Near-Field MIMO Communication Links

Abstract

A procedure to achieve near-field multiple input multiple output (MIMO) communication with equally strong channels is demonstrated in this paper. This has applications in near-field wireless communications, such as Chip-to-Chip (C2C) communication or wireless links between printed circuit boards. Designing the architecture of these wireless C2C networks is, however, based on standard engineering design tools. To attain this goal, a network optimization procedure is proposed, which introduces decoupling and matching networks. As a demonstration, this optimization procedure is applied to a 2-by-2 MIMO with dipole antennas. The potential benefits and design tradeoffs are discussed for implementation of wireless radio-frequency interconnects in chip-to-chip or device-to-device communication such as in an Internet-of-Things scenario.

Linear angular momentum multiplexing—conceptualization and experimental evaluation with antenna arrays

“…This would be further exacerbated as the radius of the array increases with narrow beams. Also, as found in [ 30 ], when the transmit and receive circular arrays are separated close to, or nearer than the Rayleigh distance based on their diameters, then the transmit and receive elements can readily couple to each other and the fundamental capacity limit is nearly reached similar to a scenario of near-field MIMO [ 28 ]. Therefore, either with directive element beams or coupling in the near field, all available OAM modes are fully exploited.…”

“…In this way, for the special case of the vehicular geometries considered, LAM multiplexing achieves similar capacity enhancements to OAM multiplexing, but does so using low-profile antenna elements and overall array dimensions that are consistent with application to the ground to rail, hyperloop or vehicle links as examples [ 27 ]. It is worthy of noting that LAM multiplexing may be thought of as like that of near-field MIMO [ 28 ], which is rather designed for static links in the near field.…”

Theory of Nonsinusoidal Small Antennas with Applications to Near-Field Communication System Analysis and Design

“…It can be inferred from (27) that when the forward gain F (ω) is very small, the inverse filter gain may become very large, leading to instability. Other considerations include the possibility that by striving to satisfy (26), the inverse filter may become noncausal. For these reasons, in practice digital equalizers like Zero-Forcing (ZF) and MMSE equalizers are often used to remove the channel effect [51,52].…”

“…The recent interest in electromagnetic near fields has pushed researchers to investigate alternative theoretical [21-23, 23, 24], experimental [21,25,26], and computational [21,[27][28][29][30][31] tools capable of realizing and demonstrating new dimensions and devices in engineering electromagnetics, and hence the motivation behind this work aiming at reexamining the usual views on antennas by exploiting the subtle but often neglected relation between space and time in radiation problems. In this paper, we follow Harmuth's suggestion to work with nonsinusoidal antennas completely in the time domain, avoiding as much as possible using frequency-domain concepts.…”

Theory of Nonsinusoidal Small Antennas for Near-Field Communication System Analysis

“…The recent interest in electromagnetic near fields has pushed researchers to investigate alternative theoretical [20][21][22][23], experimental [20,24,25], and computational [20,[26][27][28][29][30] tools capable of realizing and demonstrating new dimensions and devices in engineering electromagnetics, and hence the motivation behind this work aiming at reexamining the usual views on antennas by exploiting the subtle but often neglected relation between space and time in radiation problems. In this paper, we follow Harmuth's suggestion to work with nonsinusoidal antennas completely in the time domain, avoiding using frequency-domain concepts as much as possible.…”