Chapter 1
INTRODUCTION
Based on the slides of Dr. Andrea Goldsmith, Stanford University and Dr. Dharma P. Agrawal, University of Cincinnati
Course Objectives:
� This course will cover the fundamental aspects of wireless networks, withemphasis on current and next-generation wireless networks. Variousaspects of wireless networking will be covered including: fundamentals ofcellular communication, mobile radio propagation, multiple accesstechniques, mobility support, channel allocation, Wireless PAN/LAN/MANstandards, mobile ad-hoc networks, wireless sensor networks, Internet ofThings (IoT), and routing in wireless and mobile networks.
� The goal of this course is to introduce the students to state-of-the-artwireless network protocols and architectures with emphasis on theInternet of Things (IoT).
� We will introduce the students to wireless networking research and guidethem to investigate novel ideas in the area via semester-long researchprojects (IoT theme).
� We will also look at industry trends and discuss some innovative ideasthat have recently been developed. Some of the course material will bedrawn from research papers, industry white papers and Internet RFCs.
Wireless History
� Radio invented in the 1880s by Marconi
� Many sophisticated military radio systems were developed during and after WW2
� Cellular has enjoyed exponential growth since 1988� Ignited the recent wireless revolution
� Ancient Systems: Smoke Signals, Carrier Pigeons, …
Exciting Developments
� Internet and Mobile use exploding
� Wireless LANs growing rapidly
� Huge cell phone popularity worldwide
� Emerging systems such as Bluetooth,
UWB, Zigbee, LTE, and WiMAX opening
new doors
� Internet of Things (IoT) and Smart Objects
� Military and security wireless needs
� Important interdisciplinary applications
5
Future Wireless Networks
Wireless Internet access
Nth generation Cellular
Wireless Ad Hoc Networks
Sensor Networks
Wireless Entertainment
Smart Homes/Spaces
Internet of Things (IoT)
Automated Highways
All this and more…
Ubiquitous Communication Among People and Devices
•Hard Delay Constraints
•Hard Energy Constraints
6
Design Challenges
� Wireless channels are a difficult and capacity-limited broadcast communications medium
� Traffic patterns, user locations, and network conditions are constantly changing
� Applications are heterogeneous with hard constraints that must be met by the network
� Energy and delay constraints change design principles across all layers of the protocol stack
� Location-aware services.
� Applications, applications, applications!
7
Radio Propagation Effects
Transmitterd
Receiver
hb
hm
Diffracted
Signal
Reflected Signal
Direct Signal
Building
8
Multimedia Requirements
Voice VideoData
Delay
Packet Loss
BER
Data Rate
Traffic
<100ms - <100ms
<1% 0 <1%
10-3 10-6 10-6
8-32 Kbps 1-100 Mbps 1-20 Mbps
Continuous Bursty Continuous
One-size-fits-all protocols and design do not work well
Wired networks use this approach, with poor results
Quality-of-Service (QoS)
� QoS refers to the requirements associated with a given application, typically rate and delay requirements.
� It is hard to make a one-size-fits all network that supports requirements of different applications.
� Wired networks often use this approach with poor results, and they have much higher data rates and better reliability than wireless.
� QoS for all applications requires a cross-layer design approach.
Crosslayer Design
� Application
� Network
� Access
� Link
� Hardware
Delay Constraints
Rate Constraints
Energy Constraints
Channel-State
Adapt across design layers
Reduce uncertainty through scheduling
Provide robustness via diversity
Current Wireless Systems
� Cellular Systems
� Wireless LANs
� Satellite Systems
� Bluetooth
� Ultrawideband radios
� Zigbee radios
Fundamentals of Cellular Systems
Illustration of a cell with a mobile station and a base station
BS
MS
Cell
Hexagonal cell area
used in most models
Ideal cell area
(2-10 km radius)
Alternative
shape of a cell
MS
FDMA (Frequency Division Multiple Access)
User 1
User 2
User n
…Time
Frequency
Frequency Reuse
14
15
FDMA Bandwidth Structure
1 2 3…
nFrequency
Total bandwidth
4
FDMA Channel Allocation
Frequency 1 User 1
Frequency 2 User 2
Frequency n User n
Base Station
… …
Mobile Stations
OFDM� Conceptually, OFDM is a specialized FDM, the additional constraint
being: all the carrier signals are orthogonal to each other.
