Showing papers on "Handover published in 2011"

Data split between multiple sites

Abstract: Splitting data in a wireless communications network. Data may be split to use multiple base stations for transmission to user equipment in order to improve the bandwith if a UE is on a cell edge, or may be split by user equipment for transmission to multiple base stations in order to improve handover. Data splitting may be performed at the Packet Data Convergence Protocol layer, at the Radio Link Control layer, or at the Media Access Control layer on user equipment or on a base station. Data may instead be split in a network node, such as in a serving gateway, in order to reduce X2 interface load or delay carrier aggregation.

Methods and apparatus for facilitating robust forward handover in long term evolution (lte) communication systems

Abstract: Method and apparatus for facilitating inter-cell connections, such as during a forward handover or radio link failure (RLF), are disclosed. A user terminal such as a UE may store identity information associated with a source cell, and use this information in accessing target or other cells subsequent to radio link failure so as to facilitate access to context information of the user terminal. A base station may be configured to improve handover performance by associating context information with a newly assigned terminal identity. Handover performance may be enhanced by facilitating connection processing in the event of inability to retrieve user terminal context from a source cell.

Method and apparatus for performing handover

Abstract: A method and an apparatus perform a handover using the X2 interface. A source base station transmits a handover requirement message, for a handover to a destination base station of a user equipment (UE), to a source base station gateway. When a handover command message indicating performing of the handover to a destination base station of the UE is received from the source base station gateway, the handover command message is transmitted to the UE. When a UE context release command message is received from the source base station gateway, a context of the UE is released. And a UE context release completion message, representing that the context of the UE is released, is transmitted to the source base station gateway. The handover requirement message includes a Next-hop Chaining Counter (NCC) and an encryption key for a communication between the UE and the destination base station.

Optimized Home Evolved NodeB (eNB) Handover in an LTE Network

Abstract: A method to provide an optimized intra-HeNB GW handover operation that reduces signaling to and from an LTE MME (Mobility Management Entity) function of the 3GPP E-UTRAN Evolved Packet core (EPC). In operation, an HeNB Gateway (GW) intercepts handover requests from a source HeNB to a target HeNB and processes these requests locally, with minimal interaction from the MME. Where possible, messaging to and from the MME is minimized and/or reduced, irrespective of the 3GPP requirement that the GW relay all handover-related messages to the MME.

Method, System, and Device for Network Handoff

Abstract: A method, a system, and a device for network handoff is disclosed. A first evolved Access Network (eAN) sends a session transfer request to the target eAN that corresponds to the network handoff request. The first eAN receives a session transfer response from the target eAN. The first eAN sends a Traffic Channel Assignment (TCA) message to a User Equipment (UE) based on the session transfer response, so that the UE can switch from a Long Term Evolution (LTE) network to an evolved High Rate Packet Data (eHRPD) network based on the TCA message.

Mobile communication method

Abstract: In a mobile communication method according to the present invention includes the steps of: transmitting, from a handover source radio base station to a swithcing center, a handover request including an NCC, a PCI and a K eNB *; changing, at the swithcing center, the NCC, changing, at the swithcing center, the K eNB * on the basis of the PCI, and transmitting, from the swithcing center to the handover target radio base station, the handover request including the changed NCC and the changed K eNB *; generating, at the handover target radio base station, a first key on the basis of the K eNB *; and generating, at the mobile station, the first key on the basis of the NCC and the PCI included in a handover command.

Handoff management in a multi-layer wireless network

Abstract: One or more short-range base stations in a network environment provide a substantially smaller coverage area than a long-range base station. The coverage area provided by each of the short-range base stations fully resides within or at least partially overlaps with the coverage provided by the long-range base station. Handoffs from the long-range base station to a respective short range base station, and vise versa, can be conditional on any number of one or more factors such as a speed of a mobile device through the network environment, a type of application and/or type of data transmitted over a respective communication link between the mobile device and the long-range base station, presence of one or more radio frequency layers in the network environment, mapping of a location of the mobile device to a speed limit value derived from a geographical map, etc.

