Abstract: In this paper, a hybrid network combining visible light communication (VLC) with a radio frequency (RF) wireless local area network (WLAN) is considered. In indoor scenarios, a light fidelity (Li-Fi) access point (AP) can provide very high throughput and satisfy any illumination demands while wireless fidelity (Wi-Fi) offers basic coverage. Such a hybrid network with both fixed and mobile users has the problem of variable user locations, and thus large fluctuations in spatially distributed traffic demand. Generally, a handover occurs in such a method when a user is allocated by the central controller unit to a different AP which is better placed to serve the user. In order to be representative of real deployments, this paper studies the problem of load balancing of a dynamic system where we consider the signalling overhead for handover. We propose a scheme for dynamic allocation of resources to users, where the utility function takes into account both throughput and fairness. The simulation results show that there is a trade off between the aggregate throughput and user fairness when handover overhead is considered. The proposed dynamic scheme always outperforms the considered benchmarks in terms of fairness and can achieve better aggregate throughput in the case of low user density.

Abstract: The tremendous growth in wireless Internet use is showing no signs of slowing down. Existing cellular networks are starting to be insufficient in meeting this demand, in part due to their inflexible and expensive equipment as well as complex and non-agile control plane. Software-defined networking is emerging as a natural solution for next generation cellular networks as it enables further network function virtualization opportunities and network programmability. In this article, we advocate an all-SDN network architecture with hierarchical network control capabilities to allow for different grades of performance and complexity in offering core network services and provide service differentiation for 5G systems. As a showcase of this architecture, we introduce a unified approach to mobility, handoff, and routing management and offer connectivity management as a service (CMaaS). CMaaS is offered to application developers and over-the-top service providers to provide a range of options in protecting their flows against subscriber mobility at different price levels.

Abstract: The goal of 3GPP Long Term Evolution/System Architecture Evolution (LTE/SAE) is to move mobile cellular wireless technology into its fourth generation. One of the unique challenges of fourth-generation technology is how to close a security gap through which a single compromised or malicious device can jeopardize an entire mobile network because of the open nature of these networks. To meet this challenge, handover key management in the 3GPP LTE/SAE has been designed to revoke any compromised key(s) and as a consequence isolate corrupted network devices. This paper, however, identifies and details the vulnerability of this handover key management to what are called desynchronization attacks; such attacks jeopardize secure communication between users and mobile networks. Although periodic updates of the root key are an integral part of handover key management, our work here emphasizes how essential these updates are to minimizing the effect of desynchronization attacks that, as of now, cannot be effectively prevented. Our main contribution, however, is to explore how network operators can determine for themselves an optimal interval for updates that minimizes the signaling load they impose while protecting the security of user traffic. Our analytical and simulation studies demonstrate the impact of the key update interval on such performance criteria as network topology and user mobility.

Abstract: Enabling the spectrum handoff for multimedia applications in cognitive radio networks (CRNs) is challenging, due to multiple interruptions from primary users (PUs), contentions among secondary users (SUs), and heterogenous Quality-of-Experience (QoE) requirements. In this paper, we propose a learning-based and QoE-driven spectrum handoff scheme to maximize the multimedia users' satisfaction. We develop a mixed preemptive and non-preemptive resume priority (PRP/NPRP) M/G/1 queueing model for modeling the spectrum usage behavior for prioritized multimedia applications. Then, a mathematical framework is formulated to analyze the performance of SUs. We apply the reinforcement learning to our QoE-driven spectrum handoff scheme to maximize the quality of video transmissions in the long term. The proposed learning scheme is asymptotically optimal, model-free, and can adaptively perform spectrum handoff for the changing channel conditions and traffic load. Experimental results demonstrate the effectiveness of the proposed queueing model for prioritized traffic in CRNs, and show that the proposed learning-based QoE-driven spectrum handoff scheme improves quality of video transmissions.

Abstract: Mobile Internet traffic is growing steeply, mainly due to the deployment of new broadband wireless technologies and the ever increasing connectivity demand coming from new services being available to mobile users. Current mobile network architectures rely on centralized mobility protocols which intrinsically pose enormous burdens on the central anchors, both in terms of connectivity needs and user mobility management. In order to face these issues, a new paradigm, called Distributed Mobility Management, is being explored, based on flattening the network architecture by deploying multiple mobility anchors at the edge of the network. In this article we conduct an analytic and experimental evaluation of a network-based IP distributed mobility management solution that leverages Proxy Mobile IPv6 protocol operations. We develop an analytic model of the signaling and packet delivery costs, as well as the handover latency of both Proxy Mobile IPv6 and our distributed solution. We have also implemented a Linux-based prototype of our proposal, which has been used to experimentally assess the handover latency in a real IEEE 802.11 scenario. Finally, we use the results obtained from the analytic and experimental performance to evaluate the benefits that could be achieved by deploying a distributed mobility management solution.

