Showing papers on "Handover published in 2012"

Exploring mobile/WiFi handover with multipath TCP

Abstract: Mobile Operators see an unending growth of data traffic generated by their customers on their mobile data networks. As the operators start to have a hard time carrying all this traffic over 3G or 4G networks, offloading to WiFi is being considered. Multipath TCP (MPTCP) is an evolution of TCP that allows the simultaneous use of multiple interfaces for a single connection while still presenting a standard TCP socket API to the application. The protocol specification of Multipath TCP has foreseen the different building blocks to allow transparent handover from WiFi to 3G back and forth. In this paper we experimentally prove the feasibility of using MPTCP for mobile/WiFi handover in the current Internet. Our experiments run over real WiFi/3G networks and use our Linux kernel implementation of MPTCP that we enhanced to better support handover. We analyze MPTCP's energy consumption and handover performance in various operational modes. We find that MPTCP enables smooth handovers offering reasonable performance even for very demanding applications such as VoIP. Finally, our experiments showed that lost MPTCP control signals can adversely affect handover performance; we implement and test a simple but effective solution to this issue.

Method and apparatus for short handover latency in wireless communication system using beam forming

Abstract: Beam selection is provided. A method for handover in a mobile station includes sending a scan request message for scanning a downlink (DL) beam with respect to a serving base station (BS) and a neighboring BS, to the serving BS, and receiving a scan response message; determining the DL beam for the MS by performing scanning with the serving BS and the neighboring BS based on the scan response message; sending a scan report message comprising a result of the scanning to the serving BS; when receiving an air-HO request message from the serving BS, generating an air-HO response message comprising information of a neighboring BS to which the MS hands over based on the air-HO request message; performing beam selection with the neighboring BS of the handover based on the air-HO request message; and performing the handover.

Mobility management challenges in 3GPP heterogeneous networks

Abstract: In this article we provide a comprehensive review of the handover process in heterogeneous networks (HetNets), and identify technical challenges in mobility management. In this line, we evaluate the mobility performance of HetNets with the 3rd Generation Partnership Project (3GPP) Release-10 range expansion and enhanced inter-cell interference coordination (eICIC) features such as almost blank subframes (ABSFs). Simulation assumptions and parameters of a related study item in 3GPP are used to investigate the impact of various handover parameters on mobility performance. In addition, we propose a mobility-based inter-cell interference coordination (MB-ICIC) scheme, in which picocells configure coordinated resources so that macrocells can schedule their high-mobility UEs in these resources without co-channel interference from picocells. MB-ICIC also benefits low-mobility UEs, since handover parameters can now be more flexibly optimized. Simulations using the 3GPP simulation assumptions are performed to evaluate the performance of MB-ICIC under several scenarios.

Methods and systems for controlling handovers in a co-channel network

Abstract: At least one example embodiment discloses a method of controlling a handover of a user equipment (UE) from a serving base station to a target, base station in a heterogeneous network. The method includes determining, by a serving base station, a speed of the UE and a type of the handover, the type of the handover being one of macro cell to macro cell, macro cell to small cell, small cell to macro cell and small cell to small cell, and controlling, by the serving base station, the handover from the serving base station to the target base station based on the speed of the UE and the type of handover.

Towards Understanding the Fundamentals of Mobility in Cellular Networks

Abstract: Despite the central role of mobility in wireless networks, analytical study on its impact on network performance is notoriously difficult. This paper aims to address this gap by proposing a random waypoint (RWP) mobility model defined on the entire plane and applying it to analyze two key cellular network parameters: handover rate and sojourn time. We first analyze the stochastic properties of the proposed model and compare it to two other models: the classical RWP mobility model and a synthetic truncated Levy walk model which is constructed from real mobility trajectories. The comparison shows that the proposed RWP mobility model is more appropriate for the mobility simulation in emerging cellular networks, which have ever-smaller cells. Then we apply the proposed model to cellular networks under both deterministic (hexagonal) and random (Poisson) base station (BS) models. We present analytic expressions for both handover rate and sojourn time, which have the expected property that the handover rate is proportional to the square root of BS density. Compared to an actual BS distribution, we find that the Poisson-Voronoi model is about as accurate in terms of mobility evaluation as hexagonal model, though being more pessimistic in that it predicts a higher handover rate and lower sojourn time.

