The document discusses the Telecommunications Technical Interest Group (TIG) at Georgia Tech, which focuses on digital communications. It provides an overview of undergraduate and graduate coursework in physical layer communications and networking. Examples are also given of research conducted at Georgia Tech on topics such as optical data storage, satellite communications using adaptive antennas, and high-speed wireless network prototypes.

1. The Telecommunications TIG
Prof. Mary Ann Ingram
March 30, 2004

2. Overview
 Define Digital Telecomunication
Networks
 Curriculum
 Research Examples
 Conclusion

3. Analog vs. Digital
 Information, such as voice, can be
converted into a continuously varying
analog voltage, using a microphone for
example, and be transmitted

How telephones and cell phones used to
operate
 Alternatively, the analog information can
be quantized, and transmitted using
digital modulation

4. Digital Communications
 At any particular time, only one of a few
waveform choices are transmitted
 A noisy version of the waveform is
received
 The receiver compares the noisy
waveform to the clean ones it has
stored and decides on the clean one
that has the closest match

5. The Advantage of Digital
 In a well-designed system, the receiver
usually makes the right choice
 The noise is eliminated!
Observed
Stored

6. A Pervasive Technology
 Cellular Telephone
 Satellite Broadcasting
 Digital Subscriber Line
 Cable
 Wireless Local Area Networks
 Internet
 CDs and DVDs

7. At Georgia Tech…
 We focus on digital communications in
the Telecommunications Technical
Interest Group (TIG)

8. Communication Networks
 Networks are
organized into
standardized
layers, to allow for
interoperability

9. 7-Layer OSI (International Organ-
ization for Standardization) Model
Responsibilities
Layer
1. Physical Basic hardware components for networks.
i.e. RS-232 specification
2. Data Link Frame format, Transmitting frames over the net.
i.e. bit/byte stuffing, checksum
3. Network Address assignment, Packet's forwarding methods
4. Transport Transfer correctness
5. Session Establishing a communication session, Security, Authentication
i.e. passwords
6. Presentation Computers represent data in different ways (char, integer) thus the
protocol need to translate the data to and from the local node.
7. Application Specifications for applications using the network, how to send a
request, how to specify a filename over the net, how to respond to a
request etc..

10. Packets
 Each layer contains packets
 The payload on one layer is the payload &
header from the previous layer
Header Payload layer i
Header Payload layer i+1

11. Protocols
 A protocol is a set of rules for operation
at a given layer
 Generally, a protocol operates only on
the header and is indifferent to the
payload
??

12. Overview
 Define Digital Telecomunication
Networks
 Curriculum
 Research Examples
 Conclusion

13. UG Elective Courses
 PHY
 ECE 4601, Communications Systems
 ECE 4602, Communications Systems Lab
 NET
 ECE 4604, Networking Design and Simulation
 ECE 4894 Advanced Internetworking
 ECE 4823 Wireless Communications
 ECE 4823 Intro to Wireless and Mobile
Networking

14. Telecom Grad Courses -PHY
 ECE 6601 - Random Processes
 ECE 6602 - Digital Communications
 ECE 6603 - Advanced Digital
Communications
 ECE 6604 - Personal and Mobile
Communications
 ECE 6605 - Information Theory
 ECE 6606 - Coding Theory and Applications
 Hybrid Fiber-Coax Communication Systems
 Space-Time Processing for Communication

15. Telecom Grad Courses -NET
 ECE 6607 - Computer Communication Networks
 ECE 6608 - Performance Analysis of Comm
Networks
 ECE 6609 - ATM Networks
 ECE 6610 - Wireless Networks
 ECE 7611 - Advanced Communication Theory
 Computer Network Security
 Multimedia Communication
 Cryptography: Theory and Practice

16. Overview
 Define Digital Telecomunication
Networks
 Curriculum
 Research Examples
 Conclusion

17. Research Examples
 CD and DVD optical recording
 Ground stations for low earth orbit
(LEO) satellites
 High-speed wireless prototype

18. Binary and Nonbinary optical
recording
• Increased storage capacity of CD and DVD
- from theory to commercialization
• Binary and M-ary in optical recording
• Much of the technology developed in Prof. McLaughlin’s group
Signal from M-ary CD, DVD
Binary CD, DVD
CD and DVD:
Our system:
Information encoded in transitions
Information encoded in amplitude
Jan 25, 2013 18

19. Status
• Our ASIC integrated on CD and DVD platforms
 3x increase on CD (R, RW)
 2x increase on DVD for (R, RW, ROM)
 2x increase on Blu-ray for R, RW
 Recently announced results from dual layer
ML DVD-16 GB feasibility in ROM
 Chip available through Sanyo
 Technology gaining acceptance in
optical data storage community
 Sony, Pioneer, Ricoh, Panasonic, Mitsubishi,
Philips, Yamaha, TDK and others have efforts
 ML Alliance

20. Satellite Communications with
Adaptive and Phased Array
Antennas

21. Problem with Current Ground
Stations for LEOs
 11m Dish – System
costs $ 2- 4 million
 Single satellites Single-Line
 Satellite tracking of Site
cumbersome (LOS)-path
(mechanical) signal
 Avoidance of other
signals good (thin main
lobe)
 Located near poles
 Staff of 8

