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Summary of activities at ICSI Oct/99 to May/00. May 2000. José M. Páez. Introduction. Myself. José M Páez-Borrallo, Professor of Signal Theory and Communications in the Technical University of Madrid On leave at ICSI in the period Oct/99-Jun/00. Research interests.

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slide1

Summary of activities at ICSI

Oct/99 to May/00

May 2000

José M. Páez

slide2

Introduction

Myself

  • José M Páez-Borrallo, Professor of Signal Theory and Communications in
  • the Technical University of Madrid
  • On leave at ICSI in the period Oct/99-Jun/00

Research interests

  • Signal and Array Processing for Communications
  • Wireless Communications (WLL, WLAN, …)
  • Physical Layer: Modulations, Equalizers, Smart antennas …
  • Access Techniques: CDMA, OFDMA, Hybrid, ….
  • Mobile Digital Systems (DECT, GSM, UMTS, TD-UTRA ...)

My original project at ICSI

  • Design and analysis of MUD receiver architecturesfor CDMA. Exploiting
  • dynamic Space-Time diversity to improve the radio link
slide3

Activities carried out during my stay at ICSI

Research

  • Design and analysis of MUD receiver architecturesfor CDMA with direct
  • application to UTRA-TDD
  • Design of new waveforms for CDMA. Something intermediate between
  • DS-CDMA and MC-CDMA
  • Prospective analysis and information gathering on Ultra Wide Band Radios

Definition of future infrastructure for Research

  • Design and viability study of a Research Institute on Communications
  • with partnership of Industry, Telecom Operators and University
slide4

Contacts in Berkeley during my stay at ICSI

Cooperation with BWRC

  • Berkeley Wireless Research Center (BWRC). http://bwrc.eecs.berkeley.edu/
    • Involved in technologies for new generations of radio systems
  • Cooperation in new CDMA techniques (October-February)
  • Continued assistance to internal BWRC seminars and tech discussions
  • Invited tutorial on MC Modulation in BWRC Winter’s Retreat in Monterey, CA
  • Poster on new waveforms for CDMA in BWRC Winter’s Retreat
  • Contact at BWRC: Scientific Director, Robert Brodersen
slide5

Multiple Access: Sharing the medium

Fix services

Mobile

services

Multiple Access Defined

  • A scheme that enables many users to share a common access point
  • Requires “orthogonalization” of users so that they can be distinguished
  • Orthogonalization can be done in in time, frequency, space, or any
  • combination (e.g. using “codes”)
slide6

TDMA

Note: colors represent different users

FDMA

Time

Time

Diff. Time slots

Common band

Freq.

Diff. Frequency channels

Common time

Freq.

TIME separation

FREQ separation

DS-CDMA

  • Codes (waveforms) need to be orthogonal
  • Increase in capacity (graceful degradation)
  • Greater reuse factor in cellular systems
  • Channel impairments affect orthogonality
  • It appears Multiple Access Interference (MAI)

Time

Freq.

CODE separation

Multiple Access: CDMA vs. TDMA and CDMA

slide8

MUD receiver architectures for CDMA (1)

  • Definition of an extended multisensor signal model for Multiple Access
  • Interference MAI including multipath
  • Design and analysis of new front-ends with MAI cancellation
  • Design and analysis of Decorrelation and Optimal (MMSE) vector receivers
  • Performance evaluation of previous receivers (mono and multisensor)
  • MATLAB implementation of a radio-link simulatorwith channel impairments
  • Adaptive implementation of receivers. Reduced-rank versions of it
  • Analysis of simulated results versus receivers’ complexity
slide9

Intra

F=

Intra+Inter

MUD receiver architectures for CDMA (2)

MUD efficiency: It quantifies the amount of Intracell Interference removal

performed by the specific MUD receiver

: Cancelable Total Interference ratio

slide10

K users

.

.

.

P

MUD receiver architectures for CDMA (3)

A feasible vector MUD Decorrelation receiver architecture

Front-End

Decorrelation

User 1, L paths

1

User 1

Signature space-time

Decorrelation

Space-time

filtering

.

.

.

P

User K

User K, L paths

KL

KL

KL

KLP

1

Multipath

amplitude estimation

DOA estimation

To downlink

in TDD systems

KL

P

Channel estimation branch

Front-end: Capture the incoming active users

Channel branch: Estimate space-time info from the incoming signals

Space-time filters: Isolate different users and paths

Decorrelation: Remove the residual MAI from others users (eff. Signature)

slide11

K users

.

