mobile database systems

8/6/2019 Mobile Database Systems

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Mobile Database SystemsMobile Database Systems

Technical seminor Presented by

p . nageshmca final year

08k91f0020

tkrcet

meerpet,hyd


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Outline

Fully Connected Information Space

Personal Communication System (PCS)

Mobile Database Systems (MDS)

Transaction Management

Data Caching

Query Processing

Conclusion


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Fully connected information spaceFully connected information space


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Fully connected information space

Each node of the information space has some

communication capability.

Some node can process information.

Some node can communicate through voice

channel.

Some node can do both


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Fully connected information space

Can be created and maintained by integrating

legacy database systems, and wired and wireless

systems (PCS, Cellular system, and GSM)


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A system with the following structural and functional

properties

Distributed system with mobile connectivity

Full database system capability

Complete spatial mobility

Built on PCS/GSM platform

Wireless and wired communication capability

What is a Mobile Database System (MDS)?


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What is a mobile connectivity?

A mode in which a client or a server can establish

communication with each other whenever needed.

Intermittent connectivity is a special case of mobile

connectivity.


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A node in which only the client can establishcommunication whenever needed with the server but the

server cannot do so.

What is intermittent connectivity?


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

A system where wired and wireless networks are integrated

for establishing communication.

N: ublic witched Network.

: obile witching enter. Also called

( obile ele hone witching ffice).: ase tation.

: obile tation. Also called U ( obile Unit)

or obile Host ( H).

HLR: Home Location Register.

VLR: Visitor Location Register.

EIR: Equi ment Identify Register.AC: Access Chanel.

N

VLR

HLR

EIR

AC

MSC (MTSO)MSC (MTSO)

MSMS Wireless com onent


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Wireless Components

BS

MSC (MTSO)

MSMS Wireless component

Base Station (BS) A switch, which serves as

communication link between M and the entire

network

Mobile nits (M ) Also called Mobile Systems (MS) or

Mobile osts (M ). A mobile component, which

communicates with BS through a limited number of

wireless channels.


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Limited channels must be utilized efficiently. It is done

so by

Fre uency reuse

The same radio fre uency is used for

communication by more than one cell

sessions.

Mobile cells

To achieve fre uency reuse, the entire

wireless coverage area is divided into cells.


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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 oaming


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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.


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Roaming

Administrative constraints

Billing.

Subscription agreement.

Call transfer charges.

ser profile and database sharing.

Any other policy constraints.


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Roaming

Technical constraints

Bandwidth mismatch. For example, European

900MHz band may not be available in other

parts of the world. This may preclude some

mobile e uipment for roaming.

Service providers must be able to

communicate with each other. eeds some

standard.

Mobile station constraints.


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Location Management

Two-Tier Scheme

HLR: Home Location Register

A HLR stores user profile and the

geographical location.

LR: VisitorLocation Register

A VLR stores user profile and the current

location who is a visitor to a different cell that

its home cell.


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Location Management

Two-Tier Scheme steps. M 1 wants to talk to M 2.

M 1

M 2

Cell 1 Cell 2


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Location Management

Two-Tier Scheme steps. M 1 wants to talk to M 2.

1. VLR of cell 2 is searched for M 2s profile.

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

3. Once the location of M 2 is found, then the

information is sent to the base station of cell 1.

4. Cell 1 establishes the communication.


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Location Management

Two-Tier Scheme steps location update

1. M 2 moves from cell 1 to cell 2.

2. M 2s location is changed so new location

must be recorded.

3. HLR is updated with the new location address.

4. M 2s entry is deleted from the VLR of cell 1

and new entry is made in cell 2sVLR.


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Mobile Database Systems (MDS)Mobile Database Systems (MDS)

MDS Limitations

Limited wireless bandwidth Wireless communication speed

Limited energy source (battery power)

Less secured

Hard to make theft proof.


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MDS Issues

Data Management

Data Caching Data Broadcast (Broadcast disk)

Data Classification

Transaction Management

Query processing

Transaction processing

Concurrency control

Database recovery


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MDS Query processing

Query types

Location dependent uery

Location independent uery


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Location dependent uery

A query whose result depends on the geographical

location of the origin of the query.

Example

What is the distance of Pune railway stationfrom here?

The result of this query is correct only forhere.


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Location dependent query

Situation: Person traveling in the car desires to

know his progress and continuously asks the

same question. However, every time the answer is

different but correct.

Requirements: Continuous monitoring of the

longitude and latitude of the origin of the query.

GPS can do this.


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MDS Transaction Management

Transaction properties: ACID (Atomicity,

Consistency, Isolation, and Durability).

Too rigid for MDS. Flexibility can be introduced

using workflow concept. Thus, a part of the

transaction can be executed and committed

independent to its other parts.


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Mobile Agent Technology

A mobile agent is an independent software

module capable of

Migrating to any node on the network

Capable of spawning and eliminating itself

Capable of recording its own history


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Conclusions and summary

Wireless network is becoming a commonly used

communication platform. It provides a cheaper wayto get connected and in some cases this is the only

way to reach people. However, it has a number of

easy and difficult problems and they must be solved

before MDS can be built. This tutorial discussed

some of these problems and identified a number of

possible approaches.


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Conclusions and summary

The emerging trend is to make all service providing

disciplines, such as web, E-commerce, workflowsystems, etc., fully mobile so that any service can

be provided from any place. Customer can surf the

information space from any location at any time and

do their shopping, make flight reservation, open

bank account, attend lectures, and so on. This is

what the wireless technology driving us to.


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THANK YOU

mobile database systems

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