Network Mobility Basic Support (NEMO BS) protocol is an extension of Mobile IPv6. It provides collective mobility for a bunch of nodes in vehicular area network. The standard NEMO BS (RFC 3963) protocol suffers from a number of limitations, such as inefficient routing and increased handover latency. Most previous studies attempted to solve such problems have imposed an extra signalling load. Therefore, the mechanism of proposed scheme is based on Fast Hierarchical Mobile IPv6, which enhances Mobile IPv6 by reducing the latency of address configuration and the home- network registration. In this paper, to achieve seamless handover and delivery of real-time traffic in mobile environment, Differentiated Service model is deployed in NEMO network. The QoS management is coupled with mobility management at the IP level. In order to evaluate QoS within Mobility environment, NS-2 has been used. The simulation results demonstrate that the proposed scheme is a valuable solution for promising NEMO applications.
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In this journal article, we have investigated the effect of beaconing on network dwell time using cumulative prob- ability and individual successful beacon reception. This work has proved that the size of the beacon directly affects the individual packet reception probability (i.e. the value of P changes), especially the probability distribution of the first packet P1 and hence affects both single reception probability as well as the cumulative reception probabil- ity. However, the frequency of the beacon only affects the cumulative probability, and hence, this shows that the effect of beacon size and beacon frequency is orthogonal to each other with regard to the network dwell time. In addition, the rate of change of the probability, i.e. (P) is affected by the velocity of the vehicle and the velocity affects both the cumulative probability and the probability of successful reception. Hence, though the size and fre- quency of the beacon have orthogonal effects, the velocity of the vehicle affects both of these parameters. This work therefore significantly enhances our attempt to build a full-blown analytical model that encompasses all layers in an attempt to provide seamless handover.
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Fig. 4 shows how quad channels are used for normal communication and handover. RSUs can be well planned because they are normally deployed along roads. Two RSUs or one RSU with two channels can be in charge of one serving area, a cell. Cells are located to have overlapping area for seamless handover operation. As we can see from Fig. 4, the car in the middle is the location where it can receive all signals from RSU#1,
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.
checks whether the current network is still able to provide the required QoS. Given the running application class of service, it uses QoS information namely, bandwidth, load, delay, jitter and BER, as input parameters. If the current network is no longer able to offer an acceptable QoS to the running application, the FLC initiates an alternative handover. For instance, the input parameters depending on their availability and on the requirements of the running application are fed into a fuzzifier where they are transformed into fuzzy sets. A fuzzy set may have different membership degrees that are obtained by mapping the real values of a given variable into a membership function. For example the membership function of the bandwidth input parameter has three fuzzy sets which are low, medium and high as shown in table 1 . The fuzzy sets are then fed into an inference engine, where a set of fuzzy IF-THEN rules are applied to indicate whether a handover is required. (e.g. if we consider a steaming application: IF Bandwidth = high AND Jitter = low AND Ber = High AND Delay = medium THEN Handover= NO) as shown in fallowing table 2 . Finally, the overall obtained fuzzy sets are defuzzified to make a final precise decision (VHO is required or not). If a handover is required the network selection process is activated.
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In this paper, we briefly reviewed Chuang et al.’s se- curity handover for PMIPv6 and demonstrated that it does not satisfy the expected security attributes for a secure handover in PMIPv6. We then showed that it is vulnerable to the critical attacks, such as stolen smartcard and off-line dictionary attack, replay attack and impersonation attack. In addition, we pointed out that the identity of MNs and the session key between MN and MAG can be disclosed by an insider attacker in Chuang et al.’s mechanism; resultantly, anonymity and confidentiality between MNs and MAG will be completely broken. Therefore, in spite of the claims of Chuang et al., we showed that their scheme is not suitable to achieve a secure handover for PMIPv6. Moreover, an improved authentication scheme was proposed to overcome the security problems of Ch- uang et al.’s scheme. The security analysis showed that the improved scheme could satisfy required se- curity attributes.
