correction Code (ECC) and the communication mechanism of soft handover are adopted. After verifying the legal identity of the mobile nodes, secure communications can be established, and this can increase the amount of data transmitted. Compared to some existing schemes, the proposed scheme has significant advantages regarding network topology stability, amounts of data transferred, lifetime and safety performance of the network.

PMIPv6 Assistive Cross-Layer Design to reduce handover latency in VANET Mobility for Next Generation Wireless Networks

VANET Networks are one of the main next generation wireless networks which are envisaged to be an integration of homogeneous and heterogeneous wireless networks. The inter-networking of these wireless networks with the Internet will provide ubiquitous access to roaming network users. However, a seamless handover mechanism with negligible handover delay is required to maintain active connections during roaming across these networks. Several solutions, mainly involving host-based localized mobility management schemes, have been widely proposed to reduce handover delay among homogeneous and heterogeneous wireless networks. However, the handover delay remains high and unacceptable for delay-sensitive services such as real-time and multimedia services. Moreover, these services will be very common in next generation wireless networks. Unfortunately, these widely proposed host-based localized mobility management schemes involve the vehicle in mobility-related signalling hence effectively increasing the handover delay. Furthermore, these schemes do not properly address the advanced handover scenarios envisaged in future wireless networks. This paper, therefore, proposes a VANET mobility management framework utilizing cross-layer design, the IEEE 802.21 future standard, and the recently emerged network-based localized mobility management protocol, Proxy Mobile IPv6, to further reduce handover delay.

A Comparative Review of Vertical Handover Decision-Making Mechanisms in Heterogeneous Wireless Networks

Background/Objectives: Heterogeneous wireless networks are converging towards an all-IP network as part of the socalled next-generation network. In this paradigm, different access technologies need to be interconnected; thus, vertical handovers or vertical handoffs are necessary for seamless mobility. In this paper, we prepare a review of existing vertical handover decision-making mechanisms that aim to provide ubiquitous connectivity to mobile users. Methods/Statistical Analysis: To offer a systematic comparison, we categorize these vertical handover mechanisms based on TCP/IP layers. Subsequently, we evaluate several vertical handover decision-making mechanisms in the literature and compare them according to their advantages and limitations. Results/Findings: The paper compares the algorithms based on the network selection methods, flexibility and complexity of the technologies used. We find that the deployment of crosslayer architecture as a handover trigger and then performs handover accordingly with multi-path transmission can reduce packet losses around the handover. Conclusion/Application: The cross layer design approach seems to be a best solution for attaining seamless service continuity in order to facilitate seamless connectivity.

Analysis of handover based on the use of femtocells in LTE networks

One of the key elements in the networks LTE (Long Term Evolution) is the possibility of deploying multiple femtocells for the improvement of coverage and data rate. However, arbitrary overlapping coverage of these cells makes the handover mechanism complex and challenging. In this paper, simulations of deploying LTE femtocells in a scenario were evaluated. With this objective, measure impact and correlation of the use of femtocell parameters of QoS (Quality of Service) and handover. Possible limitations of this integration are discussed. Will be the integration of LTE femtocell a panacea? Despite this promising alternative estimates are fraught with uncertainty. The results show that the use of femtocell got worse on indicators of handover, impact on indicators of QoS.

Knapsack--TOPSIS Technique for Vertical Handover in Heterogeneous Wireless Network.

In a heterogeneous wireless network, handover techniques are designed to facilitate anywhere/anytime service continuity for mobile users. Consistent best-possible access to a network with widely varying network characteristics requires seamless mobility management techniques. Hence, the vertical handover process imposes important technical challenges. Handover decisions are triggered for continuous connectivity of mobile terminals. However, bad network selection and overload conditions in the chosen network can cause fallout in the form of handover failure. In order to maintain the required Quality of Service during the handover process, decision algorithms should incorporate intelligent techniques. In this paper, a new and efficient vertical handover mechanism is implemented using a dynamic programming method from the operation research discipline. This dynamic programming approach, which is integrated with the Technique to Order Preference by Similarity to Ideal Solution (TOPSIS) method, provides the mobile user with the best handover decisions. Moreover, in this proposed handover algorithm a deterministic approach which divides the network into zones is incorporated into the network server in order to derive an optimal solution. The study revealed that this method is found to achieve better performance and QoS support to users and greatly reduce the handover failures when compared to the traditional TOPSIS method. The decision arrived at the zone gateway using this operational research analytical method (known as the dynamic programming knapsack approach together with Technique to Order Preference by Similarity to Ideal Solution) yields remarkably better results in terms of the network performance measures such as throughput and delay.

