Programmable metasurface‐based RF chain‐free 8PSK wireless transmitter

Abstract

In this Letter, a wireless transmitter using the new architecture of programmable metasurface is presented. The proposed transmitter does not require any filter, nor wideband mixer or wideband power amplifier, thereby making it a promising hardware architecture for cost-effective wireless communications systems in the future. Using experimental results, the authors demonstrate that a programmable metasurface-based 8-phase shift-keying (8PSK) transmitter with 8 × 32 phase adjustable unit cells can achieve 6.144 Mbps data rate over the air at 4.25 GHz with a comparable bit error rate performance as the conventional approach without channel coding, but with less hardware complexity. Introduction:The fifth-generation wireless communication will soon be delivering the needed ultra-high data rates, for which massive multiple-input multiple-output (MIMO) antennas and millimetre-wave (mm-wave) are the two key technologies. However, the need for large number of high-performance RF chains means that there is an increase in the hardware complexity, leading to high cost and power consumption [1]. Although solutions such as analogue beamforming [2] and hybrid beamforming [3] have been developed in the literature, to reduce the number of RF chains, they do not fundamentally eliminate the hardware constraints. It is therefore of great significance to develop a more flexible hardware architecture for future wireless communications.On the other hand, recent advances in programmable metasurfaces have attracted much attention due to their superior capability in controlling the amplitude or phase of electromagnetic waves in real time [4]. Manipulation of reflected or transmitted electromagnetic waves can be achieved by electrically changing the reflection or transmission coefficient distributions on the metasurfaces [5], effectively realising modulation of electromagnetic waves, which has appeal in applications of wireless communications. However, using metasurface in wireless communication is still in its infancy. A recent study, in [6] where a metasurface-based binary frequency shift-keying transmitter was presented, in which the two signal frequencies representing '0' and '1' respectively were synthesised directly via a programmable metasurface. However, only a low data rate of 78.125 kbps was reported.In this Letter, we take advantage of a programmable metasurface that achieves 360°phase response coverage of reflected electromagnetic wave to develop a novel metasurface-based 8-phase shift-keying (8PSK) transmitter. The experimental results validate its feasibility by observing the demodulated constellation diagrams and measuring the bit error rate (BER) performance with an extraordinary 6.144 Mbps data rate over the air.

Wireless Communications with Programmable Metasurface: New Paradigms, Opportunities, and Challenges on Transceiver Design

“…Meanwhile, such an RF chain-free paradigm requires only one narrow band PA to manage the transmit power of the air-fed carrier signal without the need for mixers and filters, regardless of how many channels are used [12]. This thus greatly reduces the hardware complexity and implementation cost as compared with the conventional architecture in Fig.…”

Direct Antenna Modulation for High-Order Phase Shift Keying

“…By using four FSS layers rather than three, this work has increased the modulation order achievable from QPSK to 8-PSK. Compared with other DAM approaches, as shown in Table IV, this is equivalent to the modulation orders achieved by [27] and an advance over [20]. However, this comes at the cost of a greater physical depth than all the other approaches, reaching 1.71λ.…”

“…However, this comes at the cost of a greater physical depth than all the other approaches, reaching 1.71λ. This is still much smaller than the largest dimension of [27], which uses a metasurface of 5.44×1.36×0.07λ 3 . It should also be noted that [27] requires a plane wave feed to the metasurface, which is not included in the dimensions given here.…”

“…This is still much smaller than the largest dimension of [27], which uses a metasurface of 5.44×1.36×0.07λ 3 . It should also be noted that [27] requires a plane wave feed to the metasurface, which is not included in the dimensions given here. The solution in [20] is the most compact, at nearly a quarter of the aperture area of the DAM unit in this paper.…”

“…There is the suggestion that this could allow high rate modulation at millimetre wave and terahertz transmit frequencies. More recently, an electrically large reflective metasurface loaded with varactor diodes has been shown to produce order 8 phase shift keying (PSK) modulation when illuminated by a plane wave [27].…”