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A QoE maximization based vertical handover scheme for VLC heterogeneous networks

A QoE maximization based vertical handover scheme for VLC heterogeneous networks

Wan et al. [14] studied the downlink resource allocation (RA) problem for a hybrid VLC and Wi-Fi system. A resource allocation algorithm combined with optical power dynamic allocation was proposed by maximizing the best effort (BE) service users’ aggregate throughput and users’ proportional fairness under the premise of guaranteeing the minimum rate requirement of delay- constrained (DC) service users. Basnayaka et al. [15] focused on improving the per user average and outage throughput in a VLC and RF heterogeneous network. The VLC system resources were assumed to be fixed, and the spectrum and power requirements for the RF system were quantified. The simulation results showed that the network can achieve better per user rate perfor- mance. In [16], the authors presented a novel hard-link switching scheme for VLC networks using pre-scanning based on received signal strength (RSS) prediction. The proposed system achieves both hard-link switching and soft-link switching reward without exchanging device hardware and the IEEE 802.15.7 medium access con- trol (MAC) protocol. Because the hard handover may result in lost data connection, a soft handover scheme was presented in [17] by using orthogonal frequency division multiple access (OFDMA) under mobility. Wang et al. [4] investigated a Markov decision pro- cess problem and implemented a dynamic method to obtain a trade-off between the cost of switching and the delay requirement. They proposed a scheme to determine whether to perform VHO given the queue length and the condition of the optical channel. A novel VLC- HetNet protocol was proposed in [5, 6] that combined access, horizontal, and vertical handover mechanisms for a mobile terminal (MT) to resolve user mobility among different hotspots and an OFDMA system. The simulation results showed improvements in the capacity performance of the VLC-HetNet compared to that of the RF system.
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A moving direction prediction assisted handover scheme in LTE networks

A moving direction prediction assisted handover scheme in LTE networks

The 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) defines a wireless network standard for high packet transmission rate and low packet latency provisions. Handover is one of the important features for helping user equipments (UEs) to roam between LTE networks. However, LTE networks adapt a make-before-break handover procedure, which may cause a brief disconnection, therefore results in the packet transmission delay and packet loss problems. In this paper, we propose a moving direction prediction-assisted handover scheme for LTE networks to lower the number of handovers. We first track the location of user equipments (UEs) to predict their moving direction. By referencing previous locations, the next moving direction of UEs is estimated with the cosine function in order to determine the candidate E-UTRAN NodeBs (eNBs) for handover. Then, a target eNB is selected from the candidate eNBs through an angle-based dynamic weight adjustment scheme. By selecting a proper target eNB for handover, thus the quality of network transmission can be enhanced. Simulation results demonstrate the ability of the proposed scheme in reducing 17% average handover times, compared with the standard handover procedure, thereby reducing 12% average number of packet loss and 5% average packet delay time.
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A CoMP soft handover scheme for LTE systems in high speed railway

A CoMP soft handover scheme for LTE systems in high speed railway

With the development of high-speed railway and public growing demand on data traffic, people pay much more attention to provide high data rate and high reliable services under high mobility circumstance. Due to the higher data rate and lower system latency, long-term evolution (LTE) has been chosen as the next generation’s evolution of railway mobile communication system by the International Union of Railways. However, there are still many problems to be solved in the high mobility applications of LTE, especially the higher handover failure probability, which seriously degrades the reliability of railway communication. This article proposes an optimized handover scheme, in which the coordinated multiple point transmission technology and dual vehicle station coordination mechanism are applied to improve the traditional hard handover performance of LTE. The scheme enables the high speed train to receive signals from both adjacent base stations and obtain diversity gain when it moves through the overlapping areas, so it improves the quality of the received signal and provides reliable
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Quad-Channel Seamless Handover Scheme for Vehicular Networks

