Interference (wave propagation)

About: Interference (wave propagation) is a research topic. Over the lifetime, 26086 publications have been published within this topic receiving 321110 citations.

On the feasibility of full-duplex relaying in the presence of loop interference

Abstract: We consider a two-hop infrastructure-based relay link with three transmit power allocation methods. Both amplify-and-forward and decode-and-forward protocols are studied. Fundamentally, a relay can operate either in a full-duplex or in a half-duplex mode. The performance in full-duplex relaying is degraded due to loop interference from the relay output to the relay input. On the other hand, the half-duplex mode eliminates the loop interference, but this reduces the end-to-end rate. In this paper, we study the feasibility of the full-duplex mode in terms of end-to-end capacity. In particular, we evaluate break-even loop interference levels, below which the full-duplex mode outperforms the half-duplex mode. The analysis shows that the full-duplex mode is feasible in the presence of reasonably high loop interference power and can offer higher capacity than the half-duplex mode.

Entanglement of two quantum memories via fibers over dozens of kilometres

Abstract: Quantum internet will enable a number of revolutionary applications. It relies on entanglement of remote quantum memories over long distances. Despite enormous progresses so far, the maximal physical separation achieved between two nodes is 1.3 km, and challenges for long distance remain. Here we make a significant step forward by entangling two atomic ensembles in one lab via photon transmission through metropolitan-scale fibers. We use cavity enhancement to create bright atom-photon entanglement, and harness quantum frequency conversion to shift the atomic wavelength to telecom. We realize entanglement over 22 km field-deployed fibers via two-photon interference, and entanglement over 50 km coiled fibers via single-photon interference. Our experiment can be extended to physically separated nodes with similar distance as a functional segment for atomic quantum networks, thus paving the way towards establishing atomic entanglement over many nodes and over much longer distance.

A robust interference model for wireless ad-hoc networks

Abstract: Among the foremost goals of topology control in wireless ad-hoc networks is interference reduction. This paper presents a receiver-centric interference model featuring two main advantages over previous work. First, it reflects the fact that interference occurs at the intended receiver of a message. Second, the presented interference measure is robust with respect to addition or removal of single network nodes. Regarding both of these aspects our model intuitively corresponds to the behavior of interference in reality. Based on this interference model, we show that currently known topology control algorithms poorly reduce interference. Motivated by the observation that already one-dimensional network instances display the intricacy of the considered problem, we continue to focus on the so-called highway model. Setting out to analyze the special case of the exponential node chain, we eventually describe an algorithm guaranteeing to achieve a /spl I.nroot//spl Delta/-approximation (where n=4) of the optimal connectivity-preserving topology in the general highway model.

Interference Alignment on the Deterministic Channel and Application to Fully Connected Gaussian Interference Networks

Abstract: An interference alignment example is constructed for the deterministic channel model of the K-user interference channel. The deterministic channel example is then translated into the Gaussian setting, creating the first known example of a fully connected Gaussian K-user interference network with single antenna nodes, real, nonzero and constant channel coefficients, and no propagation delays where the degrees of freedom outerbound is achieved. An analogy is drawn between the propagation delay based interference alignment examples and the deterministic channel model which also allows similar constructions for the two-user X channel as well.