Optimization of Vertical handoff Decision Process for Heterogenous Wireless Networks

Santosh.A, IJRIT-392 International Journal of Research in Information Technology

(IJRIT)

www.ijrit.com ISSN 2001-5569

Optimization of Vertical handoff Decision Process for Heterogenous Wireless Networks

Santosh.A

K.S Raghu Kumar

Student, Computer Science & Engineering Dept, VTU Professor, Computer Science & Engineering Dept, VTU

RYMEC, Cantonment Bellary RYMEC, Cantonment Bellary

1[email protected] 2[email protected]

Abstract— Handover is one of the approaches used to accomplish the service persistence in the Fourth Generation Wireless Networks .Smooth continuity has been the main goal in Fourth Generation Wireless Networks, when a mobile terminal is in extending area for service continuity Handover technique is mainly used while moving in the heterogeneous wireless networks seamless connectivity is the main challenge. Vertical handover is used as a technique to minimize the processing delay in heterogeneous wireless networks. In our paper work we are mainly concentrating on handover decision Phase and to minimize the processing delay in the period of handover

.

Keywords: Vertical handover (VHO), Horizontal handover (HHO).

1. INTRODUCTION

When a mobile terminal is switching its network form one to another then it is known as Heterogeneous network which has variety of air interfaces techniques there a handover techniques is used called Vertical Handover (VHO) .VHO is mainly used to support between different air interfaces techniques during internetwork movements.

Handover is used to switch the mobile user from existing network to another network [between the subnet cells of different wireless networks] of new type and the technique is used exclusively to select suitable network to continue the service to the mobile terminal after the Handover compilation with very low processing delay.

In the classic signal strength first method , when the connection point faces very low signal strength , it searches for another connection point where the signal strength is more and chooses it .The connection points are chosen wisely based on the number of nodes and the load on it .( because overall results like the energy consumption because of the load , if the load is more congestion in the traffic and the mobile node needs more time to send the packet thus energy consumption will be more thus the cost all will be more ) .the whole description above tells us about the Handover mechanism

Figure1.1 Handover Mechanism

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Handover mechanism is mainly of two categories, the first one is the Horizontal handover mechanism and the second one is the vertical handover mechanism as shown in the below

Figure 2.1 Vertical hanover versus horizontal handover

Horizontal handover is the technique in which the mobile user is switching between the networks and where the technology is of same type example WiMax to WiMax. Vertical handover is the technique where the mobile user is switching between the networks and technology may be of different type like LTE to Wi-Fi. So in our project we are speaking about the heterogeneous networks so we are using the vertical handover technique in our project.

Handover mechanisms can be divided into four different phases:

• Handover Initiation.

• Handover decision.

• System discovery.

• Handover execution.

• Hand over Initiation Phase: The handover process is changed by valueswhich are of critical type example link quality, signal strength and more.

• Handover Decision phase: Depending upon the quality of service of the mobile user the phase compares with the surrounding neighbour networks quality of service with this decision maker quality of service and takes the decision that the mobile user has to connect to which network accordingly.

• System discovery phase: It is used to decide which mobile user is detecting the neighbouring network and the quality of services offered by that network.

• Handover Execution phase: The phase is responsible for connection creation and termination as well as the security issues are addressed by this phase.

Figure 2.2 vertical handover decision block Diagram

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Figure 2.3 Handover Decision Phase Flow Graph

3. THE PROPOSED METHOD

Here we consider the enhanced handoff choice based on the following three criterions like the cost, traffic load and battery life and the handover choice is made by seeing one or more criterions taken together and the criterions are represented as α, β and γ . Seeing each of criterions in handoff decision is given as 1. For sample let us take the battery life is seen in handoff it is represented as α = 1 or else if it is not considered it is represented as α = 0

The following flow graph explains vertical handover algorithm in following way which can be more precisely understood and it can also be considered as proposed system flow graph. After an event from the Media independent handover vertical handoff decision algorithm has the task of identifying whether the mobile node is in the service of an access point or base station, If the received signal strength is the threshold range which is less than that of an access point, at that time the mobile node can be decided to be handed off as an access point or the base station. Bank on the discussions of the handoff parameters there are the following cases of handoff decisions:

Case 1: α≡1, β≡0 γ0≡: Handoff decision is taken only when the mobile node has maximized battery lifetime of the Mobile node.

Case 2: α≡0, β≡1 γ0≡: traffic load handoff decision is taken taking into the account of the traffic load present at the new attachment point and to balance the traffic load across the different attachment points.

Case 3: α≡0, β≡0 γ0≡: Decision is taken based on the load balancing conditions and battery lifetime criteria are satisfied.

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Case 5: α≡1, β≡1 γ1≡: Handoff decision is done only if all the above factors are satisfied.

