session: 1 0.1 it 601: mobile computing session 1 introduction prof. anirudha sahoo iit bombay
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Session: 1 0.1
IT 601: Mobile Computing
Session 1Introduction
Prof. Anirudha SahooIIT Bombay
Session: 1 0.2
Course Evaluation
•Home assignment – 10%•Pop Quizzes – 5%•MidSem – 25%•Project – 25%•EndSem – 35%
Session: 1 0.3
Course Evaluation
•Academic dishonesty (in any form) will not be tolerated– will result in FF grade
•Attendance : as per Institute rules•Audit Requirements
– attendance : as per Institute rules– must appear midsem and endsem exams– may exchange endsem with project– take quiz/homework– at least CC grade in the evaluation
Session: 1 0.4
Prerequisite
• Basic Computer Networks–Sound knowledge in traditional MAC protocols–IP routing protocols–TCP
• Basics of Probability theory and queuing theory
Session: 1 0.5
References
• Mobile Communications – J. Schiller, Pearson education publishing 2003• Wireless Communications and Networks – W. Stallings, Pearson education publishing 2002•Technical papers – will be given out throughout the course
Session: 1 0.6
Introduction
• What is different in wireless network?– Bandwidth– Error rate– Media– Signal strength (fading)– MAC– Mobility– Security
Session: 1 0.7
Wireless networks
• Two types– Voice network
• Cellular systems (GSM, CDMA etc.)– Data network
• WiFi, HiperLAN• Networks are moving towards an integrated network
– GPRS– Voice over WiFi
Session: 1 0.8
Physical Layer (PHY)
• Binary (digital) data transmitted over airwave• Requires antenna• characterized by transmission range, power,
modulation scheme, frequency range
Session: 1 0.9
MAC Layer
• How wireless stations share the air medium and avoid contention to transmit data successfully
• “listen before you speak” or “speak at predetermined interval”
• Unique problems– Hidden node– Exposed node
Session: 1 0.10
Network Layer
• Responsible for facilitating multihop communication• Need to run some routing protocol• Traditional routing protocols may not work efficiently• Mobility at IP layer
Session: 1 0.11
Transport Layer
• Reliable Transport such as TCP may not work well in wireless medium– TCP inherently assumes that packet loss is due to
congestion– Needs modification for wireless network
Session: 1 0.12
Source: Matt Welsh, Harvard University
802.16
120Mbps
Session: 1 0.13
WiFi Network
Basic Service Set
gAccess Point
Access Point
Wireline network
Session: 1 0.14
WiFi Network
• 802.11b and 802.11g Use 2.4 GHz ISM band• 802.11b : 11 Mbps• 802.11g : 54 Mbps• 802.11a : uses 5 GHz band: 54Mbps
Session: 1 0.15
Bluetooth• Short range (10m),moderate data rate (720kbps) for creating an adhoc network
between personal devices• One master and upto 7 slaves in a piconet• Master controls the transmission schedules of all the devices
– TDMA scheduling• Frequency hopping used to
avoid interference with otherpiconets
– 79 channels in the 2.4GHz ISM band, with 1 MHz spacing– Frequency hopping at 1600 hops/s
PICONET
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