Finite-cardinality single-RF differential space-time modulation for improving the diversity-throughput tradeoff

Abstract

The matrix-based differential encoding invoked by Differential Space-Time Modulation (DSTM) typically results in an infinite-cardinality of arbitrary signals, despite the fact that the Transmit Antennas (TAs) can only radiate a limited number of patterns. As a remedy, the recently developed Differential Spatial Modulation (DSM) is capable of avoiding this problem by conceiving a beneficial sparse signal matrix design, which also facilitates low-complexity single-RF signal transmission. Inspired by this development, the Differential Space-Time Block Code using Index Shift Keying (DSTBC-ISK) further introduces a beneficial diverstiy gain without compromising the DSM's appealingly low transceiver complexity. However, the DSTBC-ISK's performance advantage tends to diminish as the throughput increases, especially when an increased number of Receive Antennas (RAs) is used. By contrast, the classic Differential Group Code (DGC) that actively maximizes its diversity gain for different Multiple-Input Multiple-Output (MIMO) system setups is capable of achieving a superior performance, but its detection complexity grows exponentially with the throughtput. Against this background, we propose the Differential Space-Time Shift Keying using Diagonal Algebraic Space-Time (DSTSK-DAST) scheme, which is the first DSTM that is capable of achieving the DGC's superior diversity gain at high throughputs without compromising the DSM's low transceiver complexity. As a further advance, we also conceive a new Differential Space-Time Shift Keying using Threaded Algebraic Space-Time (DSTSK-TAST) arrangement, which is capable of achieving an even further improved diversity gain at a substantially reduced signal detection complexity compared to the best DGCs. Furthermore, in order to strike a practical tradeoff, we develop a generic multi-element and multi-level-ring Amplitude Phase Shift Keying (APSK) design, and we also arrange for multiple reduced-size DSTM sub-blocks to be transmitted in a permuted manner, which exhibits an improved diversity-throughput tradeoff.

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Identifiers

ORCID for Chao Xu: orcid.org/0000-0002-8423-0342

ORCID for Rakshith Mysore Rajashekar: orcid.org/0000-0002-7688-7539

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

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