Improved QO-STBC OFDM System Using Null Interference Elimination

The quasi-orthogonal space time block coding (QO-STBC) over orthogonal frequency division multiplexing (OFDM) is investigated. Traditionally, QO-STBC does not achieve full diversity since the detection matrix of QO-STBC scheme is not a diagonal matrix. In STBC, the decoding matrix is a diagonal matrix which enables linear decoding whereas the decoding matrix in traditional QO-STBC does not enable linear decoding. In this paper it is shown that there are some interfering terms in terms of non-diagonal elements that result from the decoding process which limit the linear decoding. As a result, interference from the application of the QO-STBC decoding matrix depletes the performance of the scheme such that full diversity is not attained. A method of eliminating this interference in QO-STBC is investigated by nulling the interfering terms towards full diversity for an OFDM system. It was found that the interference reduction technique permits circa 2dB BER performance gain in QO-STBC. The theoretical and simulation results are presented, for both traditional QO-STBC and interference-free QO-STBC applying OFDM

[1]  Sooyoung Kim,et al.  A novel QO-STBC scheme with linear decoding for three and four transmit antennas , 2008, IEEE Communications Letters.

[2]  Ari Hottinen,et al.  Minimal non-orthogonality rate 1 space-time block code for 3+ Tx antennas , 2000, 2000 IEEE Sixth International Symposium on Spread Spectrum Techniques and Applications. ISSTA 2000. Proceedings (Cat. No.00TH8536).

[3]  Raed A. Abd-Alhameed,et al.  Wavelet Packet Transform Modulation for Multiple Input Multiple Output Applications , 2013 .

[4]  Hamid Jafarkhani,et al.  Quasi-Orthogonal Space-Frequency and Space-Time-Frequency Block Codes for MIMO OFDM Channels , 2008, IEEE Transactions on Wireless Communications.

[5]  Hamid Jafarkhani,et al.  A quasi-orthogonal space-time block code , 2000, 2000 IEEE Wireless Communications and Networking Conference. Conference Record (Cat. No.00TH8540).

[6]  Raed A. Abd-Alhameed,et al.  A New Approach for OSTBC and QOSTBC , 2013 .

[7]  David Tse,et al.  Fundamentals of Wireless Communication , 2005 .

[8]  Constantinos B. Papadias,et al.  Capacity-approaching space-time codes for systems employing four transmitter antennas , 2003, IEEE Trans. Inf. Theory.

[9]  Abbas Jamalipour,et al.  Wireless communications , 2005, GLOBECOM '05. IEEE Global Telecommunications Conference, 2005..

[10]  Siavash M. Alamouti,et al.  A simple transmit diversity technique for wireless communications , 1998, IEEE J. Sel. Areas Commun..

[11]  J.E. Mazo,et al.  Digital communications , 1985, Proceedings of the IEEE.