Advanced Modulation and Random Access Techniques for

5G Communication Systems

Carles Antón-Haro (co-authors: Xavier Mestre, Jesús Alonso)

Director of R&D Programs, Senior Research Associate

10 May 2016

2

Motivation

… an increase in available capacity1000x higher mobile data volumes, 10-100x higher end user rates

… an increase in the number of connected devices10-100x up to 300.000 devices per cell.

… an increase in offered reliability99.9999% for e.g. mission critical communications, control functionalities

… decreased latencydown to the millisecond scale.

… increased efficiencyresource utilization (e.g. energy and spectrum)

An in-depth re-design of the radio interface is needed to cope with 5G requirements

… an increase in available capacity1000x higher mobile data volumes, 10-100x higher end user rates

… an increase in the number of connected devices10-100x up to 300.000 devices per cell.

… an increase in offered reliability99.9999% for e.g. mission critical communications, control functionalities

… decreased latencydown to the millisecond scale.

… increased efficiencyresource utilization (e.g. energy and spectrum)

3

Outline

1) Advanced post-OFDM waveform designs (FBMC).

2) MAC protocol for massive random access (DQ).

3) Concluding remarks

4CONFIDENTIAL

Advanced post-OFDM Waveform Designs

(FBMC)

5

• Several post-OFDM waveforms under consideration for 5G • Filtered CP-OFDM, UFMC, UF-OFDM, GFDM, FBMC,…

• Emphasis on FilterBank MultiCarrier (FBMC) solutions based on OQAM symbols.

• These modulations achieve the maximum spectral efficiency.

Post-OFDM waveform designs

Staggering

... ......

M

M

...

Analysis Filter Bank...... ...

Synthesis Filter Bank

De-staggering

Staggering

Staggering

De-staggering

De-staggering

6

FBMC

Advantages of FBMC as 5G candidate

No other 5G waveform candidate has all these properties

• The use of filterbank based multicarrier modulations (FBMC) guarantees good spectral localization and avoids cyclic prefix insertion (OFDM), leading to a much higher spectral efficiency.

• Orthogonal modulation under ideal (frequency flat) conditions.• For mildly selective channels, single tap equalization (like OFDM) is sufficient.• Spectral coexistence with other systems can be guaranteed.

7

FBMC challenges…and solutions

• MIMO transceivers for FBMC: In general, MIMO techniques designed for OFDM cannot be directly applied to FBMC/OQAM because:

• Orthogonality in FBMC/OQAM is satisfied in the real domain.• In highly frequency selective channels, have to deal with inter-carrier/symbol/stream interference.

• Simplified channel estimation equalization of FBMC signals: FBMC/OQAM signals sensitive to high frequency selectivity.

• Simple & computationally efficient equalization/channel estimation schemes developed at CTTC.

• Prototyping and product development of FBMC signals. • Based on both polyphase and fast convolution approaches.• Implementing MIMO processing.• Reconfigurable to support FBMC/OQAM, FMT and single carrier with a single transmitter architecture.

Parallelized transceiver architectures for MIMO

FBMC/OQAM developed at CTTC.

8

FBMC prototyping: wireless

• FPGA-based implementation of flexible FBMC/OQAM based on fastconvolution (ICT EMPhAtiC Project) and using MIMO.

• Main application: design of a broadband Professional Mobile Radio transmission that is able to co-exist with the narrowband legacy systems(TETRA-TEDS).

Primary Terminals

FBMC TXFBMC RX

FBMC wideband PMR

Narrowband legacy PMR

9

FBMC-based system is able to suppress subcarriers and coexist with current TETRAPOL terminals…OFDM is NOT.

FBMC prototyping: wireless (cont’d)

10

FMBC product development: powerline

• Design and implementation of a Multicarrier filterbank Multicarrier Transceiver for High Voltage Power Lines (FPGA+DSP).

• This is now commercialized by a local company.

• It is a real-time TX+RX modem implementing a 10bit/s/Hz transmission• Auto-configurable to avoid narrowband interference and maximize throughput.• 3 DSPs + 1 FPGA at each modem.

11

Waveform design: CTTC experience

• Research projects: Active participation in several EU-fundedand national research projects, (both algorithms and demos):

• Physical Layer for Dynamic Spectum Access and Cognitive Radio (ICT-211887), PHYDYAS, Jan 2008- June 2010.

• Enhanced Multicarrier Techniques for Professional Ad-Hoc and Cell-Based Communications (ICT-318362), 2012–15. CTTC is the Project Coordinator.

• National research project “Multi-carrier systems with multi-antenna diversity and adaptive coding” TEC2008-06327-C03, Jan. 2009 – Dec. 2011.

• Some publications: • M. Caus, A. I. Pérez-Neira, Transmitter-Receiver Designs for Highly Frequency Selective Channels

in MIMO FBMC Systems , IEEE Transactions on SP, Vol. 60, No. 12, pp. 6519–6532, Dec 2012. • X. Mestre, M. Majoral, S. Pfletschinger, An Asymptotic Approach to Parallel Equalization of Filter

Bank Based Multicarrier Signals , IEEE Trans. on Sig. Proc., Vol. 61, pp. 3592-3606, July 2013.• M. Caus, A.I. Pérez-Neira, "Multi-stream transmission for highly frequency selective channels in

MIMO-FBMC/OQAM systems", IEEE Transactions on Signal Processing, Vol. 62, No. 4, pp. 786-796, February 2014.