Broadband wireless communications on high speed trains

Abstract: This tutorial paper provides a comprehensive overview on the recent development in broadband wireless communications for high speed trains. Starting with the introduction of the two-hop network structure, radio-over-fiber (RoF) based cell planning is described in detail. Moreover, based on the analysis of differences between conventional cellular systems and the one for high speed trains, promising techniques are recommended to improve the performance of handover, which is one of the main challenges in high speed train communications. Finally, in order to combat the fast fading caused by the high mobility, robust algorithms are needed in physical layer signal processing, including synchronization, channel estimation, modulation/demodulation, and so on.

WiZi-Cloud: Application-transparent dual ZigBee-WiFi radios for low power internet access

Abstract: The high density ofWiFi Access Points and large unlicensed RF bandwidth over which they operate makes them good candidates to alleviate cellular network's limitations. However, maintaining connectivity through WiFi results in depleting the mobile phone's battery in a very short time. We propose WiZi-Cloud, a system that utilizes a dual WiFi-ZigBee radio on mobile phones and Access Points, supported by WiZi-Cloud protocols, to achieve ubiquitous connectivity, high energy efficiency, real time intra-device/inter-AP handover, that is transparent to the applications. WiZi-Cloud runs mostly on commodity hardware such as Android phones and OpenWrt capable access points. Our extensive set of experiments demonstrate that for maintaining connectivity, WiZi-Cloud achieves more than a factor of 11 improvement in energy consumption in comparison with energy-optimized WiFi, and a factor of 7 in comparison with GSM. WiZi-Cloud has a better coverage than WiFi, and a low delay resulting in a good Mean Opinion Score (MOS) of 4.26 for a VoIP US cross-country communication.

Evaluation of postoperative handover using a tool to assess information transfer and teamwork.

Abstract: Objective:To assess the feasibility, validity, and reliability of a postoperative Handover Assessment Tool (PoHAT) and to evaluate the current practices of the postoperative handover at 2 large European hospitals.Background:Postoperative handover is one of the most critical phases in the care of a p

Coordinating Handover Parameter Optimization and Load Balancing in LTE Self-Optimizing Networks

Abstract: In this paper we present simulation results of a self-optimizing network in a long-term-evolution (LTE) mobile communication system that uses two optimizing algorithms at the same time: load balancing and handover parameter optimization. Based on previous work, we extend the optimization by a combined use case. We present the interactions of the two SON algorithms and show an example of a coordination system. The coordination system for self optimization observes system performance and controls the SON algorithms. As both SON algorithms deal with the handover decision itself, not only interactions, but also conflicts in the observation and control of the system are to be expected and are observed. The example of a coordination system here is not the optimal solution covering all aspects, but rather a working solution that shows equal performance to the individual algorithms or in the best case combining the strengths of the algorithms and achieving even better performance; although as localized gain, in time and area.

Apparatus and method for supporting mobility in a heterogeneous wireless communication system

Abstract: An apparatus and method in a heterogeneous wireless communication system reconnect a Mobile Station (MS) to a previously connected cell upon occurrence of a Radio Link Failure (RLF) in a current cell when a portion of a coverage of the second cell is included in a coverage of the first cell. A Mobile Station (MS) stores system information of a first Base Station (BS) of a first cell when performing handover from the first cell to a second cell. When changed system information of the first BS is received from a second BS of the second cell, the MS updates the stored system information using the changed system information. When detecting that a connection with the second cell is lost prior to a handover from the second cell, the MS performs reconnection to the first BS using the stored system information.

