2. May 2000 Summary of activities at ICSI Oct/99 to May/00 José M. Páez

3. Introduction 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 Myself Design and analysis of MUD receiver architectures for CDMA. Exploiting dynamic Space-Time diversity to improve the radio link My original project at ICSI 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...) Research interests

4. Activities carried out during my stay at ICSI Design and analysis of MUD receiver architectures for 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 Design and viability study of a Research Institute on Communications with partnership of Industry, Telecom Operators and University Research Definition of future infrastructure for Research

5. Contacts in Berkeley during my stay at ICSI 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 Cooperation with BWRC

6. Multiple Access: Sharing the medium 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”) Multiple Access Defined Fix services Mobile services

7. Note: colors represent different users Time Freq. Diff. Time slots Common band TDMA TIME separation Multiple Access: CDMA vs. TDMA and CDMA Time Freq. Diff. Frequency channels Common time FDMA FREQ separation Freq. Time 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) DS-CDMA CODE separation

8. MUD Receiver Architectures for CDMA systems

9. 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 simulator with channel impairments Adaptive implementation of receivers. Reduced-rank versions of it Analysis of simulated results versus receivers’ complexity

10. MUD receiver architectures for CDMA (2) F= Intra Intra+Inter MUD efficiency: It quantifies the amount of Intracell Interference removal performed by the specific MUD receiver : Cancelable Total Interference ratio

11. MUD receiver architectures for CDMA (3)...... Front-End DOA estimation Multipath amplitude estimation 1 KL Channel estimation branch Signature space-time Decorrelation User 1 User K Decorrelation...... P K users 1 P To downlink in TDD systems User 1, L paths User K, L paths A feasible vector MUD Decorrelation receiver architecture 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) Space-time filtering KLP P KL

12. A feasible vector MUD MSE receiver architecture MUD receiver architectures for CDMA (4) User 1, L paths User K, L paths...... Front-End Computing matrix transformation User filters KLP K Channel estimation branch Rank reduction User 1 User K Filtering...... P K users K KLP Training sequence K Further refinement Minimize MSE GOAL 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

13. MUD receiver architectures for CDMA (5) 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 Some simulated results

14. New TF waveforms for CDMA

15. Any symbol is carried by a set of waveforms (basis) This set of “carriers” is needed to provide “virtual” separation among users Can choose any orthogonal 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. chipsbasis (waveforms) where continuous: discrete: where New TF waveforms for CDMA: CDMA concept (1) symbol

16. T TcTc t f Note: colors represent different chips for 1 user and 1 symbol. 1/T c An unique wide-band spectrum means resistance to time-varying channel and frequency noise/jitter New TF waveforms for CDMA: Standard DS-CDMA (2) Time dispersive channel causes signal distortion and Inter-Chip-Interference (breaks orthogonality) TcTc channel Channel effect on the signals Symbol Code & Chips Waveform set: Short pulses 1 1 1 1 1 Chips are time located Signal basis: Identity matrix User i: s i =  c i User j: s j =  c j Two diff. users share the same Signal basis and have diff. codes s i T s j = c i T  T  c j =  ij T=MT c

17. Symbol Code & chips 11 Waveform set: sinusoids Chips are frequency located T=T c DFT matrix Signal basis: User i: s i =  c i User j: s j =  c j Two diff. users share the same Signal basis and have diff. codes s i T s j = c i T F T F c j =  ij New TF waveforms for CDMA: Multicarrier CDMA (3) T t  f = 1/T Note: colors represent different chips for 1 user and 1 symbol. Narrower bands means more sensitive to channel variation and frequency noise/jitter channel Channel effect on the signals Longer symbol duration minimizes ISI effect due to channel dispersion

18. T 1D-Symbol M T-chips, 1 carrier, B=1/Tc Tc Symbol duration DS-CDMA Same spread gain: M 1D-Symbol 1 T-chip, M carriers, B=M/MTc=1/Tc MTc=T MC-CDMA T-F spreading of 2D-Symbols 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 2D-Symbol... M/2 T-chips, 2 carriers, B=1/2Tc+1/2Tc 2Tc M/K T-chips, K carriers, B=K/KTc=1/Tc KTc... Increasing no. of carriers Increasing no. of T-chips New TF waveforms for CDMA: Time-frequency chips (4)

19. New TF waveforms for CDMA: Example (5) Frequency Spectra Wide-band spectra 2D Code & chips Waveform set: discrete chirps Chips are time-frequency located T=4T c Symbol 1 1 1 11 -1 1 -1 -1 -1 Time Long waveforms Discrete chirps 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 Provides intermediate level of resistance to time and frequency impairments 1 -1

20. Research Institute on Communications

21. Research Institute on Communications (1) 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 Foundation statements Center lifetime of at least 7 years with yearly reviews and 4+3 year informal commitments

22. Research Institute on Communications (2) Institute Specific Projects & Consortia Creation of start-ups Prospective & Innovation Medium and long term R&D Ph D Theses Master Theses Utilization of known R&D Continuous Analysis of extern R&D Prediction of tech needs Specific needs Multidisciplinary projects Product Focalization Own development in the CI

23. Research Institute on Communications (3) 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 issues at the Institute This is a 1st proposal. It has to be determined within the Advisory Board 3 research areas Prospective & Innovation Office

24. 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 extern public (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

25. Types of Company Partnership Associated Funding Human resources Initial Participation (commitment for 4 years) 150 Keuro/year50 Keuro/year Fix lab seats up to 2 engineers Only for Seminars Affiliated Research Institute on Communications (5)

26. Institute Advisory Board Head Telecom Faculty Head Dpt. Radiotech Head Dept. Electronics Head Dept. Networks Head Dept. Basic Sci University Head of Institute Vicehead of Institute Technology Responsible Network Responsible Application Responsible Institute 10-12 Associated Companies Industry 4 known professionals Individual Research Institute on Communications (6)

27. Member of the Advisory board Member of the Scientific 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 Benefits of being an Institute partner Asso. Affi. Research Institute on Communications (7)

28. University & hired personal and infrastructure funding University: 0.77 (22%) Hired: 0.91 (26%) 1.68 (46%) Personal Material Lab: 50 (9%) Computers: 20 (3%) Software: 12 (2%) 82 (14%) Infrastructure Univ: 0.89 (25%) Taxes: 0.27 (8%) Misc.: 0.19 (5%) 1.35 (38%) Others 3.5 Meuros Research Institute on Communications (8)

29. Institute permanent staff (estimation) 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 4 Faculty staff1 MBA 3 Grad. students 4 engineers 5 Administrative staff From UniversityHired Personal Total: 56 (61%) Total: 36 (39%) Exec. team (5%) Resarch staff (82%) Administr. & support staff (13%) Employment creation: 24/80 (30%) Research Institute on Communications (9)

30. Feasible funding sources 3.5 Meuros Research Institute on Communications (10)