Coherent versus non-coherent space-time shift keying for co-located and distributed MIMO systems

Abstract

In this thesis, we propose the novel Space-Time Coding (STC) concept of Space-Time Shift Keying (STSK) and explore its characteristics in the contexts of both co-located and cooperative Multiple-Input Multiple-Output (MIMO) systems using both coherent and non-coherent detection. Furthermore, we conceive new serially-concatenated turbo-coding assisted STSK arrangements for the sake of approaching the channel capacity limit, which are designed with the aid of EXtrinsic Information Transfer (EXIT) charts.

The basic STSK concept is first proposed for the family of co-located MIMO systems employing coherent detection. More specifically, in order to generate space-time codewords, these Coherent STSK (CSTSK) encoding schemes activate one out of Q dispersion matrices. The CSTSK scheme is capable of striking an attractive tradeoff between the achievable diversity gain and the transmission rate, hence having the potential of outperforming other classic MIMO arrangements. Since no inter-channel interference is imposed at the CSTSK receiver, the employment of single-stream-based Maximum Likelihood (ML) detection becomes realistic. Furthermore, for the sake of achieving an infinitesimally low Bit-Error Ratio (BER) at low SNRs, we conceive a three-stage concatenated turbo CSTSK scheme.

In order to mitigate the effects of potential Channel State Information (CSI) estimation errors as well as the high pilot overhead, the Differentially-encoded STSK (DSTSK) philosophy is conceived with the aid of the Cayley transform and differential unitary space-time modulation. The DSTSK receiver benefits from low-complexity non-coherent single-streambased ML detection, while retaining the CSTSK scheme’s fundamental benefits. In order to create further flexible STSK architecture, the above-mentioned co-located CSTSK scheme is generalized so that P out of Q dispersion matrices are activated during each space-time block interval. Owing to its highly flexible structure, this generalized STSK scheme subsumes diverse other MIMO arrangements.

Finally, the STSK concept is combined with cooperative MIMO techniques, which are capable of attaining the maximum achievable diversity gain by eliminating the undesired performance limitations imposed by uncorrelated fading. More specifically, considering the usual twin-phase cooperative transmission regime constituted by a broadcast phase and by a cooperative phase, the CSTSK and DSTSK schemes developed for co-located MIMO systems are employed during the cooperative transmission phase.

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Identifiers

ORCID for Lajos Hanzo: orcid.org/0000-0002-2636-5214

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