Review: bringing patient safety to the forefront through structured computerisation during clinical handover

Abstract: Aims and objectives. This review aims to examine critically, the methods and modes of delivery of handover used in contemporary health care settings and explore the feasibility of a computerised handover system for improving patient safety. Background. Clinicians play a critical role in promoting patient safety, and the handover ritual is recognised as important in exchanging information and planning patient care. Communication failures have been identified as an important cause of adverse incidents in hospitals. Design. Integrative literature review. Methods. Search of multiple electronic databases using terms: nursing handover, handoff, shift-to-shift reporting and change of shift report. Discussion. To date, the focus of research has primarily been on the vehicle of the handover, rather than the content and processes involved in ensuring the reliability and quality of clinical information. Employing a computerised handover system in the clinical arena has the potential to improve the quality and safety of clinical care. Conclusions. Whilst the handover performed from shift-to-shift is a valuable communication strategy, ambiguities and incomplete information can increase the risks of adverse events. Given the importance of effective communication, its key link to patient safety and the frequency of nursing handover, it is imperative that clinical handover undergo increased scrutiny, development and research. Relevance to clinical practice. This review underscores the challenge in clinical handover and recommends the use of technological solutions to improve communication strategies.

Signalling Cost Evaluation of Handover Management Schemes in LTE-Advanced Femtocell

Abstract: Femtocell is a small access point using the wire broadband connections or wireless technologies to access the mobile operator's network for the user equipment(UE), which can provide better indoor coverage and satisfy the upcoming demand of high data rate for wireless communication system.Femtocell related handover cost reduction is one of the important targets in LTE-Advanced SON (Self-Organising Networks). In this paper, a handover optimization algorithm based on the UE's mobility state is proposed. An analytical model was presented for the handover signalling cost analysis. Numerical results are provided to compare the signalling cost of different handover management schemes. The comparison between the proposed algorithm and the traditional handover control algorithm shows that the algorithms proposed in this paper have a significant reduction in the signalling overhead.

Using the ISBAR handover tool in junior medical officer handover: a study in an Australian tertiary hospital

Abstract: Background Despite being essential to patient care, current clinical handover practices are inconsistent and error prone. Efforts to improve handover have attracted attention recently, with the ISBAR tool increasingly utilised as a format for structured handover communication. However, ISBAR has not been validated in a junior medical officer setting. Objective To assess the effect of the ISBAR handover tool on junior medical officer (JMO) handover communication in an Australian hospital. Methods JMOs who participated in after-hours handover during an 11 week clinical term from June to August 2009 were recruited. After-hours handover was audiotaped, and JMOs completed a survey to assess current handover perception and practice. JMOs then participated in a 1 h education session on handover and use of the ISBAR handover tool, and were encouraged to handover using this method. Following the education session, participants were surveyed to measure perceived changes in handover with use of ISBAR, and handover was again audiotaped to assess differences in information transfer and duration. Results Following the introduction of ISBAR, 25/36 (71%) of JMOs felt there was an overall improvement in handover communication. Specifically, they perceived improvement in the structure and consistency of handover, they felt more confident receiving handover, and they believed patient care and safety were improved. Audio-tape data demonstrated increased transfer of key clinical information during handover with no significant effect on handover duration. Conclusions Use of the ISBAR tool improves JMO perception of handover communication in a time neutral fashion. Consideration should be given to the introduction of ISBAR in all JMO handover settings.

Vertical Handover decision schemes using SAW and WPM for Network selection in Heterogeneous Wireless Networks

Abstract: Seamless continuity is the main goal and challenge in fourth generation Wireless networks (FGWNs), to achieve seamless connectivity "HANDOVER" technique is used, Handover mechanism are mainly used when a mobile terminal(MT) is in overlapping area for service continuity. In Heterogeneous wireless networks main challenge is continual connection among the different networks like WiFi, WiMax, WLAN, WPAN etc. In this paper, Vertical handover decision schemes are compared, Simple Additive Weighting method (SAW) and Weighted product model (WPM) are used to choose the best network from the available Visitor networks (VTs) for the continuous connection by the mobile terminal. In our work we mainly concentrated to the handover decision phase and to reduce the processing delay in the period of handover. In this paper both SAW and WPM methods are compared with the Qos parameters of the mobile terminal (MT) to connect with the best network. Keyword- Handover, Vertical handover decision schemes, Simple additive weighting, Weight product method. I. I ntroduction n fourth generation wireless networks service continuity is a main goal ie., when a MT or mobile node (MN) moving in an overlapping area, continuous service must be need so the technique "HANDOVER" is done. The handover technique is mainly used to redirect the mobile user's service network from current network to a new network or one base station (BS) to another BS or one access point (AP) to another AP with same technology or among different technologies to reduce the processing delay in the overlapping area.