� In OFDM, the sub-carrier frequencies are chosen so that the sub-carriers are orthogonal to each other, meaning that cross-talk between the sub-channels is eliminated and inter-carrier guard bands are not required. This greatly simplifies the design of both the transmitter and the receiver; unlike conventional FDM, a separate filter for each sub-channel is not required.
Used also in DSL Modems
Used in Dual-Tone Multi-Frequency (DTMF)
MIMO� In radio, multiple-input and multiple-output,
or MIMO is a method for multiplying the capacity of a radio link using multiple transmit and receive antennas to exploit multipath propagation. MIMO has become an essential element of wireless communication standards including IEEE 802.11n (Wi-Fi), IEEE 802.11ac (Wi-Fi), HSPA+ (3G), WiMAX (4G), and Long Term Evolution (4G).
Analogy: Think of a shower head ☺
TDMA (Time Division Multiple Access)
Use
r 1
Use
r 2
Use
r n
…
Time
Frequency
TDMA Frame Structure
1 2 3…
nTime
Frame
4
TDMA Frame Illustration for Multiple Users
Time 1
Time 2
Time n……
Base Station
User 1
User 2
User n
…
Mobile Stations
CDMA (Code Division Multiple Access)
Use
r 1
Time
Frequency
Use
r 2
Use
r n
Code
...
Transmitted and Received Signals in a
CDMA System
Information bits
Code at
transmitting end
Transmitted signal
Received signal
Code at
receiving end
Decoded signal
at the receiver
Frequency Hopping
Frequency
f5
f4
f3
f2
f1
Frame Slot
Time
Cellular System Infrastructure
BS
Service area
(Zone)
Early wireless system: Large zone
Cellular System: Small Zone
BS BS
BS BS BS
BS BS
Service area
Cellular Systems:Reuse channels to maximize capacity
� Geographic region divided into cells� Frequencies/timeslots/codes reused at spatially-separated
locations.� Co-channel interference between same color cells.� Base stations/MSCs coordinate handoff and control functions� Shrinking cell size increases capacity, as well as networking
burden
BASE
STATION
MSC
Home phone
PSTN
MSC
BSC …
BS
…
…
MS
…
BS MS
BSC
BS MS
…
BS MS
BSC
BS MS
…
BS MS
BSC
BS MS
…
BS MS
MSC
MS, BS, BSC, MSC, and PSTN
Control and Traffic Channels
Base StationMobile Station
Steps for a Call Setup from MS to BS
BS MS
1. Need to establish path
2. Frequency/time slot/code assigned
(FDMA/TDMA/CDMA)
3. Control Information Acknowledgement
4. Start communication
Steps for a Call Setup from BS to MS
BS MS
2. Ready to establish a path
3. Use frequency/time slot/code
(FDMA/TDMA/CDMA)
4. Ready for communication
5. Start communication
1. Call for MS # pending
Cos(x) is an even function: f(x) = f(-x)
A Simplified Wireless Communication
System Representation
Information to
be transmitted
(Voice/Data)
Coding Modulator Transmitter
Information
received
(Voice/Data)
Decoding Demodulator Receiver
Antenna
AntennaCarrier
Carrier
ITU-T Framework
IEEE 802.11 – WLAN (wireless local area network)
IEEE 802.16 – WMAN (wireless metropolitan area network)
3GPP – WBA (wireless broadband access)
ITU-T – United Nations telecommunications standards
organization
Accepts detailed standards contributions from 3GPP, IEEE
and other groups
Pervasive connectivityWLAN - WMAN - WWAN
Source: 4G Wireless Evolution Conference.