Figure 3.1 Proposed systems optimized Flow Graph

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We come up with a cooperative development for vertical handoff decision for the attention of parameters like cost factor, battery life traffic load , now let us consider the parameters for improving efficiency for battery lifetime and balancing the load they stand for .

A developed formula based on the criteria’s like cost, balancing the load and batter ies given below

(X) –β

+ (X) - [γ ]

Opt −H: MaxC (α, β, ϒ)

From the above equation if α ≡ 0, β≡0, γ≡1 we take into account only cost If α ≡ 1, β≡1, γ≡1 we take into account cost, load and battery life time 3.2 algorithm Partial code in tcl script for Network simulator

#--- 1.Move next Region ---

$ns_ at 12.0 "nnode 14.0 0 0"

$ns_ at 12.1 "exec awk -f connection.awk temp NNode.tr"

$ns_ at 14.0 "source connection.tcl"

#--- 2.Move next Region ---

$ns_ at 25.0 "nnode 27.0 0 0"

$ns_ at 25.1 "exec awk -f connection.awk temp NNode.tr"

$ns_ at 27.0 "source connection.tcl"

#--- 3.Move next Region ---

$ns_ at 39.0 "nnode 41.0 0 0"

$ns_ at 39.1 "exec awk -f connection.awk temp NNode.tr"

$ns_ at 41.0 "source connection.tcl"

#--- Not Check VLR & HLR ---

#--- 1.Move next Region ---

$ns_ at 54.0 "nnode 56.0 1 0"

$ns_ at 54.1 "exec awk -f connection.awk temp NNode.tr"

$ns_ at 56.0 "source connection.tcl"

#--- 2.Move next Region ---

$ns_ at 70.0 "nnode 72.0 1 0"

$ns_ at 70.1 "exec awk -f connection.awk temp NNode.tr"

$ns_ at 72.0 "source connection.tcl"

$ns_ at 12.0 "nnode 14.0 0 0"

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$ns_ at 12.1 "exec awk -f connection.awk temp NNode.tr"

$ns_ at 14.0 "source connection.tcl"

#--- 2.Move next Region ---

$ns_ at 25.0 "nnode 27.0 0 0"

$ns_ at 25.1 "exec awk -f connection.awk temp NNode.tr"

$ns_ at 27.0 "source connection.tcl"

#--- 3.Move next Region ---

$ns_ at 39.0 "nnode 41.0 0 0"

$ns_ at 39.1 "exec awk -f connection.awk temp NNode.tr"

$ns_ at 41.0 "source connection.tcl"

#--- Not Check VLR & HLR ---

#--- 1.Move next Region ---

$ns_ at 54.0 "nnode 56.0 1 0"

$ns_ at 54.1 "exec awk -f connection.awk temp NNode.tr"

$ns_ at 56.0 "source connection.tcl"

#--- 2.Move next Region ---

$ns_ at 70.0 "nnode 72.0 1 0"

$ns_ at 70.1 "exec awk -f connection.awk temp NNode.tr"

$ns_ at 72.0 "source connection.tcl"

4 . Simulation Results in network simulator and Discussion

Figure 4.1 Energy consumption reduced in Hybrid or Heterogeneous wireless networks compared to ofdma relay networks

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Figure 4.3 Throughput is high in Hybrid networks or heterogeneous networks when compared to other cellular network technology

The simulation code vertical handover is just an sample experiment done which is simple and yet has very useful results so the proposed method also produces the results in similar manner which bring the cost down , and mainly provide mobility to the users of network with high speed and low cost and network service is available to the network user in which ever region

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5. CONCLUSION

The recommended vertical handoff decision algorithm escalates the battery life time of the mobile nodes in the heterogeneous networks ,the bundle is fairly managed on the network near the attachment points and greatly reduces the cost at the cellular network level also for the service provider by comparing analytically with the results of the strongest signal first method . The proposed method is better suited for the present day cellular networks.

6. REFERENCES

[1] M.Buddhikot,G. Chandramenon, S. Han,Y.W. Lee, S.Miller, and L. Salgarellim,“Integration of 802.11 and third-generation wireless data networks”, in Proceeding, IEEE INFOCOM, San Francisco, CA, Mar. 2003,vol. 1, pp. 503-512.

[2] A. K. Salkintzis, “Interworking techniques and architectures for WLAN/3G toward 4G mobile Data networks”, IEEE Wireless communication, vol. 11, no. 3, pp. 50-61. June 2004

[3] V. Varma, S. Ramesh, K. Wong, and J.Friedhoffer,“Mobility management in integrated UMTS/WLAN networks”, in Proceeding, IEEE ICC, Ottawa, ON, Canada, May2003, vol. 2, pp. 1048-1053.