The Telecommunications TIG

Prof. Mary Ann IngramMarch 30, 2004

Overview

Define Digital Telecomunication Networks

Curriculum Research Examples Conclusion

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

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

The Advantage of Digital

In a well-designed system, the receiver usually makes the right choice The noise is eliminated!

Observed

Stored

A Pervasive Technology

Cellular Telephone Satellite Broadcasting Digital Subscriber Line Cable Wireless Local Area Networks Internet CDs and DVDs

At Georgia Tech…

We focus on digital communications in the Telecommunications Technical Interest Group (TIG)

Communication Networks

Networks are organized into standardized layers, to allow for interoperability

7-Layer OSI (International Organ-ization for Standardization) Model

Layer Responsibilities

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..

Packets Each layer contains packets The payload on one layer is the payload

& header from the previous layer

Header Payload

Header Payload layer i

layer i+1

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

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Overview

Define Digital Telecomunication Networks

Curriculum Research Examples Conclusion

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

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

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

Telecom Grad Courses -NET

Overview

Define Digital Telecomunication Networks

Curriculum Research Examples Conclusion

Research Examples

CD and DVD optical recording Ground stations for low earth orbit

(LEO) satellites High-speed wireless prototype

Apr 9, 2023 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 fromBinary CD, DVD

M-ary CD, DVD

CD and DVD:Information encoded in transitions Our system:

Information encoded in amplitude

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

Satellite Communications with Adaptive and Phased Array Antennas

11m Dish – System costs $ 2- 4 million

Single satellites Satellite tracking

cumbersome (mechanical)

Avoidance of other signals good (thin main lobe)

Located near poles Staff of 8

Single-Line of Site (LOS)-path signal

Problem with Current Ground Stations for LEOs

Adaptive Array Ground Station

01001110010101011000110101

AdaptiveProcessor

Smaller phased array elements low on cost curve

Located anywhere No staff Electronically

steered

1. Prior to the pass: antenna with cement blocks to prevent it from blowing over. Atlanta skyline in the background. The antenna had a significant vertical wobble (ground plane) due to wind. 2. Students observing EO-1 signal spectrum.

3. Prior to pass, checking spectra of know interference.

System noise floor

Analyzer noise floor

Sirius and XM Radio interference, 1,000,000 times stronger than EO-1 signal.

In test 1, 11-19-03: EO-1 spectrum detected on analyzer

In test 2, 11-25-03:

EO-1 signal digitized, fast fourier transform performed and EO-1 spectrum observed on computer screen.

4. Detected EO-1 spectrum during pass

Georgia Tech:Successful Smart Antenna Tests at Georgia Tech 11-19-03 and 11-25-03

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

Trans. TM

1

Rec.RM

1

Multiple-input-multiple-output (MIMO)

Orthogonal Frequency Division Multiplexing (OFDM)

f

Yamacraw Network Testbed

End Host

MAC Capture PC

Software radio cage

Software radio cage

Local Client PC

TransportProtocol

Wirelesschannels

Ethernet Ethernet

array array

MAC Capture PC

End Host

TransportProtocol

FPDP FPDP

Physical Layer Architecture 4x4 Open-Loop MIMO 64 QAM over 20 MHz Each pair of MIMO channels gets 8-to-2

selection diversity

OFDMDemod

SinkSpace-Frequency

filter

P-to-S

4N*code rateForward

ErrorCorrection

4N

8-to-2Switch

N

N

N

N Receiver

FPGA

RF-to-IF

RF-to-IF

RF-to-IF

RF-to-IF

OFDMDemod

OFDMDemod

OFDMDemod

Matrix Inversion on FPGA (in progress)

8-to-2Switch

Fourantennas activated

micro-controller

micro-controller

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

MIMO OFDM Wireless Tests

Waveform:

25 Ms/s (Goal is 40 –50 Ms/s), 4x4 MIMO, 64-QAM

Channel Estimates (1 x 4)

OFDM Waveform

Constellation

8-to-2 Switch and Microcontroller Selection diversity maximizes average

SNR over band for each MIMO channel

Two 8-element antenna arrays shown with diversity switch boards

4x4 MIMO With Selection Diversity

MIMO Signal Sources and 4-port Transmit Antenna

Subcarrier Allocation MAC Protocol

Physical layer Physical layer

Transmit packets accordingto the resource allocation results

Receive packets accordingto the resource allocation results

Construct resourcemapping table

Receivedpackets

Optimum subcarrierbit-allocation

Dynamic resourceallocation

Admissioncontrol

time slots

bits persubcarrier

power

Newpackets

Packets to beretransmitted

Transmission request

Admissionrequest

Need ARQ ?

Yes

No

Piggyback

Piggybackedtransmissionrequest

Transmissionrequest

What request ?

Admissionrequest

in frame mapping subframe

in downlink controlsubframe

in uplinkcontrolsubframe

in subframesfor services

time slots

bits persubcarrier

powerallocated resources

allocated resources

Mobile Terminal Side Base Station Side

State for guaranteedand controlled-loadservices

State for all services

TCP-G

MACCACConnection request (bandwidth, conn_id)

Transmit (data)

Connection admitted(fid)

Connection tear-down request(fid)

Connection tear-down complete(fid)

Connection request (fid, bandwidth)

PCAP

ETH MAC

PHY1 PHY2

APPLIC PC SRT SRT

APPLIC

GTCP

PHY1

RAW SOCKETS

ETHERNET

PCAP

MAC ETH

PHY2 PHY1

APPLIC

GTCP

PHY1

RAW SOCKETS

ETHERNET

APPLIC PC

Connection tear-down request(conn_id)

SRT: Software Radio Test-bed

Reliable Transport Protocal with Guaranteed Services

GTCP has been implemented in user level both on Linux and Windows platforms

GTCP interaction with MAC defined using a set of interfaces, shown:=>

GTCP-software radio integration plan:=>

Overview

Define Digital Telecomunication Networks

Curriculum Research Examples Conclusion

Conclusions

Telecommunication technology is everywhere in our lives

Many courses on UG and GRAD levels

Active and exciting research area