Radio Modem Research

WINLAB IAB MeetingOctober 29-30, 2001

Narayan Mandayam

Radio Resource ManagementAdaptive Modulation/Integrated RRM

Radio Modem Research at WINLAB (pre July 2001)

PHYInterference Cancellation, Channel

Estimation, Channel Coding

RF Devices/Circuits ?Radio waves anybody ?

Soft

ware

Rad

io

Test

bed

SSF

Sim

ulat

ion

Test

bed

Radio Resource ManagementAdaptive Modulation/Integrated RRM

Radio Modem Research at WINLAB (post July 2001)

PHYInterference Cancellation, Channel

Estimation, Channel Coding

RF Devices/CircuitsWINLAB is on to Radio Waves!

Syst

em O

n Ch

ip

Soft

ware

Radi

o &

SSF

Sim

ulat

ion

Test

beds

Radio Modem Research (Pre 1999)

1kh BS k

2kh 3kh

14h BS 1

15h 16h

4kh

5kh

For anytime anywhere cellular serviceMultiuser Interference Cancellation at BSSimulation Studies on WiPPET SSF simulatorImplementation Studies on Software Radio Testbed

MS 1

MS 2

MS N

BS j

BS 1

BS 12

MS x

RAYLEIGH (short time-scale losses)

MOBILITY/GEO (long time-scale losses)

SWITCH

FwdRCH

RevRCH

WiPPET

Multicell

Mobility

Radio Resource Mgmt

Signal Processing

Propagation

Scalable Simulation Framework

SDR Testbed based on FPGAs and DSPs

SDR Architecture for Interference Cancellation

Channelizer

ReconfigurableMatched Filter

Info. Bit-streamProcessing

On-lineEstimation

Control andOff-line Estimation

DSP

FPGA

Wideband A/D

Channelizer

Bit. Proc.User 1

Control andOff-line Estimation DSP

FPGA

Wideband A/D

On-lineEstimation

SIC FILTERUser 1

SIC FILTERUser N

SIC FILTERUser 2

…

Bit. Proc.User 2

Bit. Proc.User N

Linear MUD Nonlinear SIC

Radio Modem Research (post 1999)

High rate data servicesInterference Cancellation for the DownlinkDetection & Characterization of Impulsive interferenceSpace/Time Processing & CodingMulticarrier/OFDM, Ultra Wideband (UWB)Characterization of High Speed Short Range Channels

1kh BS k

2kh 3kh

1kh BS 1

2kh 3kh

Small, separated “cells”Low power (~100 mw)Brief connections (~1 sec)Very high bit rate (~1 G bps)Simple infrastructure (LAN on a pole, IP access)Unlicensed bands ?

Maps and images

Internetaccess

Music,voicemail,

news

InfostationsA system of sweet spots for “free” bits

About 15 student projects in the RF/MODEM area

InvestigatorsEvansGreensteinLinLuMandayamSeskarSpasojevicYates

JGE 10/01

WiPPETSSFSIMULN.

INTERFERENCECANCELLATION

SOFTWARERADIOTESTBED

CODING

OFDM UWB

SYSTEM ON

CHIP

CHANNELMEAS.

SENSORS

RF

DEVICES

Range of Systems

3G Cellular

Wireless LANs

Infostations

Ad hoc Data

Common ThemeEfficient High Data Rate Transmission

• Propagation/Channel Modeling– Infostation & UWB channel models

• Outdoor & indoor channel measurements for typical scenarios – Greenstein, Mandayam, Seskar

• Interference Cancellation– “Blind” receiver techniques for the handset

• Exploit 2nd order statistics for mitigating unknown interferers– Mandayam, Seskar

– Wippet multicell downlink simulations • Characterization of power profiles and performance evaluation

– Spasojevic, Yates– Impulsive/Wideband interference cancellation

• Robust detection under alpha-stable models for interferers – Spasojevic

Common ThemeEfficient High Rate Data Transmission

• OFDM– Peak power reduction

• Heuristic iterative clipping algorithms– Evans

– Synchronization for Infostation channels• Algorithms & implementation on Testbed

– Mandayam, Seskar, Spasojevic• Space/Time Turbo Coding

– Performance on correlated fading channels• Impact of spatial & temporal correlations

– Mandayam• UWB

– Analysis, cancellation, synchronization• Several new projects being initiated

– Evans, Mandayam, Seskar, Spasojevic

Overlapping Research Areas

Infostations

Free Bits

System on Chip

RF Modem

Sensor Networks