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Improving Handover Performance in Wireless Mobile Networks  [PDF]
Saied M. Abd El-Atty,Konstantinos Lizos
International Journal of Computer Science Issues , 2012,
Abstract: In this paper, we propose an enhanced packet scheduling scheme to favour UEs that experienced handover (HO) in wireless mobile networks. The main idea of the proposed scheme is not only prioritized the HO connections at the CAC level but also prioritized the HO connections at the scheduler level. At the CAC level, a guard code scheme favours HO calls over new calls. At the scheduler level, a Packet Scheduler based-HandOver Class (PS-HOC) scheme makes use of the elapsed time of HO connections to classify the HO requests into prioritized HO and non-prioritized HO calls. Further, PS-HOC sorts the connections based on their delay sensitivity and their channel quality. The performance of the proposed scheme is compared with delay driven scheduler (DDS) scheme in terms of average packet delay, average queue size and average packet dropping rate. The simulation results show the effectiveness of our proposed scheme.
An Optimized Handover Scheme with Movement Trend Awareness for Body Sensor Networks  [PDF]
Wen Sun,Zhiqiang Zhang,Lianying Ji,Wai-Choong Wong
Sensors , 2013, DOI: 10.3390/s130607308
Abstract: When a body sensor network (BSN) that is linked to the backbone via a wireless network interface moves from one coverage zone to another, a handover is required to maintain network connectivity. This paper presents an optimized handover scheme with movement trend awareness for BSNs. The proposed scheme predicts the future position of a BSN user using the movement trend extracted from the historical position, and adjusts the handover decision accordingly. Handover initiation time is optimized when the unnecessary handover rate is estimated to meet the requirement and the outage probability is minimized. The proposed handover scheme is simulated in a BSN deployment area in a hospital environment in UK. Simulation results show that the proposed scheme reduces the outage probability by 22% as compared with the existing hysteresis-based handover scheme under the constraint of acceptable handover rate.
A Velocity-Adaptive Handover Scheme for Mobile WiMAX  [PDF]
Caiyong HAO, Hongli LIU, Jie ZHAN
Int'l J. of Communications, Network and System Sciences (IJCNS) , 2009, DOI: 10.4236/ijcns.2009.29101
Abstract: Mobile WiMAX is a wireless networking system based on the IEEE 802.16e standard. In order to support mobile, some kinds of handover schemes must be adopted, and the hard handover is defined as mandatory. Since the data transmission should be paused during the hard handover process, it causes handover delay in mobile communication. The handover delay makes severe degradation in system performance when implemented in real-time applications such as IPTV and VoIP. The existing draft standard considers only the received signal strength when deciding handover initiation. However, the velocity factor also has an important influence on handover initiation and can not be neglected. To deal with these problems, this article proposes a velocity-adaptive handover scheme. This scheme adopts dynamic handover threshold according to different velocity to skip some unnecessary handover stages, reduces handover delay and enhances the network resource utilization. The simulation result and performance analysis validate the efficiency of the proposed scheme.
An Importance Sampling Scheme on Dual Factor Graphs. II. Models with Strong Couplings  [PDF]
Mehdi Molkaraie
Physics , 2014,
Abstract: We consider the problem of estimating the partition function of the two-dimensional ferromagnetic Ising and Potts models in an external magnetic field. The estimation is done via importance sampling in the dual of the Forney factor graph representing the models. We present importance sampling schemes that can efficiently compute an estimate of the partition function in a wide range of model parameters. Emphasis is on models in which a subset of the coupling parameters is strong.
A Cost-Based Adaptive Handover Hysteresis Scheme to Minimize the Handover Failure Rate in 3GPP LTE System  [cached]
Lee Doo-Won,Gil Gye-Tae,Kim Dong-Hoi
EURASIP Journal on Wireless Communications and Networking , 2010,
Abstract: We deal with a cost-based adaptive handover hysteresis scheme for the horizontal handover decision strategies, as one of the self-optimization techniques that can minimize the handover failure rate (HFR) in the 3rd generation partnership project (3GPP) long-term evolution (LTE) system based on the network-controlled hard handover. Especially, for real-time operation, we propose an adaptive hysteresis scheme with a simplified cost function considering some dominant factors closely related to HFR performance such as the load difference between the target and serving cells, the velocity of user equipment (UE), and the service type. With the proposed scheme, a proper hysteresis value based on the dominant factors is easily obtained, so that the handover parameter optimization for minimizing the HFR can be effectively achieved. Simulation results show that the proposed scheme can support better HFR performance than the conventional schemes.
An Importance Sampling Scheme on Dual Factor Graphs. I. Models in a Strong External Field  [PDF]
Mehdi Molkaraie
Statistics , 2014,
Abstract: We propose an importance sampling scheme to estimate the partition function of the two-dimensional ferromagnetic Ising model and the two-dimensional ferromagnetic $q$-state Potts model, both in the presence of an external magnetic field. The proposed scheme operates in the dual Forney factor graph and is capable of efficiently computing an estimate of the partition function under a wide range of model parameters. In particular, we consider models that are in a strong external magnetic field.
