QOS oriented vho scheme for wifi and wimax overlay networks
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Transcript of QOS oriented vho scheme for wifi and wimax overlay networks
A QoS Oriented Vertical Handoff Scheme for WiMax/WLAN Overlay Networks
Under the Esteemed Guidance of
Mrs. S.J.Saritha
Assistant Professor & HOD
By
CH.Srilakshmi Prasanna
(11191D5801)
Outline
Introduction Handoff Process Horizontal Handoff Process Vertical Handoff Process Conclusion References
Introduction
Wireless communication system Cellular Networks Handoff Horizontal Handoff Vertical Handoff
Wireless Comm. Systems Mobility is the most important feature of a
wireless cellular communication system. A single tower at the center called a base
station (BS). Powerful transmitter attached to top of BS. Coverage area increased by making tower
taller and/or increasing transmission power.
Wireless Comm. Systems (contd.)
Goals◦ provide coverage over a large area◦ provide coverage to a large number of users◦ maintain an acceptable level of quality
Problem!
Limit on number of users due to frequency limitations (only so much spectrum)
Some way to reuse frequencies?
Solution! Cellular Systems to the rescue!
Cellular System Cellular concept:
◦ Many small base stations◦ Each BS communicates with mobiles in its
respective cell.◦ MSC (Mobile Switching Center) is responsible for
coordinating communications within the system Goals:
Large coverage area High call quality High capacity
Cellular System (cont’d)
Frequency reuse ◦ The same frequencies are reused in multiple cells.
Question
What happens when mobile moves from one cell to another? Handoff!!
◦ The process of transferring a mobile user from one channel or base station to another.
Heterogeneous wireless communication system is used to access the communication services anytime, anywhere with best QOS at minimum cost.
Heterogeneous wireless networks has different access technologies, overlapping and coverage, and network architecture, protocols for transport, routing and mobility management.
Different operators offers different services like voice,video,multimedia,text to mobile users.
Because of these variations, when the mobile users moves there is a need to handover the communication channel from network to another by considering its features and also the user requirements.
Heterogeneous wireless communication system
Handoff (Handover) Characteristics
Handoffs must be:◦ performed quickly
◦ performed infrequently◦ imperceptible to users◦ performed successfully
Types of Handoff
Types of Handoff
Vertical And Horizontal Handoff scheme
1. Handoff Initiation:- In this phase ,information is collected about the network from different layers like Link layer, Transport layer, Application layer which gives information such as RSS, Bandwidth, link speed, throughput, cost, power, user preferences and network subscription.
2. Handoff Decision:- In this phase decision is depend on the information collected during initiation phase.
3. Handoff Execution:-Authentication and authorization
Vertical Handoff Process(VHO)
Upward and Downward Handoffs.
Hard and soft Handoffs. Imperative and Alternative Handoffs. Mobile Controlled and Network Controlled Handoffs.
MCNA,NCMA
Classification of VHO
Classification of VHO
Hard and soft Handoffs
VHO Decision Making Parameters
VHO can be initiated for convenience rather than connectivity reasons.
1) Network -Related Parameters:- Bandwidth,RSS,Cost,Security.
2) Terminal-Related Parameters:-Velocity, Battery power, Location information.
3) User -Related Parameters:- user profile and preferences.
4) Services-Related Parameters:-Services capacities,QOS etc.
A technology should satisfy the following requirements. Bandwidth and delay and also user preferences such as 1. Price 2. power consumption or speed.
If the service provided by the connected network cannot satisfy the requirements, the station should switch to another network for better performance.
Proposed VHO scheme will facilitate the above mentioned
requirements.
Problem Statement
Existing System
In the existing cellular/WLAN overlay systems, there are two types of interworking architectures: tightly coupled where WLAN works as a radio access network of cellular system, and loosely coupled where different networks are independently deployed but integrated at network layer.
In previous QoS based VHO methods for overlay networks, QoS parameters are considered in handoff decisions.
The handoff procedures are normally started when the stations move across the border of WLANs.
As a result, both the fixed stations and the mobile stations within overlapped areas cannot benefit from VHOs.
Existing system
DISADVANTAGES
• High Delay
• Signal breakage
• Less packet delivery
Proposed System
In this project, we investigate the integration and VHO issues in WiMAX/WLAN overlay networks.
