1. CS441 – Mobile & Wireless Computing Wireless Network Challenges
Department of Computer Science
Southern Illinois University Carbondale
CS441 – Mobile & Wireless Computing
Wireless Network Challenges
Dr. Kemal Akkaya
Mobile & Wireless Computing

2. Mobile and Wireless Data Networks
Experiencing a tremendous growth over the last decade
Wide deployment of access infrastructure
In-door, out-door, MAN, WAN
Growth of Wireless Data
Miniaturization of computing machinery : laptop  PDA  Smart Phones  embedded sensors
Increasing mobile work force
Luxury of tether less computing
Information on demand anywhere/anyplace
Some Facts:
Majority of internet users have internet connectivity through a wireless enabled device.
The number of wireless data subscribers hit more than 1B!! by now.
What is Mobile and Wireless Computing?
Distributed systems with portable computers and wireless communications
User can access data anytime, anywhere
Mobile & Wireless Computing

3. Buzzwords Mobile Computing Nomadic Computing
Distributed systems with mobile users
In-door/Out-door
Vehicle/human speed
Nomadic Computing
Similar to Mobile computing
Focuses more on in-door communications
Pervasive Computing : Ubiquitous Computing
May add some user interface integration
Some says : AI + Mobile Computing stuff
Applications:
Military
Border control, target tracking, intrusion detection etc.
Civil
Habitat monitoring, search and rescue, meeting rooms etc.
Mobile & Wireless Computing

4. Wireless Network Types
Satellite networks
Iridium (66 satellites)
Qualcomm’s Globalstar (48 satellites)
Wireless WANs/MANs
CDPD (Cellular Digital Packet Data )
GPRS (General Packet Radio Service)
Wireless LANs
IEEE : SIU’s LAN,
Wireless PANs
e.g. Infrared: Bluetooth, Zigbee
Ad-hoc networks
e.g. Emergency relief, military
Sensor networks
e.g. Environmental sensing-motes
Wireless WAN Generations:
1G (Past)
AMPS, TACS: No data
2G (Past)
IS-136, GSM: <10Kbps circuit switched data
2.5G (Past)
GSM-GPRS, GPRS-136: <100Kbps packet switched
3G (Present)
IMT-2000: <2Mbps packet switched
4G/LTE (Present)
20-40 Mbps!!
5G (future)
Mobile & Wireless Computing

5. Examples 802.11 / WiFi Wireless LAN PicoNet Bluetooth
Mobile & Wireless Computing

6. Applications: Home Networking
Courtesy Dr. Richard Yang, Yale
Mobile & Wireless Computing

7. Applications: Outdoor Networking
ad hoc
UMTS, WLAN,
DAB, GSM,
cdma2000, TETRA, ...
Personal Travel Assistant,
PDA, laptop,
GSM, UMTS, WLAN,
Bluetooth, ...
Courtesy Dr. Richard Yang, Yale
Mobile & Wireless Computing

8. Application: Environmental Monitoring
Wireless Sensor Nodes monitor an area of interest
Mobile & Wireless Computing

9. Challenges of Wireless Computing
1) Wireless Communication
Implications of using wireless communication for mobile computing
The differences between wireless and wired media
2) Mobility
Consequences of mobility on mobile application and system design
3) Poor Resources due to Portability
Pressures that portability places in the design of mobile end-systems
Mobile & Wireless Computing

10. 1) Wireless Communication
Limited Transmission Range
10m-500m
Limited Bandwidth
Wireless networks deliver lower bandwidth than wired networks
1 Mbps Infrared communication
11 Mbps wireless local radio communications (shared), IEEE b
9.6 Kbps for wide-area wireless communication
Wired networks
Mbps for Ethernet
100 Mbps for FDDI
155 Mbps for ATM
1 Gbps for Gigabit Ethernet
Disconnections
Network partitions
Stall all applications
Uncertainty of Performance
Variance of bit errors
Variance of delays
Variance of bandwidth
Security
Easy to intrude in the wireless network
Heterogeneous devices and network connections
Wired links
Same characteristics
Outdoor: Radio
Indoor: Infrared
Rural Areas: Satellite
Mobile & Wireless Computing

11. Heterogeneous Devices
Laptop
fully functional
standard applications
battery;
Mobile phones
voice, data
simple graphical displays
GSM
Desktop
fully functional
standard applications
unlimited power supp
Gbps Ethernet
Sensors,
embedded
controllers
PDA
data
simpler graphical displays
802.11
Performance/Weight/Power Consumption
Mobile & Wireless Computing

12. 2) Mobility Ability to change locations while connected to the network
A mobile computer can change its server
DNS server, print server, etc.
Dynamic Environment
Network Access Point Changes
Address changes: IP address
Network Performance Changes
Bandwidth, delay, error rate etc.
Available resources change
Depends on the network it connected to
Data consistency changes
Writing/Reading to/from mobile databases
Security changes
Endpoint authentication harder
Mobile & Wireless Computing

13. 3) Poor Resources
Mobile devices are fundamentally different from stationary machines such as desktop computers
Must be designed with variety of constraints in mind, such as size and power consumption – properties much like a wristwatch
They should also be portable
Portability Constraints Include
Low power consumption
You would not want to carry a battery that is bigger than your computer!
Increased risk of data loss
Physical damage
Unauthorized access
Loss and Theft
Small user-interfaces
Requires a different windowing scheme
Buttons versus Recognition
Limited on-board storage, memory, CPU etc
Physical restrictions, power constraints
Mobile & Wireless Computing

14. Summary Wireless communication brings challenging network conditions
Slow and sometime disconnected communication
Mobility causes greater dynamicisim of information
Portability results limited resources to be available on board
Mobile computing designers should consider these issues in designing mobile systems, applications and networks that are comparable with the traditional stationary computing and communication in terms of operation, performance, and availability
Very active research area in the last decade
Many interesting research problems
Mobile & Wireless Computing