CS434/534: Mobile Computing and
Wireless Networks
http://zoo.cs.yale.edu/classes/cs434/
Y. Richard Yang
08/30/2012
Outline
Pervasive wireless networks and mobile
applications
Challenges facing wireless networks and
mobile computing
Course information
2
Goal of Mobile Computing
“People and their machines should be able to
access information and communicate with
each other easily and securely, in any
medium or combination of media – voice,
data, image, video, or multimedia – any
time, anywhere, in a timely, cost-effective
way.”
Dr. G. H. Heilmeier, Oct 1992
3
Pervasive Mobile Devices
“In many parts of the world, more people have
access to a mobile [wireless] device than to a
toilet or running water.” [Time Aug. 2012]
Many industrial countries reach at least 90%
mobile phone subscription penetration rate
[see phone penetration rates sheet]
PEW Internet and American Life Project:
“The mobile device will be the primary connection
tool to the Internet for most people in the world in
2020”
4
Pervasive Wireless Networks
Wireless coverage:
http://www.verizonwireless.com/wireless
-coverage-area-map.shtml
http://www.wireless.att.com/coveragevie
wer/
5
Mobile Device Usage
Source: O2
6
Mobile Traffic Growth
Source: Cisco
7
Mobile Computing Changing Our Lives
Source: TIME mobility survey; June-July 2012
8
10 Use Cases of Mobile Computing
Changing the World
Source: TIME survey; June-July 2012
9
Mobile Computing Features
with Larger Effects
Source: TIME survey; June-July 2012
10
Mobile Computing Changing Our Lives
Source: TIME survey; June-July 2012
11
Mobile Computing Changing Our Lives
Source: TIME survey; June-July 2012
12
Mobile Computing Changing Our Lives
Source: TIME survey; June-July 2012
http://www.time.com/time/interactive/0,31813,2122187,00.html
13
Use Case: Home Networks
satellite
WiFi
802.11g/n
WiFi
WiFi
Bluetooth
NFC
UWB
bluetooth
WiFi
cellular
14
Use Case: Mesh Networks
Many users still don’t
have broadband
reasons: out of service
area; some consider
expensive
15
Use Case: Mesh Network for
Disaster Recovery/Military
9/11, Tsunami, Hurricane Katrina,
South Asian earthquake …
Wireless communication and
mobile computing capability
can make a difference
between life and death !
http://www.att.com/ndr/
rapid deployment
efficient resource and energy usage
flexible: unicast, broadcast, multicast, anycast
resilient: survive in unfavorable and untrusted
environments
16
Use Case: Seamless Handoff--Always
Best Connected
LAN, WLAN
780 kbit/s
GSM 53 kbit/s
Bluetooth 500 kbit/s
UMTS Rel. 5
400 kbit/s
LAN
100 Mbit/s,
WLAN
54 Mbit/s
UMTS,
DECT
2 Mbit/s
GSM/EDGE 135 kbit/s,
WLAN 780 kbit/s
GSM 115 kbit/s,
WLAN 11 Mbit/s
UMTS Rel. 6
400 kbit/s
17
Use Case: Traffic Signal Advisor
http://www.princeton.edu/~ekoukoum/SignalGuru.html
18
Use Case: Vehicular Networks
Traffic crashes resulted
in more than 41,000 lives
lost/year
Establishing
vehicle-to-vehicle (V2V),
vehicle-to-infrastructure
(V2I) and
vehicle-to-hand-helddevices (V2D)
communications
More info: http://www.its.dot.gov/intellidrive/index.htm
19
Collision Avoidance : V2V Networks
stalled vehicle
warning
bland spots
http://www.gm.com/company/gmability/safety/news_issues/releases/sixthsense_102405.html
20
Collision Avoidance at Intersections
Two million
accidents at
intersections
per year in US
Source: http://www.fhwa.dot.gov/tfhrc/safety/pubs/its/ruralitsandrd/tb-intercollision.pdf
21
Google Glass
22
Use Case: Habitat Monitoring
A 15-minute human visit leads to 20%
offspring mortality
Patch
Network
Gateway
Transit Network
Basestation
23
Wireless and Mobile Computing
Driven by technology and vision
Mobile device capabilities and platforms
Global communication infrastructures
The field is moving fast
24
Enabling Infrastructures
