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Vodafone Chair Mobile Communications Systems, Prof. Dr.-Ing. G. Fettweis Case Study: Implementation Aspects of a GFDM-based Prototype for 5G Cellular Communications Ivan Simões Gaspar With the Vodafone Chair (Prof. Fettweis) since February 2012 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 NI RF Roundtable 2012 December 10-11, 2012, Bristol, UK

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Motivations for 5G M2M dominating subscribers diverse requirements (high and lows) : data rate, latency, mobility, quality, security asynchronous and non-orthogonal modulation Opportunistic use of spectrum time and frequency agility accurate sensing no interferer (filtering) RF roundtable 2012

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RF roundtable 2012 High rate, low latency, interactive video, apps, increased signaling vast # M2M devices low rate / complexity flexible fine-grained sharing of fragmented spectrum Wireless Access: flexible scalable content aware robust reliable CoMP RRM t f asynchronous access Challenges

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4 Our approach RF roundtable 2012 Question the strict synchronism, orthogonality and high out of band radiation of OFDM based systems with the introduction of new non-orthogonal filtered waveforms that carry the data on the physical layer. Deal with crosstalk and interference with a transceiver structure termed GFDM (Generalized Frequency Division Multiplexing). Explore the tradeoff of an increased computational complexity at the Base Stations with a more flexible construction of millions of machine type communications (MTC) devices Proof of concept prototype with a highly scalable implementation on NI’s PXI platform

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generalization of OFDM 1 up to M symbols per subcarrier Pulse shaping with circular convolution (block structure - burst) GFDM Transmitter Model Mapping Up sampling FilteringUp conversion RF roundtable 2012 M = number of symbols per subcarrier K = number of active subcarriers

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6 Matrix Model, x=Ad RF roundtable 2012 The A matrix contains all the possible impulse responses of the system Circular impulse response

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RF roundtable First Demo – ‘Player Approach’ parametervalue Channel bandwidth20 MHz Max. number of subcarriers2048 PRB30 active subcarriers360 occupied bandwidth9.8 MHz carrier frequency2,4 GHz modulationQPSK filter, roll-offRRC, a = 0.5 block size14 Demo Setup System Parameters Transmit Signals

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RF roundtable First Demo – ‘Player Approach’ Few weeks after receiving the HW we get a real time signal coming out of the box

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9 A Low Complexity Model RF roundtable 2012 Time approach: up sampling, circular convolution and up conversion Frequency approach: DFT, spectrum repetition, windowing and position shift, IDFT

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10 A Low Complexity Model RF roundtable 2012 Subcarrier processing time vs. frequency domain Subcarrier superposition in frequency domain circ. convolution repetition zero stuff windowing

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11 Low Complexity Model (Matrix) RF roundtable 2012

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12 Low Complexity Model RF roundtable 2012 GFDM Matrix Model OFDM reference GFDM Low Complex GFDM non sparse spectrum

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13 LabView Style TX Model RF roundtable 2012

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RF roundtable Second Demo – Offline TX LabVIEW interactive transmitter (offline) LabView based implementation in less than 2 months after basic training Very friendly graphical interface

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15 Out of band Radiation RF roundtable 2012 GFDM (red curve) vs. OFDM (blue curve)

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RF roundtable Third Demo – Online TX LabVIEW interactive transmitter (online) PXI based implementation in less than 6 months Very friendly RT and FPGA enviroments integration

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RF roundtable Third Demo – Online TX

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18 Current studies (RX) RF roundtable 2012 Math model Block Diagram ICIChannel distortions

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19 Future directions RF roundtable 2012 UHF white spaces

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Pulse shaped subcarriers can be achieved in GFDM at reasonable computational cost Out of band radiation in GFDM can outperform OFDM by several orders of magnitude Outlook A hardware implementation of the GFDM transceiver and its multi-user case application 20 Conclusions RF roundtable 2012

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Vodafone Chair Mobile Communications Systems, Prof. Dr.-Ing. G. Fettweis Thank you.

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