Spectrum mobility in cognitive radio networks

Abstract: Cognitive radio networks (CRNs) offer a promising solution for spectrum scarcity problem by means of dynamic spectrum access. So long as in highly dynamic environments, the secondary user (SU) communication is often interrupted, spectrum mobility is a key feature enabling continuous SU data transmission. Namely, SU performs spectrum handoff by transferring ongoing communication to a vacant channel. This article discusses some important features of spectrum mobility in CRNs. Qualitative comparison of various handoff strategies is considered with regard to handoff latency. Furthermore, essential design issues and associated research challenges are also addressed.

Modeling and Analysis for Spectrum Handoffs in Cognitive Radio Networks

Abstract: In this paper, we present an analytical framework to evaluate the latency performance of connection-based spectrum handoffs in cognitive radio (CR) networks. During the transmission period of a secondary connection, multiple interruptions from the primary users result in multiple spectrum handoffs and the need of predetermining a set of target channels for spectrum handoffs. To quantify the effects of channel obsolete issue on the target channel predetermination, we should consider the three key design features: 1) general service time distribution of the primary and secondary connections; 2) different operating channels in multiple handoffs; and 3) queuing delay due to channel contention from multiple secondary connections. To this end, we propose the preemptive resume priority (PRP) M/G/1 queuing network model to characterize the spectrum usage behaviors with all the three design features. This model aims to analyze the extended data delivery time of the secondary connections with proactively designed target channel sequences under various traffic arrival rates and service time distributions. These analytical results are applied to evaluate the latency performance of the connection-based spectrum handoff based on the target channel sequences mentioned in the IEEE 802.22 wireless regional area networks standard. Then, to reduce the extended data delivery time, a traffic-adaptive spectrum handoff is proposed, which changes the target channel sequence of spectrum handoffs based on traffic conditions. Compared to the existing target channel selection methods, this traffic-adaptive target channel selection approach can reduce the extended data transmission time by 35 percent, especially for the heavy traffic loads of the primary users.

Secure and Efficient Handover Authentication Based on Bilinear Pairing Functions

Abstract: Seamless handover over multiple access points is highly desirable to mobile nodes, but ensuring security and efficiency of this process is challenging. This paper shows that prior handover authentication schemes incur high communication and computation costs, and are subject to a few security attacks. Further, a novel handover authentication protocol named PairHand is proposed. PairHand uses pairing-based cryptography to secure handover process and to achieve high efficiency. Also, an efficient batch signature verification scheme is incorporated into PairHand. Experiments using our implementation on laptop PCs show that PairHand is feasible in real applications.

Spectrum-Aware Mobility Management in Cognitive Radio Cellular Networks

Abstract: Cognitive radio (CR) networks have been proposed as a solution to both spectrum inefficiency and spectrum scarcity problems. However, they face several challenges based on the fluctuating nature of the available spectrum, making it more difficult to support seamless communications, especially in CR cellular networks. In this paper, a spectrum-aware mobility management scheme is proposed for CR cellular networks. First, a novel network architecture is introduced to mitigate heterogeneous spectrum availability. Based on this architecture, a unified mobility management framework is developed to support diverse mobility events in CR networks, which consists of spectrum mobility management, user mobility management, and intercell resource allocation. The spectrum mobility management scheme determines a target cell and spectrum band for CR users adaptively dependent on time-varying spectrum opportunities, leading to increase in cell capacity. In the user mobility management scheme, a mobile user selects a proper handoff mechanism so as to minimize a switching latency at the cell boundary by considering spatially heterogeneous spectrum availability. Intercell resource allocation helps to improve the performance of both mobility management schemes by efficiently sharing spectrum resources with multiple cells. Simulation results show that the proposed method can achieve better performance than conventional handoff schemes in terms of both cell capacity as well as mobility support in communications.

ProSpect: A Proactive Spectrum Handoff Framework for Cognitive Radio Ad Hoc Networks without Common Control Channel

