3 : FBMC/OQAM (YongJu Won et al.: A Study of Iterative Channel Estimation and Equalization Scheme of FBMC/OQAM in a Frequency Oversampling Domain) (Re

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1 (Regular Paper) 21 3, (JBE Vol. 21, No. 3, May 2016) ISSN (Online) ISSN (Print) FBMC/OQAM a), b), a), a) A Study of Iterative Channel Estimation and Equalization Scheme of FBMC/OQAM in a Frequency Oversampling Domain YongJu Won a), JongGyu Oh b), JinSeop Lee a), and JoonTae Kim a) FBMC/OQAM(Filterbank multicarrier on offset-quadrature Amplitude Modulation) OFDM/QAM(Orthogonal frequency division multiplexing on Quadrature Amplitude Modulation) CP(Cyclic Prefix). OFDM/QAM. FBMC/OQAM. OFDM/QAM. Abstract FBMC/OQAM(Filterbank multicarrier on offset-quadrature Amplitude Modulation) system is a multicarrier modulation which is not need to use cyclic prefix(cp). The CP of OFDM/QAM (orthogonal frequency division multiplexing on Quadrature Amplitude Modulation) system decreases data transmission rate. However, SER(symbol error rate) performance of FBMC/OQAM system is worse than OFDM/QAM system with frequency 1-tap equalization scheme in the frequency selective channel. In this paper, an iterative channel estimation and equalization scheme is performed in a frequency oversampling domain about each sub-channel of FBMC/OQAM system and SER performance using computer simulation is shown. Using the proposed scheme, the SER performance approaches to that of OFDM/QAM system in a frequency selective channel. Keyword: FBMC, OFDM/OQAM, Channel estimation, Iterative Channel equalization a) (Department of Electronic Engineering, Konkuk University) b) (Korea Electronics Technology Institute) Corresponding Author : (Joon Tae Kim) jtkim@konkuk.ac.kr Tel: ORCID: () (R , ). This work was supported by Institute for Information & communications Technology Promotion (IITP) grant funded by the Korea government (MSIP) (R , Development of the next generation convergence broadcasting and monitoring systems combined with the networks) in Manuscript received February 25, 2016; Revised April 12, 2116; Accepted April 12, 2016.

2 (JBE Vol. 21, No. 3, May 2016). OFDM/QAM(Orthogonal frequency division multiplexing on Quadrature Amplitude Modulation) [1][2] [3][4]. QAM (Sub-carrier) (Rectangular function) (Prototype filter). CP(Cyclic Prefix) ISI(Inter-Symbol Interference) ISI ICI(Inter-Carrier Interference) [5]. CP.. OFDM/QAM CP CP. CP ISI ICI [6] OFDM/QAM ISI CP. OFDM/QAM CP OFDM/OQAM (OFDM on Offset-Quadrature Amplitude Modulation) [7]. 1 CP ISI ICI OFDM/QAM. OFDM/OQAM 1 QAM. OQAM [7]. OFDM/ OQAM CP OFDM/QAM. OFDM/OQAM OFDM/QAM 1. OFDM/OQAM Fig. 1. The conceptional diagram of OFDM/OQAM system

3 ., FBMC/OQAM [8]. (OFDM/ OQAM FBMC/OQAM.) [9] FBMC/OQAM Extended FFT(Extended Fast Fourier Transform) polyphase network. FBMC/OQAM OFDM/ QAM,..,,.. (Real orthogonality) [8].., FBMC/OQAM OFDM/QAM. FBMC/OQAM. (Auxiliary Pilot : AP) [10]. OFDM/QAM. FBMC/ OQAM OFDM/QAM. FBMC/OQAM (frequency oversampling domain). FBMC/ OQAM OFDM/QAM Brazil-D TU(Typical Urban) FBMC/ OQAM 3 FBMC/ OQAM. 4, OFDM/QAM. II. FBMC/OQAM OFDM/QAM QAM (1) [5]. OFDM/QAM QAM,, OFDM/QAM. (1) OFDM/QAM

4 (JBE Vol. 21, No. 3, May 2016) OFDM/ QAM.. ISI, OFDM/QAM CP ISI, CP. FBMC/OQAM (2) ISI, OFDM/QAM CP [7]. FBMC/OQAM, QAM OQAM, OQAM (3). m od FBMC/OQAM,., OQAM. [9] (4). cos,. ISI ICI, OFDM/QAM,. 1. [9] Table 1. Frequency coefficients of the prototype filter [9] (4) 256, 2-(a), (b). OFDM/QAM. FBMC/OQAM 2-(a). OFDM/QAM 1 FBMC/OQAM, 2-(b). (frequency oversampling rate). OFDM/QAM IFFT(Inverse-Fast Fourier Transform), FBMC/OQAM [9] PPN (Poly Phase Network) FFT