GSM, CDMA, UMTS…3GPP
802.16 WiMAX
802.11 Wi-Fi
802.15.3Bluetooth60 GHzUWB
802.22
LocalMetro
Regional
Personal
Wide
TVWS
Source: 4G Wireless Evolution Conference.
ITU: International Mobile Telecommunications
� IMT-2000� Global standard for third generation (3G) wireless communications� Provides a framework for worldwide wireless access by linking the diverse
systems of terrestrial and satellite based networks. � Data rate limit is approximately 30 Mbps � Detailed specifications contributed by 3GPP, 3GPP2, ETSI and others
� IMT-Advanced� New generation framework for mobile communication systems beyond
IMT-2000 with deployment around 2010 to 2015 � Data rates to reach around 100 Mbps for high mobility and 1 Gbps for
nomadic networks (i.e. WLANs)� IEEE 802.16m working to define the high mobility interface� IEEE 802.11ac and 802.11ad VHT (very high throughput) working to
define the nomadic interface
Source: 4G Wireless Evolution Conference.
Wireless Local Area Networks (WLANs)
� WLANs connect “local” computers (100m range)
� Breaks data into packets
� Channel access is shared (random access)
� Backbone Internet provides best-effort service
� Poor performance in some apps (e.g. video)
01011011
Internet
Access
Point
0101 1011
History of IEEE 802.11
� 1989: FCC authorizes ISM bands(Industrial, Scientific and Medical)
� 900 MHz, 2.4 GHz, 5 GHz
� 1990: IEEE begins work on 802.11
� 1994: 2.4 GHz products begin shipping
� 1997: 802.11 standard approved
� 1998: FCC authorizes the UNII (Unlicensed National Information Infrastructure) Band - 5 GHz
� 1999: 802.11a, b ratified
� 2003: 802.11g ratified
� 2006: 802.11n (600 Mbps) draft 2 certification by the Wi-Fi Alliance begins
20??: 802.11 ac/ad: 1 Gbps Wi-Fiac (5 GHz)Ad: (60 GHz, millimeter wave)
802.11 has pioneered commercial deployment of OFDM and MIMO – key wireless signaling technologies today
Source: 4G Wireless Evolution Conference.
Satellite Systems
� Cover very large areas
� Different orbit heights� GEOs (39000 Km) versus LEOs (2000 Km)
� Optimized for one-way transmission� GPS, Radio (XM, DAB) and movie (SatTV)
broadcasting
� Most two-way systems struggling or bankrupt� Expensive alternative to terrestrial system� Are they coming back???
Bluetooth
� Cable replacement RF technology (low
cost)
� Short range (10m, extendable to 100m)
� 2.4 GHz band (crowded)
� 1 Data (700 Kbps) and 3 voice channels
� Widely supported by telecommunications, PC, and consumer electronics companies
� Few applications beyond cable replacement
Ultrawideband Radio (UWB)
� UWB is an impulse radio: sends pulses of tens
of picoseconds(10-12) to nanoseconds (10-9)
� Duty cycle of only a fraction of a percent
� A carrier is not necessarily needed
� Uses a lot of bandwidth (GHz)
� Low probability of detection
� Excellent ranging capability
� Multipath highly resolvable: good and bad� Can use OFDM to get around multipath problem.
