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…………