ECM and SAGE based joint estimation of timing and frequency offset for DMIMO-OFDM system

Distributed multiple-input multiple-output (DMIMO) technology is a key enabler of coverage extension and enhancement of link reliability in wireless networks through distributed spatial diversity. DMIMO employs classic relay channels in between the source and the destination to opportunistically form a virtual antenna array (VAA) for emulating cooperative diversity. Use of multiple antennas at the relays further increases capacity and reliability of the relay-destination channel through multiplexing and diversity of MIMO antennas respectively. In such network, the signal received at the destination is characterized by multiple timing offsets (MTO) due to different propagation delay and multiple carrier frequency offsets (MCFO) due to independent oscillators of the relays. Hence, synchronization becomes a crucial issue in DMIMO in order to realize the distributed coherence. In this paper, we address joint estimation of MCFO and MTO in DMIMO orthogonal frequency division multiplexing (OFDM) with MIMO configuration at the relays for estimate-and-forward (EF) relaying protocol. Two iterative algorithms, based on expectation conditional maximization (ECM) and space alternating generalized expectation-maximization (SAGE) are proposed for joint estimation in presence of inter carrier interference (ICI). The robustness of both the estimators to ICI is evaluated by mathematical analysis and supported by extensive simulations. The performance of the proposed estimators is assessed in terms of mean square error (MSE) and bit error rate (BER). The theoretical Cramer-Rao lower bound (CRLB) of estimator error variance is also derived.

[1]  Hossam S. Hassanein,et al.  Cooperative vehicular ad-hoc transmission for LTE-A MIMO-downlink using Amplify-and-Forward relaying , 2013, 2013 IEEE Global Communications Conference (GLOBECOM).

[2]  Raghuraman Mudumbai,et al.  Distributed massive MIMO: Algorithms, architectures and concept systems , 2014, 2014 Information Theory and Applications Workshop (ITA).

[3]  Ying-Chang Liang,et al.  Joint channel and frequency offset estimation in distributed MIMO flat-fading channels , 2008, IEEE Transactions on Wireless Communications.

[4]  Huiming Wang,et al.  Fast Kalman Equalization for Time-Frequency Asynchronous Cooperative Relay Networks With Distributed Space-Time Codes , 2010, IEEE Transactions on Vehicular Technology.

[5]  T. Gulliver,et al.  Capacity and error probability analysis for orthogonal space-time block codes over fading channels , 2005, IEEE Transactions on Wireless Communications.

[6]  Ali A. Nasir,et al.  Transceiver Design for Distributed STBC Based AF Cooperative Networks in the Presence of Timing and Frequency Offsets , 2013, IEEE Transactions on Signal Processing.

[7]  Alfred O. Hero,et al.  Space-alternating generalized expectation-maximization algorithm , 1994, IEEE Trans. Signal Process..

[8]  Yi Guo,et al.  Time and frequency synchronisation scheme for orthogonal frequency division multiplexing-based cooperative systems , 2013, IET Commun..

[9]  Hani Mehrpouyan,et al.  Estimation, Training, and Effect of Timing Offsets in Distributed Cooperative Networks , 2010, 2010 IEEE Global Telecommunications Conference GLOBECOM 2010.

[10]  Huiming Wang,et al.  Full Diversity Space-Frequency Codes for Frequency Asynchronous Cooperative Relay Networks with Linear Receivers , 2011, IEEE Transactions on Communications.

[11]  Ali A. Nasir,et al.  DSTBC based DF cooperative networks in the presence of timing and frequency offsets , 2013, 2013 IEEE 14th Workshop on Signal Processing Advances in Wireless Communications (SPAWC).

[12]  Ali A. Nasir,et al.  Timing and Carrier Synchronization With Channel Estimation in Multi-Relay Cooperative Networks , 2012, IEEE Transactions on Signal Processing.

[13]  Hui Wu,et al.  Faster information propagation on highways: A virtual MIMO approach , 2014, 2014 IEEE Global Communications Conference.

[14]  Shaoqian Li,et al.  A New Synchronization Scheme for OFDM-Based Cooperative Relay Systems , 2010, 2010 IEEE Global Telecommunications Conference GLOBECOM 2010.

[15]  Ali A. Nasir,et al.  Blind Timing and Carrier Synchronization in Decode and Forward Cooperative Systems , 2011, 2011 IEEE International Conference on Communications (ICC).

[16]  Satya Prakash Ponnaluri,et al.  Cooperative Relaying Using OFDM in the Presence of Frequency Offsets , 2010, 2010 IEEE Global Telecommunications Conference GLOBECOM 2010.

[17]  Vijay K. Bhargava,et al.  Optimal periodic training signal for frequency offset estimation in frequency-selective fading channels , 2006, IEEE Trans. Commun..

[18]  Zhisheng Niu,et al.  On the Impact of Carrier Frequency Offsets in OFDM/SDMA Systems , 2007, 2007 IEEE International Conference on Communications.

[19]  Saswat Chakrabarti,et al.  Some interesting results on compatible BER analysis issues related to multi-band timing and frequency synchronizers applicable for MB-OFDM based UWB communications , 2011, Digit. Signal Process..

[20]  Jianhua Zhang,et al.  Timing and Frequency Synchronization for Cooperative Relay Networks , 2013, 2013 IEEE 78th Vehicular Technology Conference (VTC Fall).

[21]  Xiao Li,et al.  Timing Estimation and Resynchronization for Amplify-and-Forward Communication Systems , 2010, IEEE Transactions on Signal Processing.

[22]  Xiao-Li Meng,et al.  Maximum likelihood estimation via the ECM algorithm: A general framework , 1993 .

[23]  Yong Xi,et al.  Multiple carrier frequency offsets tracking in co-operative space-frequency block-coded orthogonal frequency division multiplexing systems , 2013, IET Commun..

[24]  Steven Kay,et al.  Fundamentals Of Statistical Signal Processing , 2001 .