Development and deployment of wireless
infrastructures
networking: in-room, in-building, on-campus, in-thefield, MAN, WAN
Development and deployment of localization
infrastructures
location: GPS, AGPS, …
Development and deployment of sensor
networks
25
Wireless Bit Rates
1.2 kbps
9.6 kbps
384 kbps
2 Mbps
100 Mbps
1 Gbps
NMT
1981
GSM
1992
IMT-2000
2001
(WCDMA; CDMA)
IMT-Advanced
~2012
26
Enabling Infrastructure:
Networks
Standard
GSM GPRS Class 10
GSM EDGE Evolution
CDMA EV-DO Rev. 0
CDMA EV-DO Rev. A
CDMA EV-DO Rev. B
WiFi: 802.11b
Flash-OFDM: Flash-OFDM
WiFi: 802.11g
WiFi: 802.11a
LTE
WiMAX: 802.16m
WiFi: 802.11n
HSPA+
LTE Advanced (Cat 8)
WiFi: 802.11ac (8aAP; 4a ST)
All units are Mbps
Peak Downlink Peak Uplink Tech
0.0856
0.0428
1.6
0.5 TDMA/FDD
2.458
0.1536 CDMA/FDD
3.1
1.8 CDMA/FDD
4.9
1.8 CDMA/FDD
11
11 DSSS
15.9
5.4 Flash-OFDM
54
54 OFDM
54
54 OFDM
300
75 OFDMA/MIMO
365
376 MIMO/SOFDMA
600
600 OFDM/MIMO
672
2998.6
3470
168 CDMA/FDD/MIMO
1497.8 MIMO
3470 MU-MIMO
27
Enabling Infrastructure:
Measurements
Source: A Close Examination of Performance and Power Characteristics of 4G LTE; Mobisys’12
28
Improving Infrastructure:
Power Efficiency
Source: A Close Examination of Performance and Power Characteristics of 4G LTE; Mobisys’12
29
Enabling Device Capabilities, Platforms
Improving device capabilities, mobile
application frameworks, applications, e.g.,
andriod
iphone/ipad
windows phone
30
Processing Capability:
Javascript Benchmark
31
Processing Capability:
Javascript Benchmark
32
Processing Capability:
Javascript Benchmark
33
Processing Capability:
Javascript Benchmark
34
Processing Capability:
Javascript Benchmark
35
Processing Capability:
Javascript Benchmark
36
Processing Capability:
Javascript Benchmark
37
Sensing Capability (iphone 4)
38
Why is the Field Challenging?
Challenge 1: Unreliable and
Unpredictable Wireless Coverage
Wireless links are not reliable: they may
vary over time and space
Reception v. Distance
Reception vs. Power
*Cerpa, Busek et. al
What Robert Poor (Ember) calls “The good, the bad and the ugly”
40
Challenge 2: Open Wireless
Medium
Wireless interference
S1
R1
S2
R1
41
Challenge 2: Open Wireless
Medium
Wireless interference
S1
R1
S2
R1
Hidden terminals
S1
R1
S2
42
Challenge 2: Open Wireless
Medium
Wireless interference
S1
R1
S2
R1
Hidden terminals
S1
R1
S2
Exposed terminal
R1
S1
S2
R2
43
Challenge 2: Open Wireless
Medium
Wireless interference
S1
R1
S2
R1
Hidden terminals
S1
R1
R2
Exposed terminal
R1
S1
Wireless security
S2
R2
eavesdropping, denial of service, …
44
Challenge 3: Mobility
Mobility causes poor-quality wireless links
Mobility causes intermittent connection
under intermittent connected networks,
traditional routing, TCP, applications all break
Mobility changes context, e.g., location
45
Challenge 4: Portability
Limited battery power
Limited processing, display and storage
Sensors,
embedded
controllers
Smart phone
• data
• smaller graphical displays
• 802.11/3G
Tablet/Laptop
Mobile phones
• voice, data
• simple graphical displays
• GSM/3G/4G
Performance/Weight/Power Consumption
46
Challenge 5: Changing Regulation and
Multiple Communication Standards
47
Challenge 5: Changing Regulation and
Multiple Communication Standards
cellular phones
1981:
NMT 450
satellites
1986:
NMT 900
1992:
GSM
1994:
DCS 1800
analogue
1984:
CT1
1988:
InmarsatC
1991: 1991:
CDMA D-AMPS
1993:
PDC
2000:
GPRS
wireless
LAN
1980:
CT0
1982:
InmarsatA
1983:
AMPS
cordless
phones
1992:
Inmarsat-B
Inmarsat-M
1987:
CT1+
1989:
CT 2
1991:
DECT
1998:
Iridium
199x:
proprietary
1997:
IEEE 802.11
1999:
802.11b, Bluetooth
2000:
IEEE 802.11a
2001:
IMT-2000
digital
Fourth
Generation
(Internet
based)
48
Wireless Communication Standards
49
What Will We Cover?