5 5 4 Time Impulse response of Prototype Filter K = 1(OFDM/QAM) K = 2 K = 3 K = 4(This paper) 1 Frequency Impulse response & Coefficients of Prototype Filter K = 1(OFDM/QAM) K = 2 K = 3 K = 4(This paper) Value 2 Magnitude Time Sub-channel Index (a) (b) (c) 2. : (a), (b) (c) ( ) [9] Fig. 2. The responses of the prototype filter depend on the overlapping factor K and the frequency response of filterbank (a) Time impulse response, (b) Frequency response, (c) Frequency response of filterbank( ) [9] FFT. FFT 4 1 [9]. FBMC/OQAM 2-(c) IFFT Fig. 3. Inverse-FFT module in the transmitter 4. Offset-QAM Fig. 4. Offset-QAM scheme

6 (JBE Vol. 21, No. 3, May 2016) ( ). IFFT. CP OFDM/QAM FBMC/OQAM 4 QAM Offset-QAM [7]. FBMC/OQAM, OQAM (5) [7]. 1 2 [9]. (5) 2. frequency de-spreading Table 2. The result of frequency de-spreading process about neighboring sub-channels in the receiver OQAM j j j j j j j j De-Overlapping FFT Fig. 5. De-Overlapping operation and Extended FFT module in the receiver

7 .,,. (5). real orthogonality, [7]. FBMC/OQAM 5 Sliding. FFT,, [9]. III. FBMC/OQAM FBMC/OQAM 3 4. FBMC/OQAM 6., index., ( 6 )., FBMC/OQAM OFDM/QAM., OQAM,, [10]. (6) [10]. index,. 6. Frequency de-sreading Fig. 6. The result of the frequency de-spreading process in the receiver

8 (JBE Vol. 21, No. 3, May 2016) r mp n p n m p n p (8),. [10].,, (9) [10]. (9) 7 Neighboring Data 7 Auxiliary Pilot. IV.. (8). FBMC/OQAM [9] 7. Fig. 7. The placement and calculation sub-channel index of auxiliary pilot 8. Fig. 8. Channel estimation in the frequency oversampling domain

9 [11]. (8) cubic spline 8. OQAM, OQAM FFT,, (10). 9-(b). (10) (8),. (10)., (10), (11). (10). 10 FBMC/OQAM. 10-(a) FBMC/OQAM de-overlapping FFT Frequency de-spreading (7).. 10-(b). 10-(b) FBMC/OQAM. (a) (b) 9. FBMC/OQAM : (a), (b) Fig. 9. The FBMC/OQAM channel equalizer using extended-fft module : (a) Frequency one-tap equalizer, (b) Frequency oversampling domain equalizer

10 (JBE Vol. 21, No. 3, May 2016) (a) (b) 10. FBMC/OQAM : (a), (b) Fig. 10. Channel equalizer for the FBMC/OQAM system : (a) Frequency one-tap equalizer, (b) Iterative channel equalizer for the frequency oversampling domain FFT sub-carrier Frequency de-spreading... Channel Store/Modification. Time Interpolation Frequency Interpolation Sub-carrier Channel Equalizer Frequency de-spreading (10). Channel Store/Modification (11). (10). 11., (8). FBMC/ 11. Fig. 11. The flow chart of the proposed channel estimation and equalization algorithm OQAM OFDM/QAM.

