Handover

About: Handover is a(n) research topic. Over the lifetime, 24219 publication(s) have been published within this topic receiving 296416 citation(s). The topic is also known as: handoff.

Comments on "Teletraffic model and performance analysis for cellular mobile radio telephone systems with prioritized and nonprioritized handoff procedures"

Abstract: A traffic model and analysis for cellular mobile radio telephone systems with handoff are described. Three schemes for call traffic handling are considered. One is nonprioritized and two are priority oriented. Fixed channel assignment is considered. In the nonprioritized scheme the base stations make no distinction between new call attempts and handoff attempts. Attempts which find all channels occupied are cleared. In the first priority scheme considered, a fixed number of channels in each cell are reserved exclusively for handoff calls. The second priority scheme employs a similar channel assignment strategy, but, additionally, the queueing of handoff attempts is allowed. Appropriate analytical models and criteria are developed and used to derive performance characteristics. These show, for example, blocking probability, forced termination probability, and fraction of new calls not completed, as functions of pertinent system parameters. General formulas are given and specific numerical results for nominal system parameters are presented.

Fast Handovers for Mobile IPv6

Abstract: Mobile IPv6 enables a Mobile Node to maintain its connectivity to the Internet when moving from one Access Router to another, a process referred to as handover. During handover, there is a period during which the Mobile Node is unable to send or receive packets because of link switching delay and IP protocol operations. This "handover latency" resulting from standard Mobile IPv6 procedures, namely movement detection, new Care of Address configuration, and Binding Update, is often unacceptable to real-time traffic such as Voice over IP. Reducing the handover latency could be beneficial to non-real- time, throughput-sensitive applications as well. This document specifies a protocol to improve handover latency due to Mobile IPv6 procedures. This document does not address improving the link switching latency. This memo defines an Experimental Protocol for the Internet community.

An empirical analysis of the IEEE 802.11 MAC layer handoff process

Abstract: IEEE 802.11 based wireless networks have seen rapid growth and deployment in the recent years. Critical to the 802.11 MAC operation, is the handoff function which occurs when a mobile node moves its association from one access point to another. In this paper, we present an empirical study of this handoff process at the link layer, with a detailed breakup of the latency into various components. In particular, we show that a MAC layer function - probe is the primary contributor to the overall handoff latency. In our study, we observe that the latency is significant enough to affect the quality of service for many applications (or network connections). Further we find variations in the latency from one hand-off to another as well as with APs and STAs used from different vendors. Finally, we discuss optimizations on the probe phase which can potentially reduce the probe latency by as much as 98% (and a minimum of 12% in our experiments). Based on the study, we draw some guidelines for future handoff schemes.

Traffic Model and Performance Analysis for Cellular Mobile Radio Telphone Systems with Prioritized and Non-Prioritized Handoff Procedures.

Abstract: A traffic model and analysis for cellular mobile radio telephone systems with handoff are described. Three schemes for call traffic handling are considered. One is nonprioritized and two are priority oriented. Fixed channel assignment is considered. In the nonprioritized scheme the base stations make no distinction between new call attempts and handoff attempts. Attempts which find all channels occupied are cleared. In the first priority scheme considered, a fixed number of channels in each cell are reserved exclusively for handoff calls. The second priority scheme employs a similar channel assignment strategy, but, additionally, the queueing of handoff attempts is allowed. Appropriate analytical models and criteria are developed and used to derive performance characteristics. These show, for example, blocking probability, forced termination probability, and fraction of new calls not completed, as functions of pertinent system parameters. General formulas are given and specific numerical results for nominal system parameters are presented.

Vertical handoffs in wireless overlay networks

Abstract: No single wireless network technology simultaneously provides a low latency, high bandwidth, wide area data service to a large number of mobile users. Wireless Overlay Networks – a hierarchical structure of room-size, building-size, and wide area data networks – solve the problem of providing network connectivity to a large number of mobile users in an efficient and scalable way. The specific topology of cells and the wide variety of network technologies that comprise wireless overlay networks present new problems that have not been encountered in previous cellular handoff systems. We have implemented a vertical handoff system that allows users to roam between cells in wireless overlay networks. Our goal is to provide a user with the best possible connectivity for as long as possible with a minimum of disruption during handoff. Results of our initial implementation show that the handoff latency is bounded by the discovery time, the amount of time before the mobile host discovers that it has moved into or out of a new wireless overlay. This discovery time is measured in seconds: large enough to disrupt reliable transport protocols such as TCP and introduce significant disruptions in continuous multimedia transmission. To efficiently support applications that cannot tolerate these disruptions, we present enhancements to the basic scheme that significantly reduce the discovery time without assuming any knowledge about specific channel characteristics. For handoffs between room-size and building-size overlays, these enhancements lead to a best-case handoff latency of approximately 170 ms with a 1.5% overhead in terms of network resources. For handoffs between building-size and wide-area data networks, the best-case handoff latency is approximately 800 ms with a similarly low overhead.