A Case Study On System Issues And Impact Of Mobility In Wireless Mobile Computing

International Journal of Innovative Research in Computer Science & Technology (IJIRCST)
ISSN: 2347- 5552, Volume-1, Issue-1, September- 2013
1
A Case Study on System Issues and Impact of
Mobility in Wireless Mobile Computing
Dr. Mahendra Singh Bora, Amarjeet Singh
Abstract- In Mobile computing there are many Issues and
impact that we identify and investigate their technical
significance in this research paper. In new research, problems
include management of location dependent data, information
services to mobile users, frequent disconnections, wireless data
broadcasting, and energy efficient data access. The rapidly
expanding technology of cellular communications, wireless
LAN, and satellite services will make it possible for mobile
users to access information anywhere and at anytime. In the
near future, millions of users will be carrying a portable
computer, often called a personal digital assistant or a
personal communicator. These devices will be diskless; store
data in clouds. These devices will be powerful laptop
computers with large memories and powerful processors.
Regardless of size, all mobile computers will be equipped with
a wireless.
Index Terms- Cellular communication, location depandent
data, information services, wireless LAN, satellite service,
portable computer
I. INTRODUCTION
What is really different about mobile computing? The
computers are smaller and bits travel by wireless rather than
Ethernet. How can this possibly make any difference? Isn’t
a mobile system merely a special case of a distributed
system? Are there any new and deep issues to be
investigated, or is mobile computing just the latest fad?
Solutions to communication and synchronization problems
in distributed systems have so far been designed
for networks comprising solely of static hosts. In systems
with static hosts, connectivity of the underlying
network does not change in the absence of link and/or host
failures. On the other hand, mobile hosts are capable of
moving between different locations (‘‘roaming’’) while
maintaining their connection to the network, e.g. via a
cellular connection or a wireless LAN. Mobile computers1
such as laptops and palmtops, frequently operate in a
disconnected or ‘‘doze’’ mode. Mobility of hosts introduces
a new set of issues that were not present in distributed
Manuscript received September 07, 2013.
Dr. Mahendra Singh, Assistant Professor, Dept. of Computer Science,
Shriram Institute of Management & Technology, Kashipur, Uttarakhand.
India,(e-mail: mahendra.singh.bora@gmail.com,).
Amarjeet Singh, Assistant Professor, Dept. of Computer Science, Shriram
Institute of Management & Technology, Kashipur, Uttarakhand,India
(e-mail-singhamarjeet.9@gmail.com)
systems with static hosts. Firstly, to deliver a message to a
mobile host, it is necessary that the destination host be first
located within the network. Second as hosts move, the
physical connectivity of the network changes. Hence, any
logical structure, which many distributed algorithms
exploit, cannot be statically mapped to a set of physical
connections within the network. Third, mobile hosts have
severe resource constraints in terms of limited battery life
and often operate in a ‘‘doze mode’’ or entirely disconnect
from the network. Lastly, communication between a mobile
host and the rest of the network occurs via a wireless
medium. Such a medium physically supports broadcast
communication within a specified region (‘‘cell’’). These
aspects are characteristic of mobile computing and need to
be considered in the design of distributed algorithms. Prior
work in related areas include file systems for mobile users
[11, 16], data management issues [7, 5, 6, 8, and 2] and
network-layer routing protocols and addressing schemes.
Constraints of Mobility
Mobile elements are resource-poor relative to static
elements.
For a given cost and level of technology, considerations of
weight, power, size and ergonomics will exact a penalty in
computational resources such as processor speed, memory
size, and disk capacity. While mobile elements will
improve in absolute ability, they will always be resource-
poor relative to static elements.
Mobility is inherently hazardous.
A Wall Street stockbroker is more likely to be mugged on
the streets of Manhattan and have his laptop stolen than to
have his workstation in a locked office be physically
subverted. In addition to security concerns, portable
computers are more vulnerable to loss or damage.
Mobile connectivity is highly variable in performance and
reliability.
Some buildings may offer reliable, high-bandwidth wireless
connectivity while others may only offer low-bandwidth
connectivity. Outdoors, a mobile client may have to rely on
a low-bandwidth wireless network with gaps in coverage.
Mobile elements rely on a finite energy source.