Quad-Channel Seamless Handover Scheme for Vehicular Networks

Fig. 1 shows the proposed ITS system architecture considering all possible components such as pedestrian, car (road system), and train (railroad system). There may or may not exist control center for smart ITS services but in the system architecture shown in Fig. 1, control center is configured for centralized control. Different types of ITS users such as person, car, and train are connected to the ITS system through Road Side Units (RSUs). Interface between ITS users and RSU is called Vehicle to Infrastructure (V2I) interface. ITS users need to communicate each other using the air interface called Vehicle to Vehicle (V2V) interface. In some cases, RSUs need to communicate each other using the interface called Infrastructure to Infrastructure interface (I2I), which is not defined in the standards. Since communication distance between trains, railroad system may not provide V2V communication. For such case, new communication type, V2V with I2I needs to be newly defined. V2V with I2I is communication a inter vehicle communication when direct communication is not possible due to its long communication distance. In this case, RSUs relay one vehicle’s packets to the destination vehicles. From the vehicles’ perspective, RSUs’ relay should be seen transparently. By utilizing the proposed ITS system architecture, total ITS services can be provided and the proposed handover scheme can be performed with maximum efficiency.
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A Survey : Handover scheme of High Speed Train Environment

A Survey : Handover scheme of High Speed Train Environment

Train Relay station: The author [13] proposed the dual link handover scheme based on two hop architecture. In TRS two antennas are installed on the train one is on front end other is on the rear end. When moving train is at the cell boundary, the front antenna performs handover to targeted base station (target eNB). While the rear antenna still communicating with serving eNB. Maintain the connection during entire handover mechanism In that use of bi-casting method to supports the lossless handover. As shown in fig 4 bi-casting from serving gateway to serving eNB and target eNB during handover. In which some delay may occur due to same data forwarding to both station as serving and also target eNB.
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Game Approach for Handover Scheme Based on Road-section in VANET

Game Approach for Handover Scheme Based on Road-section in VANET

Abstract—In VANET (Vehicular Ad Hoc Network), vehicles moving from one RSU’s coverage region to another will cause access congestion problem if vehicles use improper handover scheme. In this paper, we present a novel mobility handover scheme for vehicles with seamless Internet access in urban VANET scenario, which is called Game approach for Handover Scheme based on Road-section (GHSR). The main advantages of our scheme are that it uses Sequential Game and it based on 802.11p standard proceeding from service and the vehicles needing to handover will game each other to gain no smaller payoff by selecting an appropriate road-section. Performance evaluations demonstrate that our scheme outperforms the threshold scheme significantly in terms of both the traffic load of RSUs and the QoS (Quality of Service) of vehicles users, and QoS of vehicle users increase by up to 33.68%.
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Seamless Handover Scheme in Broadband Wireless Communication Systems for High  Speed Rail

Seamless Handover Scheme in Broadband Wireless Communication Systems for High Speed Rail

wireless-communications in communication interru- ption, high-speed rail during handover could seriously degrade the experiences of passengers on the train. Intending to reduce the interruption time, a seamless handover scheme based on a dual-layer and dual-link system architecture has proposed in this paper, where a Train Relay Station is employed to execute handover for all users in a train and two antennas are mounted at the front and rear of a train. The front antenna executes handover while the rear antenna is still communicating with Base Station (BS), so that the communication can keep non-interruptive throughout the handover. Additional, bi-casting is adopted to eliminate the data forwarding delay between the serving BS and target BS in the prospective scheme. A exhaustive handover protocol is designed and the performance of the proposed scheme is examined. It can be seen from analytical results that the handover failure probability decreases as cell overlap increases and the communi- cation interruption probability decreases with the decrease of train handover location and the increase of cell overlap. The communication interruption proba- bility is smaller than 1% when the handover and the simulation results show that in the proposed scheme. Location is properly selected and the system throughput is not affected by handover is shown. In conclusion, both theoretical and simulation results show that the proposed scheme can efficiently perform seamless handover for high-speed rail with low implementation overhead.
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An Efficient Handover Scheme for PMIPv6 in IEEE 802.16/WiMAX Network

An Efficient Handover Scheme for PMIPv6 in IEEE 802.16/WiMAX Network

Abstract— In the era of wireless communication, mobility management is an important issue. The world is deploying WiMAX (Worldwide Interoperability for Microwave Access) as the standard for broadband wireless communication because of it’s wide application areas, high speed and architecture for seamless handover. Alongside, a network-based mobility management protocol called PMIPv6 (Proxy Mobile Internet Protocol version 6) is being actively standardized and is starting to attract considerable attention among the telecommunication and Internet communities for its less handover latency. In PMIPv6, the functioning network provides control of the mobility management on behalf of the mobile node. Thus the mobile node is relieved from any mobility related signaling. However, the PMIPv6 suffers from handover latency and packet loss during handover. In this paper, an efficient handover scheme is proposed within a PMIPv6 domain in the WiMAX network. The proposed scheme reduces handover latency by eliminating the need of a Policy Server (PS) and by pre-registration of the mobile node for a new access point. Furthermore, a comprehensive analysis has been done by NS-2 (Network Simulator-2) for evaluating the delay of our proposed handover scheme and that of general PMIPv6. The analysis results reveal that the proposed strategy for handover has significantly reduced the handover latency of general PMIPv6.
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Secure Handover Scheme for Traffic Optimization based on OLSR Protocol

