Data Management in Mobile Computing

Kien A. Hua

School of EECS

University of Central Florida

Applications

• Location-based services

• Ubiquitous Computing

• Traffic and incident management

• Environmental monitoring

• Mobile communication

Challenge

• Traditional and spatial databases cannot handle the rate of location update from moving objects

Processing Range-Monitoring Query

• What is range-monitoring query?

– Retrieve mobile objects in a spatial region, and

– continuously monitor the population in the area

Range-Monitoring Queries

aQ2

Q1 bc

f

d

e

Range-Monitoring Queries

a

Q2

Q1bc

f

d

e

• How to minimize location updates?

– Each update involves mobile communication

costs and server processing costs

• How to minimize monitoring update cost?

– Query results keep changing

Research Issues

Q1

Q5

Q2

Q4

Safe Regions

Q3

Circular Safe Region

RectangularSafe Region

a

Problems with Safe Regions

• Computing a safe region takes from O(n) to

O(n log3 n)

• Adding a new query requires re-computation

of safe regions for all objects

How to provide

– accurate query results, and

– real-time updates?

Challenge

Proposed: Monitoring-Query Management

Q1

Q2

Q7

Q6

Q3

Q5

Q4

a

Resident Domain

• Given an object’s position P and its processing

capability N, its resident domain should

Computing a Resident Domain

– contain position P, and

– be as large as possible, but

– contain no more than N queries

Domain and Query Decomposition

Q1

Q4

Q2

Q3

R1

R42

R21

R31

R22

R41

Domain and Query Decomposition

Q1

Q4

Q2

Q3

R1

R42

R21

R31

R22

R41

a

Domain and Query Decomposition

Q1

Q4

Q2

Q3

R1

R42

R21

R31

R22

R41

a

Binary Partitioning Tree (BP-tree)

D

D domain node

data node

D

d1

d1 d2d2

Binary Partitioning Tree (BP-tree)

d1

d1 d2d21

d22

d21 d22

D

Binary Partitioning Tree (BP-tree)

Mobile Communication Cost

0

5

10

15

20

25

30

10 20 30 40 50 60 70 80 90 100Num

ber

of

mes

sage

s se

nt

by m

obile

obj

ects

(m

illio

ns)

Number of monitoring queries (thousands)

MQM

Safe Region

Server Processing Cost

0.1

1

10

100

1000

10 20 30 40 50 60 70 80 90 100Num

ber

of in

dex

node

s ac

cess

ed (

mill

ions

)

Number of monitoring queries (thousands)

MQMSafe Region

Significant and Impact of MQM

• MQM is highly scalable, in terms of

• mobile communication costs, and

• server processing costs,

for real-time range-monitoring query management