Multi-radio handover manager system and algorithms for heterogeneous wireless networking

Abstract: A multi-radio handover manager and supporting algorithms are disclosed. The multi-radio handover manager (MRHM) minimizes the "on" time of one radio when the other radio is connected to the Internet. The MRHM also prevents unnecessary inter-RAT (radio access technologies) WLAN-to-WWAN handovers in a "multi-AP" WLAN, where intra-RAT WLAN-to-WLAN (layer 2) roaming is possible. The MRHM minimizes the impact of IP address changes due to WWAN-to-WLAN handover on an active TCP/IP session. And, the MRHM optimizes its handover-triggering algorithm based on traffic and environment.

Behavior-based mobility prediction for seamless handoffs in mobile wireless networks

Abstract: The field of wireless networking has received unprecedented attention from the research community during the last decade due to its great potential to create new horizons for communicating beyond the Internet. Wireless LANs (WLANs) based on the IEEE 802.11 standard have become prevalent in public as well as residential areas, and their importance as an enabling technology will continue to grow for future pervasive computing applications. However, as their scale and complexity continue to grow, reducing handoff latency is particularly important. This paper presents the Behavior-based Mobility Prediction scheme to eliminate the scanning overhead incurred in IEEE 802.11 networks. This is achieved by considering not only location information but also group, time-of-day, and duration characteristics of mobile users. This captures short-term and periodic behavior of mobile users to provide accurate next-cell predictions. Our simulation study of a campus network and a municipal wireless network shows that the proposed method improves the next-cell prediction accuracy by 23~43% compared to location-only based schemes and reduces the average handoff delay down to 24~25 ms.

Optimal Distributed Vertical Handoff Strategies in Vehicular Heterogeneous Networks

Abstract: This paper addresses the problem of optimal vertical handoff (VHO) in a vehicular network setting The VHO objective can be minimizing the data transfer time or alternatively minimizing the cost of transmitting traffic As a framework for performance evaluations, we first analyze a heterogeneous network consisting of a wide-area cellular network interworking with wireless local area networks (WLAN) with fixed inter-distance between access points (APs) placed along roadsides We further analyze a scenario with random inter-distance between WLAN APs In both aforementioned cases, only Vehicle-to-Infrastructure (V2I) capability is assumed We show that in order to minimize the cost of transmission or alternatively transmission time, performing VHOs is an appropriate choice at lower speeds, whereas it would be better to avoid VHO and stay in the cellular network at higher speeds We further generalize our study, to investigate the VHO strategies in a random inter-distance scenario with both V2I and Vehicle-to-Vehicle (V2V) communication capabilities We demonstrate that the combination of WLAN plus cellular plus ad hoc networking outperforms any other networking strategies considered in this work in terms of transmission times and transmission costs The presented results provide insightful guidelines for optimal VHO decision making based on the characteristics of the network as well as the user mobility profile

Method and apparatus for biasing a handoff decision based on a backhaul link

Abstract: A decision whether to perform a handover between a relay and a base station may depend, at least in part, on a backhaul link between the relay and the donor base station serving the relay. That is, the relay may provide information relating to a characteristic of the backhaul link to the user equipment, and the user equipment may utilize this information to bias its measurements of signals transmitted from the relay and the base station in accordance with the characteristic of the backhaul link. In this way, if the backhaul link suffers such that it becomes a bottleneck, the handover decision between the relay and the base station is better informed than a decision based solely on the transmissions from the relay and from the base station.