Abstract: Cognitive Radio (CR) technology is a promising solution to enhance the spectrum utilization by enabling unlicensed users to exploit the spectrum in an opportunistic manner. Since unlicensed users are temporary visitors to the licensed spectrum, they are required to vacate the spectrum when a licensed user reclaims it. Due to the randomness of the appearance of licensed users, disruptions to both licensed and unlicensed communications are often difficult to prevent, which may lead to low throughput of both licensed and unlicensed communications. In this paper, a proactive spectrum handoff framework for CR ad hoc networks, ProSpect, is proposed to address these concerns. In the proposed framework, Channel-Switching (CW) policies and a proactive spectrum handoff protocol are proposed to let unlicensed users vacate a channel before a licensed user utilizes it to avoid unwanted interference. Network coordination schemes for unlicensed users are also incorporated into the spectrum handoff protocol design. Moreover, a distributed channel selection scheme to eliminate collisions among unlicensed users in a multiuser spectrum handoff scenario is proposed. In our proposed framework, unlicensed users coordinate with each other without using a Common Control Channel (CCC), which is highly adaptable in a spectrum-varying environment. We compare our proposed proactive spectrum handoff protocol with a reactive spectrum handoff protocol, under which unlicensed users switch channels after collisions with licensed transmissions occur. Simulation results show that our proactive spectrum handoff outperforms the reactive spectrum handoff approach in terms of higher throughput and fewer collisions to licensed users. Furthermore, our distributed channel selection can achieve higher packet delivery rate in a multiuser spectrum handoff scenario, compared with existing channel selection schemes.

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

Abstract: Due to frequent handovers in broadband wireless communications in high-speed rail, communication interruption during handover could seriously degrade the experiences of passengers on the train. Aiming to reduce the interruption time, this paper proposes a seamless handover scheme based on a dual-layer and dual-link system architecture, 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. In the proposed scheme, the front antenna executes handover while the rear antenna is still communicating with BS, so that the communication can keep non-interruptive throughout the handover. Moreover, bi-casting is adopted to eliminate the data forwarding delay between the serving BS and target BS. A complete handover protocol is designed and the performance of the proposed scheme is analyzed. It can be seen from analytical results that the handover failure probability decreases as cell overlap increases and the communication interruption probability decreases with the decrease of train handover location and the increase of cell overlap. The simulation results show that in the proposed scheme, the communication interruption probability is smaller than 1% when the handover location is properly selected and the system throughput is not affected by handover. 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.

Short message transmission and handover procedures

Abstract: The present invention relates to an improved method for handover of a mobile node from E-UTRAN to UTRAN in a scenario where SMS is the only service of the mobile node. The improved handover method allows saving radio resources by establishing the signalling connection for SMS exchange in the target network, and avoiding the data connection in the target network, since it is not used. The MME takes the decision to establish or not the data connection in the target UTRAN, and accordingly instructs the SGSN and UE to set the corresponding PDP contexts for the data connection to a “preserved” state, so as to avoid the establishment of same. Embodiments further relate to improved SMS delivery for IDLE mode UEs that activate ISR so as to avoid the involvement of the MSC server. Instead, packet-switched domain nodes are to be involved only.

Seamless Wireless Connectivity for Multimedia Services in High Speed Trains

Abstract: The recent advent of high speed trains introduces new mobility patterns in wireless environments. The LTE-A (Long Term Evolution of 3GPP - Advanced) networks have largely tackled the Doppler effect problem in the physical layer and are able to keep wireless service with 100Mpbs throughput within a cell in speeds up to 350 km/h. Yet the much more frequent handovers across cells greatly increases the possibility of service interruptions, and the problem is prominent for multimedia communications that demand both high-throughput and continuous connections. In this paper, we present a novel LTE-based solution to support high throughput and continuous multimedia services for high speed train passengers. Our solution is based on a Cell Array that smartly organizes the cells along a railway, together with a femto cell service that aggregates traffic demands within individual train cabins. Given that the movement direction and speed of a high-speed train are generally known, our Cell Array effectively predicts the upcoming LTE cells in service, and enables a seamless handover that will not interrupt multimedia streams. To accommodate the extreme channel variations, we further propose a scheduling and resource allocation mechanism to maximize the service rate based on periodical signal quality changes. Our simulation under diverse network and railway/train configurations demonstrates that the proposed solution achieves much lower handover latency and higher data throughput, as compared to existing solutions. It also well resists to network and traffic dynamics, thus enabling uninterrupted quality multimedia services for passengers in high speed trains.

Vertical Mobility Management Architectures in Wireless Networks: A Comprehensive Survey and Future Directions

Abstract: Mobile users and applications are putting pressure on wireless network operators to improve the seamless handover of devices and services. Strong business competition for subscribers, along with the ever increasing availability of wireless networks will give nomadic and mobile users the opportunity, and systems the power, to make better handover decisions. In this paper, we present a comprehensive review of the literature on mobility management architectures for seamless handover of mobile users in heterogeneous networks. We describe the design rationale for selected architectures, with an in-depth analysis of their main goals, assumptions, and requirements. We also provide directions for further work in this field by highlighting the mandatory requirements and the features of future architectures. We then present a new architecture called Context-Aware Mobility Management System (CAMMS). CAMMS is a new cross-layer, context-aware and interactive approach to seamless handover of users and services. With that proposal, we identified the essential functional entities that must be part of future architectures.