IEEE 802.15.4 / ZigBee Radios
� Low-Rate Low-Cost WPAN
� Data rates of 20, 40, 250 kbps
� Star clusters or peer-to-peer operation
� Support for low latency devices
� CSMA-CA channel access
� Very low power consumption
� Frequency of operation in ISM bands
Focus is primarily on radio and access techniques
Data rate
10 kbits/sec
100 kbits/sec
1 Mbit/sec
10 Mbit/sec
100 Mbit/sec
0 GHz 2 GHz1GHz 3 GHz 5 GHz4 GHz 6 GHz
802.11a
UWB
ZigBee
Bluetooth
ZigBee
802.11b
802.11g
3G
UWB
Range
1 m
10 m
100 m
1 km
10 km
0 GHz 2 GHz1GHz 3 GHz 5 GHz4 GHz 6 GHz
802.11a
UWB
ZigBee BluetoothZigBee
802.11b,g
3G
UWB
Power Dissipation
1 mW
10 mW
100 mW
1 W
10 W
0 GHz 2 GHz1GHz 3 GHz 5 GHz4 GHz 6 GHz
802.11a
UWB
UWB
ZigBee
Bluetooth
ZigBee
802.11bg3G
Emerging Systems
� Ad hoc wireless networks
� Sensor networks
� Distributed control networks
Ad-Hoc and Vehicular Networks
� Peer-to-peer communications.
� No backbone infrastructure.
� Routing can be multihop.
� Topology is dynamic.
� Fully connected with different link SIRs
� IEEE 802.11s and IEEE 802.11p (WAVE)
� Cognitive Radio IEEE 802.11af
� IEEE 802.22 (WRAN; TV White Spaces)
Design Issues
� Ad-hoc networks provide a flexible network infrastructure for many emerging applications.
� The capacity of such networks is generally unknown.
� Transmission, access, and routing strategies for ad-hoc networks are generally ad-hoc.
� Crosslayer design critical and very challenging.
� Energy constraints impose interesting design tradeoffs for communication and networking.
Sensor NetworksEnergy is the driving constraint
�Nodes powered by nonrechargeable batteries�Data flows to centralized location.�Low per-node rates but up to 100,000 nodes.�Data highly correlated in time and space.�Nodes can cooperate in transmission, reception,
compression, and signal processing.� IEEE 802.11ah (900 MHz)
The Internet of Things (IoT) is the interconnection of uniquely identifiable embedded computing devices within the existing Internet infrastructure.
Projected market share of dominant IoT applications by 2025
The whole annual economic impact caused by the IoT is estimated to be in range of $2.7 trillion to $6.2 trillion by 2025
Internet of Things (IoT)� Internet: Interconnected computer networks, based on a
standard communication protocol (TCP/IP)
� Things: any unique object in the world
� Internet of Things: Internet Connected Objects (ICOs)
uniquely addressable, based on standard communication
protocol
� Example of IoT: Imagine when you approach your home,
your car send signals to open garage door, turn on air
condition/ heat system, lights, TV, Stove, etc. to find
everything ready for you, making your life easier and save
your money buy saving energy.
History of IoT
� IoT was originally introduced by the Auto-ID
research center at MIT (Massachusetts Institute)
in 1999
� Founded by Kevin Ashton, David Brock and
Sanjay Sarma to develop the Electronic Product
Code or EPC to uniquely identify products
Source: Government Accountability Office (GAO)
RFID (Radio Frequency Identification)
� Microchip used for tagging objects for automated identification
� RFID systems consist of a reading device called a reader, and one or more
tags
� The reader is a powerful device with memory and computational resources
� Able to identify objects wirelessly (track things or send specs info.)
� Active tags can sense the channel, detect collisions, reliable, accurate,
expensive, contains transmitter, and power source like battery.
