Information Technology Reference
In-Depth Information
In the mobile computing environment, the characteristics of mobile devices
and limitations of wireless communication technology pose challenges on broad-
casting strategy as well as methods to retrieve data. Major issues of concern
include reducing power consumption, reducing access latency, and disseminat-
ing relevant data of interest to the public user. User profiling, monitoring the
access patterns, application of indexing, broadcasting over parallel channels, data
distribution and replication strategy, conflict resolution, and scheduling of data
retrieval are solutions to these issues that have advanced in the literature.
This chapter is intended to review and analyze these solutions. Comprehensive
simulation results to demonstrate the effectiveness of each solution based on
performance metrics such as access time and power consumption are presented
and analyzed.
1. Introduction ........................................
3
1.1.OnDemand-BasedServices ............................
4
1.2.Broadcast-BasedServices .............................
5
2.MobileComputing ....................................
7
2.1. Wireless Communication Technology .......................
7
2.2.CharacteristicsoftheMobileEnvironment ....................
9
3.BroadcastingIssues....................................
10
3.1.BroadcastContents .................................
11
3.2.IndexingObjectsontheBroadcastChannel....................
17
3.3.SingleBroadcastChannelOrganization......................
19
3.4.ParallelBroadcastChannelOrganization .....................
23
3.5. Access Conflict
...................................
23
3.6. Access Patterns
...................................
24
4.ObjectOrganizationonSingleBroadcastChannel...................
30
4.1.ApproximateLinearOrderAlgorithm........................
31
4.2.PartiallyLinearOrderAlgorithm ..........................
32
4.3.PerformanceEvaluation ..............................
34
4.4.SectionConclusion .................................
37
5.ParallelChannelsObjectOrganization .........................
38
5.1.LargestObjectFirst(LOF).............................
38
5.2.ClusteringCritical-Path(CCP)...........................
38
5.3.PerformanceEvaluation ..............................
41
5.4.SectionConclusion .................................
42
6.EnergyEfficientIndexing ................................
43
6.1.IndexingonSingleBroadcastChannel ......................
44
6.2.IndexingonParallelAirChannels .........................
49
6.3.SectionConclusion .................................
54
7. Conflict Resolution and Generation of Access Patterns—Heuristic Solution .....
55
7.1. Retrieving Objects from Parallel Broadcast Air Channels in the Presence of
Conflicts.......................................
55
