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CHAPTER 26

Data Management in Wireless

Mobile Environments

SANDEEP K. S. GUPTA

Department of Computer Science and Engineering, Arizona State University, Tempe

PRADIP K. SRIMANI

Department of Computer Science, Clemson University, Clemson, South Carolina

26.1 INTRODUCTION

The need for “information anywhere anytime” has been a driving force for the increasing

growth in Web and Internet technology, wireless communication, and portable computing

devices. The field of mobile computing is the result of the merger of these advances in

computing and communication with the aim of providing a seamless and ubiquitous com￾puting environment for mobile users. In such mobile environments, database applications

are enhanced with useful features of wireless technology. For example, users are allowed

to establish a mobile office from which they can communicate with other users, access in￾formation, and manage their work while staying mobile. This feature is important for sup￾porting ubiquitous services such as weather and forecasting services, financial market re￾porting, yellow pages, road maps and directions, telematics, point-of-sale applications,

in-field work dispatch, and law enforcement and military support to mobile users. By na￾ture, mobile computing environments have severe resource constraints and unstable oper￾ating conditions, which add a new dimension to the technical challenges for data process￾ing and computing.

Many software problems associated with data management, transaction management,

and data recovery have their origin in distributed database systems. In mobile computing,

however, these problems become more difficult to solve, mainly because of the narrow

bandwidth of the wireless communication channels, the relatively short active life of the

power supply in mobile devices, and the changing locations of required information

(sometimes in cache, sometimes in air, sometimes at the server) and users. Further, in

many mobile database applications, data changes very rapidly (or even constantly). Users

need to receive timely information in order to make critical decisions (e.g., stock market

information and trading).

Traditionally, data management is concerned with the modeling, efficient storage, re￾trieval, and manipulation of information. From a data management standpoint, mobility of

the clients/nodes provides an interesting variation on distributed computing. The mobile

computing environment considered in this chapter is shown in Figure 26.1. In this envi￾553

Handbook of Wireless Networks and Mobile Computing, Edited by Ivan Stojmenovic´

Copyright © 2002 John Wiley & Sons, Inc.

ISBNs: 0-471-41902-8 (Paper); 0-471-22456-1 (Electronic)

ronment, the mobile hosts (MHs) query the database servers that are connected to a static

network. The mobile hosts communicate with the servers via wireless cellular networks

consisting of mobile switching stations (MSS) and base stations. In this environment, mo￾bile databases can be distributed within the spectrum of the following two extreme config￾urations:

1. The entire database can be distributed among the wired components, possibly with

full or partial replication. A base station, with a DBMS-like functionality, has full

control of its own database.

2. the database is distributed among wired and wireless components. Data manage￾ment responsibility is shared among base stations and mobile devices.

Thus, these different ways of managing data in mobile environments entail additional con￾siderations and variation with regard to distributed database management.

Moreover, location-based services are gaining a lot of momentum. In addition to the

FCC regulation that requires mobile service carriers to implement E911 in the near future,

mobile users are interested in services that find locations of nearest emergency centers or

that notify of parking availability at an airport. With integration of positioning technolo￾554 DATA MANAGEMENT IN WIRELESS MOBILE ENVIRONMENTS

Figure 26.1 Mobile computing environment.