Class Info: Personnel
Instructor
• Y. Richard Yang, yry@cs.yale.edu, AKW 308A
• office hours: to be posted
• Ramki Gummadi, ramki@cs.yale.edu, AKW 413
Teaching fellow
• To be posted
• office hours: to be posted on class page
Course home page
http://zoo.cs.yale.edu/classes/cs434/
51
Class Goals
Learn both fundamentals and applications
of wireless networking and mobile
computing
Obtain hands-on experiences on developing
on wireless, mobile devices
wireless networking: GNU radio
mobile computing: Android (you may explore
IOS or Windows Mobile in your project)
Discuss challenges and opportunities in
wireless networking and mobile computing
52
The Layered Reference Model
Application
Application
Transport
Transport
Network
Network
Data Link
Physical
Radio
Network
Network
Data Link
Data Link
Data Link
Physical
Physical
Physical
Medium
Often we need to implement a function across multiple layers.
53
Course Topic:
Communications/Connectivity
Physical layer: channel and diversity
Link layer: channel sharing
Network and transport: routing, reliability
54
Course Topic: Mobile OS/App
Framework
Android app framework
Activity, service, intent, content provider,
handler/AsyncTask, …
Virtualizing mobile OS
Measuring/profiling mobile app
Why are web browser slow on smartphones?
Why did some small percentage of Pandora’s
traffic is responsible for a large fraction of
energy use on my phone? …
55
Course Topic: Mobile Network App
Techniques
Informed usage of networks
MatchMaking
Using peer-to-peer connections
Wifi Direct, Microcast, NFC
Hybrid mobile/cloud/server
Cloud messaging
Code partition (MAUI, Cloudlet)
Aggregation (SmartVNC)
Storage partition
56
Course Topic: Sensory Framework/App
Location
Localization (GPS, lateration, acoustic,
siganture)
Location based services
• Google MapView, Map API
Sensing
Detecting the environment using cameras,
microphones, and collaborations
• signalGuru, Darwin Phone
57
Course Topics
OS/Application Platform
Communications
Sensing
Security
(will
not
cover)
58
Class Materials
Chapters of reference books
Selected conference and journal papers
Other resources
MOBICOM, SIGCOMM, Mobisys proceedings
IEEE Network, Communications, Pervasive
magazines
59
Suggested Reference Books
“Fundamentals of Wireless
Communication”, by David
Tse and Pramod Viswanath,
Cambridge University Press
(available online)
“802.11 Wireless
Networks: the Definitive
Guide” by Matthew Gast,
O’Reilly (available online)
60
Suggested Reference Books (2)
“The Android Developer’s
Cookbook”, by James
Steele and Nelson To
“Hello, Android”, by Ed
Burnette
 Developer guide: http://developer.android.com/guide/components/index.html
61
What You Need to Do
Your prerequisite
motivated, critical
basic programming skill
•
•
Gnuradio: GUI, python, C++
Android: Java, C (if you decide to hack into the kernel)
Your workload
class participation
• actively participate in class discussions
3-4 assignments
One project
One midterm
62
Class Project
Goal: obtain hands-on experience
We’ll suggest potential topics
You may also choose your own topic
Initial proposal + midterm progress report
+ final report + [presentation]
We provide help in obtaining
Mobile devices
Amazon/Google cloud service accounts
63
Grading
Project
35%
Assignments
35%
Exam
20%
Class
Participation
10%
More important is what you realize/learn
than the grades
64
Class Survey
Please take the class survey
help me to determine your background
help me to determine the depth and
topics
suggest topics that you want to be
covered
65
Questions?
Backup
67
Evolution of Mobile Systems to 3G
68
3G Networks
http://en.wikipedia.org/wiki/List_of_mobile_network_operators_of_the_Americas#United_States
69
Mobile Computing Changing Our Lives
Source: TIME survey
70
IMT Advanced Requirements
All-IP communications.
Peak data rates
100 Mbit/s for high mobility
1 Gbit/s for low mobility
Scalable channel bandwidth, between 5 and
20 MHz, optionally up to 40 MHz
Peak link spectral efficiency
15 bit/s/Hz (downlink); 6.75 bit/s/Hz (uplink)
System spectral efficiency
3 bit/s/Hz/cell (downlink)
2.25 bit/s/Hz/cell (indoor)
71