Method of mobility management for mobile terminal in a heterogeneous network environment

Abstract: A method for managing mobility of a terminal in a heterogeneous network environment is provided. According to an aspect, there is provided an operation method of a terminal receiving parameters for Coordinated Multi-point transmission/reception (CoMP) operation in a heterogeneous network environment, the operation method including, at the terminal, receiving at least one parameter among a CoMP operation mode parameter, a time information parameter regarding a time at which the CoMP operation starts, a point information parameter about points that participate in the CoMP operation, and a CoMP operation parameter, from a base station, through a layer-3 message. Therefore, it is possible to avoid an unnecessary ping-pong handover and efficiently provide service continuity.

Cross-Layer Handoff Design in MIMO-Enabled WLANs for Communication-Based Train Control (CBTC) Systems

Abstract: Communication-Based Train Control (CBTC) system is an automated train control system using bidirectional train-ground communications to ensure the safe operation of rail vehicles. Handoff design has significant impacts on the train control performance in CBTC systems based on multi-input and multi-output (MIMO)-enabled WLANs. Most of previous works use traditional design criteria, such as network capacity and communication latency, in handoff designs. However, these designs do not necessarily benefit the train control performance. In this paper, we take an integrated design approach to jointly optimize handoff decisions and physical layer parameters to improve the train control performance in CBTC systems. We use linear quadratic cost for the train controller as the performance measure. The handoff decision and physical layer parameters adaptation problem is formulated as a stochastic control process. Simulation result shows that the proposed approach can significantly improve the control performance in CBTC systems.

Analysis of Reactive Spectrum Handoff in Cognitive Radio Networks

Abstract: In this paper, we present an analytical framework to evaluate the effects of multiple spectrum handoffs on channel utilization and latency performances in cognitive radio (CR) networks. During the transmission period of a secondary connection, multiple interruptions from the primary users result in multiple spectrum handoffs. In order to decide the target channel for each spectrum handoff and resume the unfinished transmission, wideband sensing is performed in an on-demand reactive manner. Although spectrum handoff procedure can enhance channel utilization, transmission latency of the secondary users is prolonged due to multiple handoffs. Thus, two fundamental issues in CR networks with multiple spectrum handoffs arise: (1) to what extent the channel utilization can be improved; and (2) how long the transmission latency will be extended for the secondary users. To solve the first problem, we introduce the preemptive resume priority (PRP) M/G/1 queueing network to characterize the channel usage behaviors of CR networks. Based on this queueing network, channel utilization under various traffic arrival rates and service time distributions can be evaluated. Furthermore, on top of the proposed queueing network, a state diagram is developed to characterize the effects of multiple handoff delay on the transmission latency of the secondary users. The analytical results can provide a helpful insight to study the effects of traffic arrival rates and service time on channel utilization and transmission latency and then facilitate the designs of admission control rules for the secondary users subject to their performance requirements.

Method and apparatus for supporting local ip access and selected ip traffic offload

Abstract: A method and apparatus for home Node-B (HNB) mobility with a local IP access (LIPA) packet data network (PDN) connection are described. A target home node-B (HNB) may receive a handover request message from a source HNB to handover a wireless transmit/receive unit (WTRU). A path switch request may be transmitted to a local gateway (LGW) to change a downlink data path towards the target HNB in response to the handover request message. The LGW may act as a mobility management and local mobility anchor for the handover; and informing an HNB gateway (GW) about the handover so that the downlink data path for core network (CN) traffic is modified towards the target HNB.