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WIMAX (Worldwide Interoperability for Microwave Access) is a wireless communication standard designed to provide 30 to 40 megabit-per- second data rates.Extensible Authentication protocol (EAP) is an authentication framework widely used in WLANs. Authentication mechanisms built on EAP are called EAP methods. The requirements for EAP methods in WLAN authentication have been defined in RFC 4017 to achieve user efficiency and robust security, lightweight computation and forward secrecy. In modified EAP-AKA protocol, handover happens in the HLR database.
Multiple types of wireless remote access networks have been executed in latest years and have become inseparable components of the Internet. TCP was originally designed for wired stationery hosts, the most broadly utilized transportation decorum on the Internet, yet it faces serious difficulties when users move around in various networks and hence handoff happens intermittently. Most Internet traffic uses TCP for dependable end-to-end packet delivery. Be that as it may, TCP sees packet loss as the consequence of network clog, making it unfit for mobile wireless networks where sporadic and temporary packet losses are usually caused by shadowing, fading, hand-off, and other radio impacts. The issue of end-to- end connectivity and reliability management for TCP turns out to be more serious during the vertical hand-off between distinct wireless systems.In the second commitment of the proposition, we are proposing a fresh TCP version, called ISN- TCP, which handles typical TCP issues, for example, packet reordering, spurious timeouts, packet losses and under / over use of network for TCP associations during transfer. It presents an extra cross layer between the transport and the network layer at both the mobile node and the respective node (the other end of the TCP stream), which is utilized to activate TCP for associated actions to be transferred. ISN-TCP needs freezing to keep link consistency during handover, but it introduces additional network delay. Freezing delay for the UMTS network is additionally not tolerable.Furthermore, ISN- TCP is extended and an enhanced TCP variant ISN-TCP- PLUS is proposed. For link maintenance used by ISN-TCP, this system does not involve freezing. ISN-TCP-PLUS considerably increases TCP efficiency during handover by filtering out duplicate acknowledgments (dAcks) and calculating the fresh flying network's retransmission timer (RTT), the suggested system utilizes a congestion window approximation (CWnd) calculation comparable to the methods used for equation-based TCP congestion control. ISN-TCP- PLUS performance was evaluated using simulation outcomes and it demonstrates that the suggested version works much better than standard wireless TCP (WP-TCP) and ISN-TCP.
This leads to increase in access delay, which has the impact on the net throughput. Treating channel as busy avoids such situations and the concept of circularity is implemented for the above-mentioned reasons. With optimum value of circularity for low and high density of nodes in a network scenario lesser number of DATA packets is refraining from transmission thereby making the system coverage a steady state. An integer value is given to circularity and the value of counter is made to vary from 1 to C values as specified by the user. Initially Deferring process of transmission opportunities is checked and then as we need to treat the channel as busy for particular DATA packets based on circularity counter % circularity = 0 is checked. If the condition is true then that particular DATA packet refrained from the transmission by treating as channel busy else that DATA packet is send. After sending the DATA packet a further check is done to see if the DATA has been send successfully without collision. If no collision has taken place and ACK arrived for that particular node then transmission is successful, else the process again resumes from the beginning.In order to explain the effects of the principle of circularity on the handover request mechanism, we carry out a flow analysis as shown in Fig. 5 that depicts the events that occur during the mechanism. Network topology acquisition process consists of scanning neighboring BSs and association. The former refers to obtain DCD / UCD and DL-MAP / UL-MAP information of the neighboring BSs. The latter indicates to synchronize and associate with the neighboring BSs.
In recent years, Mobile and Wireless Communication is popular, many people uses the mobile communication services, Such as web-browsing, all multimedia applications, video conferencing anytime, anywhere. Mobile ipv6 (MIPv6) host-based mobility management protocol was developed by IETF NETLMM Working Group, for mobile nodes continuous service is maintained when it migrate with different foreign network. This MIPv6 does not suitable for real time applications because it has long handover delay during the handover process. To overcome this MIPv6 problems the IETF NETLMM developers introduced a network-based localized mobility management protocol called proxy mobile IPv6 (PMIPv6) has the characteristics namely are:1)MNs allowed for access network in same ipv6 2)in wireless link, it avoids the tunneling overhead 3)signaling overhead is reduced. PMIPv6 compared to MIPv6 it reduces the handover latency, but it still suffers from packet loss problem, inefficient authentication procedure and easily destroyed by the security threads.
