Class Number – CS486 Class Name – Mobile and Sensor Data Management Instructor – Sanjay Madria...

Class Number – CS486Class Name – Mobile and Sensor Data Management

Instructor – Sanjay Madria

Lesson Title - Introduction

What is Pervasive Computing?

• “Pervasive computing is a term for the strongly emerging trend toward:– Numerous, casually accessible, often invisible computing devices– Frequently mobile or embedded in the environment– Connected to an increasingly ubiquitous network structure.”

– NIST, Pervasive Computing 2001

Party on Friday• Update Smart Phone’s calendar with guests

names.• Make a note to order food from Dinner-on-

Wheels.• Update shopping list based on the guests

drinking preferences.

• Don’t forget to swipe that last can of beer’s UPS label.

• The shopping list is always up-to-date.

Party on Friday• AutoPC detects a near Supermarket that advertises

sales.

• It accesses the shopping list and your calendar on the Smart Phone.

• It informs you the soda and beer are on sale, and reminds you that your next appointment is in 1 hour.

• There is enough time based on the latest traffic report.

Party on Friday

• Smart Phone reminds you that you need to order food by noon.

• It downloads the Dinner-on-Wheels menu from the Web on your PC with the guests’ preferences marked.

• It sends the shopping list to your CO-OP’s PC.• Everything will be delivered by the time

you get home in the evening.

Mobile Applications

• Expected to create an entire new class of Applications– new massive markets in conjunction with the Web

– Mobile Information Appliances - combining personal computing and consumer electronics

• Applications:– Vertical: vehicle dispatching, tracking, point of sale

– Horizontal: mail enabled applications, filtered information provision, collaborative computing…

Mobile and Wireless Computing • Goal: Access Information Anywhere, Anytime,

and in Any Way.• Aliases: Mobile, Nomadic, Wireless, Pervasive,

Invisible, Ubiquitous Computing.• Distinction:

• Fixed wired network: Traditional distributed computing.• Fixed wireless network: Wireless computing.• Wireless network: Mobile Computing.

Key Issues: Wireless communication, Mobility, Portability.

Terminologies• GSM - Global System for Mobile Communication

– GSM allows eight simultaneous calls on the same radio frequency and uses narrowband TDMA. It uses time as well as frequency division.

• TDMA - Time Division Multiple Access– With TDMA, a frequency band is chopped into several

channels or time slots which are then stacked into shorter time units, facilitating the sharing of a single channel by several calls

• CDMA - Code Division Multiple Access– data can be sent over multiple frequencies simultaneously,

optimizing the use of available bandwidth.– data is broken into packets, each of which are given a

unique identifier, so that they can be sent out over multiple frequencies and then re-built in the correct order by the receiver.

Wireless Technologies

• Wireless local area networks (WaveLan, Aironet) – Possible Transmission error, 1.2 Kbps-15 Mbps

• Cellular wireless (GSM, TDMA, CDMA)– Low bandwidth, low speed, long range - Digital: 9.6-14.4 Kbps

• Packet radio (Metricom) -Low bandwidth, high speed, low range and cost

• Paging Networks – One way• Satellites (Inmarsat, Iridium(LEO)) – Long Latency,

long range, high cost

Mobile Network Architecture

FIXED NETWORK

PDA

FIXEDHOSTBASE

STATION

BASESTATION

BASESTATION

Mbps to Gbps

MOBILE HOST

WIRELESS LAN CELL2Kbps - 15Mbps

WIRELESS RADIO CELL9Kbps - 14Kbps

BASESTATION

PDA

Wireless characteristics• Variant Connectivity

– Low bandwidth and reliability

• Frequent disconnections • predictable or sudden

• Asymmetric Communication – Broadcast medium

• Monetarily expensive– Charges per connection or per message/packet

Connectivity is weak, intermittent and expensive

Portable Information Devices• PDAs, Personal Communicators

– Light, small and durable to be easily carried around

– dumb terminals, palmtops, wristwatch PC/Phone,

– will run on AA+ /Ni-Cd/Li-Ion batteries

– may be diskless

• I/O devices: Mouse is out, Pen is in

• Wireless connection to information networks– either infrared or cellular phone

• Specialized Hardware (for compression/encryption)

Portability Characteristics

• Battery power restrictions– transmit/receive, disk spinning, display, CPUs,

memory consume power

• Battery lifetime will see very small increase– need energy efficient hardware (CPUs, memory)

and system software– planned disconnections - doze mode

Power consumption vs. resource utilization

Portability Characteristics Cont.

