Bandung Institute of Technology, Indonesia ISMS 2018 8th International Conference on Intelligent Systems, Modelling and Simulation 8-10 May, Kuala Lumpur Carrier frequency offset estimation using cyclic prefix in gfdm systems for machine type communication application Rahmah Niyati Hasyim Effrina Yanti Hamid Bandung Institute of Technology, Indonesia

content Introduction Background Theory Overview GFDM Parameter System MTC Carrier Frequency Offset Research Problem and Research Aim Proposed Method Result Conclusion

introduction

5G URLL MTC eMBB 5G application Low Energy Consumption Narrowbandwidth Loose Synchronization

4G GFDM OFDM 5G Orthogonal Non-orthogonal

Background theory

Overview GFDM A H-1 B vv Channel Mapping Demapping Add CP GFDM Modulator Add CP Channel synchronization Remove CP Equalization Demapping Demodulator H-1 A B

Modulator gfdm Ʃ Serial to Parallel d0,0 d0,M-1 dK-1,0 dK-1,M-1 Data bits do, d1, ...dn Serial to Parallel d0,0 d0,M-1 dK-1,0 dK-1,M-1 M-QAM Upsampler MK g0,0[n] g0,M-1[n] gK-1,0[n] gK-1,M-1[n] Ʃ x[0],x[1],...x[N-1] .......

Parameter system of mtc scenario [1] Value Number of subcarriers (K) 4 Active Subcarrier 1 Number of subsymbols (M) 15 CP Length ( 1/4) Roll of factor 0.5 (RRC) Modulation Order 2 Sampling frequency 0.96 MHz Subcarrier spacing 240 kHz [1] J.Ferreira, H.Rodrigues, A.Gonzales, A.Nimr, M.Matthe, D.Zhang,L.Mendes, and G.Fettweis, “GFDM Frame design for 5G application scenarios,”JOURNAL OF COMMUNICATION AND INFORMATION SYSTEMS, Vol.32. No.1, 2017.

Carrier frequency offset When frequency of transmitter oscillator and receiver oscillator does not match, then offset will occure. This offset or called as carrier freqeuncy offset will also occure when the transmitter or receiver is moving, because of doppler effect.

Frequency Error of Oscillator (ppm: part per million) Normalized CFO 5 ppm 0.17 20 ppm 0.7 40 ppm 1.3 Where foffset is frequency carrier multiple by frequency error of Oscillator and fsc is subcarrier spacing. In this simulation, frequency carrier is 8 GHz and subcarrier spacing is 240 KHz

Research problem and research aim

Research problem GFDM has disadvantage in which its performance becomes poor when the carrier frequency offset (CFO) exists in the system. Range of estimation CFO that is narrow which cannot estimate bigger value of normalized CFO

Research aim The aim of this paper is to propose a new CFO estimation technique using CP in GFDM with MTC scenario system. This proposed estimation technique is actually similar to that in [2] for OFDM. It later shows that the proposed technique can increase the range of normalized CFO. [2] S.E.Ibrahim, K.A.Elbarbary, R.M.El-Sagheer, “Maximizing CFO estimation range using a new OFDM symbol structure,” International Journal of Computer Application (0975-8887), vol.88,no.4, February 2014.

Proposed method

Structure of proposed method x(N-Ng),...,x(N-1) x(0),x(1),...,x(Ng-1) x(Ng),...,x(N-1) CP GFDM Symbol x(0),...,x(N-Ng-1)

Cfo estimation of proposed method Received signal with normalized cfo effect Received signal after CFO estimation

result

effect of cfo in ser performance

Result of estimation technique actual value of estimate value of 0.17 0.1883 0.7 0.787 1.3 1.2847 This result is taken while the SNR value is 20 dB. It is clear that the proposed technique can estimate the normalized CFO almost accuratelly

Comparison of ser performance

Comparison of mse performance

conclusion

In this paper we show the synchronization performance of GFDM using parameter for MTC technology. Overall performance with proposed method can handle the normalized CFO. Compare with others method of synchronization, the proposed method can work well for less data symbol and give good mean square error. It shows that GFDM with proposed method of synchronization suitable for 5G scenario or MTC technology.

acknowledgment The authors wish to express their gratitude for the financial support of this research from the Lembaga Pengelola Dana Pendidikan Indonesia (Indonesia Endowment Fund for Education) Scholarship.

Thank you