11 V. FBMC/OQAM FBMC/OQAM OFDM/QAM DVB-T2 [3] Brazil-D TU(Typical Urban)-6 symbol error rate. 12-(a) 1024 OFDM/QAM 3. Table 3. Transmission parameters for the computer simulation Parameter Value Fading Model SubChannel Number 1024 or Transmission Bandwidth(MHz) 6 Pilot Spacing in Freq., Time Domain (sub-channels) BrazilD Channel Path Delay[us] [0.15, 0.63, 2.22, 3.05, 5.86, 5.93] BrazilD Channel Path Power[dB] [-0.1, -3.8, -2.6, -1.3, 0.0, -2.8] BrazilD Constellation Mapping 4, QAM TU6 Channel Path Delay[us] [0.0, 0.2, 0.5, 1.6, 2.3, 5.0] TU6 Channel Path Power[dB] [-3.0, 0.0, -2.0, -6.0, -8.0, -10.0] TU6 Channel mobile velocity(km/h) 210 TU6 Constellation Mapping 16 QAM Static Rayleigh 10 0 SER Performances over BrazilD Channel 10 0 SER Performances over TU6 Channel SER (Symbol Error Rate) 10-1 FBMC Tap FBMC 1024 Oversampling FBMC 1024 Oversampling 2nd Iter FBMC 1024 Oversampling 3rd Iter FBMC 1024 Oversampling 5th Iter FBMC Tap FBMC 4096 Oversampling FBMC 4096 Oversampling 2nd Iter FBMC 4096 Oversampling 3rd Iter OFDM 1024 OFDM SNR (Signal to Noise ratio) SER (Symbol Error Rate) FBMC Tap FBMC 1024 Oversampling FBMC 1024 Oversampling 2nd Iter FBMC 1024 Oversampling 3rd Iter FBMC Tap FBMC 4096 Oversampling 3rd Iter OFDM 1024 OFDM SNR (Signal to Noise ratio) 12. Brazil-D TU-6 (Symbol Error Rate) : (a) Brazil-D, (b) TU-6 Fig. 12. Symbol error rate performances under Brazil-D, TU-6 channel : (a) Brazil-D channel, (b) TU-6 channel

(JBE Vol. 21, No. 3, May 2016) FBMC/OQAM.. 3 OFDM/QAM. 4096 OFDM/QAM FBMC/OQAM. TU-6 12-(b) 1024.. (References) [1] F.

12 (JBE Vol. 21, No. 3, May 2016) FBMC/OQAM.. 3 OFDM/QAM OFDM/QAM FBMC/OQAM. TU-6 12-(b) (References) [1] F. Khan, LTE for 4G Mobile Broadband: Air Interface Technologies and Performance, Cambridge Univ. Press, [2] S. Sesia, I. Toufik, and M. Baker, Eds., LTE: The UMTS Long Term Evolution. John Wiley and Sons, [3] Digital Video Broadcasting (DVB): Frame structure channel coding and modulation systems for a second generation digital terrestrial television broadcasting system(dvb-t2), ETSI EN v [4] L. Fay, L. Michael, D. Gómez-Barquero, N. Ammar, and W. Caldwell, An overview of the ATSC 3.0 physical layer specification, IEEE Trans. Broadcast., vol. 62, no. 1, [5] W. Y. Zou, and Y. Wu, COFDM: An overview, IEEE Trans. Broadcasting, vol. 41, pp. 18, Mar [6] J. Du and S. Signell, Classic OFDM systems and pulse-shaping OFDM/OQAM systems, Technical Report (KTH - Royal Institute of Technology), pp. 132, Feb [7] H. Bölcskei, P. Duhamel, and R. Hleiss, Design of pulse shaping OFDM/OQAM systems for high data-rate transmission over wireless channels." in Proc. of IEEE International Conference on Communications (ICC), Vancouver, BC, Canada, June 1999, vol. 1, pp [8] P. Siohan, C. Siclet, and N. Lacaille, Analysis and design of OFDM-OQAM systems based on filterbank theory, IEEE Trans. Signal Processing, vol. 50, no.5, pp , May [9] M. G. Bellanger. "FBMC physical layer: a primer." PHYDYAS, Jan [10] J.-P. Javaudin, D. Lacroix, and A. Rouxel, Pilot-aided channel estimation for OFDM/OQAM, in Vehicular Technology Conference VTC 2003-Spring, vol. 3, Apr. 2003, pp [11] C.Faria da Rocha and M.Bellanger, Sub-channel equalizer design based on geometric interpolation for FBMC/OQAM systems, Proc. of IEEE-ISCAS 2011 conference, Rio, May 2011, pp : ~ : - ORCID : - :,,

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8-VSB (Vestigial Sideband Modulation)., (Carrier Phase Offset, CPO) (Timing Frequency Offset),. VSB, 8-PAM(pulse amplitude modulation,, ) DC 1.25V, [2

8-VSB (Vestigial Sideband Modulation)., (Carrier Phase Offset, CPO) (Timing Frequency Offset),. VSB, 8-PAM(pulse amplitude modulation,, ) DC 1.25V, [2 VSB a), a) An Alternative Carrier Phase Independent Symbol Timing Offset Estimation Methods for VSB Receivers Sung Soo Shin a) and Joon Tae Kim a) VSB. VSB.,,., VSB,. Abstract In this paper, we propose