Secure Handover Scheme for Traffic Optimization based on OLSR Protocol

In the present time, key to provide mobile users with required QoS will be seamless handoff between homogenous or heterogeneous wireless access networks. Also the continuation of user application should not be compromised. Generally handover bring up the process of transferring an active call or data session from one cell in a cellular network to another. There are many reasons to perform handover between three cellular networks, and the most important reason is to deliver uninterrupted service to a user [12, 13]. There are some rules to initialize the handoff and it can be divided into two types:
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Cross Layer Handover Scheme for Multimedia Communications in Next Generation Wireless Networks

Cross Layer Handover Scheme for Multimedia Communications in Next Generation Wireless Networks

2.3. The OSM. In next generation wireless networks, the network infrastructure is heterogeneous and all-IP. There are multiple protocols and functional modules to support the handover (see Figure 1). Note that the conventional approaches for improving the handover performance are combined by SIP and MIH, while our proposed handover approach is a combination of SIP, FMIP and MIH. For comparison, we briefly describe the original SIP and MIH combined handover mechanism (OSM), which is a make- beforebreak handover mechanism. The OSM provides the IP mobility between heterogeneous networks as illustrated in the message flow of Figure 2. Recalling that IP mobility is achieved by the REINVITE signaling of SIP, the MN sends the REINVITE signaling to its corresponding node (CN) to reestablish the communicational session with the new IP address. Before the handover process begins, the MN retrieves the prefix of the NAR through the IS in advance. In order to complete handover process before previous link down, the new IP address configuration and the REINVITE signaling of SIP are triggered by MIH’s link going down event (LGD) in OSM. After exchange Router Solicitation (RS) and Router Advertisement (RA) signaling, the MN connects to the NAR.
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Online Full Text

Online Full Text

Recently, many research works are related to the handoff and performance issue based on MIP. [16] designed a client-based handoff management system as a common network interface at a client side and provided transparent services to IP/MIP layers without any modifications to the existing IP/MIP stack and core network. [17] introduced a distributed and dynamic mobility management strategy where the signaling burden was even and the regional network boundary was dynamical based on HMIP. In [18], a new handover scheme using the L2 information of user terminal at the AP (Access Point) or AR (Access Router) was introduced which reduced the handover latency time by means of L3 based fast handover and got rid of triangle problem through data tunneling between ERs (Edge Routers). In [19], the authors proposed MIP routing to eliminate triangle routing. In [12], HSIEH proposed so called S-MIP by predicting the information of mobile modes so as to reduce intra-domain handoff latency. TLMM, an approach of combing intra-domain care of address (CoA) with global CoA, implemented MIP-based three-tier mobile model [20]. Another method in [21] is a mathematical way, by which KAMAL etc. set the special proxy to obtain the minimal overall cost of updating the mobile register information and searching mobile nodes. DIP-MIP, constructed by introducing distributed independent paging extensions to mobile IP, can save energy consumption when the mobile nodes are inactive [22].
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Implementing Horizontal Handover among
Homogenous Network in WiMAX