Abstract: In this article we present an approach to object tracking handover in a network of smart cameras, based on self-interested autonomous agents, which exchange responsibility for tracking objects in a market mechanism, in order to maximise their own utility. A novel ant-colony inspired mechanism is used to learn the vision graph, that is, the camera neighbourhood relations, during runtime, which may then be used to optimise communication between cameras. The key benefits of our completely decentralised approach are on the one hand generating the vision graph online, enabling efficient deployment in unknown scenarios and camera network topologies, and on the other hand relying only on local information, increasing the robustness of the system. Since our market-based approach does not rely on a priori topology information, the need for any multicamera calibration can be avoided. We have evaluated our approach both in a simulation study and in network of real distributed smart cameras.

Abstract: In this paper we discuss the evolution of mobility management mechanisms in mobile networks. We emphasize problems with current mobility management approaches in case of very high dense and heterogeneous networks. The main contribution of the paper is a discussion on how the Software-Defined Networking (SDN) technology can be applied in mobile networks in order to efficiently handle mobility in the context of future mobile networks (5G) or evolved LTE. The discussion addresses the most important problems related to mobility management like preservation of session continuity and scalability of handovers in very dense mobile networks. Three variants of SDN usage in order to handle mobility are described and compared in this paper. The most advanced of these variants shows how mobility management mechanisms can be easily integrated with autonomie management mechanisms, providing much more advanced functionality than is provided now by the SON approach. Such mechanisms increase robustness of the handover and optimize the usage of wireless and wired mobile network resources.

Abstract: The popularity of smartphones and smartphone applications means that data is the dominant traffic type in current mobile networks. In this paper we present our work on a systematic investigation into facets of the LTE/EPC architecture that impact the performance of TCP as the predominant transport layer protocol used by applications on mobile networks. We found that (1) load increase in a cell causes dramatic bandwidth reduction on UEs and significantly degrades TCP performance, (2) seamless handover causes significant TCP losses while lossless handover increases TCP segments' delay.

Abstract: The present invention discloses a cellular communication system, an inter-cell handover method for a UE, and a macro base station. The cellular communication system includes a macro base station and at least one micro base station within coverage of the macro base station. The macro base station is configured to: establish a control channel for a UE served by the micro base station; perform an access management operation for the UE served by the micro base station within the coverage of the macro base station; and receive a handover request of the UE and hand over the UE to another micro base station within the coverage of the macro base station. The micro base station is configured to establish a data channel for the accessed UE and perform data transmission with the UE. With the present invention, the control plane of the user served by the micro base station can be separated from the data plane of the user, so that the resources of the micro base station can be better used for data communication. Hence, the negative impacts on the system which are caused by the coexistence of macro cells and micro cells in the networking can be reduced.

Abstract: Several solutions have been proposed for improving the Quality of Service (QoS) in wireless cellular networks, such as Call Admission Control (CAC) and handover strategies. However, none of them considers the usage of different interfaces for different conditions. In this work, apart from using only Base Stations (BSs) as an important device of cellular networks, we propose a multi-interface approach in order to avoid BS overloads and improve the QoS of wireless communications. We propose a system, where each node is equipped with two interfaces: the traditional cellular network interface and Mobile Ad hoc Networks (MANET) interface. The main difficulty for this system is how to choose the right interface in order to guarantee a minimal usage of network resources and at the same time keeping the communication performance in a satisfactory level. For this purpose, in this paper we propose a Fuzzy-Based Multi-Interface System (FBMIS), where each node is able to switch from cellular to Ad hoc and vice versa. We consider three input parameters and one output parameter. From the simulation results, our system shows a good performance.

Abstract: Optimizing the balance between different handover parameters for network selection is one of the challenging tasks for seamless communication in heterogeneous networks. Traditional approaches for network selection are mostly based on the Receive Signal Strength (RSS) from the Point of Attachment (PoA) of a network. Most of these schemes are suffered from high handover delay, false handover indications, and inappropriate network selection for handover. To address these problems, we present an optimized network selection scheme based on the speed of a mobile node. A mechanism based on two different thresholds on the speed of a Mobile Node (MN) is integrated in the proposed scheme. If the speed of an MN is greater than any of the threshold, the MN performs handover to a particular network. We employ Grey Relational Analysis (GRA) in the proposed scheme to select the best PoA of the selected network. Similarly, to deal with false handover indications, we proposed an optimized handover triggering technique. We compare our proposed scheme with existing schemes in context of energy consumption for scanning, frequent and failed handovers, packet loss ratio, and handover delay. The proposed scheme shows superior performance and it outperforms existing schemes used for similar purpose. Moreover, simulation results show the accuracy and performance of the proposed scheme.