Terminal for a content centric network and method of communication for a terminal and a hub in a content centric network

Abstract: A method of communication for a terminal and/or a hub in a content-centric network is provided. The method includes suspending a data message associated with a content from being provided to a face before a handover when the handover is expected to occur in the terminal that requests the content, and transmitting, to a hub, a new interest message after the handover associated with the content so that the hub may provide the data message associated with the content to the face after the handover. The invention further relates to a terminal, a hub and a combined communication system comprises at least one terminal and at least one hub.

QoS-enabled group communication in integrated VANET-LTE heterogeneous wireless networks

Abstract: Ubiquitous integration of high-speed WLANs with wide-range 3GPP systems results in the service extension of the backbone cellular network. This paper envisions such heterogeneous wireless network architecture by integrating IEEE 802.11p VANETs with 3GPP LTE to achieve seamless data connectivity for uninterrupted multimedia sessions amongst spatially-apart vehicular clusters. Issues on cluster head-based multicasting and QoS are explored in this paper. An adaptive multi-metric Cluster Head (CH) election mechanism is proposed to manage the VANET sub-clusters. In addition to this, construction of a 2-hop virtual overlay mesh-based shared multicast tree for lower-level multicasting within VANETs is discussed. Following this, the process of VANET-LTE upper-level communication is detailed, addressing the issues of CH and gateway handover, and resource allocation of the LTE eNB. The envisioned architecture enables the LTE to effectively schedule multimedia sessions based on the service requirements of the VANET gateways, thus satisfying QoS. Requisite simulation results are presented to evaluate the integrated network.

Route classification using cellular handoff patterns

Abstract: Understanding utilization of city roads is important for urban planners. In this paper, we show how to use handoff patterns from cellular phone networks to identify which routes people take through a city. Specifically, this paper makes three contributions. First, we show that cellular handoff patterns on a given route are stable across a range of conditions and propose a way to measure stability within and between routes using a variant of Earth Mover's Distance. Second, we present two accurate classification algorithms for matching cellular handoff patterns to routes: one requires test drives on the routes while the other uses signal strength data collected by high-resolution scanners. Finally, we present an application of our algorithms for measuring relative volumes of traffic on routes leading into and out of a specific city, and validate our methods using statistics published by a state transportation authority.

Apparatus and method for performing handover in multiple component carrier system

Abstract: A method for performing handover in a multiple component carrier system includes a UE transmitting a measurement report message, including measurement values for one or more cells, to a source BS, the source BS transmitting a handover request message, including at least one of a candidate cell list including at least one candidate cell to be used in a target BS, an aggregatable cell list including at least one aggregatable cell in which UE capability is taken into consideration, and a list of sensible cells including at least one cell defined based on a similarity sensitivity of a measured frequency, to the target BS based on the measurement value, the source BS checking the cell included in the at least one list, receiving a handover ACK message including a final cell from the target BS, and determining handover, and the source BS transmitting a handover command message to the UE.

Performance analysis of spectrum handoff for cognitive radio ad hoc networks without common control channel under homogeneous primary traffic

Abstract: Cognitive radio (CR) technology is regarded as a promising solution to the spectrum scarcity problem. Due to the spectrum varying nature of CR networks, unlicensed users are required to perform spectrum handoffs when licensed users reuse the spectrum. In this paper, we study the performance of the spectrum handoff process in a CR ad hoc network under homogeneous primary traffic. We propose a novel three dimensional discrete-time Markov chain to characterize the process of spectrum handoffs and analyze the performance of unlicensed users. Since in real CR networks, a dedicated common control channel is not practical, in our model, we implement a network coordination scheme where no dedicated common control channel is needed. Moreover, in wireless communications, collisions among simultaneous transmissions cannot be immediately detected and the whole collided packets need to be retransmitted, which greatly affects the network performance. With this observation, we also consider the retransmissions of the collided packets in our proposed discrete-time Markov chain. In addition, besides the random channel selection scheme, we study the impact of different channel selection schemes on the performance of the spectrum handoff process. Furthermore, we also consider the spectrum sensing delay in our proposed Markov model and investigate its effect on the network performance. We validate the numerical results obtained from our proposed Markov model against simulation and investigate other parameters of interest in the spectrum handoff scenario. Our proposed analytical model can be applied to various practical network scenarios. It also provides new insights on the process of spectrum handoffs. Currently, no existing analysis has considered the comprehensive aspects of spectrum handoff as what we consider in this paper.