22. Adaptive Array Ground Station
 Smaller phased
array elements low
on cost curve
 Located anywhere
 No staff
 Electronically
steered
0100111001010 Adaptive
1011000110101 Processor

24. Georgia Tech:Successful Smart Antenna Tests
at Georgia Tech 11-19-03 and 11-25-03
System noise floor
Analyzer noise floor
Sirius and XM Radio
interference,
1,000,000 times
stronger than EO-1
signal.
1. Prior to the pass: antenna with
cement blocks to prevent it from
blowing over. Atlanta skyline in the
background. The antenna had a In test 1, 11-19-03:
significant vertical wobble (ground EO-1 spectrum
plane) due to wind. detected on analyzer
2. Students observing EO-1 signal
spectrum. In test 2, 11-25-03:
3. Prior to pass, checking spectra of EO-1 signal digitized,
know interference. fast fourier transform
performed and EO-1
spectrum observed
4. Detected EO-1 spectrum during
on computer screen.
pass

25. Yamacraw Wireless System
Prototype
 State and Industry-funded project to
build a “gigabit per second” wireless
link for wireless LAN applications
 Based on MIMO and OFDM
1 1
Trans.   Rec.
f MT MR
Orthogonal Frequency Division
Multiplexing (OFDM) Multiple-input-multiple-output
(MIMO)

26. Yamacraw Network Testbed
MAC Capture MAC Capture
PC Wireless PC
channels
array array
End Host End Host
FPDP FPDP
Transport Ethernet Local Client Software Software Ethernet Transport
Protocol PC radio cage radio cage Protocol

27. Physical Layer Architecture
 4x4 Open-Loop MIMO 64 QAM over 20 MHz
 Each pair of MIMO channels gets 8-to-2 selection
diversity
8-to-2 RF-to OFDM N
Switch -IF Demod
4N*code
Four micro- OFDM N Forward rate
RF-to
antennas controller Demod Space- 4N Error P-to-S Sink
-IF
activated Frequency Correction
8-to-2 RF-to OFDM N filter
FPGA
Switch -IF Demod
micro- RF-to OFDM N Receiver
controller -IF Demod
Matrix Inversion on
FPGA (in progress)

28. PEAK DATA RATES
CURRENT OFFLINE PROCESSING:
25 MHz*(200/256) subcarriers * 6 bits/symbol * 4
channels = 468 Mb/s
GOAL AT END OF PROJECT (Upper Limit)
50 MHz*(200/256) subcarriers * 6 bits/symbol * 4
channels = 937 Mb/s
*Actual real-time implementation speed will depend on processing and
hardware limitations

29. MIMO OFDM Wireless Tests
OFDM Waveform
Waveform:
25 Ms/s (Goal is 40 –50 Ms/s),
4x4 MIMO, 64-QAM
Channel Estimates (1 x 4) Constellation

30. 8-to-2 Switch and Microcontroller
 Selection diversity maximizes average
SNR over band for each MIMO channel

31. 4x4 MIMO With Selection Diversity
Two 8-element antenna arrays
shown with diversity switch
boards
MIMO Signal Sources and
4-port Transmit Antenna

32. Subcarrier Allocation MAC
Protocol
State for guaranteed
and controlled-load in frame mapping subframe Construct resource
services mapping table
in downlink control
subframe Piggybacked
State for all services transmission
Dynamic resource
Admission request allocation
request Transmission New Packets to be
request packets retransmitted Optimum subcarrier Admission
bit-allocation control
Piggyback
Received Transmission Admission
packets request request
in uplink in subframes
time slots Yes
control for services
subframe bits per No time slots
subcarrier Need ARQ ? What request ?
bits per
power subcarrier
allocated resources power
Transmit packets according Receive packets according allocated resources
to the resource allocation results to the resource allocation results
Physical layer Physical layer
Mobile Terminal Side Base Station Side

33. Reliable Transport Protocal with
Guaranteed Services
TCP-G
 GTCP has been Connection request Transmit Connection
implemented in user (fid, bandwidth) (data) tear-down
complete(fid)
level both on Linux and
Windows platforms Connection Connection tear-
admitted(fid) down request(fid)
 GTCP interaction with Connection request
(bandwidth, conn_id)
MAC defined using a CAC Connection tear-
down
MAC
set of interfaces,
request(conn_id)
shown:=> APPLIC PC SRT SRT APPLIC PC
APPLIC APPLIC
 GTCP-software radio GTCP
PCAP PCAP
GTCP
integration plan:=> RAW SOCKETS
ETH MAC MAC ETH
RAW SOCKETS
ETHERNET ETHERNET
PHY1 PHY2 PHY2 PHY1
PHY1 PHY1
SRT: Software Radio Test-bed

34. Overview
 Define Digital Telecomunication
Networks
 Curriculum
 Research Examples
 Conclusion

35. Conclusions
 Telecommunication technology is
everywhere in our lives
 Many courses on UG and GRAD levels
 Active and exciting research area