Abstract: The invention relates to an improved handover procedure for a mobile terminal. Under control of the target base station, the mobile terminal is to perform a handoff to a target base station, wherein it is to be configured for communication with the target base station via a target radio cell comprising a downlink carrier and an uplink carrier. The mobile terminal receives a handoff command message for the handoff to the target base station including a handoff execution condition as trigger for executing handoff to the target base station. Then, the mobile terminal determines, based on the received handoff execution condition, whether or not the mobile terminal is to trigger execution of the handoff to the target base station. In case the mobile terminal determines that it is to trigger execution of the handoff to the target base station, the mobile terminal executes the handoff to the target base station.

Abstract: Background and objectives Handover and communication failures are a recognised threat to patient safety. Handover in emergency care is a particularly vulnerable activity owing to the high-risk context and overcrowded conditions. In addition, handover frequently takes place across the boundaries of organisations that have different goals and motivations, and that exhibit different local cultures and behaviours. This study aimed to explore the risks associated with handover failure in the emergency care pathway, and to identify organisational factors that impact on the quality of handover. Methods Three NHS emergency care pathways were studied. The study used a qualitative design. Risks were explored in nine focus group-based risk analysis sessions using failure mode and effects analysis (FMEA). A total of 270 handovers between ambulance and the emergency department (ED), and the ED and acute medicine were audio-recorded, transcribed and analysed using conversation analysis. Organisational factors were explored through thematic analysis of semistructured interviews with a purposive convenience sample of 39 staff across the three pathways. Results Handover can serve different functions, such as management of capacity and demand, transfer of responsibility and delegation of aspects of care, communication of different types of information, and the prioritisation of patients or highlighting of specific aspects of their care. Many of the identified handover failure modes are linked causally to capacity and patient flow issues. Across the sites, resuscitation handovers lasted between 38 seconds and 4 minutes, handovers for patients with major injuries lasted between 30 seconds and 6 minutes, and referrals to acute medicine lasted between 1 minute and approximately 7 minutes. Only between 1.5% and 5% of handover communication content related to the communication of social issues. Interview participants described a range of tensions inherent in handover that require dynamic trade-offs. These are related to documentation, the verbal communication, the transfer of responsibility and the different goals and motivations that a handover may serve. Participants also described the management of flow of patients and of information across organisational boundaries as one of the most important factors influencing the quality of handover. This includes management of patient flows in and out of departments, the influence of time-related performance targets, and the collaboration between organisations and departments. The two themes are related. The management of patient flow influences the way trade-offs around inner tensions are made, and, on the other hand, one of the goals of handover is ensuring adequate management of patient flows. Conclusions The research findings suggest that handover should be understood as a sociotechnical activity embedded in clinical and organisational practice. Capacity, patient flow and national targets, and the quality of handover are intricately related, and should be addressed together. Improvement efforts should focus on providing practitioners with flexibility to make trade-offs in order to resolve tensions inherent in handover. Collaborative holistic system analysis and greater cultural awareness and collaboration across organisations should be pursued. Funding The National Institute for Health Research Health Services and Delivery Research programme.

Abstract: Handover is the mechanism that transfers information from one terminal to another as a user moves through the coverage area of a cellular system. Here the Network selection is the handover decision process between various network environments. This handover decision will be either mobile or network initiated. In 2G GSM handover decision method especially concentrates on Received frequency signals (RFS). Upcoming technologies (3G/4G) the number of available networks increase the selection process should evaluate additional factors such as cost, network services, network terminology, system conditions, user and operators performances and needed energy to work in an exceedingly network. In Future networks (IEEE or 4G standards) offer facilities such as network routes, handover routing messages, network and client reports, message exchange with handover triggers and handover negotiation. In this study we have a tendency to discuss the utilization of a cost function to perform associate a network selection exploitation information provided by these standards, such as network coverage or network properties. The efficient function provides flexibility to balance the various factors within the network selection, and our research is focused on rising each seamlessness and energy efficiency of the devices in handovers. We have a tendency to evaluate our approach supported usage scenarios over 2G, 3G and 4G GSM networks. Our results show the optimal networks and handovers were generate appropriate times to increase overall network connectivity as compared to traditional network schemes, at the same time optimizing energy consumption of network devices.

