1. 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

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

3. introduction

4. 5G URLL MTC eMBB 5G application Low Energy Consumption Narrowbandwidth
Loose Synchronization

5. 4G
GFDM
OFDM 5G
Orthogonal
Non-orthogonal

6. Background theory

7. 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

8. 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]

9. 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.

10. 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.

11. 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

12. Research problem and research aim

13. 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

14. 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 ( ), vol.88,no.4, February 2014.

15. Proposed method

16. 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)

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

18. result

19. effect of cfo in ser performance

20. 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

21. Comparison of ser performance

22. Comparison of mse performance

23. conclusion

24. 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.

25. 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.

26. Thank you