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The earliest works on providing information exchange capability are based on seamless handover among Radio Access Networks (RANs) provided by interworking. Mobile data offloading is an instance of this approach, where complementary network technologies such as wireless LAN (WiFi) are used for delivering data originally targeted for cellular mobile networks . Offloading reduces the amount of data being carried by the mobile system, freeing radio resources for other users. Such approach is also used to address poor indoor radio coverage. Since each of the access technologies have been designed based on different mindsets, interworking among them requires sophisticated protocols and imposes significant signalling overhead, thus might further increase the corresponding end-to-end latency. Interworking techniques result in a complicated mesh of access technologies  thus compromise efficiency and horizontal scalability which is crucial in versatile development of M-CPSs .
has to move. Seamlessness in this paper is defined as follows: the current session, QoS and Service Level Agreements (SLA) must be maintained during and after handover. In other words, a seamless handover is a handover that is seamless to the user. Obviously this also depends on the kind of service the user is requiring. With real-time applications like videoconferencing or streaming media, the user will probably notice a decrease of the connection. On the other hand, while browsing a website or transferring a file, the user does not have to notice anything of the handover process. The latency and packet loss are the two crucial factors for seamless handover. These two factors have to be as small as possible to make the handover seamless [TTL99].
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is maintained by MS and BS. Diversity set is a list of the BS’s, which are involved in the handover procedure as shown in Figure There is always one BS in the diversity set that is defined as an anchor BS. The HHO is a special case of MDHO when there is only one BS in the diversity set. There might be also BSs that can be reached with the MS, but the signal is too weak for real traffic. These BSs are kept outside the diversity set and named as neighbour BSs. Naturally, while moving towards a neighbour BS, at some moment the signal is strong enough and the BS can be included in the diversity set, or if the signal strength is too weak the BS will be removed off form the diversity set.
In this paper we have proposed a HANDOVER MANAGER concept to modify the handover technique of SeaHO-LEO satellite handover management where we have shown that our proposed method is more effective than the existing one by also showing theoretically as well as by simulation that it reduces handover latency, data loss, scanning time, cost and forced call termination probability. Our proposed handover method is also better as compare to the time delay and the binding updates as it itself compares the signal strength and chooses the next ip where the packets are to be forwarded it has reduced the extra binding updates and as the search is done when the previous data is being forwarded it also reduces the searching time after the first data sent. So comparing all the aspects our work is practically applicable to any areas. In future we will find how to improve the efficiency of HM. Also we have to find a specific algorithm under which it will select the appropriate next IP in the network where the data is to be sending next. We can also used different algorithm according to the signal strength of the MNs. As the scanning time is reduced so we must search for appropriate threshold level under which the handover procedures will be started.
In present-days, different wireless networks like as WLANs, roadside-to-vehicle communication systems and telecommunication systems have become widely available and interconnected. Wireless access services are offered through interconnected mobile telecommunication networks. Wireless telecommunications refers to the transfer of information between two or more points that are not connected physically. It circumscribes different types of mobile and portable applications, cellular telephones, personal digital assistants (PDAs), and wireless networking. In wireless telecommunications, the term handoff or handover refers to the process of transferring an ongoing call or data session from one channel connected to the core network to another through some Access Points. In satellite communications it is the process of transferring satellite control responsibility from one earth station to another without loss or interruption of service. To provide seamless access services for mobile users (e.g., PDA, laptop computer, smart phone and vehicle) without being limited by the geographical coverage of each access point, authentication process during handover have been implemented. It is important to have an efficient handover protocol when a mobile user travels from one area of coverage or cell to another cell within call duration the call should be transferred to the new cell’s base station. Alternatively, the call will be dropped because the link with the current base station becomes too weak as the mobile recedes.