Performance Analysis of PMIPv6-Based NEtwork MObility for Intelligent Transportation Systems

Abstract: While host mobility support for individual mobile hosts (MHs) has been widely investigated and developed over the past years, there has been relatively less attention to NEtwork MObility (NEMO). Since NEMO Basic Support (NEMO-BS) was developed, it has been the central pillar in Intelligent Transport Systems (ITS) communication architectures for maintaining the vehicle's Internet connectivity. As the vehicle moves around, it attaches to a new access network and is required to register a new address obtained from the new access network to a home agent (HA). This location update of NEMO-BS often results in unacceptable long handover latency and increased traffic load to the vehicle. To address these issues, in this paper, we introduce new NEMO support protocols, which rely on mobility service provisioning entities introduced in Proxy Mobile IPv6 (PMIPv6), as possible mobility support protocols for ITS. As a base protocol, we present PMIPv6-based NEMO (P-NEMO) to maintain the vehicle's Internet connectivity while moving and without participating in the location update management. In P-NEMO, the mobility management for the vehicle is supported by mobility service provisioning entities residing in a given PMIPv6 domain. To further improve handover performance, fast P-NEMO (FP-NEMO) has been developed as an extension protocol. FP-NEMO utilizes wireless L2 events to anticipate the vehicle's handovers. The mobility service provisioning entities prepare the vehicle's handover prior to the attachment of the vehicle to the new access network. Detailed handover procedures for P-NEMO and FP-NEMO are provided, and handover timing diagrams are presented to evaluate the performance of the proposed protocols. P-NEMO and FP-NEMO are compared with NEMO-BS in terms of traffic cost and handover latency.

A Survey on Handoffs — Lessons for 60 GHz Based Wireless Systems

Abstract: Wireless communication is playing an important role in our daily life since it offers flexibility and mobility. New multimedia services demand data-rates of up to hundreds of Mbps and thus higher frequency bands are being explored to support these new high data rate services. However, to support mobility, handoff is a must in many of these networks and systems. In the mean time the 60 GHz band has received much attention due to its 5 GHz of the available spectrum globally. However, the 60 GHz channels face many challenges such as high attenuation and NLOS propagation. The high reduction in signal strength as a function of distance results in a small coverage area, thereby causing frequent handoffs for mobile terminals. In this paper, we discuss and compare handoff algorithms intended for WLAN, GSM, UMTS, etc. We study these algorithms from the point of view of their usability in 60 GHz networks and make recommendations for handoff algorithms in such networks.

Handover in VLC systems with cooperating mobile devices

Abstract: Visible Light Communications (VLC) is emerging as viable means to overcome the crowded radio spectrum for highly-localized communications systems With such an approach, luminaires can be adopted for supporting data communication in addition to illumination in what we call Cellular Lighting However, in these systems, the directionality of light as the communication medium introduces new challenges in sustaining network connectivity especially under mobility scenarios In this paper we investigate mobility in VLC devices and propose an approach to managing handover adopted from wireless cellular systems, but with very small cells and directional characteristic Moreover, this technique provides the coordination and cooperation among VLC devices to achieve seamless connectivity in two different indoor scenarios consisting of overlapping (uniform lighting) and non-overlapping (spotlighting) cases Results indicate how different design decisions in supporting luminaire placement achieve full coverage at varying data rates

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

Abstract: 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 communication between train and ground eNodeBs. Numerical analysis and simulation results show that the proposed scheme can decrease the outage probability remarkably during handover and guarantee the reliability of train to ground communication.

Vertical handoff decision algorithm for improved quality of service in heterogeneous wireless networks

Abstract: Fourth-generation networks are expected to integrate heterogeneous wireless technologies. To ensure seamless mobility across disparate wireless technologies, efficient handoff schemes are required to enhance quality of service (QoS) and offer reliable ubiquitous computing environment. This study reviews classical and existing fuzzy approaches adopted for vertical handoff to ensure seamless mobility across overlaid heterogeneous networks. A neuro-fuzzy multi-parameter-based vertical handoff decision algorithm (VHDA) is proposed. The proposed VHDA considers six parameters and applies rule-based system for vertical handoff decision. The number of vertical handoffs measured in a simulated environment shows that average number of vertical handoffs for the proposed VHDA reduces by 13.3 and 29.8% for the existing fuzzy technique and the classical technique, respectively. Further, reduction in number of unnecessary vertical handoffs in the proposed algorithm shows reduction in ping-pong effect by 15.9%, improvement in end-point service availability (ESA) and throughput by 16.57 and 5.97%, with respect to existing fuzzy technique leading towards improved QoS. Finally, the results of performance assessment, carried out using handoff quality indicator (used to quantify QoS) which is dependent upon ping-pong effect, ESA and throughput, show that the proposed VHDA offers better QoS than existing vertical handoff techniques.