Integrated ubiquitous connectivity and centralised information platform for intelligent public transportation systems

The study proposes an easily deployable platform for providing ubiquitous connectivity to public transportation vehicles. The platform is capable to exploit the connectivity offered by heterogeneous wireless networks owned by different operators and it integrates a centralised information system (CIS) which stores the context information (CI) characterising the heterogeneous networks. The study describes the network and traffic monitoring processes, proposes a synchronisation mechanism between the mobile routers of the vehicles and the CIS and a vertical handover (VHO) mechanism adapted to the developed architecture. Simulation results based on CI acquired during field tests are reported in the study. These results validate the developed VHO mechanism using the locally available or the centralised CI.

Delay-Centric Handover Issues in Voice Transmissions with Multihomed SCTP

The Stream Control Transmission Protocol (SCTP) establishes a transport layer framework for multihomed communication where the standard failover mechanism improves the transmission resilience. A delay-centric handover mechanism for SCTP have been proposed to improve the end-to-end delay of real-time multimedia transmissions. In this paper, we explore the coexistence of delay-centric handover and standard SCTP failover to identify whether they work together to select a communication path that preserves voice transmission quality. The study was performed using computer simulations, which allowed us to evaluate users' perceived quality and network stability for several conditions of traffic load and packet loss ratio. Although voice quality is generally improved, conflicting decision about interface selection resulted in performance degradation under certain conditions. The global stability of the delay-centric operation when multiple independent voice transmissions compete for the available bandwidth was also evaluated. Simulations showed that under high link utilization, instabilities due to frequent path switching may lead to lower voice quality.

Extended Gradient RSSI Predictor and Filter for Signal Prediction and Filtering in Communication Holes

In wireless communication, received signal strength indicator (RSSI) is a measurement of power in the received signal. This parameter is mainly used in radio frequency (RF) based distance estimation, position estimation, and handover mechanisms. In real-time applications such as object tracking, a handover mechanism, distance estimations require continuous reception of RSSI measurements in order to accurately estimate the position of the object. However, there are some constraints such as signal attenuation, signal loss, multi-path effects. These parameters cause variations in RSSI, and hence it becomes weak, which produces communication holes. Communication holes refer to the phenomenon when the signal drops to zero, and there is a communication blockage, which is practically negligible and can be considered as disconnection. This communication hole occurs due to various factors such as multi-path effects, noise, moving out of the coverage zone, device manufacturing faults, and inquiry procedure as well. The main focus of this paper is to address the issue of communication holes in Bluetooth networks. In Bluetooth networks communication holes also occur due to the delay in the inquiry procedure. Therefore, an existing gradient filter is modified based on the most recent measurements received. The proposed extended gradient filter is tested using simulated and real time RSSI measurements and compared with Kalman Filter and Kalman Smoother. The results show better performance in case of communication holes occurrence.

Using fuzzy logic to reduce ping-pong handover effects in LTE networks

Recently, mobile communications have been widely used in people's everyday lives. Their handover process facilitates people to transfer an ongoing call or a data session from one service area to another without conducting any communication interruption. However, in mobile communications, the ping-pong effect is a serious problem since it may cause unnecessary handover and lead to data loss and high computation cost. This is the case when a user equipment (UE) moves between two or among more evolved Node Bases (eNBs), due to signal strength reason, the UE in a very short time period alternatively switches among the eNBs. Consequently, the eNBs bounce the communication link the UE connected to them back and forth. Although several previous researches have been made to mitigate the ping-pong effect, what seems to be lacking is effectively eliminating unnecessary handover. Therefore, in this paper, we propose a fast and simple fuzzy-logic-based handover decision system, named Fuzzy based Low Ping-Pong Effect Handover System (FPEHS for short), to reduce the ping-pong effect in an LTE network. In the FPEHS, five parameters, including current signal-to-noise ratio (SNR), detected SNR, bandwidth of serving eNB, bandwidth of target eNB, and remaining energy of the underlying user's device, are inputted to the fuzzy logic unit to make handover decision. Our simulation results show that the FPEHS can effectively decrease the ping-pong effect about 92.94 % in average compared with that of the standard LTE's handover mechanism.

Enabling vehicular mobility in city-wide IEEE 802.11 networks through predictive handovers

The increasing number of IEEE 802.11 networks deployed worldwide gives mobile users the possibility of experiencing high-speed wireless access on the move. Moreover, the high density of these deployments in urban areas make IEEE 802.11 a suitable access technology for moving vehicles. However, in order to provide a seamless access to vehicles, the transition between Access Points (APs) must be quick and reliable. The main bottleneck of existing handover mechanisms is the long AP scanning process, which only provides a snapshot of the available networks at a given location, impacting the handover decision on moving vehicles. To overcome this limitation, we propose coper, a context-based predictive handover mechanism that considers vehicle's trajectory, road topology, and network deployment information to decide the best handover location and candidate access points. We validate with real experiments in a city-wide 802.11 network and show that coper can provide better average signal strength, data rate, and connected time than other existing handover approaches.

