Presented By:
SuKyoung Lee*, Kotikalapudi Sriram Kyungsoo Kim¡, JongHyup Lee*, YoonHyuk Kim¡, and Nada GolmieÂ
Abstractâ€
There are currently heterogeneous wireless access networks. A large variety of applications utilizing these networks will demand features such as real-time, high-availability and even instantaneous high-bandwidth in some cases. Therefore, it is imperative for network service providers to make the best possible use of the combined resources of available heterogeneous networks for connection support. Thus, with regard to vertical handoff performance, there is a critical need for developing algorithms for connection management and optimal resource allocation for seamless mobility. In this paper, we develop a vertical handoff decision algorithm that enables a wireless access network to not only balance the overall load among all attachment points but also to maximize the collective battery lifetime of Mobile Nodes (MNs). Simulation results are also presented to demonstrate the efficacy of the proposed algorithms
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http://antd.nist.gov/~ksriram/vho_two_column.pdf
Please I need a code on handoff algorithm
Vertical Handover (McNair and Zhu, 2004), is a mechanism in which user maintains connection when switched from one WAN to another WAN technology (e.g., from WLAN to UMTS and vice versa (see Fig. 1). In IEEE, 2005 and Lee et al., 2009, VHO is different from conventional horizontal handover where the MT moves from one base station to another within the same network. In VHO, a session is seamlessly handed over to a new WAN in an interoperable region based on a criterion which evaluates the signal quality. The handover management procedures remain a widely studied issue in the case of heterogeneous network environment. In (Patowary, 2010), MTs should be able to move among these heterogeneous networks in a seamless manner. Various activities of working groups are currently under way such as IEEE 802.21 (I. 802.21, 2006), IETF MIP (Perkins, 2002), or 3GPP standards (3GPP, 2007). IEEE 802.21 supports a mobile-controlled handover (MCHO) scheme and MIP as its mobility management protocol. The details of network selection entity and the specification of handover policies that control handovers are outside the scope of the 802.21.
The objective of a VHO strategy is to guarantee QoS for a variety of applications. In general, the strategy can perform a complex decision criterion that combines large number of (QoS) metrics. The first VHO decision scheme, that considered multiple criteria policies, was proposed by Wang et al. (1999). It introduced a cost function to select the best available WAN based on three policy parameters (bandwidth, power consumption, and cost). Reference (Zhu and McNair, 2006) proposed also a multiservice VHO decision algorithm based on cost function. However, for more efficiency and taking into account more criteria, context-aware decision solution has inspired the authors in Ahmed et al., 2006, Hasswa et al., 2006 and Balasubramaniam and Indulska, 2004. In Hasswa et al., 2006 and Saaty, 1990, the authors designed a cross-layer architecture providing context-awareness, smart handover, and mobility control in a W-WAN to WLAN environment. They proposed a VHO decision, with a cost function-based solution, taking into account network characteristics and higher level parameters from transport and application layers. References (Ahmed et al., 2006, Balasubramaniam and Indulska, 2004 and Xu et al., 2010) are based on a multiple criteria decision-making algorithm, analytic hierarchy process (AHP). A more advanced multiple criteria decision algorithms are presented in Chan et al., 2001 and Chan et al., 2002, wherein the authors applied the concept of fuzzy logic (FL). They employ decision criteria such as user preferences, page link quality, cost, or QoS. Upon literature review, mobility prediction schemes in handoff procedure were found to be very critical in the handoff performance. The handoff procedure is typically based on the received RSS from the base station. There exist several models, schemes and algorithms for handoff procedure which is based on the RSS values as proposed in Chiu and Bassiouni, 2000, Pollini, 1996, Liu et al., 2008 and Taniuchi et al., 2009. These published methods are regularly based on hysteresis and threshold methods.
In this paper, we propose a comprehensive methodology for mobility-prediction based VHO scheme. In this respect, the proposed VHO algorithm considers the received SINR as its handoff criterion. Moreover, the handover process is split into number of phases: handover initiation decision which involves the decision to which point of attachment to execute the handover and its timing. Next is the radio page link transfer, which is the task of establishing links to the new point of attachment. This phase is based on the estimates of a number of significant QoS metrics that are seen to satisfy the basic requirements of a variety of applications. This paper is organized as follows; Section 3 outlines the SINR based VHO strategy. Section 4, presents a signal prediction model to predict future SINR evolution and enhances the handoff process. In Section 5, a set of QoS parameters necessary for handover is analytically formulated. Section 6, presents a network selection scheme with examples to validate its performance in Wi Fi, Wi MAX and UMTS networks. The research work carried out in this paper is concluded in Section 7.