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This paper gives an overview of recent advancements in multiple-input multiple-output (MIMO) systems under W-CDMA to increase the system performance and spectral efficiency. We investigate the effects of predicting the CSI using linear fading envelope predictors under AWGN and multipath Rayleigh fading by considering semi-blind channel schemes in spatial multiplexing and STBC to enhance the performance...
The Golden code has been proposed as an optimal space-time code for multiple-input multiple-output (MIMO) communication systems. This paper considers a ??blind?? MIMO system where the channel is assumed to be unknown. The Golden code is unidentifiable under this condition and can not be used directly. A block code modification is described which makes the Golden code usable in the context of blind...
The multi-carrier code-division multiple-access (MC-CDMA) multiple-input multiple-output (MIMO) system with quasi-orthogonal space-time block codes (QO-STBC) is studied in this paper. Considering QO-STBC scheme that involves three or four transmit antennas, a subspace-based blind channel estimation is proposed. With the estimated channel coefficients, the minimum output energy (MOE) and eigenspace...
This paper considers the randomized distributed orthogonal space-time block coding (DOSTBC) system proposed by Sirkeci-Mergen and Scaglione, and considers a situation where some of the cooperative relays can disconnect from the network during the data frame transmission. Such an event translates into abrupt changes of the virtual channel matrix at the receiver; and a coherent detector, which assumes...
The spectral efficiency achievable with joint processing of pilot and data symbol observations is compared with that achievable through the conventional (separate) approach of first estimating the channel on the basis of the pilot symbols alone, and subsequently detecting the data symbols. Studied on the basis of a mutual information lower bound, joint processing is found to provide a non-negligible...
Estimating the channel state information (CSI) of several transmitters that use orthogonal space-time block codes (OSTBC) to communicate with a single receiver is considered. Based on rank revealing QR (RRQR) factorization and propagator method (PM), two new algorithms to estimate multiuser MIMO channels are proposed. The algorithm estimates the subspace spanned by the user channels use only a few...
A dual mode 2times2 MIMO OFDM & OFDMA receiver is implemented with shared hardware resources. This dual mode receiver functions well in both static and mobile channels. It follows the specification requirement of EWC HT PHY V1.27 and IEEE 802.16e-2005, and proposes a PHY baseband simulation model to meet the specifications. Additionally, equalization supports both static and dynamic channel estimation...
In this paper, a 2times2 MIMO-OFDM digital baseband receiver for IEEE 802.16 WMAN-OFDM PHY is presented. The inner receiver design includes the timing and carrier frequency synchronization, the channel estimation and the MIMO detection with adaptive equalization technique. In order to enhance the robustness of the system, the BLMS algorithm is derived to track the channel variation for the Alamouti-scheme...
We present a pilot-assisted method for estimating the frequency selective channel in a MIMO-OFDM system. The pilot sequence is designed using the DFT of the Golay complementary sequences. Novel exploitation of the perfect autocorrelation property of Golay complementary sequences, in conjunction with OSTBC based pilot waveform scheduling across multiple OFDM frames, facilitates simple separation of...
We consider improving the performance of orthogonal frequency-division multiplexing (OFDM)-based mobile broadband wireless communication (MBWC) systems over time-varying frequency-selective fading channels. To battle the problem related to frequency-selective fading, we can use space-time block coding (STBC) on each OFDM subcarrier. To battle the problem related to time varying as well as that related...
This paper presents a new blind adaptive receiver for the multiple-input multiple-output (MIMO) antennas system, with space-time block code (ST-BC). First, we extend the signal model of the frequency flat channel to the multipath fading channel for the MIMO-CDMA system with ST-BC. The new proposed scheme is based on the linearly constrained constant modulus (LCCM) criterion. To reduce the complexity...
We present a pilot-assisted method for estimating the frequency selective channel in a MIMO-OFDM (Multiple Input Multiple Output - Orthogonal Frequency Division Multiplexing) system. The pilot sequence is designed using the DFT (Discrete Fourier Transform) of the Golay complementary sequences. Novel exploitation of the perfect autocorrelation property of the Golay codes, in conjunction with OSTBC...
The combination of multiple antennas and multicarrier code division multiple access (MC-CDMA) is a strong candidate for the downlink of future mobile communications. The study of such systems, in scenarios that model real-life transmissions is an additional step towards an optimised achievement. Channel estimation is employed to improve its performance by characterising the channel. In this paper...
In this paper, the new detection scheme proposed by Tarokh and Alamouti is investigated and expanded to two schemes of two transmit two receive antennas and four transmit one receive antennas. Previously, Tarokh and Alamouti, based on the simple transmit diversity scheme proposed by Alamouti, have provided two new detection methods to decode signals at the receiver without channel information. We...
In this paper, a decision-directed multiple-input multiple-output (MIMO) receiver is proposed for a code-division multiple access (CDMA) system using space-time block coding (STBC) over a multipath fading channel. In contract to the conventional MMSE receiver, the proposed blind receiver can provide a reliable performance without requirement of the pilot symbols.
The reliability of mobile packet data transmission in multi-input multi-output (MIMO) communication systems is degraded by time-varying multi-path channel fading. This so-called Doppler-effect can be mitigated by using a shorter packet length and/or inserting more pilot training symbols and frequently tracking the channel at the receiver at the cost of additional rate overhead. A judicious choice...
Joint channel-symbol estimation has been recently applied to a differential unitary space-time coded Multiple Input Multiple Output (MIMO) system in order to reduce the SNR penalty of differential encoding relative to coherent communications. Using unitary codes restricts the data rate to one symbol per channel use. A block differential MIMO technique was presented in which allows the use of non-orthogonal...
DSTBC (differential space-time block coding) system does not require CSI (channel state information) in both transmitter and receiver sides, but its SNR (signal to noise ratio) versus BER (bit error rate) characteristic is degraded compared with original STBC scheme which utilizes CSI at the receiver. In this paper, attempting to recover this performance loss originated from the differential decoding,...
In this paper a new subspace method for blind estimation of frequency-selective channels is proposed. Specifically, we consider the case of broadband space-time block coded (STBC) transmissions such as STBC-OFDM, space-frequency block coding (SFBC), or time-reversal STBC. The proposed technique is able to exactly recover the channel within a limited number of data blocks, and its computational complexity...
In this paper, we use a 4times4 MIMO testbed to investigate the experimental performance of the blind channel estimation technique presented in (Shahbazpanahi et al., 2005). The operating frequency throughout all experiments was selected to be 2.47 GHz and the transmission bandwidth was 20 MHz. Our experimental results show that the performance of the blind technique can be very close to that of non-blind...
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