Following coevals nomadic webs are expected to accomplish a high grade of inter-networking so that the nomadic users can truly experience omnipresent entree through exchanging between heterogenous webs. We mean that the device neither requires user intercession nor does it interrupt the bing session during the wireless exchanging procedure. IP based networking is the key to turn this vision into a world. Future clientele devices tend to be equipped with multiple web interfaces. Mobile devices that cater to one type of entree engineering have the ability to roll among webs of the same type are referred to as horizontal handoff. Seamless entree to services between assorted entree engineerings such as WLAN, WCDMA, Cellular webs, WiMAX etc, irrespective of the wireless engineering being used is referred as perpendicular handoff.
Furthermore, our proposed solution is a daemon attack to perpendicular handoff. We develop a devil that accomplishes the handoff procedure between assorted wireless interfaces back uping IP. This faculty addresses seamless, handoff determination & A ; interface choice jobs faced during the perpendicular handoff. The handoff can be achieved at the client devices and there is no demand of any handoff agents or waiters required. Linux being the fastest turning runing system for wireless devices and the flexibleness it offers for the developer makes it the most suited for the execution of this solution. This devil runs at the user degree and the consequences show that the handoff happens at less than 1ms.
Nowadays there is a gradual tendency towards utilizing non merely one radio web, but to use all interfaces available on a nomadic device. The calculation power and storage capableness on nomadic devices are increasing quickly, and together with new synergistic services this creates a demand for more bandwidth. To maintain path of this development, the usage of heterogenous webs has gained focus. Heterogeneous Networks means webs of different types. Alternatively of merely utilizing one type of web, it is desired to use all interfaces available on a device, and therefore take the one best suited for communicating. The challenge in this context will be to supply handoff without user interaction.
On most of the devices today wired and wireless LAN cards have become basic constituents, apart from back uping other wireless entree engineerings such as Bluetooth, GPRS etc. If these devices are to link to assorted webs and execute a uninterrupted informations transmittal whatever location they roam to, while exchanging from one web to another, technique of perpendicular handoff is needed.
WLAN, Bluetooth, GSM, WiMAX etc are the assorted complementary entree engineerings developed with service intended to provide to different subdivisions of nomadic users. Each of these engineerings has its ain diverse set of criterions, protocols and support homogenous web mobility in their ain manner. For illustration, a nomadic device can travel between Access Points of a WLAN or WiMAX, handoff occurs when there is motion between cells of the same web type. With the current substructure and the addition in heterogenous webs, it often possible to hold wireless entree of one type or another everyplace, yet there is non a individual strong architecture, which embraces all these engineerings and provides seamless interoperability between these disparate interfaces. Since these radio substructures have developed independently of each other, we now have to incorporate them in order to accomplish seamless roaming.
There are several cardinal issues that are associated with the execution of perpendicular handoff 1 ) Seamless Continuity 2 ) Handoff Decision & A ; 3 ) Interface Selection. First, we have to guarantee that the device makes a switch between hardware interfaces to link to the best available web. In our instance, whenever a connexion to a WLAN is available, we connect to it and exchange to the Cellular Network when beyond the available scope of the WLAN. Next, the shift between the webs has to be crystalline to the user. The wireless user should non hold to configure anything for the switch to happen. In the homogenous web handoff mechanism, the web substructure makes it possible for wireless devices to travel without interrupting the bing connexion. Similarly, heterogenous web exchanging should besides guarantee that the on-going session is maintained. We have to do certain that the shift is fast plenty so that the user connexion is kept integral at the TCP bed.
Existing devices can non integrate limitless figure of interfaces and so we restrict the experiment to hold two different webs interface cards 1 ) Ethernet NIC 2 ) WLAN NIC each holding the same IP reference. It is besides assumed that the proposed architecture besides suits different web interface cards back uping IP. We use a 2.6.32 version of the Linux Kernel that is suited for running on a Laptop or an embedded device with higher calculating power.
