Data Management in Mobile Computing

1
Data Management in Mobile Computing
Kien A. Hua School of EECS University of Central
Florida
2
Applications

• Location-based services
• Ubiquitous Computing
• Traffic and incident management
• Environmental monitoring
• Mobile communication

3
Challenge

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

4
Processing Range-Monitoring Query

• What is range-monitoring query?
• Retrieve mobile objects in a spatial region, and
• continuously monitor the population in the area

5
Range-Monitoring Queries
Q2
a
d
e
Q1
c
b
f
6
Range-Monitoring Queries
Q2
a
d
Q1
e
b
c
f
7
Research Issues

• 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

8
Safe Regions
Rectangular Safe Region
Q1
Q2
Q5
a
Q3
Q4
Circular Safe Region
9
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

10
Challenge

• How to provide
• accurate query results, and
• real-time updates?

11
Proposed Monitoring-Query Management
Q1
Q6
Q3
Q2
a
Q5
Q7
Q4
Resident Domain
12
Computing a Resident Domain

• Given an objects position P and its processing
  capability N, its resident domain should

• contain position P, and

• be as large as possible, but

• contain no more than N queries

13
Domain and Query Decomposition
Q2
Q3
R1
R21
R22
Q1
R31
Q4
R42
R41
14
Domain and Query Decomposition
Q2
Q3
R1
R21
R22
Q1
R31
a
Q4
R42
R41
15
Domain and Query Decomposition
Q2
Q3
R1
R21
R22
Q1
R31
a
Q4
R42
R41
16
Binary Partitioning Tree (BP-tree)
D
domain node
D
data node
17
Binary Partitioning Tree (BP-tree)
D
d1
d2
d1
d2
18
Binary Partitioning Tree (BP-tree)
D
d21
d1
d2
d1
d21
d22
d22
19
Mobile Communication Cost
30
25
20
Safe Region
15
Number of messages sent by mobile objects
(millions)
MQM
10
5
0
10
20
30
40
50
60
70
80
90
100
Number of monitoring queries (thousands)
20
Server Processing Cost
1000
100
Safe Region
10
MQM
Number of index nodes accessed (millions)
1
0.1
10
20
30
40
50
60
70
80
90
100
Number of monitoring queries (thousands)
21
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