Wireless Communication
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Ancient Systems: Smoke Signals,
Carrier Pigeons, …
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Radio invented in the 1880s by Marconi
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Many sophisticated military radio systems
were developed during and after WW2
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Cellular has enjoyed exponential growth
since 1988, with about 6 billion users
worldwide today ignited the wireless revolution
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Voice, data, and multimedia ubiquitous
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Use in both developed and developing countries
growing rapidly
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Wifi also enjoying tremendous success and
growth
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--Wide area networks (e.g. Wimax) and short-range
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systems other than Bluetooth (e.g. UWB) less
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successful
What is Wireless Communication?
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Transmitting and receiving voice and data using
electromagnetic waves in open space
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The information from sender to receiver is carried over a
well-defined frequency band (channel)
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Each channel has a fixed frequency bandwidth and
capacity
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Different channels can be used to transmit information in
parallel and independently
Types of Wireless Communication
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Mobile
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GSM /CDMA2000.1x
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Portable
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IEEE 802.11b (WiFi)
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IEEE 802.15.3(UWB)
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Fixed
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IEEE 802.16(WirelessMAN)
Typical Frequencies
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FM Radio ~ 88 Mhz
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TV Broadcast ~ 200 MHz
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GSM Phones ~ 900 MHz
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GPS ~ 1.2 GHz
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PCS Phones ~ 1.8 GHz
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Bluetooth/WiFi ~ 2.4 GHz
Why Wireless Communication?
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Freedom from wires
– No cost of installing wires or rewiring
– No bunches of wires running here and there
– “Auto magical” instantaneous communications without
physical connection setup, e.g., Bluetooth, WiFi
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Global Coverage
– Communication can reach where wiring is infeasible or
costly; e.g., rural areas, old buildings, battle field,
vehicles, outer space(through communicationsatellites)
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Stay Connected
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– Roaming allows flexibility to stay connected anywhere and
any time
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– Rapidly growing market attests to public need for mobility
and uninterrupted access
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Flexibility
– Services reach you whereever you go (Mobility); E.g., you
don't have to go to your lab to check your mail
– Connect to multiple devices simultaneously (no physical
connection required)
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Increasing dependence on telecommunication
services for business and personal reasons
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Consumers and businesses are willing to pay for
it
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Basic Mantra: Stay connected -anywhere,
anytime
2G wireless system
2G GSM 10kbps
2G CDMA 10kbps
2.5G GPRS ~50 kbps
2.5G EDGE 200 kbps
~
GSM: Global system for mobile communications
CDMA: Code Division Multiple Access
GPRS: General Packet Radio Service
EDGE: Enhanced Data for GSM Evolution
Voice + data
3G Wireless Standards
3G WCDMA/UMTS 384kbps
3G CDMA 2000 384kbps
3.5G HSDPA/HSUPA 5-30Mbps
3.5 1X EVDO 5-30 Mbps
Rev A,B,C
WCDMA: wide band C D M A,
UMTS: universal mobile telecommunication standard
HSDPA: high speed downlink packet access,
HSUPA:high speed uplink packet access
1XEVDO: Evolution Data Optimized
Voice+data+video calling
4G Wireless systems
4G LTE 100-2000 Mbps
4G WiMAX 100-200 Mbps
LTE: Long Term Evolution
WiMAX: Worldwide interoperabilty for microwave access
Online gaming +HDTV
Challenges
Network/Radio Challenges
Gbps data rates with “no” errors
5 AdHoc
Energy efficiency G
Short-Range
Scarce/bifurcated spectrum
Reliability and coverage
Heterogeneous networks
Seamless internetwork handoff
Device/SoC Challenges
BT
Performance Radio
Complexity GPS
Cellular
Size, Power, Cost Cog
High frequencies/mmWave
Mem WiFi
Multiple Antennas
Multiradio Integration CPU mmW
Coexistance
Challenges
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Efficient Hardware
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--Low power Transmitters, Receivers
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--Low power signal processing tools
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Efficient use of finite radio spectrum
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--Cellular frequency reuse, medium access control
protocols
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Integrated services
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--voice, data, multimedia over a single network
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--service differentiation, priorities, resource
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sharing
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Network support for user mobility (mobile
scenario)
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--location identification, handover,...
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Maintaining quality of service over unreliable
links
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Connectivity and coverage(internetworking)
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Fading
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Multipath
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Higher probability of data corruption
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-- Channel coding
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Security issues
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-- privacy, authentication....
Software-Defined (SD) Radio:
Is this the solution to the device challenges?
BT A/D
FM/XM
Cellular GPS
A/D
DVB-H
Apps
DSP
Processor WLAN A/D
Media
Processor Wimax A/D
Wideband antennas and A/Ds span BW of desired signals
DSP programmed to process desired signal: no specialized
HW
Today, this is not cost, size, or power efficient
SubNyquist sampling may help with the A/D and DSP requirements
IoT
Different requirements than smartphones: low rates/energy
What would Shannon say?
We don’t know the Shannon
capacity of most wireless channels
Time-varying channels.
Channels with interference or
relays.
Cellular systems
Ad-hoc and sensor networks
Channels with delay/energy/$$$
constraints.
Shannon theory provides design insights
and system performance upper bounds
Current/Emerging Wireless Systems
Current:
5G Cellular Systems (LTE-Advanced)
5G Wireless LANs/WiFi (802.11ac)
Satellite Systems
Bluetooth
Zigbee
WiGig
Emerging
6G Cellular and WiFi Systems Much room
mmWave Systems For innovation
Ad/hoc and Cognitive Radio Networks
Energy-Harvesting Systems
Future Wireless Networks
Ubiquitous Communication Among People and Devices
Next-generation
Cellular
Wireless Internet
Access
Wireless Multimedia
Sensor Networks
Smart Homes/Spaces
Automated Highways
In-Body Networks
All this and more …
Mobile Phone
Reference: www.qualcomm.co.in
Mobile Phone
Mobile Phone
Wireless Generations
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Wi r e l e s s G e n e r a t i o n s
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Wireless Generations
Wi r e l e s s G e n e r a t i o n s
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Wi r e l e s s G e n e r a t i o n s
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Wireless Generations
Wi r e l e s s G e n e r a t i o n s
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Assume a spectrum of 120 kHz is allocated over
a base frequency for communication between A
and B
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Three channels of 40 kHz bandwidth each
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Need for Guard band Frequency or time?