The CrMES scheme as an alternative to Importance Sampling: The tail regime of the order-parameter distribution  [PDF]
Anastasios Malakis,Nikolaos G. Fytas
Physics , 2005, DOI: 10.1016/j.physa.2006.01.018
Abstract: We review the recently developed critical minimum energy-subspace (CrMES) technique. This scheme produces an immense optimization of popular algorithms, such as the Wang-Landau (WL) and broad histogram methods, by predicting the essential part of the energy space necessary for the estimation of the critical behavior and provides a new route of critical exponent estimation. A powerful and efficient CrMES entropic sampling scheme is proposed as an alternative to the traditional importance sampling methods. Utilizing the WL random walk process in the dominant energy subspace (CrMES-WL sampling) and using the WL approximation of the density of states and appropriate microcanonical estimators we determine the magnetic properties of the 2D Ising model. Updating $(E,M)$ histograms during the high level WL-iterations, we provide a comprehensive alternative scheme to the Metropolis algorithm and by applying this procedure we present a convincing analysis for the far tail regime of the order-parameter probability distribution.
An accelerating handover process scheme for IEEE 802.16j multi-hop relay networks
Jau-Yang Chang
EURASIP Journal on Wireless Communications and Networking , 2013, DOI: 10.1186/1687-1499-2013-45
Abstract: IEEE 802.16j multi-hop relay network systems provide the mobile wireless communication environment. In such network systems, the handover scanning procedure allows a mobile station (MS) to obtain the information about the handover target base stations (BSs) or relay stations (RSs). The network systems need more time to negotiate the association parameters and to handle scanning the BSs and the RSs when the number of BS and RS increases. It results in more overhead for the handover scanning procedure. In order to accelerate the handover process and reduce the transmission interruption, efficient handover scanning procedure schemes and corresponding algorithms must be developed and designed. A novel relative angle computing algorithm is proposed in this article to accelerate the handover process by taking into account the moving behavior of the MS, and the distances among the MS, the RS, and the BS. The main idea of this algorithm is to reduce the management information overhead and to estimate the potential moving path of the MS in the wireless mobile communication networks. By using the proposed scheme, we eliminate the unnecessary associations and scanning intervals, and reduce the handover scanning procedure efficiently. Simulation result demonstrate the superior performance of our proposed scheme and its ability to strike the appropriate performance in the handover overhead and the message delay for IEEE 802.16j multi-hop relay network systems.
Analysis of WIMAX Handover  [PDF]
Rambir Joon,Sandeep,Manveen Singh Chadha
International Journal of Soft Computing & Engineering , 2012,
Abstract: WIMAX is Wireless Interoperability for Microwave Access. It is a telecommunication technology that provides wireless data over long distances in several ways, from point-to-point links to full mobile cellular type access. The main consideration of Mobile Wimax is to achieve seamless handover such that there is no loss of data. In Wimax both mobile station (MS) and base station (BS) scans the neighbouring base stations for selecting the best base station for a potential handover. Two types of handovers in wimax are: Hard handover (break before make) and Soft handover (make before break). To avoid data loss during handover we have considered soft handovers in this paper. We have proposed a technique to select a base station for potential soft handover in Wimax. We have developed a base station selection procedure that will optimize the soft handover such that there is no data loss; handover decision is taken quickly and thus improving overall handover performance. We will compare the quality of service with hard handover and soft handover. We have analysed the proposed technique with an existing scheme for soft handover in Wimax with simulation results.
Handover Call Admission Control for Mobile Femtocells with Free-Space Optical and Macrocellular Backbone Networks  [PDF]
Mostafa Zaman Chowdhury,Nirzhar Saha,Sung Hun Chae,Yeong Min Jang
Computer Science , 2014, DOI: 10.7236/JASC2012.1.1.1
Abstract: The deployment of mobile femtocellular networks can enhance the service quality for the users inside the vehicles. The deployment of mobile femtocells generates a lot of handover calls. Also, numbers of group handover scenarios are found in mobile femtocellular network deployment. The ability to seamlessly switch between the femtocells and the macrocell networks is a key concern for femtocell network deployment. However, until now there is no effective and complete handover scheme for the mobile femtocell network deployment. Also handover between the backhaul networks is a major concern for the mobile femtocellular network deployment. In this paper, we propose handover control between the access networks for the individual handover cases. Call flows for the handover between the backhaul networks of the macrocell-to-macrocell case are proposed in this paper. We also propose the link switching for the FSO based backhaul networks. The proposed resource allocation scheme ensures the negligible handover call dropping probability as well as higher bandwidth utilization.
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