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Journal ArticleDOI

Improvement of Handoff Latency by GPS based Handoff Technique

31 Jul 2011-International Journal of Computer Applications (Foundation of Computer Science (FCS))-Vol. 25, Iss: 4, pp 14-21
TL;DR: This paper proposes a better scanning mechanism to reduce handoff latency and uses GPS to determine the direction of velocity of the MN as well as position and reduces the time to find the closest and best AP among all neighbor APs.
Abstract: Presently IEEE 802.11b based wireless networks are being widely used in various fields like personal as well as business applications. Handoff is a critical issue in IEEE 802.11b based wireless networks. When a mobile node (MN) moves away from the range of its current access point (AP) it needs to perform a link layer handoff. This causes data loss and interruption in communication. According to IEEE 802.11b link layer2 (L2) handoff consists of three phases - scanning, authentication and re,association. Scanning process delay is 90% of the total handoff delay. So in this paper we propose a better scanning mechanism to reduce handoff latency. Using GPS we determine the direction of velocity of the MN as well as position. It reduces the time to find the closest and best AP among all neighbor APs. This process effectively reduces the handoff latency.

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Citations
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Proceedings ArticleDOI
31 Dec 2012
TL;DR: This paper implements a new handoff scheme which is applicable for both regular and irregular motion of MS, and simulation results show the effectiveness of the proposed scheme in practical field.
Abstract: In wireless communication, handoff has become an important topic of research. A mobile station (MS) requires handoff when it travels out of the coverage area of its current access point (AP) and tries to associate with another AP. But handoff failure probability provides a serious barrier for such services to be made available to mobile platforms. Throughout the last few years plenty of research had been done to reduce handoff failure probability, whereas very few of them can be applied for an irregular (haphazard) motion of MS. In this paper, we are going to implement a new handoff scheme which is applicable for both regular and irregular motion of MS. We will find the minimum time interval (T) that the MS should stay within the handoff region (the particular area within a cell where the handoff is initiated and performed). We will repeat the scanning process number of times at different points of MS trajectory within the handoff region until the total scanning time exceeds the fixed time interval (T) and by doing so we can find out the most significant AP. Our simulation results show the effectiveness of our proposed scheme in practical field.

2 citations

Proceedings ArticleDOI
31 Dec 2012
TL;DR: A new scanning technique where the hexagonal cell is divided in three angular segments and for each segment two neighbour BSs are reserved for handover, which shows the effectiveness of the proposed scheme in practical field.
Abstract: In wireless & mobile communication the mobility management technique is an important issue of research. To fulfill the criteria of the all time connectivity, the mobile station (MS) should be connected with a base station (BS) during its operating mode, irrespective of its mobility. When a MS travels within the cell, no special technique is required to maintain its connectivity. But when a MS travels out of the coverage area of its current BS and tries to associate with another BS, a delay occurs during the handover of connection which leads to a failure of connection. Throughout the last few years plenty of researches had been done to reduce this handover delay by reducing the scanning delay as the scanning process causes ninety percent of the total handover delay. In this paper, we propose a new scanning technique where the hexagonal cell is divided in three angular segments and for each segment two neighbour BSs are reserved for handover. MS will measure its distance from the reserved BSs at fixed time intervals and the handover of connection will be performed to the nearest BS when the handover will be required. Our simulation results show the effectiveness of our proposed scheme in practical field.

1 citations

References
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Journal ArticleDOI
TL;DR: This work has implemented a vertical handoff system that allows users to roam between cells in wireless overlay networks and presents enhancements to the basic scheme that significantly reduce the discovery time without assuming any knowledge about specific channel characteristics.
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.

756 citations


"Improvement of Handoff Latency by G..." refers background in this paper

  • ...11b based wireless and mobile networks [5], also called Wi-Fi commercially, are experiencing a very fast growth upsurge and are being widely deployed for providing variety of services as it is cheap, and allows anytime, anywhere access to network data....

    [...]