A Robust Regression Model for Handover Prediction In Wireless Networks

The recent applications of wireless networks demand high Quality of Service (QoS) andmobility management between access networks. For this reason, emergent Advances inIEEE 802.11 standards have been witnessed to achieve seamless communicationbetween mobile nodes. However, since existing handover mechanisms haveshortcomings in terms of mobility handover cost and latency, more robust handoverdecision approach should be considered. To this end, in this research, we propose adecision approach to accurately trigger handover process between current and nextaccess point. The proposed approach incorporates robust regression model is to predictthe received signal strength (RSS) of the wireless channel between the mobile node(MN) and the access point. Thus, the MN makes an accurate handover decision as wellas layer 3 handover process occurs in advance to the one in layer 2. Our theoreticalanalysis and simulation results show that the proposed handover decision approach is farsuperior to the existing handover decision schemes in terms of handover latency andcost.

EPD-NEMO: efficient PMIPv6-based distributed network mobility management

Current network mobility management protocols allow users to access broadband Internet while moving in vehicles or from vehicles to fixed locations without breaking ongoing sessions. These protocols rely on a central mobility anchor such as home agent or local mobility anchor. Thus, some issues, including a single point of failure, long handover delay, and scalability, are exposed in these existing approaches. Ever-increasing demand for mobile Internet traffic changes the mobile network from a hierarchical architecture to a flat architecture and distributed schemes are being researched for the purpose of adapting to new flat architecture and overcoming the aforementioned issues. In this paper, we do a survey of existing network mobility management protocols, current solutions for distributed mobility management, and present an efficient PMIPv6-based distributed network mobility management scheme. The proposed scheme consists of characteristics of distributed mobility management and a new handover mechanism to reduce the packet delivery overhead while keeping seamless Internet access to users in vehicles. By numerical analysis, we prove that our new approach improves service disruption time and packet delivery cost compared to exiting solutions under various environment conditions.

Cdc48-independent proteasomal degradation coincides with a reduced need for ubiquitylation.

Ubiquitin fusion degradation (UFD) substrates are delivered at the proteasome by a handover mechanism involving the ubiquitin-selective chaperone Cdc48 and the ubiquitin shuttle factor Rad23. Here, we show that introduction of a 20 amino acid peptide extension not only rendered degradation independent of Cdc48, in line with the model that this chaperone is involved in early unfolding events of tightly folded substrates, but at the same time relieved the need for efficient polyubiquitylation and the ubiquitin shuttle factor Rad23. Removal of the ubiquitylation sites in the N-terminal UFD signal made the degradation of this substrate strictly dependent on the peptide extension and also on Cdc48 and, importantly the presence of a functional ubiquitylation machinery. This suggests that the extension in the absence of N-terminal ubiquitylation sites is not properly positioned to engage the unfoldase machinery of the proteasome. Thus the need for efficient ubiquitylation and Cdc48 in facilitating proteasomal degradation are tightly linked but can be bypassed in the context of UFD substrates by the introduction of an unstructured extension. Our data suggest that polyubiquitin-binding complexes acting upstream of the proteasome, rather than the proteasome itself, can be primary determinants for the level of ubiquitylation required for protein degradation.

Comments on “SPAM: A Secure Password Authentication Mechanism for Seamless Handover in Proxy Mobile IPv6 Networks”

Recently, Chuang et al. have introduced a secure password authentication mechanism for seamless handover in Proxy Mobile IPv6 (SPAM). SPAM aimed at providing high-security properties while optimizing the handover latency and the computation overhead. However, it is still vulnerable to replay and malicious insider attacks, as well as the compromise of a single node. This paper formally and precisely analyzes SPAM based on the Burrows–Abadi–Needham logic, followed by its weaknesses and related attacks.

