157 research outputs found
Safetynet version 2, a packet error recovery architecture for vertical handoffs
Mobile devices are connecting to the Internet through an increasingly heterogeneous network environment. This connectivity via multiple types of wireless networks allows the mobile devices to take advantage of the high speed and the low cost of wireless local area networks and the large coverage of wireless wide area networks. To maximize the benefits from these complementing characteristics, the mobile devices need to be able to switch seamlessly between the different network types. However, the switch between the technologies, also known as a vertical handoff, often results in significant packet loss and degradation of connectivity due to handoff delay and also increased packet loss rate on the border of the coverage area of the networks. In our previous work, we have proposed an inter technology mobility management architecture which addresses the packet losses using selective resending of packets lost during the handoff period. In this paper, we extend the architecture to address packet losses due to wireless errors more efficiently by taking advantage of erasure codes to form redundancy packets. We propose to send these redundancy packets over both links. We show that this proposal reduces both the chances of packet loss and the buffering requirements of the original Safetynet scheme
A packet error recovery scheme for vertical handovers mobility management protocols
Mobile devices are connecting to the Internet through an increasingly heterogeneous network environment. This connectivity via multiple types of wireless networks allows the mobile devices to take advantage of the high speed and the low cost of wireless local area networks and the large coverage of wireless wide area networks. In this context, we propose a new handoff framework for switching seamlessly between the different network technologies by taking advantage of the temporary availability of both the old and the new network technology through the use of an "on the fly" erasure coding method. The goal is to demonstrate that our framework, based on a real implementation of such coding scheme, 1) allows the application to achieve higher goodput rate compared to existing bicasting proposals and other erasure coding schemes;
2) is easy to configure and as a result 3) is a perfect candidate to ensure the reliability of vertical handovers mobility management protocols. In this paper, we present the implementation of such framework and show that our proposal allows to maintain the TCP goodput(with a negligible transmission overhead) while providing in a timely manner a full reliability in challenged conditions
A packet error recovery scheme for vertical handovers mobility management protocols
Mobile devices are connecting to the Internet through an increasingly heterogeneous network environment. This connectivity via multiple types of wireless networks allows the mobile devices to take advantage of the high speed and the low cost of wireless local area networks and the large coverage of wireless wide area networks. In this context, we propose a new handoff framework for switching seamlessly between the different network technologies by taking advantage of the temporary availability of both the old and the new network technology through the use of an âon the flyâ erasure coding method. The goal is to demonstrate that our framework, based on a real implementation of such coding scheme, 1) allows the application to achieve higher goodput rate compared to existing bicasting proposals and other erasure coding schemes; 2) is easy to configure and as a result 3) is a perfect candidate to ensure the reliability of vertical handovers mobility management protocols. In this paper, we present the implementation of such framework and show that our proposal allows to maintain the TCP goodput (with a negligible transmission overhead) while providing in a timely manner a full reliability in challenged conditions
Optimization of Vertical Handover Performance Using Elimination Based MCDM Algorithm
In heterogeneous networks environment, Vertical Handover Decision (VHD) algorithms help mobile terminals to choose the best network between all the available networks. VHD algorithms provide the QoS to a wide range of applications anywhere at any time. In this paper, a generic and novel solution to solve the Vertical Handover (VHO) problem has been developed. This solution contains two major subsystems: The first subsystem is called elimination system. Elimination system is received the different VHO criteria such as received signal strength, network load balancing and mobile station speed from the different available networks. After that, the inappropriate alternatives are eliminated based on the elimination conditions. The second subsystem is a Multiple Criteria Decision Making (MCDM) system that chooses the appropriate alternative from the remaining alternatives of the elimination phase. For simulate the proposed solution, MATLAB program is used with aid of MATLAB-based toolbox that is called RUdimentary Network Emulator (RUNE). The combination of both subsystems avoids the processing delay caused by unnecessary computation over available networks which do not ensure connection performance. Also it avoids increasing the number of unnecessary handovers, ping pong effect, blocking rate and dropping rate by reducing the handover failure rate. A performance analysis is done and results are compared to other reference algorithms. These results demonstrate a significant improvement over other reference algorithms in terms of handover failure rate, percentage of satisfied users, and percentage of the low cost network usage
An Overview of Vertical Handoff Decision Algorithms in NGWNs and a new Scheme for Providing Optimized Performance in Heterogeneous Wireless Networks
Because the increasingly development and use of wireless networks and mobile technologies, was implemented the idea that users of mobile terminals must have access in different wireless networks simultaneously. Therefore one of the main interest points of Next Generation Wireless Networks (NGWNs), refers to the ability to support wireless network access equipment to ensure a high rate of services between different wireless networks. To solve these problems it was necessary to have decision algorithms to decide for each user of mobile terminal, which is the best network at some point, for a service or a specific application that the user needs. Therefore to make these things, different algorithms use the vertical handoff technique. Below are presented a series of algorithms based on vertical handoff technique with a classification of the different existing vertical handoff decision strategies, which tries to solve these issues of wireless network selection at a given time for a specific application of an user. Based on our synthesis on vertical handoff decision strategies given below, we build our strategy based on solutions presented below, taking the most interesting aspect of each one.Vertical Handoff, Genetic Algorithms, Fuzzy Logic, Neural Networks, AHP
Vertical Handoff Decision Algorithms Using Fuzzy Logic
This paper reports on the design and implementation of multi-criteria vertical handoff decision algorithms in a heterogeneous wireless wide area network (WWAN) and a wireless local area network (WLAN) environment. An IP-centric Field Workforce Automation" project aims to ensure free movement of field workers between networks while always connected in an IP mode, and to allow a user to use one device across many types of networks. This requires the integration and interoperation of heterogeneous networks, and the provision of seamless vertical handoff. We use a fuzzy logic inference system to process a multi-criteria vertical handoff decision metrics.