While battery technology will undoubtedly improve over
time, the need to be sensitive to power consumption will
not diminish. Concern for power consumption must span
many levels of hardware and software to be fully effective.

A Case Study on System Issues and Impact of Mobility in Wireless Mobile Computing
2
II. DEFINING MOBILITY
There is ample evidence of the significant interest in
mobility and the issues related to ‘being mobile’. The
explosive growth in mobile devices, the emergence and
convergence of information and communication
technologies (ICTs), and substantial investments in wireless
infrastructures are some of the many indicators of a society
becoming increasingly mobile. A rising interest in the
issues surrounding mobility can also be found in the
academic community, where the design of mobile
information systems, value of mobile applications, use of
mobile geographical positioning systems, and the impact of
mobile communications are some of the research domains
examined (Varshney, 2003). While the importance of
mobility and potential value of ‘being mobile’ are
understood, issues surrounding mobility are still explored
without a clear understanding of mobility itself. In many
cases, the term “mobile” is used in place of “wireless” and
“portable” such as mobile devices and mobile applications;
other frequent uses of the term include “remote” such as
mobile office or “flexible” such as mobile lifestyles
(Kakihara & Sorensen, 2001). These
Examples illustrate the diverse ways that the terms are
being used today. An understanding of what mobility
means, how it has been used, and its underlying dimensions
(see Figure 1) are, therefore, critical pre-cursors to
determining its enterprise value.
Mobile
1. Capable of movement; movable; not fixed or stationary.
2. Characterized by facility of movement.
Mobility
1. Ability to be moved or to be moved; capacity of change
of place.
2. Ability to change quickly or easily; instability,
fickleness.
III. ISSUES IN MOBILE COMPUTING
A. Mobile elements are resource-poor relative to static
elements.
For a given cost and level of technology considerations of
weight, power, size and ergonomics will exact a penalty in
computational resources such as processor speed, memory
size, and disk capacity. While mobile elements will
improve in absolute ability, they will always be resource-
poor relative to static elements.
B. Mobility is inherently hazardous.
A Wall Street stockbroker is more likely to be mugged on
the streets of Manhattan and have his laptop stolen than to
have his workstation in a locked office be physically
subverted. In addition to security concerns, portable
computers are more vulnerable to loss or damage.
C. Mobile connectivity is highly variable in performance
and reliability.
Some buildings may offer reliable, high-bandwidth wireless
connectivity while others may only offer low-bandwidth
connectivity. Outdoors, a mobile client may have to rely on
a low-bandwidth wireless network with gaps in coverage.
D. Mobile elements rely on a finite energy source.
While battery technology will undoubtedly improve over
time, the need to be sensitive to power consumption will
not diminish. Concern for power consumption must span
many levels of hardware and software to be fully effective.
These constraints are not artifacts of current technology, but
are intrinsic to mobility. Together, they complicate the
design of mobile information systems and require us to
rethink traditional approaches to information access.
IV. THE NEED FOR ADAPTATION
Mobility exacerbates the tension between autonomy and
interdependence that is characteristic of all distributed
systems. The relative resource poverty of mobile elements
as well as their lower trust and robustness argues for
reliance on static servers. But the need to cope with
unreliable and low-performance networks, as well as the
need to be sensitive to power consumption argues for self
reliance.
Any viable approach to mobile computing must strike a
balance between these competing concerns. This balance
cannot be a static one; as the circumstances of a mobile
client change, it must react and dynamically reassign the
responsibilities of client and server. In other words, mobile
clients must be adaptive.
A. Global Estimation from Local Observations
Adaptation requires a mobile client to sense changes in its
environment, make inferences about the cause of these
changes, and then react appropriately. These imply the
ability to make global estimates based on local
observations. To detect changes, the client must rely on
local observations. For example, it can measure quantities
such as local signal strength, packet rate, average round-trip
times, and dispersion in round-trip times. But interpreting
evolution of biological species, and its influence on the
capabilities of computing systems[4]. Although Hans
comments are directed at robotic systems, I believe that his
observation applies equally well to a much broader class of
distributed computing systems involving mobile elements.
Mobility will influence the evolution of distributed systems
in ways that we can only dimly perceive at the present time.
In this sense, mobile computing is truly a seminal influence
on the design of distributed systems.