• Resource constraints – Mobile computers are resource poor

– Reduce program size – interpret script languages (Mobile Java?)

– Computation and communication load cannot be distributed equally

• Small screen sizes

Asymmetry between static and mobile computers

Mobility Characteristics

• Location changes• location management - cost to locate is added to

communication

• Heterogeneity in services– bandwidth restrictions and variability

• Dynamic replication of data• data and services follow users

• Querying data - location-based responses

• Security and authenticationSystem configuration is no longer static

What Needs to be

Reexamined? • Operating systems - TinyOS• File systems - CODA• Data-based systems – TinyDB• Communication architecture and protocols• Hardware and architecture• Real-Time, multimedia, QoS• Security• Application requirements and design• PDA design: Interfaces, Languages

Mobility Constraints• CPU• Power• Variable Bandwidth• Delay tolerance, but unreliable• Physical size• Constraints on peripherals and GUIs • Frequent Location changes • Security• Heterogeneity• Expensive• Frequent disconnections but predictable

What is Mobility?

• A device that moves between– different geographical locations– Between different networks

• A person who moves between – different geographical locations– different networks– different communication devices– different applications

Device mobility• Laptop moves between Ethernet, WaveLAN and

Metricom networks– Wired and wireless network access– Potentially continuous connectivity, but may be

breaks in service– Network address changes– Radically different network performance on

different networks– Network interface changes

• Can we achieve best of both worlds?– Continuous connectivity of wireless access– Performance of better networks when available

Mobility Means Changes• Addresses

– IP addresses

• Network performance– Bandwidth, delay, bit error rates, cost, connectivity

• Network interfaces– PPP, eth0, strip

• Between applications– Different interfaces over phone & laptop

• Within applications– Loss of bandwidth trigger change from color to B&W

• Available resources– Files, printers, displays, power, even routing

Bandwidth Management

• Clients assumed to have weak and/or

unreliable communication capabilities

• Broadcast--scalable but high latency

• On-demand--less scalable and requires

more powerful client, but better response

• Client caching allows bandwidth

conservation

Energy Management

• Battery life expected to increase by only

20% in the next 10 years

• Reduce the number of messages sent

• Doze modes

• Power aware system software

• Power aware microprocessors

• Indexing wireless data to reduce tuning time

Why Mobile Data Management?

• Wireless Connectivity and use of PDA’s, handheld computing devices on the rise

• Workforces will carry extracts of corporate databases with them to have continuous connectivity

• Need central database repositories to serve these work groups and keep them fairly upto-date and consistent

Mobile Data Applications

• Sales Force Automation - especially in

pharmaceutical industry, consumer goods,

parts• Financial Consulting and Planning• Insurance and Claim Processing - Auto,

General, and Life Insurance• Real Estate/Property Management -

Maintenance and Building Contracting• Mobile E-commerce

Mobility – Impact on DBMS• Handling/representing fast-changing data• Scale• Data Shipping v/s Query shipping• Transaction Management• Replica management• Integrity constraint enforcement• Recovery• Location Management• Security• User interfaces

• Most RDBMS vendors support the mobile scenario - but no design and optimization aids

• Specialized Environments for mobile applications:

Sybase Remote Server

Synchrologic iMOBILE

Microsoft SQL server - mobile application support

Oracle Lite

Xtnd-Connect-Server (Extended Technologies)

Scoutware (Riverbed Technologies)

DBMS Industry Scenario

Query Processing

• New Issues– Energy Efficient Query Processing

– Location Dependent Query Processing• Old Issues - New Context

– Cost Model

Location Management• New Issues

– Tracking Mobile Users

• Old Issues - New Context– Managing Update Intensive Location

Information– Providing Replication to Reduce Latency for

Location Queries– Consistent Maintenance of Location

Information

Transaction Processing• New Issues

– Recovery of Mobile Transactions

– Lock Management in Mobile Transaction

• Old Issues - New Context

• Extended Transaction Models

– Partitioning Objects while Maintaining Correctness

Data Processing Scenario• One server or many servers• Shared Data• Some Local Data per client , mostly subset of

global data• Need for accurate, up-to-date information, but some

applications can tolerate bounded inconsistency• Client side and Server side Computing• Long disconnection should not constraint availability• Mainly Serial Transactions at Mobile Hosts• Update Propagation and Installation

Personal Communication System Personal Communication System (PCS)(PCS)

A system where wired and wireless networks are integrated for establishing

communication.