Implementing Horizontal Handover among Homogenous Network in WiMAX

In 2008 Salhani, M., et.al A model of mobility for WiMAX network users, introducing horizontal handover mechanism with channel reservation was the goal of this paper to improve horizontal handover. To perform the channel reservation they considered three different approaches: by neighbor nodes (NNs) (cooperative approach), by the BSs (individual approach) or by both (mixed approach). It is shown that the channel reservation mechanism reduces clearly the handover blocking rate and it does not degrade the performance of the system [1]. Similarly, in 2009, Hamid et.al explains in paper that handover is very significant factor in the performance of mobile WiMAX, but because of the presence of unnecessary ranging/scanning in Layer two along with the network re-entry procedure enormous handover latency occurs. Due to the HO delay and wireless resource waste, there occurs significant level of service level degradation. For the elimination of such degradation in service level; adequate intelligence utilizing neighbor advertisement message for efficient scanning algorithm, modified dedicated ranging and network re-entering method are proposed[2]. In 2011 Ashoka et.al describes that order to increase the efficiency of handover schemes in paper presented an experimental study on network-based handover and host-based handover in mobile WiMAX. Analysis of the performance of the two standardized handover schemes, namely the Mobile IP and the ASN-based Network Mobility (ABNM), in mobile WiMAX were made using simulation. Overall this paper demonstrated that the ABNM handover scheme can strengthen the capability of mobile WiMAX network operators to manage and control their networks more efficiently in terms of handover delay and throughput [3]. Same year Bala et.al describes the impact of mobility on QoS of WiMAX (IEEE 802.16e) with CBR application was analyzed by. This paper analyzed the impact of mobility on the QoS parameters (Throughput, Average Jitter and Average end to end Delay) of a mobile WiMAX network (IEEE 802.16e) with CBR (Constant Bit Rate) application. The results concluded that as the handover takes place, then due to connection timeouts, connection time lags, data traffic congestion and interference, jitter occurs and because of this average end to end delay increases, but when mobile node again come to its registered base station both jitter and average end to end delay will decrease although [4].
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Authenticated Key Management Scheme for Intra-Mme Handover Over LTE Networks

Authenticated Key Management Scheme for Intra-Mme Handover Over LTE Networks

Abstract : In the intra-MME handover over the Long-Term Evolution (LTE), the key management takes place in between the source eNodeB and target eNodeB under the same Mobility Management Entity (MME). 3GPP has specified some security mechanisms to insure the safety of intra-MME handover key management, but nevertheless there exists a few vulnerabilities compromising the protection of the LTE entities, one of the most harmful is the desynchronization attack.The major contribution of this paper is; to put forward a new authenticated key management scheme, to overcome the desynchronization attack, by keeping out the source eNodeB and use MME as a third trusted party for intra-MME handover. The proposed scheme is analyzed under three adversary models. A formal security analysis is performed as well using a specialized model checker, Scyther. Moreover, a performance evaluation of the proposed scheme is conducted. Finally, a comparison with the current intra-MME handover scheme is introduced.
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On  the  Design  of  a  Secure  Proxy  Signature-based  Handover  Authentication  Scheme  for  LTEWireless  Networks

On the Design of a Secure Proxy Signature-based Handover Authentication Scheme for LTEWireless Networks

Cao et al. [15] described replay attacks, de-synchronization attacks and lack of back- ward security as three main vulnerabilities of LTE handover scheme. To address these vulnerabilities, some schemes [16,17,18] have suggested the participation of Authen- tication, Authorizing, and Accounting (AAA) servers. However, these schemes incur so much authentication traffic. In addition, these server are far away from the base stations that incorporating them demands much time that makes these network not fast enough.

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An accelerating handover process scheme for IEEE 802 16j multi hop relay networks

An accelerating handover process scheme for IEEE 802 16j multi hop relay networks

system is proposed in [14] to decrease handover signal- ing overhead, latency, and unnecessary handovers. The authors propose a handover method that reduces inter- cell handover but increases intra-cell handover events by modifying the BSID format into the hierarchical BS/RS ID. Becvar et al. [15] propose an optimal handover scan- ning procedure (OHSP) in IEEE 802.16j network systems to reduce the management information overhead and to maximize the user data throughput. The modification of scanning procedure is based on the uplink direction by adding identification addresses of all recommended sta- tions for scanning into one scanning request message. In [16], this article presents handover schemes in multi- hop cellular networks (HSMCN) where RSs are located either inside a cell or on the boundary between two ad- jacent cells. By deploying RSs on the boundary between two adjacent cells, the service-interruption time caused by inter-cell handover is reduced. Yun et al. [17] propose a fast handover scheme (FHS) to reduce the handover signaling cost and to decrease handover delay by apply- ing fast handovers for mobile IPv6 (FMIPv6) to IEEE 802.16j networks, which determines the cross-subnet handover in advance through the interaction of MAC layer messages. Sultan et al. [18] perform simulation study of three handover techniques (SSTHT) within the IEEE 802.16j standards and prove that the macro diver- sity handover (MDHO) outperforms the HHO and fast base station switching. MDHO is the process by which an MS maintains connection with two or more access stations called a diversity set. In [19], a topology-aware macro diversity handover technique (TMDHT) is pro- posed to improve the conventional MDHO.
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Dual Triggering for Improvement of Handover in Mobile WiMax

