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 E-mail: kemal@cs.siu.edu Mobile & Wireless Computing 1

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 2

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 3

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 802.11 : 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 4

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

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

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 7

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

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 9

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 802.11b 9.6 Kbps for wide-area wireless communication Wired networks 10-100 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 10

Heterogeneous Devices Laptop fully functional standard applications battery; 802.11 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 11

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 12

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 13

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 14