V. THE EXTENDED CLIENT-SERVER MODEL
Another way to characterize the impact of mobile
computing constraints is to examine their effect on the
classic client-server model. In this model, a small number
of trusted server sites constitute the true home of data.
Efficient and safe access to this data is possible from a

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much larger number of untrusted client sites. Techniques
such as caching and read-ahead can be used to provide good
performance, while end-to-end authentication and
encrypted transmission can be used to preserve security.
This model has proved to be especially valuable for
scalability [2]. In effect, the client-server model
decomposes a large distributed system into a small nucleus
that changes relatively slowly, and a much larger and less
static periphery of clients. From the perspectives of security
and system administration, the scale of the system appears
to be that of the nucleus. But from the perspectives of
performance and availability, a user at the periphery
receives almost standalone service.
Coping with the constraints of mobility requires us to
rethink this model. The distinction between clients and
servers may have to be temporarily blurred, resulting in the
extended client-server model. The resource limitations of
clients may require certain operations normally performed
on clients to sometimes be performed on resource-rich
servers. Conversely, the need to cope with uncertain
connectivity requires clients to sometimes emulate the
functions of a server. These are, of course, short-term
deviations from the classic client-server model for purposes
of performance and availability. From the longer-term
perspective of system administration and security, the roles
of servers and clients remain unchanged.
A. Caching Metrics
Caching plays a key role in mobile computing because of
its ability to alleviate the performance and availability
limitations of weakly-connected and disconnected
operation. But evaluating alternative caching strategies for
mobile computing is problematic. Today, the only metric of
cache quality is the miss ratio. The underlying assumption
of this metric is that all cache misses are equivalent (that is,
all cache misses exact roughly the same penalty from the
user). This assumption is valid when the cache and primary
copies are strongly connected, because the performance
penalty resulting from a cache miss is small and, to a first
approximation, independent of file length. But the
assumption is unlikely to be valid during disconnected or
weakly-connected operation. The miss ratio also fails to
take into account the timing of misses. For example, a user
may react differently to a cache miss occurring within the
first few minutes of disconnection than to one occurring
near the end of the disconnection. As another example, the
periodic spin down of disks to save power in mobile
computers makes it cheaper to service a certain number of
page faults if they are clustered together than if they are
widely spaced. To be useful, new caching metrics must
satisfy two important criteria. First, they should be
consistent with qualitative perceptions of performance and
availability experienced by users in mobile computing.
Second, they should be cheap and easy to monitor. The
challenge is to develop such metrics and demonstrate their
applicability to mobile computing Initial work toward this
end is being done by Ebling [3].
VI. THE ENTERPRISE VALUE OF MOBILE ICT
The potential value of mICTs in enterprises is tremendous.
Enabling access to information and people anywhere and
anytime, enhancing decision making capabilities, and
creating a user-centric environment are some of the exciting
examples of mICTs in enterprises (Heck, 2004; Kalakota &
Robinson, 2002). While mobility itself offers tremendous
value to enterprises, there are several other aspects that
make the enterprise adoption and infusion of mICTs
compelling.
Unique Characteristics of mICT : mICTs exhibit a number
of unique characteristics, which include ubiquity,
connectivity, accessibility, reach ability, portability, and
localization.
Connectivity: Mobile connectivity is one of the
fundamental aspects of mICTs. Mobile connectivity refers
to the capability of connecting users to machines (U2M),
machines to machines (M2M), and users to users (U2U). In
comparison to the wired network environment, people and
users are not constrained by the location and availability of
network plug-ins. Today, mobile connectivity is constrained
by limited wireless network coverage. However, as mICTs
continue to advance, network coverage and bandwidth will
be abundant, and users will remain permanently connected
anywhere.
Accessibility and Reachability: Accessibility and
reachability are results of mobile connectivity. A necessary
precursor to both accessibility and reachability is that
sufficient wireless network coverage is available and that
the mobile device is switched on. Reachability builds on the
assumption that users and machines have the capability to
be in touch and be reached by other entities, while
accessibility refers to the capability of access to a wireless
network at any place and any time.
Portability: The most unique and distinguishing
characteristic of m-ICTs is the ability to physically move
computing and communications products and services with
the user. Traditional wired computing environments limited
users to the location of the device and network plug-in.
