Phase Shift Keying on the Hypersphere: Peak Power-Efficient MIMO Communications
This work addresses power efficiency challenges in MIMO systems for wireless communications, presenting an incremental improvement over conventional PSK methods.
The paper tackles the problem of improving power efficiency in MIMO communications by introducing Phase Shift Keying on the Hypersphere (PSKH), a generalization of PSK that distributes constellation points on a hypersphere to achieve a Peak-To-Average-Sum-Power-Ratio (PASPR) of 1, enabling high power efficiency with load-modulated transmitters.
Phase Shift Keying on the Hypersphere (PSKH), a generalization of conventional Phase Shift Keying (PSK) for Multiple-Input Multiple-Output (MIMO) systems, is introduced. In PSKH, constellation points are distributed on a multidimensional hypersphere. The use of such constellations with a Peak-To-Average-Sum-Power-Ratio (PASPR) of 1 allows to use load-modulated transmitters which can cope with a small backoff, which in turn results in a high power efficiency. In this paper, we discuss several methods how to generate PSKH constellations and compare their performance. After applying conventional Pulse-Amplitude Modulation (PAM), the PASPR of the continuous time PSKH signal depends on the choice of the pulse shaping method. This choice also influences bandwidth and power efficiency of a PSKH system. In order to reduce the PASPR of the continuous transmission signal, we use spherical interpolation to generate a smooth signal over the hypersphere and present corresponding receiver techniques. Additionally, complexity reduction techniques are proposed and compared. Finally, we discuss the methods presented in this paper regarding their trade-offs with respect to PASPR, bandwidth, power efficiency and receiver complexity.