Handover

About: Handover is a research topic. Over the lifetime, 24219 publications have been published within this topic receiving 296416 citations. The topic is also known as: handoff.

Icar: an integrated cellular and ad hoc relaying system

Abstract: The cellular concept was introduced for wireless communication to address the problem of having scarce frequency resource. It is based on the sub-division of geographical area to be covered by the network into a number of smaller areas called cells. Frequency reuse in the cells far away from each other increases system’s capacity. But at the same time, the cell boundaries prevent the channel resource of a system to be fully available for users. No access to Data Channels (or DCHs) in other cell by the mobile host (or MH) limits the channel efficiency and consequently the system capacity. In this dissertation, we propose a new wireless system architecture based on the integration of cellular and modern ad hoc relaying technologies, called iCAR. It can efficiently balance traffic loads and share channel resource between cells by using Ad hoc relaying stations (ARSs) to relay traffic from one cell to another dynamically. This not only increases the system’s capacity costeffectively, but also reduces transmission power for mobile hosts and extends system coverage. We analyze the system performance in terms of the call blocking probability and queuing delay using multi-dimensional Markov chains for the new call requests and the call dropping probability for handoff requests, and verify the analytical results via simulations. Our results show that with a limited number of ARSs and some increase in the signaling overhead (as well as hardware complexity), the call blocking/dropping probability in a congested cell as well as the overall system can be reduced. We also propose a seed-growing approach for ARS placement, and discuss the upper bound on the number of seed ARSs needed in the system. In order to quantitatively evaluate ARS placement strategies, we introduce the concept of a new performance metric called quality of (ARS) coverage (QoC) for the comparison of various ARS placement strategies, and propose three rules of thumb as guidelines for cost-effective ARS placement in iCAR. Furthermore, we propose the signaling and routing protocols for establishing QoS guaranteed connections for IP traffic in iCAR. In particular, we discuss how a relaying route between a MH and a BTS in a nearby cell can be established via ARSs, and evaluate the performance of the protocols in terms of request rejection rate and signaling overhead through simulations. In addition, we propose a novel concept called “managed mobility” and address the ARS mobility management in iCAR.

Proactive seamless service provisioning in mobile networks through transferring of application context

Abstract: A method for supporting relocation of an IP session during a network layer handover in a mobile communication system. In the method, application context information indicating activities that are advantageously executed pro-actively before the network layer handover is sent. The indicated activities are then pro-actively executed in a receiving network node. An advantage of the method and arrangement of the invention is that the pro-active actions, including pre-allocation of some critical resources for seamless handover of an ongoing IP session, facilitate timely implementation of the activities required for handing over an IP session, and/or selection of a target access router.

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.