Today, there is a important tendency toward utilizing non merely one radio web, but to use all bearers available on a nomadic device. In add-on, for real-time applications like voice, it is desired to do a seamless alteration of web without user interaction. To maintain path of this development, the usage of heterogenous webs has gained focus. Alternatively of merely utilizing one type of web, it is desired to use all bearers available on a device, and therefore take the one best suited. Furthermore it is proposed an application-layer handover strategy for session continuity in heterogenous webs [ 3 ]
Conducting the handover procedure at a higher bed can supply supplying transparence to the heterogenous seamless handover. By that manner, efficient handover determinations for perpendicular handover are made with more figure of restraints that will take to high public presentation, handiness and low cost. Making this possible is by supplying Quality of Experience ( QoE ) and obtaining current information of the throughput by measurings in the web. Analyzing and construing the statistics collected through measurings are critical in footings of decision-making and to make up one’s mind when to execute perpendicular handover. This undertaking consists of the execution of measuring faculty in two different attacks ( Payload Dependent Approach and Payload Independent Approach ) that will supply these statistics to the storage faculty in PERIMETER undertaking. [ 1 ]
Now a yearss nomadic devices back up several interfaces although the protocol stack used in each interface tends to be interface specific at the lower beds. This limits the ability of a device to exchange back and Forth between webs as demand and chance dictates. As a measure towards supplying a more flexible handover substructure, this undertaking addresses the issue of incorporating heterogenous, nomadic ad-hoc webs that use different MAC bed protocols. The end is to supply an end-to-end communicating abstraction that hides heterogeneousness. [ 2 ]
Another solution is to present handoff waiters to recognize perpendicular handoff. In USHA [ 4 ] system, all nomadic hosts connect to the Internet with the aid of a handoff waiter, which is equipped with multiple web interfaces with heterogenous physical belongingss. Hence, nomadic hosts can pass on with the handoff waiter in assorted physical connexions. The IP tunneling technique ( IP encapsulation ) is used in USHA with the handoff waiter operation as one terminal and the nomadic host as the other. Upper bed communications are bounded to a practical interface – the tunnel interface, alternatively of physical interfaces. All informations packages are transmitted through this IP tunnel. When the handoff event occurs, the implicit in physical connexion of the practical tunnel is automatically switched to the new physical interface. In the interim, the nomadic host besides notifies the handoff waiter of its alteration in physical connexion. However, USHA tries to maintain the upper bed TCP connexion during the perpendicular handoff, and so the informations packages can merely be transmitted utilizing UDP connexions between nomadic hosts and the handoff waiter. This causes new jobs. In add-on, similar to the nomadic IP strategy, the handoff waiter may be overloaded, as the web graduated table is acquiring big.
Across heterogenous webs, when a user is in rolling province and still wants to keep all active Sessionss, an automatic handoff mechanism is needed to alter the communicating flow and the physical wireless interface in usage. This mechanism besides needs to turn to the issue that handoff to be achieved without altering the IP reference of the nomadic host device. Then, under an substructure web, the gateway should be notified of the handoff events so that it can set the communicating flow for the incoming packages. Furthermore, the handoff mechanism should be user unaware, so that the handoff procedure can be handled swimmingly.
Figure [ ] provides a high-ranking position of the Linux web stack. The top most beds is the application, which defines the users/clients of the web stack. The following bed, responsible for peer-to-peer communicating is the conveyance bed. Below the conveyance bed is the web bed, which is responsible for send oning packages to their finishs. At the underside of the stack is the nexus bed. The nexus bed refers to the device drivers supplying entree to the assorted physical bed mediums, such as Ethernet devices or WLAN devices etc [ 5 ] . Now, depending on the active device drivers the nexus bed chooses the NIC card through which packages have to be transmitted. This NIC card is bound till the session is completed. The job we face here is that during the perpendicular handoff at that place needs to be a exchanging between different NIC cards depending on the handiness of the active cards. Presently the Linux web stack doesnaa‚¬a„?t have a support for perpendicular handoff.
Our proposed solution is development of devil to accomplish perpendicular handoff. We develop a faculty model that accomplishes the handoff procedure between assorted wireless interfaces back uping IP. We integrate our handoff devil straight into the Linux meat. It consists of two sub faculties 1 ) Decision Maker 2 ) Interface Selector. First, the determination shaper faculty takes determinations when to execute a handoff. Second the interface picker chooses the best interface through which packages can be transmitted and received.
During the package transmittal, all the packages from the applications are directed to our perpendicular handoff faculty. These packages are so put frontward to the interface chosen by the interface picker faculty. Then the several packages are transmitted through this interface. But, when the determination shaper faculty suggests for a handoff, the interface picker sends an ARP package that contains the IP and MAC reference of the freshly selected interface to the immediate node. The immediate node will so update its ARP tabular array with the new MAC reference.
The hardware used in the apparatus is as follows:
Sony VAIO laptop running Ubuntu Linux 9.04
Kernel version 2.6.32
Supporting 2 Interfaces
Wireless local area network
Linksys WRT54G2 Accesspoint
Server running Ubuntu Linux 9.04
The most hard portion of the execution was the hardware apparatus and following through the meat codification, which involved a batch of clip dedicated to happening the right resources and happening the right constellation.
Conclusion & A ; Future Work
The proposed handoff procedure can be achieved straight at the client devices and there is no demand of any handoff agents or waiters required. This devil is wholly implemented at the user degree of the Linux operating system. Presently our proposed perpendicular handoff faculty is restricted to assorted physical interfaces holding the same IP reference. In our hereafter work, we will turn to the dynamic reference job faced during perpendicular handoff procedure. A practical interface bed will be introduced between the web bed & A ; the nexus bed and eventually incorporate into the bing Linux meat.