Abstract: A method and apparatus for performing a handover procedure in a wireless communication system is provided. A master eNodeB (MeNB), in dual connectivity, performs a handover decision from a source secondary eNB (SeNB) to a target SeNB, and transmits an offloading request message, which includes contexts of E-UTRAN radio access bearers (E-RABs) to be offloaded and an offloading indication, to the target SeNB. The MeNB receives an offloading request acknowledge message, which includes identifiers (IDs) of E-RABs accepted by the target SeNB, as a response to the offloading request message from the target SeNB, and transmits an offloading mobility indication to a user equipment (UE).

Abstract: Some demonstrative embodiments include devices, systems and/or methods of handover of a wireless beamformed link. For example, an apparatus may include a wireless communication unit to communicate between a wireless communication node and a mobile device via a beamformed link between the wireless communication node and the mobile device, the wireless communication unit is to determine a handover candidate for handing over the mobile device, based on at least one beamforming parameter of the beamformed link.

Abstract: Recently, the performance of mobile data networks has been evaluated from many aspects, e.g., TCP/IP protocols, comparison with WiFi or even satellite communication, under different movements within a metropolis area. Nevertheless, the result is still unknown in high-speed mobility scenarios and in a scale that crosses different metropolis and geographic areas. To fill in this blank, we carry out a comprehensive measurement study on the performance of mobile data networks under high-speed mobility, i.e., 300 km/h or above. Such speed is the current de facto standard of the China Railway High speed (CRH) network, the largest commercial high-speed railway network in the world so far. We first present an overview on the TCP performance over LTE networks. We observe that decent throughput may exist under high-speed mobility. However, comparing to the stationary and driving (100 km/h) scenarios, the throughput and RTT not only are worse, but also have a large variance. We then take an in-depth investigation into two key factors affecting the performance, i.e., The wireless channel and handoff. We believe our study on these factors is useful not only for TCP, but also for other upper-layer protocols.

Abstract: Communication failures in the pre-hospital/hospital interface have been identified as a major preventable cause of patient harm. This interface has not adequately been studied in Italy. In this study, we: (1) evaluated the communication of pre-hospital and hospital providers during handover through the analysis of simulation sessions; (2) identified the critical information that should be routinely communicated during handover with a survey administered to emergency triage nurses; (3) measured communication within this interface through the adaptation of an existing tool from a multidisciplinary focus group; (4) validated the adapted tool with the inter-rater agreement of physicians who reviewed video recordings from multidisciplinary simulations sessions; and (5) developed a handover training for pre-hospital providers and evaluated the communication improvement between pre- and post-training. In our simulations we found an absence of standardization of the handover communication process, marked variability in information communicated, and a lack of formal transfer of responsibility of patient care. We adapted existing handover communication tools for local use and developed a checklist for the evaluation of handover communication that had good inter-rater reliability. Lectures coupled with high-fidelity simulation exercises on handover did result in a statistically significant improvement in handover communication.

Abstract: A Machine-to-machine (M2M) terminal ( 11 ) comprises a radio communication unit ( 111 ) and a controller ( 112 ). The radio communication unit ( 111 ) is configured to communicate with a base station ( 13 ). The controller ( 112 ) is configured to change at least one of a cell selection operation, a cell reselection operation, and a handover operation according to whether a specific coverage enhancement processing is required or according to whether the specific coverage enhancement processing is supported by at least one of a cell ( 13 ) in which the M2M terminal ( 11 ) camps on and a neighbouring cell ( 14 ) of the cell ( 13 ) which the M2M terminal ( 11 ) camps on. It is thus possible to provide an improved technique for allowing the M2M terminal that is supporting a special coverage enhancement processing for M2M terminals to camp on an appropriate cell.

Abstract: High-speed rail systems are becoming increasingly popular among long-distance travelers. With the explosive growth in the number of mobile devices, the provision of high-quality telecommunication and Internet access services on high-speed trains is now a pressing problem. Network mobility (NEMO) has been proposed to enable a large number of mobile devices on a vehicle to access the Internet; however, several issues must be solved before it can be put into practice, e.g., frequent handovers, long handover latency, and poor quality of service. To resolve these problems, we propose an LTE femtocell-based network mobility scheme that uses multiple egress network interfaces to support seamless handover for high-speed rail systems called MEN-NEMO. The results of simulations show that the proposed MEN-NEMO scheme reduces the handover latency and transmission overhead of handover signaling substantially.

