Space–time block code

Abstract: In this paper, we propose a novel signal detection method that achieves the maximum likelihood (ML) performance but requires much less computational complexity than the ML detection. When the well-known linear decoding method is used for space-time block coded (STBC) OFDM systems in fast-fading channels, co-channel interference (CCI) as well as inter-carrier interference (ICI) occurs. A maximum likelihood (ML) method can be employed to deal with the CCI; however, its computational complexity is very high. In this paper, we propose a signal detection method for orthogonal space-time coded OFDM systems that achieves the identical error performance as the ML method, but requires much less computational complexity.

Abstract: Single-carrier (SC) transmission using frequency-domain space-time block coded joint transmit/receive diversity (FD-STBC-JTRD) combined with transmit frequency-domain equalization (FDE) obtains full spatial diversity gain and frequency diversity gain. Channel state information (CSI) is required only at transmitter for transmit FDE. In our previous study of SC FD-STBC-JTRD, single transmit FDE weight matrix was used. In this paper, noting that a sequence of data blocks is STBC encoded into a code-word composed of a new sequence of coded data blocks, we derive the optimal transmit FDE weight design. Multiple transmit FDE weight matrices, each associated with each coded block in a STBC code-word, are used unlike our previous transmit FDE weight design. Transmit FDE weight matrices are jointly optimized based on the minimization of the mean square error (MSE) between the transmitted signal before STBC encoding and the received signal after STBC decoding. We show by theoretical analysis that the optimal transmit FDE weight design can achieve 1/RSTBC times higher signal-to-interference plus noise power ratio (SINR) than our previous design (single transmit FDE weight matrix), where RSTBC denotes the STBC coding rate. And then, we show, by computer simulation, the optimal transmit FDE weight design achieves better bit error rate (BER) performance than our previous design.

Abstract: In this paper, a new blind channel estimation technique for multiple- input multiple-output (MIMO) space-time block coded (STBC) systems is proposed. The technique is solely based on second-order statistics (SOS), and it consists on the extraction of the main eigenvector of a modified correlation matrix. Furthermore, it can be interpreted as a deterministic technique, i.e., in the absence of noise it is able to exactly recover the channel, up to a real scalar, within a finite number of observations. Unfortunately, in many practical cases there exist ambiguities associated to the problem of blind channel estimation from SOS. In order to resolve these problems we propose a new transmission technique, which is based on the combination of different STBCs (code diversity). In the simplest case, this technique reduces to a rotation or permutation of the transmit antennas (non-redundant precoding). Finally, the performance of the proposed method is demonstrated by means of some simulation examples.

Abstract: In this paper, we present an original use of Reed-Solomon (RS) codes as space-time block codes (STBCs) and compare them to orthogonal STBCs (OSTBCs). Due to their symbol structure, they can have a representation close to that of an STBC. RS codes are admittedly more complex to decode as they have no orthogonal properties. However, they offer much higher coding rates. In addition, a wide range of these codes can be easily generated. To decode them, we have developed a new algorithm using a sliding encoding-window (SEW), which is combined with the decoding-based Chase algorithm. We compare the RS(15,7) code to the Alamouti one, both having an equivalent coding rate. Its performance compared to Alamouti gets better as the receive diversity increases. Moreover, RS codes do not require the channel to remain constant over the code duration. In fact, they offer better results if the channel changes rapidly, which can be obtained virtually by introducing interleaving