In the second approach, Neumann et al. (2009) defined a Session Mobility Anchor (SMA), Virtual Mobility Anchor (VMA) and a Steady Anchor Point in order to support seamless mobility for a MN that roamed between different PMIPv6 domains. Although Neumann’s proposal offers inter-domain mobility support to MN, there was a problem. Under Neumann’s proposal, the LMA played the role of both home LMA (HLMA) and the new LMA (NLMA). Consequently, LMA had to keep a Binding Cash Entry (BCE) for two kinds of MN. The ﬁrst MN is the one that registered itself in this domain. As MN’s HLMA, LMA keeps the BCE for MN no matter what domain the MN resided. In addition, LMA also keeps the BCE for the MN that was visiting its domain. Under Neumann’s proposal, the number of BCEs increased. If there are many MN visiting the domain, the number of BCEs will become a burden for LMA and will limit the serving range of LMA. Jee-Hyeon et al., (2008) on the other hand, proposed a roaming mechanism to provide seamless and transparent inter-domain mobility between PMIPv6 domains. Yet, it could not support seamless service continuity during the inter-domain handover because of the long handover latency.
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The electronic copy is updated when time allows, by whoever is able to; on a couple of occasions, it was one of the student nurses who undertook this task. Updating the handover sheet involves asking questions of the nurses and health care assistant (HCA), but may also involve checking the medical record or nursing notes for a patient, to determine if a certain task has been completed (e.g. an ultrasound scan) or to find out the results of an investigation (e.g. an MRSA swab). Sometimes a change is made just to one patient’s details, motivated by a conversation with a colleague. For example, on one occasion, the student nurse updated details of a patient’s nutrition needs following a conversation with the dietician.
The fast growth of mobile wireless communications over the most recent years has generated many wireless networks  . These networks will be incorporated to identify network user access in all-IP design. Different wireless technologies such as WLAN, Wi-Fi and UMTS are interconnected to offer internet access to mobile users anywhere anytime. In order to meet seamless connectivity, two protocols have been proposed. Host based mobility management and Network based mobility management protocols, in which MIPv6, HMIPv6 and FMIPv6 are host based protocols where PMIPv6 is a network based protocol .
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Handovers occur in a multitude of work and other settings o n an everyday basis but are often not recognized as such. For example, a handover occurs as one helpdesk operative passes on information about outstanding problems requiring resolu- tion to a colleague starting his or her shift. The ‘work’ of han- dover is the essence of collaborative work: it is fundamentally about communication of information and coordination of work activities. In the particular case of shift change, the goal of handover according to Lardner  is “the accurate, reliable communication of task-relevant information across shift changes, thereby ensuring continuity of safe and effective working.”. Where medical staff work in shifts, as is often the case today, handovers should take place at each shift change and effective handovers make a crucial contribution to the continuity and safety of patient care . In essence, incoming staff need to construct a mental model of the state of the sys- tem that allows them to assume effective responsibility for it. Handover and the various strategies employed in handover facilitate the construction of this model. In a medical setting, this is achieved through the communication of information such as the current status and treatment of patients, tasks that need to be done, cases that require urgent review and events that are likely to occur during the forthcoming shift.
The frequency-domain supposed to be used for Wireless ATM, situated in the Ghz range, will imply the exis- tence of small size cells, to cope also with the increased demands regarding system capacity. This will lead, in conjunction with a higher terminal mobility, to a very large number of handover of virtual connections. Fur- thermore, smaller cells have tighter delay constraints, as the overlapping distances of the cells are smaller. The more complex handover procedure has higher requirements regarding radio resource management functions for the air interface paired with network signaling and control functions for handover control, Quality of Service (QoS) management and rerouting of the connection to the new network access point. Exactly these rerouting procedures are the subject of this paper. A new operational concept based on Virtual Paths is introduced and the principles of handover hysteresis are analyzed using a discrete Markov chain model.
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