Abstract: A method for a serving base station to determine a handover time in a communication system is provided. The method includes determining whether to set up dual connectivity (DC) with respect to a terminal with a target base station that transmits the beacon if it is recognized that the terminal receives a beacon including a plurality of pieces of service coverage area information, and determining whether to execute a handover to the target base station based on a measurement report of the terminal, which is received after the DC is set up if the DC is set up.

Abstract: Due to frequent handovers in broadband wireless communications for the high-speed railway system, communication interruption caused by handover failures could seriously degrade the users' experience. Aiming at reducing the handover failure probability, this paper proposes an effective handover scheme based on the distributed antenna system (DAS) and mobile-relay-aided two-link architecture, i.e., ground-relay link and relay-onboard link, where the mobile relay is mounted on top of the moving train. In addition, an antenna selection scheme with optimal power allocation is proposed to improve handover performance. Our simulation and analysis results show that the DAS structure with macrodiversity can reduce the unnecessary handovers, as well as reduce the handover failure and link outage probabilities compared with the traditional cell without DAS. In addition, the proposed DAS with an antenna selection scheme performs better in terms of handover failure and link outage probabilities than that of DAS with a equal power allocation (EPA) scheme.

Abstract: The deployment of small cells in Heterogeneous Networks (HetNets) raises new challenges in relation to the Handover process and the mobility management. In fact, the performance of a mobile user within a HetNet scenario highly depends on the setting of the handover parameters in relation to other context parameters, such as the channel conditions and the user position and speed. In this paper, we derive a general theoretical analysis to characterize the user performance as a function of the mobility model, the power profile received from the neighboring cells, and the handover parameters. More in detail, we propose a Markov-based framework to model the user state during the handover process and, based on such model, we derive an optimal context-dependent handover criterion. The mathematical model is validated by means of simulations, showing that our strategy outperforms conventional handover optimization techniques by exploiting the context information.

Abstract: In a heterogeneous network, enhanced handover and reestablishment procedures are proposed within a local area network. The enhanced procedures are more efficient, e.g., with less signaling and less data interruption than the legacy mobility mechanism. In a local area network, a UE is served by an anchor eNB in macro cell layer and one or more drift eNBs in small cell layer. When the UE moves within the local area network, the UE anchor does not need to change. For cell change within the same anchor, the enhanced procedures reduces signaling overhead and data interruption time.

Abstract: Methods, systems, and devices are described for managing wireless communications. In the methods, systems, and devices, historical information associated with mobility patterns of a mobile device may be accessed. A mobility parameter may be modified for at least one neighboring cell of a set of neighboring cells for measurement by the mobile device. The mobility parameter may be modified based on the historical information associated with the mobility patterns of the mobile device.

Abstract: Self-Organizing Networks (SONs) aim to raise the level of automated management in cellular technologies. In this field, Load Balancing (LB) and Handover Optimization (HOO) are two important functions to improve network performance. As these two functions can adjust the same parameters, a conflict may happen if LB and HOO tune them at the same time. In this paper, the conflict resolution of both functions in Long-Term Evolution (LTE) networks is addressed. Results show that the proposed coordination effectively provides better performance in those situations in which the adjusted mobility parameter is close to its saturation.

Abstract: Embodiments of the present invention disclose a channel measurement method, including: receiving reference signal resource configuration information of a target cell, where a quantity of pieces of the reference signal resource configuration information of the target cell is greater than 1; performing channel measurement on the target cell according to the reference signal resource configuration information; and reporting a channel measurement result of the target cell to a serving cell. Accordingly, the present invention further discloses a cell handover method, a related apparatus, and a system. According to the present invention, a problem in the prior art that channel quality of beams, having different downtilts, of a target cell cannot be obtained is resolved, and a channel measurement result of a target cell for beams having different downtilts is reported to a serving cell to perform cell handover, which greatly optimizes flexibility of cell handover, improves resource utilization or spectral efficiency, improves a system capacity, and better implements dynamic changes in coverage of cells.

Abstract: A method at a user equipment for handover from a serving cell to a target cell, the method sending a measurement report to the serving cell; and transmitting a reconfiguration complete message to the target cell; wherein the measurement report includes downlink timing measurements for the target cell. Further, a method at a source network element for handover of a user equipment from the source network element to a target network element, the method receiving a measurement report from the user equipment; sending a handover request to the target network element; receiving a handover request acknowledgement from the target network element, the handover request acknowledgement including a reconfiguration message and at least one downlink subframe in which an uplink grant is expected at the target network element for the user equipment; and forwarding the reconfiguration message and at least one downlink subframe to the user equipment.