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This paper proposes a low-complexity parameter update algorithm to spatio-temporal filter for suppressing the cochannel interference in multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) modulation systems. The conventional spatiotemporal filter employs the recursive eigenvalue decomposition algorithm to perform the parameter estimation and update. In the mobile environment, all the points during a data OFDM symbol are used for parameter update. This paper proposes an incomplete parameter update for the conventional spatio-temporal filter, where only a fraction of points during a data OFDM symbol are used for parameter update, while the others are ignored. In this way, the computational complexity of the parameter update can be reduced to some extent with negligible performance degradation. Computer simulations under IEEE 802.11a demonstrate the validity of the proposed incomplete parameter update algorithm. [ABSTRACT FROM AUTHOR]

This paper proposes an adaptive joint combination of the maximum likelihood detection (MLD) and MMSE detection with successive interference cancellation (MMSE-SIC) for MIMO-OFDM coded system. The coded system employs the linear convolutional code as the channel encoder, in order to deal with the severe fading. The cyclic redundancy check (CRC) is attached in the tail of the channel coder to detect whether there exists error in the detected information bits. To utilize the CRC function sufficiently, this paper proposes an adaptive joint combination of MLD and MMSE-SIC for the coded systems. The number of data streams to be detected by MLD is adaptively increased if the CRC finds some error in the detected information bits. This procedure ends when there is no error in the detected bits or the number of streams to be detected by MLD exceeds a predetermined threshold. Computer Simulation results show that the proposed scheme can achieve near-MLD performance with very low detection complexity. [ABSTRACT FROM AUTHOR]

This paper proposes a novel joint filtering technique in order to suppress the cochannel interference for multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) modulation systems. There are conventionally two techniques to suppress cochannel interference: 1) spatio-temporal filtering (STF) the received signals prior to the fast Fourier transform (FFT), termed preFFT-STF; 2) the spatial filtering (SF) the received signals posterior to FFT, termed postFFT-SF. With limited number of preamble symbols, preFFT-STF outperforms postFFT-SF due to the superiority in the parameter estimation accuracy. While with a large number of preamble symbols, preFFT-STF is poorer than postFFT-SF because it only has limited filtering capability. To achieve a suitable tradeoff between the filtering capability and parameter estimation accuracy, this paper proposes a novel joint filtering technique. The transmitted packet is firstly divided into two parts, and then the first part is detected by preFFT-STF while the second part is detected by postFFT-SF. Simulation results show that the proposed scheme outperforms significantly both the preFFT-STF and postFFT-SF systems [ABSTRACT FROM AUTHOR]

This paper proposes the circular antenna array to suppress the cochannel interference for multiple-input multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) modulation systems. The conventional cochannel interference suppression system employs the linear antenna array in the receiver side, and the capability of circular antenna array in suppressing cochannel interference is not investigated so far. This paper proposes the circular antenna array to the conventional cochannel interference suppression system, and derives a theoretical measurement for evaluating the cochannel interference suppression capability. Computer simulations under IEEE 802.11a demonstrate the validity of the proposed circular antenna array. [ABSTRACT FROM AUTHOR]