1. Wireless & Mobile
Computing
Submitted by : Manika Gandhi
115325
Company
N1
LOGO

2. Company
LOGO Contents
1.Wireless communication 7.CDMA & DAMA
2.Effects of device portability 8.Wireless networks
3.Mobile computing platform 9.CSMA problems
4.Wireless & fixed networks 10.Hidden terminal problem
5.Wireless management 11.Applications
6.Building blocks 12.Security concerns

3. Company
LOGO Mobile/wireless communication
Two aspects of mobility:
 user mobility: users communicate
(wireless) “anytime, anywhere, with
anyone”
 device portability: devices can be
connected anytime, anywhere to the
network

4. Company
LOGO

5. Company
LOGO Effects of device portability
 Power consumption
–limited computing power, low quality
displays
–loss of data with higher probability
 Limited user interfaces
–compromise between size of fingers and
portability
–character/voice recognition, abstract
symbols

6. Company
LOGO MobileComputing Platforms Platforms
Mobile Computing
Server
Mobile Device (Web Server, eMail server,
(Cell Phone, PDA, Pocket PC) Mainframe)
Application Application
Middleware Middleware
Services Mobile Services
Computing
Local Network Platform Local Network
Platform Transport Platform Transport
Services Services Services Services
Physical Wireless Network
(Antennas, Transceivers, Base Stations,
Cellular Networks, 802.11 LANs,
Satellites)

7. Company
LOGO Wireless v/s fixed networks
 Higher loss rates due to interference
 Restrictive regulationsTEXTfrequencies
TEXT
of TEXT
 Low transmission rates
 Higher delays, higher jitter
 Lower security, simpler active attacking
 Always shared medium

8. Company
LOGO Wireless Management & Business
STRATEGIC PLANNING
• Business Strategy Analysis
•Analyzing Business Processes and Business Workflows
•Mobile Application Identification and Selection.
CAPABILITY EVALUATION
ORGANIZING/STAFFING •Wireless Infrastructure Planning
. Mobile Virtual Teams •Capacity Planning & Traffic Engineering
. Mobile Real-time Enterprises •Resource and Cost Estimation
MONITORING AND CONTROL
DEVELOPMENT AND DEPLOYMENT
•Wireless fault and
• Mobile application development
performance management
• Wireless infrastructure development
•Wireless Security and Outsourcing the Wireless Infrastructure
configuration management

9. Company
LOGO The Building Blocks of Mobile Computing
Drivers
•Wireless Business,
Mobile Business, Government, and Life Regulations, and
Standards
Mobile Computing Applications
•Architectures and
Integration
Mobile Computing Platforms
(Wireless Middleware, Mobile IP)
•Wireless Security
Wireless Networks •Management and
(Wireless LANs, Cellular Networks, Support
Satellites, Wireless Local Loops)
Enablers

10. Company
LOGO Demand Assignment Multiple Access
 In a DAMA protocol, nodes first reserve
slots which they intend to use for
broadcasting.
 Each round of broadcast is preceded by a
reservation round.
 DAMA protocols are widely used in
satellite communication and increasingly
being used in wireless networking.

11. Company
LOGO Code Division Multiplexing
 CDMA has been adopted for the 3G
mobile phone technology.
 CDMA is not very suitable for ad hoc
networking as we cannot expect
specialized hardware/software support at
the nodes.
 TDMA and its variations are most suitable
for ad hoc networking.

12. Company
LOGO Wireless Networks
Wireless Networks
Wireless LANs Wireless MANs Wireless WANs
Wireless Cellular Satellite Paging
Personal Business Local Loops Networks Systems Networks
Area LANs (Fixed Wireless)
Networks
Example1: Example1: Example1: Example1: Example1: Example1:
Bluetooth 802.11b LMDS GSM, 9.6 Kbps, Motorola FLEX,
1 Mbps, 11 Mbps, 37 Mbps, wide coverage Iridium
10 Meters 100 Meters 1.2 Kbps
2-4 Km up to 64 Mbps
Example2: globally
Other examples: Other Example2: 3G, 2 Mbps, Example2:
wireless sensor examples: FSO wide coverage Example 2: ReFLEX,
networks, UWB 802.11g, 1.25 Gbps Deep space 6.4Kbps
HiperLAN2 1-2 KM communication

13. Company
LOGO Physical layers in wireless networks
 Use a medium that has neither absolute nor readily
observable boundaries outside which stations are
unable to receive frames
 Are unprotected from outside signals
 Communicate over a medium significantly less
reliable than wired PHYs
 Have dynamic topologies
 Lack full connectivity and therefore the assumption
normally made that every station (STA) can hear
every other STA in invalid (I.e., STAs may be “hidden”
from each other)
 Have time varying and asymmetric propagation
properties

14. Company
LOGO CSMA Problems in Wireless Network
 Collision detection is easy in wired networks but
difficult in wireless medium
 With only one antenna, nodes can only listen or
send
 Full duplex radios are extremely expensive
 CSMA gives rise to hidden terminal and exposed
terminal problems

15. Company
LOGO Hidden Terminal Problem
 Wireless transmission is usually short
range. Even if the medium is free near the
transmitter, it may not be free near the
intended receiver.
A B C
Collision
at B

16. Company
LOGO Message Loss due to Collision
 Using CSMA in wireless medium results in
message loss and requires retransmission of
lost messages.
 A node spends much more energy while
receiving or transmitting messages. Hence,
retransmission wastes a lot of energy.
 The other alternative is to use a reservation
based TDM protocol.

17. Company
LOGO Applications I
 Mobile, pervasive, ubiquitous, nomadic
computing
 Computing anytime anywhere
TEXT
 Distributed computing, CORBA TEXT
 Cellular and satellite networks
 Ad hoc networks: rescue, battlefield, conference
 Sensor networks: monitoring environment to
detect object movement or presence of
TEXT
chemicals, fire, temperature reports
 Mesh networks;: rooftop networks for multi-hop
wireless Internet access

18. Company
LOGO Applications II
 Vehicles
–transmission of news, road condition, weather, music
–personal communication using GSM
–position via GPS
–local ad-hoc network with vehicles close-by to prevent
accidents, guidance system, redundancy
–vehicle data (e.g., from busses, high-speed trains) can be
transmitted in advance for maintenance
 Emergencies
– early transmission of patient data to the hospital
– replacement of a fixed infrastructure in case of
earthquakes, hurricanes, fire etc.

19. Company
LOGO Security Concerns
 Authentication is critical
» Normal network point of attachment is a wall
tap
» Wireless access makes network attachment
too easy
 Exposure to over-the-air wiretapping
» Any transmitter can also be a receiver
» Some wireless networks provide secure air
links
» Made more difficult by spread spectrum
technologies

20. Company
LOGO
Thanks