Self-organizing communication networks

Abstract: A self-organizing network (SON) capability is provided. A SON may be configured by building intelligence and automation into the network to enable network operators to address various challenges associated with operation of the network. A SON may include one or more of a self-configuration function, a physical cell identifier (PCI) configuration function, a neighbor relationship management function, an energy savings function, a cell outage function, a cellular coverage function, a handoff function, a load-balancing function, an Inter-Cell Interference Coordination (ICIC) function, a Random Access Channel (RACH) function, a capacity function, or the like. A SON provides a network operator with a path to increase network performance with less effort, enables reductions in Operating Expenditure (OPEX), enables relatively rapid adaptation to network conditions, enables increases in network quality, and so forth.

Handover patterns: an observational study of critical care physicians

Abstract: Background Handover (or 'handoff') is the exchange of information between health professionals that accompanies the transfer of patient care. This process can result in adverse events. Handover 'best practices', with emphasis on standardization, have been widely promoted. However, these recommendations are based mostly on expert opinion and research on medical trainees. By examining handover communication of experienced physicians, we aim to inform future research, education and quality improvement. Thus, our objective is to describe handover communication patterns used by attending critical care physicians in an academic centre and to compare them with currently popular, standardized schemes for handover communication.

Handoff Performance Improvements in MIMO-Enabled Communication-Based Train Control Systems

Abstract: Communication-based train control (CBTC) is an automated control system for railways using data communications. CBTC systems have stringent communication latency requirements. For rail transit systems, wireless local area network (WLAN)-based CBTC is a popular approach due to the wide availability of commercial-off-the-shelf WLAN equipment. However, WLANs were not originally designed for high-speed environments with frequent handoffs, which may result in communication interrupt and long latency. In this paper, we propose a handoff scheme in CBTC systems based on WLANs with multiple-input-multiple-output (MIMO) technologies to improve the handoff latency performance. In particular, we consider channel estimation errors and the tradeoff between MIMO multiplexing gain and diversity gain in making handoff decisions. The handoff problem is formulated as a partially observable Markov decision process (POMDP), and the optimal handoff policy can be derived to minimize the handoff latency. Simulations results based on real field channel measurements are presented to show the effectiveness of the proposed scheme.

The collaborative communication model for patient handover at the interface between high-acuity and low-acuity care

Abstract: Background Cross-unit handovers transfer responsibility for the patient among healthcare teams in different clinical units, with missed information, potentially placing patients at risk for adverse events. Objectives We analysed the communications between high-acuity and low-acuity units, their content and social context, and we explored whether common conceptual ground reduced potential threats to patient safety posed by current handover practices. Methods We monitored the communication of five content items using handover probes for 22 patient transitions of care between high-acuity ‘sender units’ and low-acuity ‘recipient units’. Data were analysed and discussed in focus groups with healthcare professionals to acquire insights into the characteristics of the common conceptual ground. Results High-acuity and low-acuity units agreed about the presence of alert signs in the discharge form in 40% of the cases. The focus groups identified prehandover practices, particularly for anticipatory guidance that relied extensively on verbal phone interactions that commonly did not involve all members of the healthcare team, particularly nursing. Accessibility of information in the medical records reported by the recipient units was significantly lower than reported by sender units. Common ground to enable interpretation of the complete handover content items existed only among selected members of the healthcare team. Conclusions The limited common ground reduced the likelihood of correct interpretation of important handover information, which may contribute to adverse events. Collaborative design and use of a shared set of handover content items may assist in creating common ground to enable clinical teams to communicate effectively to help increase the reliability and safety of cross-unit handovers.

Methods and apparatus to handle bearers during circuit switched fallback operation

Abstract: Methods and apparatus to provide packet switched service continuity during circuit switched fallback operation are described. One example method includes determining that a target system does not support packet switched handover; determining if non-3GPP access for packet switched service is available; and triggering handover to the non-3GPP access.

Theoretical analysis of handover failure and ping-pong rates for heterogeneous networks

Abstract: In this paper, we characterize the relation between handover failure and ping-pong rates in a 3GPP heterogeneous network scenario as a function of relevant system parameters such as time-to-trigger, user equipment velocity, range expansion bias, etc. Under the assumptions that the picocell coverage and radio link failure areas are circular regions, and that users follow linear trajectories, handover failure and ping-pong rates are derived in closed-form expressions. Simulation results verify the accuracy of our analytical derivations, which shed new light on key aspects of the handover process in a heterogeneous network.