Presentation By : Presentation By : Mohit Vats (11912303913)
Presentation By :Presentation By : Mohit Vats
(11912303913)
IntroductionIntroduction Mobile Computing
Mobile (Moving)
+
Computing ( using computer)
Mobile Computing is an umbrella term used to describe technologies that enable people to access network services anyplace, anytime, and anywhere
Mobile Computing
In recent years, distributed computer has become the norm, especially after the advent of the internet.
Today, technological advances are shaping a new computing environment where the user is free from the need to work at a specific location, and is even enabled to work while on the move.
This new paradigm is often called MOBILE COMPUTING.
A device that moves
Between different geographical locations
Between different networks
Between different applications
Such as Palm-top, laptop, Cell phonesCell phones
A device due to which mobile communication is possible
Modems.
What Is Mobility ?What Is Mobility ?
Mobile Computing Devices
Wireless Network Technology : Inside It
Tor K Moseng, Handoff in Wireless Internet Access
Wireless Internet AccessDifferent wireless networks available
E.g. GSM/GPRS, UMTS, WiFi, WiMAX
Mobility is EssentialChanges the users’ behaviorInternet access from any wireless device
Always best connectedMulti-mode equipment
Introduction
Internet
Tor K Moseng, Handoff in Wireless Internet Access
Wireless Internet AccessWhat is handover?
Changing the point of connection while communicating
Why is handover needed?MobilityUser preferences
What is the objective?Handover procedure without a users notice Seamless handover
Introduction
Tor K Moseng, Handoff in Wireless Internet Access
Network Coverage
Introduction
WPAN WLAN WMAN WWAN Satellite
BluetoothRFID
WiFiIEEE 802.11
WiMAXIEEE 802.16
GSM/GPRSUMTS
GPSGALILEO
Wireless Personal Area Network – In a person’s proximityWireless Local Area Network – Home, Hotel, AirportWireless Metropolitan Area Network – City wideWireless Wide Area Network – Regional, Cellular systemsSatellite – Worldwide coverage
Tor K Moseng, Handoff in Wireless Internet Access
Introduction – Use Case 1BSC
BS1 BS2 BS3
1. Connect to BS1 and start conversation2. Moving out of BS1’s coverage – connect to BS23. Moving out of BS2’s coverage – connect to BS34. Conversation ended – still within BS3’s coverage
Tor K Moseng, Handoff in Wireless Internet Access
Horizontal HandoverHorizontal handover is when a mobile terminal
changes its point of connection within the same type of networkE.g. from a cell to another in GSME.g. from an access point to another in WiFi
Reasons for handover
Worse signal quality or loss of signal
Traffic load balancing
Cost
Horizontal Handover
BSC
BS1 BS2 BS3
BSC
BS1 BS2 BS3
BSC
BS1 BS2 BS3
Tor K Moseng, Handoff in Wireless Internet Access
Handover in GSMNetwork-controlled, mobile terminal assisted
handoverThe network takes the handover decisionsThe mobile terminal supervises and reports its
signal quality
Three types of handoverIntra-BSC handoverInter-BSC handoverInter-MSC handover
Horizontal Handover
BSCBSC BSC
MSC
MSC
BSC
Tor K Moseng, Handoff in Wireless Internet Access
Vertical HandoverVertical handover is when a mobile terminal
changes its point of connection in a different type of networkE.g. from a wired Ethernet connection to an access
point in WiFiE.g. from an access point in WiFi to a cell in UMTS
Reasons for handoverWorse signal quality or loss of signalPerformance requirements (e.g. bandwidth)CostPower consumption
Vertical Handover
Ethernet
WiFi
WiFi
UMTS
Ethernet
WiFi
UMTS
Ethernet
WiFi
UMTS
Ethernet
WiFi
WiFi
UMTS
Ethernet
WiFi
UMTS
Ethernet
WiFi
UMTS
Ethernet
WiFi
UMTS
Ethernet
WiFi
UMTS
Tor K Moseng, Handoff in Wireless Internet Access
Challenges in Vertical HandoverMulti-mode devicesPower consumptionQoS
Available capacitySecurity
TimingThe business modelSession continuity
Tor K Moseng, Handoff in Wireless Internet Access
Handover ApproachesHandover objective is a seamless handover
Smooth handover: low lossFast handover: low delaySmooth and fast handover gives a seamless
handover
Lower layers handoverHard handoverSoft handover
Handover Approaches
”break before make”
Tor K Moseng, Handoff in Wireless Internet Access
Hard Handover
Old connection is broken before a new connection is activated
Primarily used in FDMA and TDMA systems (e.g. GSM) Different frequency ranges used in adjacent cells to minimize the
interference
When to perform hard handover? E.g. based on measurements of the signal quality Different schemes to avoid unnecessary handovers
Handover Approaches
”make before break”
Tor K Moseng, Handoff in Wireless Internet Access
Soft Handover
New connection is activated before the old is broken
Used in UMTS to improve the signal quality Uplink and downlink signals may be combined for better signal A mobile may in UMTS spend a large part of the connection time in soft
handover Better connection reliability
More seamless handover
Handover Approaches
Thank You…………