A Novel Model on Curve Fitting and Particle Swarm Optimization for Vertical Handover in Heterogeneous Wireless Networks

The vertical handover mechanism is an essential issue in the heterogeneous wireless environments where selection of an efficient network that provides seamless connectivity involves complex scenarios. This study uses two modules that utilize the particle swarm optimization (PSO) algorithm to predict and make an intelligent vertical handover decision. In this paper, we predict the received signal strength indicator parameter using the curve fitting based particle swarm optimization (CF-PSO) and the RBF neural networks. The results of the proposed methodology compare the predictive capabilities in terms of coefficient determination (R2) and mean square error (MSE) based on the validation dataset. The results show that the effect of the model based on the CF-PSO is better than that of the model based on the RBF neural network in predicting the received signal strength indicator situation. In addition, we present a novel network selection algorithm to select the best candidate access point among the various access technologies based on the PSO. Simulation results indicate that using CF-PSO algorithm can decrease the number of unnecessary handovers and prevent the “Ping-Pong” effect. Moreover, it is demonstrated that the multiobjective particle swarm optimization based method finds an optimal network selection in a heterogeneous wireless environment.

WLAN 환경에서 네트워크 가상화를 통한 끊김 없는 핸드오버 매커니즘 연구

WLAN 환경에서 네트워크 가상화를 통한 끊김 없는 핸드오버 매커니즘 연구

MAC layer handover mechanism for continuous communication support in healthcare mobile wireless sensor networks

The use of wireless sensor networks (WSNs) is growing up in the last few years. Therefore, new challenges arise every day and one of the emerging challenges in WSNs is the nodes mobility support. This feature increases the application areas of these technologies but also raises new challenges to solve. This paper proposes a new handover mechanism, called Hand4MAC (Handover mechanism for MAC layer supporting continuous communication in mobile wireless sensor networks), to deal with body sensors mobility in scenarios where patients are hospitalized. This approach tries to provide continuous monitoring and communication with these sensor nodes when they move across different access points wireless coverage range. The proposed method for medium access control (MAC) layer considers that nodes remain within the same network. The evaluation study of the proposed algorithm was performed by simulation and evaluated in comparison with the well-known RSSI-based handover algorithm. It was concluded that Hand4MAC performs better and reveals promising results for real deployment.

Optimized handover strategy with hybrid satisfaction mechanisms

One of the key features of cellular systems is the possibility to switch the connection over several cells while the user is moving. This handover between cells has been upgraded to tackle different operator/users' objectives, and even it has been proposed between two access technologies for what is known as vertical handover. The long term evolution-advanced technology uses two kinds of cells within its coverage design, the macrocell to provide larger coverage at the extent of lower data rate; and the smallcell (i.e., femtocell) that is designed for very high data rate while low coverage is provided. Therefore, special mechanisms for handover between macrocells and smallcells are required. Along this paper we propose two handover mechanisms over such scenario where the objectives vary among larger data rate, lower energy consumption and load balancing. Special concern is given to green communications that have emerged as one of the most important trends in wireless communications because of its several advantages of interference reduction, battery life increase and electrical bill cut. The presented handover mechanism can tackle more than one objective at a time in order to provide satisfaction both to the operator and users. Interesting conclusions are obtained about the presented approach through computer simulations.

Impact of sensor nodes scaling and velocity on handover mechanisms for healthcare wireless sensor networks with mobility support

Health promotion in hospital environments can be improved using the most recent information and communication technologies. The Internet connectivity to small sensor nodes carried by patients allows remote access to their bio-signals. To promote these features the healthcare wireless sensor networks (HWSN) are used. In these networks mobility support is a key issue in order to keep patients under real-time monitoring even when they move around. To keep sensors connected to the network, they should change their access points of attachment when patients move to a new coverage area along an infirmary. This process, called handover, is responsible for continuous network connectivity to the sensors. This paper presents a detailed performance evaluation study considering three handover mechanisms for healthcare scenarios (Hand4MAC, RSSI-based, and Backbone-based). The study was performed by simulation using several scenarios with different number of sensors and different moving velocities of sensor nodes. The results show that Hand4MAC is the best solution to guarantee almost continuous connectivity to sensor nodes with less energy consumption.

Congestion-Aware Handover in LTE Systems for Load Balancing in Transport Network

Long-Term Evolution employs a hard handover procedure. To reduce the interruption of data flow, downlink data is forwarded from the serving eNodeB (eNB) to the target eNB during handover. In cellular networks, unbalanced loads may lead to congestion in both the radio network and the backhaul network, resulting in bad end-to-end performance as well as causing unfairness among the users sharing the bottleneck link. This work focuses on congestion in the transport network. Handovers toward less loaded cells can help redistribute the load of the bottleneck link; such a mechanism is known as load balancing. The results show that the introduction of such a handover mechanism into the simulation environment positively influences the system performance. This is because terminals spend more time in the cell; hence, a better reception is offered. The utilization of load balancing can be used to further improve the performance of cellular systems that are experiencing congestion on a bottleneck link due to an uneven load.