PSTN: Public Switched Network.MSC: Mobile Switching Center. Also called MTSO

(Mobile Telephone Switching Office).BS: Base Station.MS: Mobile Station. Also called MU (Mobile Unit)

or Mobile Host (MH).HLR: Home Location Register.VLR: Visitor Location Register.EIR: Equipment Identify Register.AC: Access Chanel.

PSTN

BS

VLR

HLR

EIR

AC

MSC (MTSO)MSC (MTSO)

MSMS Wireless component


Wireless Components

BS

MSC (MTSO)

MS Wirelesscomponent

MS

Cell


Mobile cells

The entire coverage area is a group of a number of cells.

The size of cell depends upon the power of the base

stations.

PSTNMSC

Personal Communication System (PCS)Personal Communication System (PCS)

Problems with cellular structure

How to locate of a mobile unit in the entire coverage area?

Solution: Location management

How to maintain continuous communication between two parties in the presence of mobility?

Solution: Handoff How to maintain continuous communication

between two parties in the presence of mobility?

Solution: Roaming


Handoff

A process, which allows users to remain in touch, even

while breaking the connection with one BS and

establishing connection with another BS.

Old BS New BS

MSC

Old BS New BS

MSC

MSC

Old BS New BS New BSOld BS

MSC


Handoff To keep the conversation going, the

Handoff procedure should be completed while

the MS (the bus) is in the overlap region.

G

Old BS New BS

Cell overlap region


Roaming

Roaming is a facility, which allows a

subscriber to enjoy uninterrupted communication

from anywhere in the entire coverage space.

A mobile network coverage space may be

managed by a number of different service providers.

They must cooperate with each other to provide

roaming facility.

Roaming can be provided only if some

administrative and technical constraints are met.


Roaming

Administrative constraints

Billing.

Subscription agreement.

Call transfer charges.

User profile and database sharing.

Any other policy constraints.


RoamingTechnical constraints

Bandwidth mismatch. For example,

European 900MHz band may not be available

in other parts of the world. Integration of a new service provider into the network.

A roaming subscriber must be able to detect this new

provider.

Service providers must be able to

communicate with each other. Needs some

standard.

Mobile station constraints.


Roaming

Two basic operations in roaming management are

Registration (Location update): The

process of informing the presence or

arrival of a MU to a cell. Location tracking: the process of locating

the desired MU.


RoamingRegistration (Location update): There are six different

types of registration.

Power-down registration. Done by the MU when it

intends to switch itself off. Power-up registration. Opposite to power-down

registration. When an MU is switched on, it

registers. Deregistration. A MU decides to acquire control

channel service on a different type of network

(public, private, or residential).


Roaming

Registration (Location update): There are six different

types of registration.

New system/Location area registration: when the location

area of the MU changes, it sends a registration message. Periodic registration: A MU may be instructed to periodically

register with the network. Forced registration: A network may, under certain

circumstances, force all MUs to register.


Registration

Two-Tier Scheme

HLR: Home Location Register

A HLR stores user profile and the geographical

location of each moving object at a pre-

specified location

VLR: Visitor Location Register

A VLR stores user profile and the current

location who is a visitor to a different cell than

its home cell.


Registration

Two-Tier Scheme steps. MU1 moves to cell 2.

MU1

MU1

Cell 1 Cell 2


Registration

Steps

1. MU1 moves to cell 2. The MSC of cell 2 launches a

registration query to its VLR 2.

2. VLR2 sends a registration message containing MU’s

identity (MIN), which can be translated to HLR address.

3. After registration, HLR sends an acknowledgment back

to VLR2.

4. HLR sends a deregistration message to VLR1 (of cell 1)

to delete the record of MU1 (obsolete). VLR1

acknowledges the cancellation.

Personal Communication Personal Communication System (PCS)System (PCS)

Location tracking (MU2 wants to communicate with MU1)

Steps

1. VLR of cell 2 is searched for MU1’s profile.

2. If it is not found, then HLR is searched.

3. Once the location of MU1 is found, then the

information is sent to the base station of cell

1.

4. Cell 1 establishes the communication.

Class Number – CS486 Class Name – Mobile and Sensor Data Management Instructor – Sanjay Madria...

Documents

Transcript of Class Number – CS486 Class Name – Mobile and Sensor Data Management Instructor – Sanjay Madria...