Generalized Space-Time Shift Keying Designed for Flexible Diversity-, Multiplexing- and Complexity-Tradeoffs

In this paper, motivated by the recent concept of Spatial Modulation (SM), we propose a novel Generalized Space-Time Shift Keying (G-STSK) architecture, which acts as a unified Multiple-Input Multiple-Output (MIMO) framework. More specifically, our G-STSK scheme is based on the rationale that P out of Q dispersion matrices are selected and linearly combined in conjunction with the classic PSK/QAM modulation, where activating P out of Q dispersion matrices provides an implicit means of conveying information bits in addition to the classic modem. Due to its substantial flexibility, our G-STSK framework includes diverse MIMO arrangements, such as SM, Space-Shift Keying (SSK), Linear Dispersion Codes (LDCs), Space-Time Block Codes (STBCs) and Bell Lab's Layered Space-Time (BLAST) scheme. Hence it has the potential of subsuming all of them, when flexibly adapting a set of system parameters. Moreover, we also derive the Discrete-input Continuous-output Memoryless Channel (DCMC) capacity for our G-STSK scheme, which serves as the unified capacity limit, hence quantifying the capacity of the class of MIMO arrangements. Furthermore, EXtrinsic Information Transfer (EXIT) chart analysis is used for designing our G-STSK scheme and for characterizing its iterative decoding convergence.

I. Introduction

OVER the last two decades diverse Multiple-Input Multiple-Output (MIMO) arrangements have been developed for achieving diversity, multiplexing and/or beam-forming gains [1]. For example, while Bell Lab's Layered Space-Time (BLAST) scheme [2] was designed for high-rate transmission, the class of Space-Time Block Codes (STBCs) [3] was developed for achieving a beneficial diversity gain. Furthermore, in [4] Hassibi and Hochwald proposed the unified space-time concept of Linear Dispersion Codes (LDCs), which strikes a flexible tradeoff between the attainable diversity and multiplexing gains.