GFDM based Prototype for 5G Cellular Communications

Ivan Simões Gaspar With the Vodafone Chair (Prof. Fettweis) since: February 2012 NI's RF / Communications Lead User program participant Studies: Electrical Engineering (M.Sc.) at the National Institute of Telecommunications in Brazil - INATEL Research area: robust non-orthogonal multi-carrier modulation schemes for future cellular systems

Motivation for 5G Vodafone Chair’s approach Transmitter Model (OFDM/GFDM) Out of band radiation (GFDM vs. OFDM) A Low Complexity TX Model Our Transmitter Demos Conclusion

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Agenda

M2M dominating subscribers. higher density per cell diverse requirements (high and lows) :

data rate, latency, mobility, quality, security asynchronous transmission

Opportunistic use of spectrum

time and frequency agility accurate sensing low out of band radiation (no interferer)

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Motivations for 5G

We look for a modulation beyond OFDM, with relaxation of strict synchronism, orthogonality and better out of band radiation (crosstalk and interference)

Our proposal is to investigate a new non-orthogonal filtered waveform, termed GFDM (Generalized Frequency Division Multiplexing), to carry the data on the physical layer

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Vodafone Chair‘s approach

FBMC filter bank multi carrier IA-PFT interference avoidance transmission by partitioned frequency and time domain processing OFDM/OQAM-IOTA orthogonal frequency division multiplexing with offset QAM and isotropic orthogonal transform algorithm GFDM generalized frequency division multiplexing

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Filtered Multicarrier Schemes

OFDM 1 symbol per subcarrier

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OFDM Transmitter Model

Mapping

Up conversion

K = number of active subcarriers

OFDM generalization 1 up to M symbols per subcarrier Pulse shaping with circular convolution (block structure - burst)

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GFDM Transmitter Model

Mapping

Up sampling Filtering Up conversion

K = number of active subcarriers M = number of symbols per subcarrier

The A matrix contains all the possible impulse responses of the system

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GFDM Transmitter Model (Matrix)

Circular impulse response

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Out of band radiation benefit

GFDM (red curve) vs. OFDM (blue curve)

Time model: up sampling, circular convolution and up conversion

Frequency model (ℱ = Fourrier Transform): DFT, spectrum repetition, windowing and position shift, IDFT

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Low Complexity TX Model

( )2

Tx[ ] [ ][ ] [ ] ·kj nN

kk m

x n mN g nm en dπ

δ−

−

= ∑∑

times repetition of ][ ] [m

kd mN n mδ − ∑ kf

Nδ −

[ ]21

Tx[ ] [] ]·[ [] Nm

kj n

kk

dx n n mN gm enπ

δ−− = −

∑∑

low compleximplementation!

copy from memory shift in memory

Low Complexity TX Model

Subcarrier processing in time and frequency domain

Subcarrier superposition in frequency domain

circ. convolution

repetition

zero stuff

windowing

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LabView TX Model (detail)

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Low Complexity TX Model (Matrix)

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Low Complexity TX Model

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GFDM Matrix Model

OFDM reference

GFDM Low Complex

GFDM non sparse spectrum

First Demo – ‘‘Player‘‘

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DEMO

Few weeks after receiving the HW we get a real time signal coming out of the box

First Demo – ‘‘Player‘‘

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DEMO

Second Demo – Offline TX

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DEMO

Third Demo – Online TX

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DEMO

Third Demo – Online TX

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Pulse shaped subcarriers can be achieved in GFDM at reasonable computational cost, outperforming the out of band radiation of OFDM by several orders of magnitude NI’s PXI Platforms is powering our research with a software engineering dimension, enabling to come up with a high level real time prototype that facilitates the exploration of 5G challenges Outlook

A hardware implementation of the GFDM transceiver and its multi-user case application

.

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Conclusion

Thank you!

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GFDM based Prototype for 5G Cellular CommunicationsAgendaMotivations for 5GVodafone Chair‘s approachFiltered Multicarrier SchemesOFDM Transmitter ModelGFDM Transmitter ModelGFDM Transmitter Model (Matrix)Out of band radiation benefitLow Complexity TX ModelLow Complexity TX ModelLabView TX Model (detail)Low Complexity TX Model (Matrix)Low Complexity TX ModelFirst Demo – ‘‘Player‘‘First Demo – ‘‘Player‘‘Second Demo – Offline TXThird Demo – Online TXThird Demo – Online TXConclusion���Thank you!