� Passive tags have limited computational capacity, no ability to sense the
channel, detect collisions, doesn’t contain transmitter, and power source
� Semi-passive tags have an on-board power source that can be used to
energize their microchip, contains power source but without transmitter
Corresponding NodeHome Agent
ReaderRFID Tag
IPv6 request
IPv6 response
RFID request
RFID response
IPv6 request
IPv6 response
2
5
6
1
3
4
Source : Sandra Dominikus
Simple scenario of RFID functionality
Architecture of IoT
Source: Future Internet , 2012
Network Layer Secure Transmission
Wifi, Bluetooth, ZigBee, etc
Perception LayerPhysical Objects
RFID, Barcode, Infrared Sensors
Middleware Layer
Info Processing
Ubiquitous Computing Database
Service Management Decision Unit
Application LayerSmart Applications and Management
Business Layer Business Models Flowcharts
System Management Graphs
IoT layers - Perception (Device) Layer
� Perception (Device) Layer:
� Consists of the physical objects and sensor
devices
� The sensors can be RFID, 2D-barcode, or any
sensor depending on required functionality
� Collection of information by the Sensors
� Collected information passed to Network layer for
secure transmission to the information processing
system in middleware layer
� Network Layer (Transmission):
�Transfer information securely from
sensor devices in Perception
(device) layer to the information
processing system in Middleware
layer
IoT layers - Network Layer
IoT layers - Middleware Layer � Middleware Layer:
� Middleware is the software the connects software
components together.
� Responsible for the service management and has
link to the database related with each sensor.
� Performs information processing and ubiquitous
computation and makes a decision by sending
specific sensor info to the related applications in
Application layer to do specific jobs.
� Application Layer:
� Provides a global management for the
application based on the objects processed in
Middleware layer
� Applications can be smart health, smart farming,
smart home, smart city, intelligent transportation,
etc.
IoT layers - Application Layer
IoT layers - Business Layer
� Business Layer:
� Maintain overall IoT system including the
applications and services.
� Build business models, graphs, flowcharts, etc.
based on the data received from Application layer.
� Analyzing and monitoring of models results, which
helps to determine the future actions and business
strategies.
IoT Application examples
� Manufacturing, logistics and retail
� Energy and utilities
� Intelligent transportation systems
� Environment monitoring systems
� Home management and monitoring
� Healthcare
� Smart Library Services
Roadmap of key technological developments with IoT
Source : Jayavardhana Gubbi
①Global addressing schemes such as IPv6
②Standardization for interoperability
③Low lower and thin batteries
④Cloud storage⑤Security in RFID and
cloud ⑥Smart sensors in
healthcare⑦Data centers⑧WSN test beds
①Smart antennas②Networking sensors ③Enhanced RFID
security and privacy ④Miniaturized readers ⑤Interoperability
between RFID and WSNs
⑥Cloud computation as a service
⑦Energy harvesting ⑧Intelligent analytics ⑨Wireless power ⑩RFID in retail 11Industrial ecosystems 12Low cost SCADA
system
①Energy harvesting and recycling
②Large scale wireless sensor networks
③Highly enhanced security
④Deploy and forget networks
⑤Self adaptive system of systems
⑥Cloud storage, computation and online analytics
⑦Biodegradable materials and nanopower units
⑧Critical infrastructure monitoring
⑨Smart grid and household metering
①Smart tags for logistics and vehicle management
②Vehicle to infrastructure
③System level analytics ④Autonomous vehicles
using IoT services ⑤Heterogeneous
systems with interaction between other sub-networks
⑥Smart traffic⑦Automatically driven
vehicles ⑧ intelligent
transportation and logistics
2010 2015 2020 2025 & +
Home and personal
Enterprise
Utility
Transport
Plug & play smart objects
Spectrum Regulation
� Spectral Allocation in US controlled by FCC (commercial) or OSM (defense)
� FCC auctions spectral blocks for set
applications.
� Some spectrum set aside for universal use
� Worldwide spectrum controlled by ITU-RRegulation can stunt innovation, cause economic
disasters, and delay system rollout
Standards
� Interacting systems require standardization
� Companies want their systems adopted as standard
� Alternatively try for de-facto standards
� Standards determined by TIA/CTIA in US
� IEEE standards often adopted
� Process fraught with inefficiencies and conflicts
� Worldwide standards determined by ITU-T� In Europe, ETSI is equivalent of IEEE
� Protocols are standardized by IETF as RFCs