Comparison of ML carrier estimation schemes based on APSSB and preamble for OFDMA in fading channel

The paper proposes a novel estimation scheme of carrier frequency offset (CFO) based on Added Preamble Sequence Semi-Blind (APSSB) scheme. The proposed maximum-likelihood (ML) CFO estimator is based on APSSB OFDMA model in which Gold sequence is added to the output of IFFT modulator and exploited for CFO estimation at the receiver. CFO estimators based on APSSB scheme and preamble are compared by both SINR analysis and simulation. We propose that the APPSB scheme should be employed for fine frequency synchronization in OFDMA especially in delay-insensitive service. In this paper, we propose the APSSB OFDMA model in which APSSB sequence is added to the output of IFFT modulator. The APSSB sequence is exploited for CFO estimation by correlation detection with the local APSSB sequence at the receiver. Comparison of SINR is made between CFO estimation schemes based on APSSB and preamble. The APSSB scheme suffers no data rate loss, and is more accurate than preamble scheme when APSSB symbol number for CFO estimation is large enough to excess the threshold. Compared with preamble scheme, the APPSB scheme has the property of better accuracy as well as larger delay. We propose the APPSB scheme should be employed for fine frequency synchronization in delay-insensitive service. The rest sections of the paper are organized as follows. In Section 2, the proposed APSSB OFDMA system model is described. Based on this model, section 3 presents the ML CFO estimation scheme based on APSSB. A comparison is made in section 4 in terms of SINR of the two schemes in fading channel. Simulation and analysis are presented in section 5. Finally, section 6 concludes the paper.

[1]  Sergio Barbarossa,et al.  Non-data-aided carrier offset estimators for OFDM with null subcarriers: identifiability, algorithms, and performance , 2001, IEEE J. Sel. Areas Commun..

[2]  O. Edfors,et al.  Time and frequency synchronization for OFDM using PN-sequence preambles , 1999, Gateway to 21st Century Communications Village. VTC 1999-Fall. IEEE VTS 50th Vehicular Technology Conference (Cat. No.99CH36324).

[3]  Jian Sun,et al.  Frequency and timing synchronization and channel estimation in preamble based OFDM system , 2002, IEEE 2002 International Conference on Communications, Circuits and Systems and West Sino Expositions.

[4]  Ananthram Swami,et al.  Blind frequency-offset estimator for OFDM systems transmitting constant-modulus symbols , 2002, IEEE Communications Letters.

[5]  Sergio Barbarossa,et al.  Channel-independent non-data aided synchronization of generalized multiuser OFDM , 2001, 2001 IEEE International Conference on Acoustics, Speech, and Signal Processing. Proceedings (Cat. No.01CH37221).

[6]  Geoffrey Ye Li,et al.  Robust channel estimation for OFDM systems with rapid dispersive fading channels , 1998, ICC '98. 1998 IEEE International Conference on Communications. Conference Record. Affiliated with SUPERCOMM'98 (Cat. No.98CH36220).

[7]  Kwang-Cheng Chen,et al.  Data-aided maximum likelihood frequency synchronization for OFDM systems , 2003, GLOBECOM '03. IEEE Global Telecommunications Conference (IEEE Cat. No.03CH37489).

[8]  Tung-Sang Ng,et al.  A blind carrier frequency offset detector used for feedback frequency synchronization in OFDM receivers , 2003, IEEE International Conference on Communications, 2003. ICC '03..

[9]  Visa Koivunen,et al.  Blind CFO estimation in OFDM systems using diagonality criterion , 2004, 2004 IEEE International Conference on Acoustics, Speech, and Signal Processing.

[10]  G.B. Giannakis,et al.  Carrier frequency offset estimation for OFDM-based WLANs , 2001, IEEE Signal Processing Letters.

[11]  S.H. Muller-Weinfurtner.  Comparison of preamble structures for burst frequency synchronization , 2000, Globecom '00 - IEEE. Global Telecommunications Conference. Conference Record (Cat. No.00CH37137).

[12]  Michele Morelli,et al.  Timing and frequency synchronization for the uplink of an OFDMA system , 2004, IEEE Transactions on Communications.

[13]  Jichang Guo,et al.  Symbol timing and channel estimation of IEEE802.11a based on OFDM , 2003, CCECE 2003 - Canadian Conference on Electrical and Computer Engineering. Toward a Caring and Humane Technology (Cat. No.03CH37436).