Mobile video streaming using location-based network prediction and transparent handover

Abstract: A well known challenge with mobile video streaming is fluctuating bandwidth. As the client devices move in and out of network coverage areas, the users may experience varying signal strengths, competition for the available resources and periods of network outage. These conditions have a significant effect on video quality. In this paper, we present a video streaming solution for roaming clients that is able to compensate for the effects of oscillating bandwidth through bandwidth prediction and video quality scheduling. We combine our existing adaptive segmented HTTP streaming system with 1) an application layer framework for creating transparent multi-link applications, and 2) a location based QoS information system containing GPS coordinates and accompanying bandwidth measurements, populated through crowd-sourcing. Additionally, we use real-time traffic information to improve the prediction by, for example, estimating the length of a commute route. To evaluate our prototype, we performed real-world experiments using a popular tram route in Oslo, Norway. The client connected to multiple networks, and the results show that our solution increases the perceived video quality significantly. Also, we used simulations to evaluate the potential of aggregating bandwidth along the route.

Time Coordinated V2I Communications and Handover for WAVE Networks

Abstract: A wide variety of information technology (IT) services will become available for vehicles through the IEEE 802.11p, IEEE 1609, and wireless access in vehicular environment (WAVE) standards, and naturally the need for service handover will become a necessity. For WAVE networks, a time coordinated medium access control (MAC) protocol named WAVE point coordination function (WPCF) is proposed in this paper. The mathematical derivations and simulation analysis demonstrate that the proposed WPCF protocol can significantly enhance the utilization efficiency and can support more users based on an equal-length access period when compared to point coordination function (PCF), enhanced distributed channel access (EDCA), or hybrid coordination function (HCF) controlled channel access (HCCA) for vehicle to infrastructure (V2I) communications. The paper also demonstrates the effectiveness of the proposed WAVE handover controller (WHC) and WPCF in minimizing service disconnection time when used for V2I handover. In addition, technical enhancements and messages are added to enable seamless communication services over soft-handover (SHO), and enable minimum handover delay in hard-handover (HHO) situations. The mathematical performance evaluation and the simulation results show that the proposed scheme can significantly improve the handover latency compared to the performance that can be delivered by the current protocols.

Using an open-source IEEE 802.21 implementation for network-based localized mobility management

Abstract: Taking advantage of the multimode ability of modern mobile terminals, cellular operators are investing in alternate access networks (e.g., IEEE802.11 and IEEE802.16) to complement the increasingly overloaded cellular accesses. Complementing this, IP mobility support is gradually being introduced into network architectures, providing session continuity. To facilitate and optimize handover procedures between different access technologies in a seamless way, the IEEE 802.21 Media Independent Handover Services standard provides technology agnostic mechanisms to obtain information and control link layers. Implementations of the standard are appearing, but since support of IEEE 802.21 primitives directly at the link driver level is not yet realized, they have to revert to proprietary wrapping mechanisms or use specific operating system solutions to circumvent this issue. In this article we present ODTONE, an IEEE 802.21 implementation that is operating-system-independent and open source, and offers a novel approach to interfacing with different link layers that facilitates the deployment of IEEE 802.21 mobility mechanisms in multiple scenarios. We present a scenario where we integrate our middleware with an IP mobility management protocol, Proxy MIP IPv6, highlighting ODTONE?s supporting features and impact while providing an open handover control architecture for network- based localized mobility management.