Dual Triggering for Improvement of Handover in Mobile WiMax

In this paper two new schemes have been proposed, one for the minimization of the excessive scanning involved in the selection of a TBS and second for reducing the handover delay involved for the actual handover initiation. The minimization is being done by predicting Target base station from the information provided by the GPS system. This prediction helps in the number of frequencies of channel to be scanned by the MS thereby decreasing the delay involved in the handover. Since the MS has to remain disconnected with the SBS till the scanning is being done the delay is introduced which is reduced by minimizing the number of frequencies needed to be scanned and hence reducing the delay. For the minimization of handover delay a dynamic distance handover scheme is proposed. According to the existing draft version of 802.16e standard, the HO initiation is performed if the RSSI of the serving BS is lower than the RSSI of TBS. However, it does not consider the distance between the MS and BS in the HO process, so there is a handover delay involved. To cope with this problem the proposed scheme makes use of dynamic distance threshold which allows handover between the two BSs depending on the velocity of the MS and establishes the connection before the MS overruns the boundary of NBS to a much extent in terms of distance thereby decreasing the handover delay involved.
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LOCATION BASED PREDICTIVE MODELLING OF HANDOFF MANAGEMENT IN WIRELESS NETWORK

LOCATION BASED PREDICTIVE MODELLING OF HANDOFF MANAGEMENT IN WIRELESS NETWORK

Our suggested handover scheme is applied on the broadband wireless networks. The aim of this scheme is to reduce the delay incurred during handover to minimize call dropping and packet loss. In our suggested scheme the source BS predicts the time state of the handover and initiates the handover procedure with the target BS. The proposed scheme is based on the generation of mobility profiles using a statistical technique and using these profiles to predict the handover of a UE using neural networks. The suggested handoff scheme involves the following three steps, 1) input data preparation, 2) predicting target BS using MFFN, 3) initiating handover procedures.
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Introduction of Handover Manager for Better Handover Latency and Handover Throughput during Leo Satellite Handover

Introduction of Handover Manager for Better Handover Latency and Handover Throughput during Leo Satellite Handover

LEO satellite has an important role in global communication system. They have advantages like low power requirement and lower end-to-end delay, efficient frequency spectrum utilization between satellites and spotbeams over MEO and GEO satellites. So in future they can be used as a replacement of modern terrestrial wireless networks. There are a lot of handover techniques for LEO satellites like seamless handover (SeaHO-LEO) ,PatHO-LEO .In our proposed work we have suggested a new handover technique for SeaHO- LEO by introducing a Handover Manager (HM) during the handover process and by simulation we have also shown that it a better approach by comparing it with other existing handover techniques as it reduces the handover latency, propagation delay, call blocking probability more than any other technique.
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Light-Weight Authentication Scheme for Handoff in Long Term Evolution (LTE)

Light-Weight Authentication Scheme for Handoff in Long Term Evolution (LTE)

This dissertation has survey various security methods related to the LTE and its handover operation. It has been identified that the computational cost to ensure authentication in LTE has come the high cost. This thesis has presented a new approach to make handover secured using Light weight authentication system. Proposed method has adopted the idea of the message digest for exchanging the authentication key with AP’s (eNB to UE’s and eNB to eNB) and termed as AD (Authentication Digest). For making immune to attack the AD has been covered it with hash function. This method is better than existing cryptographic method due to hash function and elimination of the cryptographic computational overhead (RSA KEY generation and Validation including exponentiation overhead).
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A Moving Direction and Historical Information Assisted Fast Handover in LTE-A

A Moving Direction and Historical Information Assisted Fast Handover in LTE-A

In relation to LTE-A E-UTRAN networks, handover mechanism or handoff is one of the important features which allows the UE which is connected to the base station either to transfer to the next base station or to switch between sectors without session disconnection. This is called seamless handover as the process is fast and reliable [5]. Therefore, mobility, high QoS, security, and user’s reliability will be based on seamless handover. According to LTE-A features which support the UE’s speed up to 500 km/h, this will reduce the accuracy and efficiency of the wireless system and handover will be more critical [6], [7]. In addition, handover in LTE/LTE-A depends purely on hard handover (HHO) instead of soft handover that is used in Third Generation (3G) network. Using HHO means that the interruption handover time, data loss and buffering will be in User Equipment (UE) plane, and the data forwarding is within distributed controllers in handover instead of being centralized controllers in soft handover [8].
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