Journal ArticleDOI
TL;DR: In this article, the current state of the art for mobility management in next-generation all-IP-based wireless systems is presented, and the previously proposed solutions based on different layers are reviewed, and their qualitative comparisons are given.
Abstract: Next-generation wireless systems are envisioned to have an IP-based infrastructure with the support of heterogeneous access technologies. One of the research challenges for next generation all-IP-based wireless systems is the design of intelligent mobility management techniques that take advantage of IP-based technologies to achieve global roaming among various access technologies. Next-generation wireless systems call for the integration and interoperation of mobility management techniques in heterogeneous networks. In this article the current state of the art for mobility management in next-generation all-IP-based wireless systems is presented. The previously proposed solutions based on different layers are reviewed, and their qualitative comparisons are given. A new wireless network architecture for mobility management is introduced, and related open research issues are discussed in detail.

672 citations

Book
02 Oct 2000
TL;DR: Lin and Chlamtac use a unique sustained example approach to teach how PCS concepts apply to real network operation in chapters on network signaling, mobility, security/handoff, and mobile prepaid services.
Abstract: From the Publisher: This book gives network engineers and managers a window on the world of wireless and mobile networks, from the enabling technologies and protocols to creating and managing mobile services." "Lin and Chlamtac use a unique sustained example approach to teach you how PCS concepts apply to real network operation. For example, they use location update to illustrate concepts in chapters on network signaling, mobility, security/handoff, and mobile prepaid services.

465 citations

Proceedings ArticleDOI
07 Mar 2004
TL;DR: A novel and efficient data structure, neighbor graphs, is described, which dynamically captures the mobility topology of a wireless network as a means for prepositioning the station's context ensuring that the station’s context always remains one hop ahead.
Abstract: User mobility in wireless data networks is increasing because of technological advances, and the desire for voice and multimedia applications. These applications, however, require fast handoffs between base stations to maintain the quality of the connections. Previous work on context transfer for fast handoffs has focused on reactive methods, i.e. the context transfer occurs after the mobile station has associated with the next base station or access router. In this paper, we describe the use of a novel and efficient data structure, neighbor graphs, which dynamically captures the mobility topology of a wireless network as a means for prepositioning the station's context ensuring that the station's context always remains one hop ahead. From experimental and simulation results, we find that the use of neighbor graphs reduces the layer 2 handoff latency due to reassociation by an order of magnitude from 15.37ms to 1.69ms, and that the effectiveness of the approach improves dramatically as user mobility increases.

322 citations

Journal ArticleDOI
TL;DR: The simulation results show that by controlling the total traffic rate, the original 802.11 protocol can support strict QoS requirements, such as those required by voice over Internet protocol (VoIP) or streaming video, and at the same time achieve high channel utilization.
Abstract: This paper studies an important problem in the IEEE 802.11 distributed coordination function (DCF)-based wireless local area network (WLAN): how well can the network support quality of service (QoS). Specifically, this paper analyzes the network's performance in terms of maximum protocol capacity or throughput, delay, and packet loss rate. Although the performance of the 802.11 protocol, such as throughput or delay, has been extensively studied in the saturated case, it is demonstrated that maximum protocol capacity can only be achieved in the nonsaturated case and is almost independent of the number of active nodes. By analyzing packet delay, consisting of medium access control (MAC) service time and waiting time, accurate estimates were derived for delay and delay variation when the throughput increases from zero to the maximum value. Packet loss rate is also given for the nonsaturated case. Furthermore, it is shown that the channel busyness ratio provides precise and robust information about the current network status, which can be utilized to facilitate QoS provisioning. The authors have conducted a comprehensive simulation study to verify their analytical results and to tune the 802.11 to work at the optimal point with maximum throughput and low delay and packet loss rate. The simulation results show that by controlling the total traffic rate, the original 802.11 protocol can support strict QoS requirements, such as those required by voice over Internet protocol (VoIP) or streaming video, and at the same time achieve high channel utilization.

278 citations


"Improvement of Handoff Latency by G..." refers background in this paper

  • ...Three strategies have been proposed to detect the need for hand off[2]: 1....

    [...]