Localization: Localization refers to the ability to locate the
geographical position of a user or mobile device. Similar to
portability, localization is one of the unique characteristics
of mICTs. Localization is particularly important when the
user requires location-specific information, or the location
context itself wants to provide feedback to the user.
Ubiquity: The ultimate form of mobility includes the
integration of all the aforementioned characteristics. Users
have the capability to access the network at any place and
any time, and be in touch, be reached, and located at any
place and any time using always connected portable
devices. Ubiquity therefore exemplifies the ultimate form of
spatial, temporal, and contextual mobility (Junglas &
Watson, 2003).

A Case Study on System Issues and Impact of Mobility in Wireless Mobile Computing
4
Efficiency: It is human nature to try to make everyday
activities as efficient as possible. With the use of mICTs
enterprises provide a mean to utilize their desks and on-the-
go are capable of having access to information and people
from anywhere, raising the overall productivity level.
Mobile professionals that travel frequently can utilize their
“dead time” at airports or hotels more efficiently by
checking, updating, and viewing important corporate
information (Kalakota & Robinson, 2002).
Fundamentally, mICTs change the way people work and
interact. In addition to being able to address time-critical
and instantaneous needs, mICTs also enable enterprises
lower cost expenditures. Using a single device to perform a
variety of tasks reduces the overall equipment costs an
enterprise often has to bare with traditional wired network
environments and computing services (Anckar & D'Incau,
2002). In essence, mICTs applied in the right functional
areas and deployed to the right users therefore lead to a
more agile, adaptive, real-time, and cost-efficient enterprise
(Gribbins, et al., 2003).
Effectiveness: An equally significant contribution of
mICTs is the contribution to task effectiveness. Time-
critical and location-sensitive tasks are excellent candidates
for mobilization. By providing information at the point-of-
action, task effectiveness improves (Tarasewich, 2002). In
this paper, the author goes one step further and proposes
that a higher potential of task and decision-effectiveness is
achieved when the right information is delivered to the right
place, at the right time and to the point-ofthought.
Convenience. mICTs offer several conveniences.
First, it delivers a whole new way of interacting. The
convergence of wireless communications and the Internet
allows users to interact and communicate via voice, data, or
multimedia (Deans, 2002; Shapiro & Varian, 1999). Users
can check their voice mail, send an e-mail or view the latest
video conference, all from a mobile device. This leads to
the second convenience of mICT. The use of mobile
applications often involves the operation of only a single,
integrated device. The ability to perform several different
tasks with a single device increases a user’s familiarity,
proficiency and utilization (Anckar & D'Incau, 2002).
While personalization of services has been used extensively
in the traditional wired environment, it is an even more
important condition in the mICT domain. This is mainly
due to the limited screen size and computing capabilities of
today’s mobile devices, where personalized and localized
information adds significant value to the user (Tarasewich,
2002).
It should be cautioned that the mere adoption of mICTs
does not necessarily lead to increased levels of efficiency,
effectiveness, and convenience. In fact, there are some tasks
that are more suitable than others for enablement through
mICTs. (Gribbins, et al., 2003) argue that mICTs
implemented in the right enterprise functions and processes,
and made available to the right set of users, will provide the
greatest value. The implementation of mICTs, hence,
requires a detailed understanding on which types of tasks,
functional areas, and users will benefit from it. Other
challenges exist as well. Security, privacy, and user
identification are some examples. Adoption and
implementation strategies will therefore differ from
enterprise to enterprise (Ward & Peppard, 2002). The next
section discusses some of the critical issues that enterprises
should consider when planning to adopt, implement, and
infuse mICTs.
VII. CONCLUSION
Understanding the value of mobility is a critical step when
planning to adopt and implement mICTs. This research
argues that mobility fundamentally changes the way users
and enterprises interact. Mobility is not constrained to
geographic movement, but also applies to spatial, temporal,
and contextual aspects. As mICTs continue to advance,
mobility provides enterprises with a number of important
value propositions. When integrated and deployed
appropriately, mICTs can deliver higher levels of
efficiency, effectiveness, and convenience. However, the
discussion above also illustrates the complexity and
challenges of successfully adopting and implementing
mICTs. These challenges are what require further analysis
and which provide a number of exciting research
opportunities. The emergence of mobile computing
invalidates these assumptions and additionally introduces
new physical characteristics to the resulting computing
environment such as different operating modes, wireless
broadcast communication and constraints on battery power
consumption at mobile hosts. In this paper, we first
presented a system model that explicitly incorporates
mobility of hosts and highlights the effects of host mobility
on the static segment of the network. We then looked at
how mobility of hosts and the new physical features of
mobile hosts will fundamentally affect the design of
distributed algorithms. Finally we discussed some new
research issues that we are currently investigating under this
model. It is our thesis that introduction of mobile
computing will require and stimulate a fresh approach to
distributed computation.
