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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 Simes 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 Slide 2 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) 2 10.12.2012RF roundtable 2012 Slide 3 3 10.12.2012RF 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 Slide 4 4 Our approach 10.12.2012RF 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 NIs PXI platform Slide 5 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 5 10.12.2012RF roundtable 2012 M = number of symbols per subcarrier K = number of active subcarriers Slide 6 6 Matrix Model, x=Ad 10.12.2012RF roundtable 2012 The A matrix contains all the possible impulse responses of the system Circular impulse response Slide 7 10.12.2012RF roundtable 2012 7 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 Slide 8 10.12.2012RF roundtable 2012 8 First Demo Player Approach Few weeks after receiving the HW we get a real time signal coming out of the box Slide 9 9 A Low Complexity Model 10.12.2012RF roundtable 2012 Time approach: up sampling, circular convolution and up conversion Frequency approach: DFT, spectrum repetition, windowing and position shift, IDFT Slide 10 10 A Low Complexity Model 10.12.2012RF roundtable 2012 Subcarrier processing time vs. frequency domain Subcarrier superposition in frequency domain circ. convolution repetition zero stuff windowing Slide 11 11 Low Complexity Model (Matrix) 10.12.2012RF roundtable 2012 Slide 12 12 Low Complexity Model 10.12.2012RF roundtable 2012 GFDM Matrix Model OFDM reference GFDM Low Complex GFDM non sparse spectrum Slide 13 13 LabView Style TX Model 10.12.2012RF roundtable 2012 Slide 14 10.12.2012RF roundtable 2012 14 Second Demo Offline TX LabVIEW interactive transmitter (offline) LabView based implementation in less than 2 months after basic training Very friendly graphical interface Slide 15 15 Out of band Radiation 10.12.2012RF roundtable 2012 GFDM (red curve) vs. OFDM (blue curve) Slide 16 10.12.2012RF roundtable 2012 16 Third Demo Online TX LabVIEW interactive transmitter (online) PXI based implementation in less than 6 months Very friendly RT and FPGA enviroments integration Slide 17 10.12.2012RF roundtable 2012 17 Third Demo Online TX Slide 18 18 Current studies (RX) 10.12.2012RF roundtable 2012 Math model Block Diagram ICIChannel distortions Slide 19 19 Future directions 10.12.2012RF roundtable 2012 UHF white spaces Slide 20 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 10.12.2012RF roundtable 2012 Slide 21 Vodafone Chair Mobile Communications Systems, Prof. Dr.-Ing. G. Fettweis Thank you.