.

.

P

User 1

MUD receiver architectures for CDMA (4)

A feasible vector MUD MSE receiver architecture

Minimize

MSE

Front-End

Filtering

GOAL

User 1, L paths

KLP

K

Rank

reduction

.

.

.

User

filters

User K

User K, L paths

K

K

KLP

Training

sequence

Computing matrix

transformation

Further refinement

Channel estimation branch

Front-end: Capture the incoming active users

Channel branch: Estimate rank-reduction matrix from space-time info

Space-time filters: Isolate different users and recover the desired signals

Training: Provides the info sequence to form the goal function

slide12

MUD receiver architectures for CDMA (5)

Some simulated results

Spreading gain: 15

1000 QPSK symbols

5 active users

2 paths per user (span 1/4 symbol)

Linear array of 8 sensors

4 different architectures

slide14

New TF waveforms for CDMA: CDMA concept (1)

  • Any symbol is carried by a set of waveforms (basis)
  • This set of “carriers” is needed to provide “virtual” separation among users
  • Can choose anyorthogonal basis -- each user is not limited to one time or frequency slot
  • This generalization results in a “code” space where users may overlap in frequency/time
  • Much research has been done and many different flavors exist: DS-CDMA, MC-CDMA, etc.

continuous:

where

symbol

chips

basis (waveforms)

discrete:

where

slide15

Channel effect on the signals

Note:colors represent different chips for 1 user and 1 symbol.

Tc

channel

t

T

Tc

An unique wide-band spectrum means resistance to time-varying channel and frequency noise/jitter

1/Tc

f

Time dispersive channel causes signal distortion and Inter-Chip-Interference (breaks orthogonality)

Waveform set:

Short pulses

Signal basis:

Identity matrix

1

Code & Chips

-1

User i: si=Yci

User j: sj=Ycj

1

siTsj =ciTYTYcj=dij

1

-1

-1

1

1

T=MTc

Symbol

Two diff. users share the same

Signal basis and have diff. codes

Chips are time located

New TF waveforms for CDMA: Standard DS-CDMA (2)

slide16

Channel effect on the signals

Note: colors represent different chips for 1 user and 1 symbol.

Df = 1/T

T

Narrower bands meansmore sensitive to channel variation and frequency noise/jitter

t

channel

Longer symbol duration minimizes ISI effect due to channel dispersion

Waveform set:

sinusoids

T=Tc

Signal basis:

DFT matrix

User i: si=Yci

User j: sj=Ycj

Symbol

siTsj =ciTFTFcj=dij

1

-1

-1

1

Code & chips

Two diff. users share the same

Signal basis and have diff. codes

Chips are frequency located

New TF waveforms for CDMA: Multicarrier CDMA (3)

slide17

1D-Symbol

T-F spreading of 2D-Symbols

Symbol duration

1D-Symbol

Tc

DS-CDMA

M T-chips, 1 carrier, B=1/Tc

T

...

Same spread gain: M

M/2 T-chips, 2 carriers, B=1/2Tc+1/2Tc

2D-Symbol

2Tc

M/K T-chips, K carriers, B=K/KTc=1/Tc

...

Better spectral efficiency (lower side lobes)

More resistance to channel time dispersion

It allows to exploit spectral knowledge of channel

Research 2D orthogonal or pseudorandom codes

Increasing

no. of carriers

Increasing

no. of T-chips

KTc

MTc=T

1 T-chip, M carriers, B=M/MTc=1/Tc

MC-CDMA

New TF waveforms for CDMA: Time-frequency chips (4)

slide18

Spectra

Wide-band spectra

Frequency

New TF waveforms for CDMA: Example (5)

DS-CDMA is tiled in time and is susceptible to distortion caused by time-dispersive channel

MC-CDMA is tiled in frequency is susceptible to channel variations and frequency noise/jitter

Discrete chirps

Waveform set:

discrete chirps

Long waveforms

-1

-1

1

1

2D Code & chips

-1

-1

1

1

-1

1

1

1

T=4Tc

Time

Symbol

Chips are time-frequency located

Provides intermediate level of resistance to time and frequency impairments

slide20

Research Institute on Communications (1)