REFERENCES
[1] M. Satyanarayanan School of Computer Science Carnegie Mellon
University, "Fundamental Challenges in Mobile Computing"
[2] Satyanarayanan, M. The Influence of Scale on Distributed File System
Design. IEEE Transactions on Software Engineering 18(1), January,
1992.
[3] Ebling, M.R. Evaluating and Improving the Effectiveness of Caching
Availability. PhD thesis, Department of Computer Science, Carnegie
Mellon University, 1997 (in preparation)
[4] Kistler, J.J. Disconnected Operation in a Distributed File System. PhD
thesis, Department of Computer Science, Carnegie Mellon University,
May, 1993
[5] Kumar, P., Satyanarayanan, M. Log-Based Directory Resolution in the
Coda File System. In Proceedings of the econd International
Conference on Parallel and Distributed Information Systems. San
Diego, CA, January, 1993.
[6] Kumar, P. Mitigating the Effects of Optimistic Replication in a
Distributed File System. PhD thesis, School of Computer Science,
Carnegie Mellon University, December, 1994.

5
[7] T. Imielinski and B. R. Badrinath. Querying in highly mobile
distributed environments. In 18 Intl.Conference on Very Large
Databases, pages 41–52, 1992.
[8] T. Imielinski and B. R. Badrinath. Mobile wireless computing:
Solutions and challenges in data management.Technical report,
WINLAB/Rutgers Tech. Rept., February, 1993.
[9] J. Ioannidis, D. Duchamp, and G. Q. Maguire. Ipbased
protocols for mobile internetworking. In Proc. of ACM SIGCOMM
Symposium on Communication, Architectures and Protocols, pages
235–245, September 1991.
[10] John Ioannidis and Gerald Q. Maguire Jr. The design
and implementation of a mobile internetworking architecture. In
1992 Winter Usenix, Jan. 1993.
[11] James Kistler and M. Satyanarayanan. Disconnected
operation in the coda file system. ACM Trans. on Computer
Systems, 10(1), Feb. 1992.
[12] G. Le Lann. Distributed systems, towards a formal approach. IFIP
Congress, Toronto, pages 155–160, 1977. [13] K. Raymond. A tree-
based algorithm for distributed mutual exclusion. ACM Transactions
on Computer Systems, 7(1), Feb. 1989.
[14] Yakhov Rekhter and Charles Perkins. Optimal routing
for mobile hosts using ip’s loose source route option. In Internet
Draft, October 1992.
[15] Samuel Sheng, Ananth Chandrasekaran, and R. W.
Broderson. A portable multimedia terminal for personal
communications. IEEE Communications Magazine, December
1992.
[16] Carl D. Tait and Dan Duchamp. Service interface and replica
management algorithm for mobile file system clients. In Proc. First
Intl. Conf. on Parallel and Distributed Information Systems, 1991
[17] Hiromi Wada, Takashi Yozawa, Tatsuya Ohnishi, and Yasunori
Tanaka. Mobile computing environment based on internet packet
forwarding. In 1992 Winter Usenix, Jan. 1993.
[18] Anckar, B., & D'Incau, D. (2002). Value Creation in
Mobile Commerce: Findings from a Consumer Survey. Journal of
Information Technology Theory and Application, 4(1), 43
[19] Cooper, R. B., & Zmud, R. W. (1990). Information
Technology Implementation Research: A Technological Diffusion
Approach. Management Science, 36(2), 123-139.
[20]Deans, C. (2002). Global Trends and Issues for Mobile/Wireless
Commerce. Paper presented at the Eighth Americas Conference on
Information Systems.
[21]Decanio, S. J., Dibble, C., & Amir-Atefi, K. (2000).
The Importance of Organizational Structure For The Adoption of
Innovations. Management Science, 46(10), 1285.

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