A network mobility management architecture for a heteregeneous network environment
Network mobility management enables mobility of personal area networks and vehicular networks across heterogeneous access networks using a Mobile Router. This dissertation presents a network mobility management architecture for minimizing the impact of handoffs on the communications of nodes in the mobile network. The architecture addresses mobility in legacy networks without infrastructure support, but can also exploit infrastructure support for improved handoff performance. Further, the proposed architecture increases the efficiency of communications of nodes in the mobile network with counter parts in the fixed network through the use of caching and route optimization. The performance and costs of the proposed architecture are evaluated through empirical and numerical analysis. The analysis shows the feasibility of the architecture in the networks of today and in those of the near future.Verkkojen liikkuuvudenhallinta mahdollistaa henkilökohtaisten ja ajoneuvoihin asennettujen verkkojen liikkuvuuden heterogeenisessÀ verkkoympÀristössÀ kÀyttÀen liikkuvaa reititintÀ. TÀmÀ vÀitöskirja esittÀÀ uuden arkkitehtuurin verkkojen liikkuvuudenhallintaan, joka minimoi verkonvaihdon vaikutuksen pÀÀtelaitteiden yhteyksiin.
Vanhoissa verkoissa, joiden infrastruktuuri ei tue verkkojen liikkuvuutta, verkonvaihdos tÀytyy hallita liikkuvassa reitittimessa. Standardoitu verkkojen liikkuvuudenhallintaprotokolla NEMO mahdollistaa tÀmÀn kÀyttÀen ankkurisolmua kiinteÀssÀ verkossa pakettien toimittamiseen pÀÀtelaitteiden kommunikaatiokumppaneilta liikkuvalle reitittimelle. NEMO:ssa verkonvaihdos aiheuttaa kÀynnissÀ olevien yhteyksien keskeytymisen yli sekunnin mittaiseksi ajaksi, aiheuttaen merkittÀvÀÀ hÀiriötÀ viestintÀsovelluksille.
EsitetyssÀ arkkitehtuurissa verkonvaihdon vaikutus minimoidaan varustamalla liikkuva reititin kahdella radiolla. KÀyttÀen kahta radiota liikkuva reititin pystyy suorittamaan verkonvaihdon keskeyttÀmÀttÀ pÀÀtelaitteiden yhteyksiÀ, mikÀli verkonvaihtoon on riittÀvÀsti aikaa. KÀytettÀvissa oleva aika riippuu liikkuvan reitittimen nopeudesta ja radioverkon rakenteesta. Arkkitehtuuri osaa myös hyödyntÀÀ infrastruktuurin tukea saumattomaan verkonvaihtoon. Verkkoinfrastruktuurin tuki nopeuttaa verkonvaihdosprosessia, kasvattaenmaksimaalista verkonvaihdos tahtia. TÀllöin liikkuva reitin voi kÀyttÀÀ lyhyen kantaman radioverkkoja, joiden solun sÀde on yli 80m, ajonopeuksilla 90m/s asti ilman, ettÀ verkonvaihdos keskeyttÀÀ pÀÀtelaitteiden yhteyksiÀ.