Foundation statements

  • Provide an environment for research into the issues necessary to support Technology, Networks and Applications for future mobile communication systems.
  • Center for education of new engineers in the field of Wireless Technologies and Services
  • Mixed participation of Industry, Telecom operators and University
  • Promote start-up companies from the Institute on own results
  • The Institute will pursue an active policy of placing research results in the public domain as determined by the Scientific Board

Center lifetime of at least 7 years with yearly reviews

and 4+3 year informal commitments

slide21

Research Institute on Communications (2)

Medium and long term

R&D

Specific

Projects & Consortia

Ph D Theses

Master Theses

Specific needs

Multidisciplinary projects

Institute

Utilization of known R&D

Continuous Analysis of extern R&D

Prediction of tech needs

Product Focalization

Own development in the CI

Prospective &

Innovation

Creation of

start-ups

slide22

Radio Access & Technologies

Low power RF design

Audio & Video coding

Mobile multimedia communications

Fix-mobile convergent services

Universal spectrum sharing

Mobile IP, WLL and WLANs

Multicast over IP networks

Bandwidth-on-demand management

Interconnectivity and networks transparency

Digital TV & Radio, WebTV, etc

Multimedia content production

Research Institute on Communications (3)

Research issues at the Institute

Prospective & Innovation

Office

3 research areas

This is a 1st proposal. It has to be determined

within the Advisory Board

slide23

Research Institute on Communications (4)

  • 2 Workshops per year:
  • Research staff is committed to present their results publicly
  • Monographic sessions, Poster presentations and Tech discussions
  • Open assistance to externpublic (other companies, institutes, etc)
  • 2 montly Seminars:
  • Given by CI staff, company partners and invited speakers
  • Semester calendar of seminars (as continuing education for some companies)
  • Non-partners assistance by invitation or payment
  • 2 montly technical meetings per research area
  • Development of research agenda and summary of work done
  • Paper Reading and discussion sessions
  • Restricted assistance to associated partners
slide24

Research Institute on Communications (5)

Initial Participation (commitment for 4 years)

Associated

Affiliated

Funding

150 Keuro/year

50 Keuro/year

Fix lab seats up to 2 engineers

Only for

Seminars

Human

resources

Types of Company Partnership

slide25

Research Institute on Communications (6)

University

Head Telecom Faculty

Head Dpt. Radiotech

Head Dept. Electronics

Head Dept. Networks

Head Dept. Basic Sci

Industry

10-12 Associated

Companies

Institute

Head of Institute

Vicehead of Institute

Technology Responsible

Network Responsible

Application Responsible

Individual

4 known

professionals

Institute Advisory Board

slide26

Research Institute on Communications (7)

Benefits of being an Institute partner

Affi.

Asso.

  • Memberof theAdvisory board
  • Memberof theScientific board (Impact on the research agenda)
  • Participation in large pre-competitive, interdisciplinary research

effort with relatively modest investment

  • Free Assistance to workshops and seminars
  • Free assistance to periodic technical meetings
  • In-situ involvement with a large number of outstanding students

and staff (1-2 engineers per year)

  • Co-utilization of lab installations and tech resources
  • First hand knowledge of Center results and free development of them
  • Unlimited explotation rights of developed technologies and prototypes
  • Direct access to a number of graduates who have expertise in the area

of mobile communications

slide27

Personal

University: 0.77 (22%)

Hired: 0.91 (26%)

1.68(46%)

Infrastructure

Material Lab: 50 (9%)

Computers: 20 (3%)

Software: 12 (2%)

82(14%)

Research Institute on Communications (8)

University & hired personal and infrastructure funding

3.5 Meuros

Others

Univ: 0.89 (25%)

Taxes: 0.27 (8%)

Misc.: 0.19 (5%)

1.35(38%)

slide28

Research Institute on Communications (9)

Institute permanent staff (estimation)

From University

Hired Personal

4 Faculty staff

1 MBA

Exec. team

(5%)

13 Faculty staff (4 per area +1)

12 PhD students (4 per area)

24 Master students (8 por área)

14 Doctors (4 per area+2)

12+ Industry engineers

Resarch staff

(82%)

4 engineers

5 Administrative staff

Administr. &

support staff

(13%)

3 Grad. students

Total: 56 (61%)

Total: 36 (39%)

Employment creation: 24/80 (30%)

slide29

Research Institute on Communications (10)

Feasible funding sources

3.5 Meuros