• X. Mestre, D. Gregoratti, “A parallel processing approach to filterbank multicarrier MIMO transmission under strong frequency selectivity”, IEEE ICASSP, 4-9 May 2014, Florence (Italy).

• Patent:• X. Mestre et al. “Method for equalizing filterbank multicarrier modulations”,

USA 13/847,020, EP13159897.1, Granted 2014.

12CONFIDENTIAL

MAC Protocol for Massive Random Access (DQ)

13

• However in

Random Access mechanisms mostly based in ALOHA and variants(Frame Slotted with/out feedback, Dynamic FSA, Diversity FSA, + SuccessiveInterference Cancellation, + Duty Cycling, + Reservation)

• “Medium Access Control” is a popular research topic:• Google: 496.000 hits• Google Scholar: 107.000 hits• IEEE Xplore: 6.169 papers

…as of 21st April 2016.

Interestingly…

14

• New stringent requirements for future wireless systems (MTC, 5G)• Huge number of devices (10x-100x), simultaneous access.• Small Data Transmissions (few bps)• Constraints on maximum latency/access delay.• Energy efficient operation, extended lifetime, energy harvesting.

• Lots of research on random access enhancements:

Interestingly…

• Go for an alternative approach?

15

Distributed Queuing Random Access

• “Infinite” number of connected devices. • Overall performance independent of network size /

composition.• Congestion-free under any load conditions:

• Random access -> reservation access.• Fair allocation of radio resources.• Traffic prioritization: QoS-enabled• Collision-free data transmissions • Minimization of idle periods (no random backoff).• PHY-layer agnostic.

16

Distributed Queuing Random Access

• Frame structure:

• Collision Resolution Algorithm (CRA) separate from Data Transmission.• If CRA faster than DT stable system.• No random back-off mechanism…just queues !!

• Two (virtual) distributed queues• Data Transmission Queue (DTQ):

• For devices with successful access requests (ARS).• Device in the first position of DTQ transmits data (DATA) in next frame.

• Collision Resolution Queue (CRQ)• For devices with collisions when requesting access (ARS).• Devices in the first position of CRQ send new requests (ARS) in next frame.

17

Example of DQ with 6 devices

• 6 data packets transmitted in 8 frames…just 2 idle frames !!

18

Experimental validation: IoTWorld

IoTWorld Testbed @ CTTC (Zigbee part)

Frame slotted-ALOHA (5 slots, 5 devices) DQ(5 slots, 5 devices)

DQ(5 slots, 10 devices)

19

Current Status and Prospects• Extensively validated at the simulation level: LTE, WiFi, WBAN, 3G.

• A. Laya, C. Kalalas, F. Vazquez-Gallego, L. Alonso, and J. Alonso-Zarate, “Goodbye, ALOHA!“, IEEE Access, no. 99, April 2016 (OPEN ACCESS)

• A. Laya, L. Alonso, and J. Alonso-Zarate, "Contention Resolution Queues for Massive Machine TypeCommunications in LTE," in proc. of the IEEE PIMRC, Workshop on Machine-to-Machine Communications, July 2015.

• A. Laya, L. Alonso, and J. Alonso-Zarate, "Efficient Contention Resolution in Highly Dense LTE Networks forMachine-Type Communications", in Proc. of to IEEE Globecom 2015, December 2015.

• A. Laya, L. Alonso, J. Alonso-Zarate, “Is the Random Access Channel of LTE and LTE-A Suitable for M2M Communications? A Survey of Alternatives”, IEEE Communications Surveys and Tutorials, Special Issue on Machine-to-Machine Communications, vol. 16, issue 1, Jan 2014.

• Research projects:• Advanced Communications and Information processing in smart grid systems

(FP7-607774), ADVANTAGE, Jan 2014 - Dec 2017.• Virtual Small Cells for Spectral and Energy Efficient Communications in 5G

Networks (TEC2014-60130-P), CELLFIVE, Jan 2015 – Dec. 2017.• Potential application areas:

• Next generation cellular communications (MMC-Massive Machine Communications, 3GPP, 5G, RACH-LTE-A).

• Evolution of Wi-Fi / short-range communication standards (amendments). • RFID…

20CONFIDENTIAL

CONCLUDING REMARKS

21

Concluding remarks

• Presented research work @ CTTC on:• Advanced waveform and transceiver design based on FBMC• Novel MAC protocols for massive random access (DQ)

• Extensively validated via simulations and/or prototyping/product development.

• Outcome of publicly-funded research projects and/or industrial contracts.

• Widely described in publications from the literature.• Ready for standardization work / additional product development?

22

THANKS FOR YOUR KIND ATTENTION !

Carles Antón-Haro, PhD, MBADirector of R&D Programmes, Senior Research AssociateCentre Tecnològic de Telecomunicacions de CatalunyaParc Mediterrani de la Tecnologia, Av. Carl Friedrich Gauss 708860 Castelldefels (Barcelona) - SPAIN

carles.anton@cttc.es Tel: +34.93.645.29.23

QUESTIONS ?