We address architecture to support our VHO scheme. We propose a tightly coupled interworking structure. And proactive handoff method
To achieve a proactive handoff, we design a VHO manager (VHOM) to control the whole handoff process, which works on the medium access control (MAC) layers of WiMAX and WLAN interfaces at the station.
Block Diagram of VHOM
WiMax Unit
Handoff controller
Wimax<--->WLAN
WLAN Unit
Delay Analyzer Bandwidth estimation
Primary network◦ Primary users:
Primary users have the license to operate in certain spectrum bands
◦ Primary base station: Controls the access of primary users to spectrum
Secondary network◦ Secondary users:
Secondary users have no licensed bands assigned to them.
◦ Secondary base-station: A fixed infrastructure component with cognitive radio capabilities and
provides single hop connection to secondary users.
Proposed System
Movement-AwareV ertical Handoff Algorithm
Step1:
Initializing a mobile node it can access both WiMAX/WLAN.
Initialize WiMAX/ WLAN networks. Step2:
Node will check the available networks. Step3:
If {network available} {
If {only one network} {
Get communication from that.
}
else
{
For {each network}
{
Checks which are the best networks in terms of Bandwidth and packet delay
Theory of Bandwidth calculation for Wi-MAX is given as follows.
Bandwidth calculation for Wi-MAX
𝐵𝑑=(1− ) =(1− )𝐴𝐴𝑠𝑑𝑠𝑑 𝛿𝑑𝑠𝑑𝑇𝑓 𝐵𝑢 𝐴𝐴𝑠𝑢𝑠𝑢 𝛿𝑢𝑠𝑢𝑇𝑓 Delay calculation for WIMAX 𝑡= + + +𝑡𝑠 𝑡𝑞 𝑡𝑚 𝑡𝑡 Bandwidth for WLAN = − / +12 , ( −1)𝐵𝑊 𝐵𝑜 𝐿𝑁𝐴𝑉 𝑇𝑛 𝑇𝑛 𝑐 𝑁 Delay for WLAN = + = 21− + 𝑡 𝑡𝑞 𝑡𝑎 𝑡𝑎 𝑡𝑎 𝑡𝑎} Step 4: Mobile node compares both networks VHOM selects best
Step 5: If no AP or BS detected Checks whether any other mobile station available AP or BS connection and have enough bandwidth limit. If mobile station detected with enough quality and then switch to mobile station communication.
Step 6: Else No communication.
MAV Algorithm
Parameters Values
Wi-MAX nodes 1
WI-FI nodes
3
Mobile nodes 11
Routing protocol AODV
WI-FI coverage 100m
Wi-MAX coverage 400m (for testing only)
Simulation time 10s
Network Model Values
Simulation time Previous EnhancedSend pkts Received
pkts Send pkts Received pkts
10s 20052 20013 27540 27502
20s 57130 57050 80107 80028
30s 109046 108924 155523 155402
40s 174950 174786 252908 252745
50s 254848 254642 372309 372103
60s 348759 348510 513708 513459
70s 456661 456370 677104 676813
80s 578576 578242 862521 862187
90s 714482 714105 1069935 1069559
100s 864400 863980 1528759 1528299
Table: Different Simulation times for X-graph
RESULT•Throughput performance
10 20 30 40 50 60 70 80 90 1000
5000
10000
15000
20000
25000
preenhanced
simulation time (sec)
thro
ughp
ut k
b/s
•Packet Delivery Ratio
10 20 30 40 50 60 70 80 90 1000.997
0.9975
0.998
0.9985
0.999
0.9995
1
preenhanced
simulation time
Packet
delivery
rati
o
• Average End-to-End Delay
10 20 30 40 50 60 70 80 90 1000
0.00050.001
0.00150.002
0.00250.003
0.00350.004
0.0045
preenhanced
Simulation time
Avera
ge E
nd -
to-E
nd
dela
y S
ec
• Packet Loss Ratio
10 20 30 40 50 60 70 80 90 1000
0.0005
0.001
0.0015
0.002
0.0025
preenhanced
simulation time
packet
loss r
ati
o %
Conclusion
MAV decision Algorithm provide the mobile nodes with best QOS at minimum cost according to the user preferences.
FUTURE WORK
To provide best network services several parameters to be considered such as TCP performance issues, security issues.
THANK YOU