LisÀksi ehdotettu arkkitehtuuri tehostaa kommunikaatiota kÀyttÀen cache-palvelimia liikkuvassa ja kiinteÀssÀ verkossa ja optimoitua reititystÀ liikkuvien pÀÀtelaitteiden ja kiinteÀssÀ verkossa olevien kommunikaatiosolmujen vÀlillÀ. Cache-palvelinarkkitehtuuri hyödyntÀÀ vapaita radioresursseja liikkuvan verkon cache-palvelimen vÀlimuistin pÀivittÀmiseen. HeterogeenisessÀ verkkoympÀristossÀ cache-palvelimen pÀivitys suoritetaan lyhyen kantaman laajakaistaisia radioverkkoja kÀyttÀen. Liikkuvan reitittimen siirtyessÀ laajakaistaisen radioverkon peitealueen ulkopuolelle pÀÀtelaitteille palvellaan sisÀltöÀ, kuten www sivuja tai videota cache-palvelimelta, sÀÀstÀen laajemman kantaman radioverkon rajoitetumpia resursseja.
Arkkitehtuurissa kÀytetÀÀn optimoitua reititystÀ pÀÀtelaitteiden ja niiden kommunikaatiokumppaneiden vÀlillÀ. Optimoitu reititysmekanismi vÀhentÀÀ liikkuvuudenhallintaan kÀytettyjen protokollien langattoman verkon resurssien kulutusta. LisÀksi optimoitu reititysmekanismi tehostaa pakettien reititystÀ kÀyttÀen suorinta reittiÀ kommunikaatiosolmujen vÀlillÀ.
Esitetyn arkkitehtuurin suorituskyky arvioidaan empiirisen ja numeerisen analyysin avulla. Analyysi arvioi arkkitehtuurin suorituskykyÀ ja vertaa sitÀ aikaisemmin ehdotettuihin ratkaisuihin ja osoittaa arkkitehtuurin soveltuvan nykyisiin ja lÀhitulevaisuuden langattomiin verkkoihin.reviewe
Access Network Selection in Heterogeneous Networks
The future Heterogeneous Wireless Network (HWN) is composed of multiple Radio Access
Technologies (RATs), therefore new Radio Resource Management (RRM) schemes
and mechanisms are necessary to benefit from the individual characteristics of each RAT
and to exploit the gain resulting from jointly considering the whole set of the available
radio resources in each RAT. These new RRM schemes have to support mobile users
who can access more than one RAT alternatively or simultaneously using a multi-mode
terminal. An important RRM consideration for overall HWN stability, resource utilization,
user satisfaction, and Quality of Service (QoS) provisioning is the selection of the
most optimal and promising Access Network (AN) for a new service request. The RRM
mechanism that is responsible for selecting the most optimal and promising AN for a
new service request in the HWN is called the initial Access Network Selection (ANS).
This thesis explores the issue of ANS in the HWN. Several ANS solutions that attempt
to increase the user satisfaction, the operator benefits, and the QoS are designed, implemented,
and evaluated.
The thesis first presents a comprehensive foundation for the initial ANS in the H\VN.
Then, the thesis analyses and develops a generic framework for solving the ANS problem
and any other similar optimized selection problem. The advantages and strengths of the
developed framework are discussed. Combined Fuzzy Logic (FL), Multiple Criteria
Decision Making (MCDM) and Genetic Algorithms (GA) are used to give the developed
framework the required scalability, flexibility, and simplicity.
The developed framework is used to present and design several novel ANS algorithms
that consider the user, the operator, and the QoS view points. Different numbers of
RATs, MCDM tools, and FL inference system types are used in each algorithm. A
suitable simulation models over the HWN with a new set of performance evolution
metrics for the ANS solution are designed and implemented. The simulation results show
that the new algorithms have better and more robust performance over the random, the service type, and the terminal speed based selection algorithms that are used as reference
algorithms. Our novel algorithms outperform the reference algorithms in- terms of the
percentage of the satisfied users who are assigned to the network of their preferences and
the percentage of the users who are assigned to networks with stronger signal strength.
The new algorithms maximize the operator benefits by saving the high cost network
resources and utilizing the usage of the low cost network resources. Usually better
results are achieved by assigning the weights using the GA optional component in the
implemented algorithms
Mobility Management in 4G Networks
Over the past 25 years, the evolution of the internet and the advances of wireless technologies have made a tremendous impact on lifestyle of people around the world. Together, these two factors have changed the way people communicate, work, and get their entertainment. In order to be always best connected for various applications, the network selection procedure in heterogeneous multi-access environment during vertical handover decision is intended to choose the most suitable network for mobile user. In this paper, a performance study using the fuzzy logic concept is done and the integration of UMTS and WiMAX network is taken as an example to show that the proposed vertical handoff decision algorithm is able to determine when a handoff is required, and selects the best access network that is optimized to network conditions, quality of service requirements, received signal strength, bandwidth requirements and user preferences
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