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We consider a wireless sensor network that uses inductive near-field coupling for wireless powering or communication, or for both. The severely limited range of an inductively coupled source-destination pair can be improved using resonant relay devices, which are purely passive in nature. Utilization of such magneto-inductive relays has only been studied for regular network topologies, allowing simplified...
Magneto-inductive (MI) systems for wireless communications or power transfer usually suffer from coil mis-alignment, because of mobility or deployment. The impact on performance is hard to analyze because mutual inductance is an involved function of geometry. We focus on links whose coil separation exceeds coil dimensions, which is characteristic for communications links and becoming increasingly...
In this paper, we propose to serve the mobile stations in an urban traffic hotspot by combining user cooperation with traffic offloading to the vast amount of residential WLAN access points. Different to existing virtual MIMO approaches, we include local users, which are assigned to the access points and compete for the physical resources. Furthermore, all signal processing shall be done on the mobile...
Concepts like the internet of things (IOT) and heterogeneous networks would allow large communication node densities. In such scenarios, the communication system performance is usually interference limited. Classical methods for interference management are either inefficient with regards to spectral efficiency or consume much power. However, in such scenarios nodes may be very near to each other in...
Wireless physical layers based on inductive coupling are receiving attention in the context of RFID and, more recently, sensor networks. In this work we present the first method for localization in inductively coupled networks which only requires a single anchor. The utilization of passive relays with known positions resolves the associated problem of localization ambiguity. We demonstrate that a...
We study wireless ultra wideband (UWB) sensor networks operating in the environment of marine engines for telemetry purposes. In the harsh propagation environment posed by the engine room, UWB enables robust communication without the need for complex sensor node implementations. For this work, we therefore present the first UWB channel measurements performed around, on, and inside a marine diesel...
For a network consisting of inductively coupled nodes, we experimentally demonstrate circuit-based localization of a passive and chipless agent device. By using measurements of the input reflection at multiple anchor nodes, we reconstruct the unknown position of an agent node in a coplanar arrangement for both random and optimized anchor arrangements. A key step for applying this localization scheme...
In this paper we present a novel way of jointly estimating the coupling matrix of closely spaced receive antennas as well as the spatial channel of compact MIMO systems. Unlike conventional approaches, we do not assume any knowledge of the types and geometries of the antennas, or their separations, or having line of sight spatial channels. Our algorithm is based only on changing the load impedances...
In this paper, we propose and investigate a self-calibration method which estimates the locations and clock offsets of the anchors based on TOA measurements. The agent locations are not surveyed and hence they can be realized by a single moving agent, which makes the calibration procedure simple and cost effective. Instead of considering a specific clock synchronization scenario, which was the case...
Future MIMO terminals are expected to be equipped with a higher number of antennas. A possible intermediary solution between using the optimal but complex SIC decoder and the simple but poor performing MMSE decoder, is to consider different group decoders, namely, group SIC (GSIC) and group parallel decoding (GPD). The performances of such decoders strongly depend on the grouping strategy. In this...
We consider the downlink of a "post-cellular" network in which base stations (BSs) are no longer evenly spread in the entire area of service but rather placed where they can easily be installed. Accordingly, the BSs are not necessarily close to the users anymore but have to serve distant mobiles with aggressive spatial multiplexing, possibly with the help of additional low-complexity relays...
In this paper we jointly consider the normally distinct worlds of communication system design and circuit theory. We introduce the — up to our knowledge — first algorithm to optimize the uncoupled matching network (UC-MN) at a receiver that uses a linear MMSE equalizer in a MU-MIMO system with compact antenna array at the receiver. We design our adaptive UC-MN in order to either maximize the minimum...
With the two conflicting demands of increasing the number of antennas in terminals and decreasing the devices sizes, considering compact MIMO systems became inevitable. Such systems suffer from both antenna coupling and noise correlation. This has led to the observation that the impedance matching network fundamentally affects the performance of such MIMO enabled communications systems. In this paper...
In this paper we propose a decentralized target rate precoding for multi-user multiple-input multiple-output downlink setups. It is well suited for joint transmission and works for arbitrary cooperation sets. The precoding is optimized for each link separately with respect to the transmit and leakage power. This allows to control the interference into the network and to design the precoding flexibly...
In this paper, we address the problem of sensor network localization based on Time-of-Arrival (TOA) measurements under the presence of anchor location errors. We consider the practically appealing setup where the agents are low-complexity transmit-only nodes whose clocks' are not synchronized with that of the anchors. The maximum likelihood (ML) solution of the localization problem is formulated and...
In this paper, we study the interdependency between leakage reduction and transmit power control for rate maximization in leakage based precoding (LBP) for a multi user multiple-input multiple-output (MU-MIMO) scenario. We propose a LBP scheme which provides the rate optimal precoding for each MIMO link under a joint leakage and transmit power constraint and derive an iterative closed form solution...
We consider a cellular network in which the base stations (BSs) are supported by a large amount of very low-complexity relays that are spread over the entire area, like a carpet. This carpet of relays enables massive antenna arrays and sophisticated multi-user MIMO transmission at the BSs, as they see only the static relays as the nodes they communicate with. On the other hand, the communication via...
We consider the problem of locating a sensor in a network of nodes which use inductive coupling as means of interaction. Conventional approaches in this setting require the located node to have a power supply or complex circuitry. By analysis of the circuit model underlying inductive coupling, we develop a localization method which allows for passive nodes with a simple layout. The proposed method...
Compact arrays are known to be associated with antenna coupling and noise correlation. The noise can be either antenna noise, LNA noise or downstream noise. Due to these effects, it was shown that the matching network affects the performance of MIMO systems with coupled receiver antennas. Since the optimal multiport matching network is of very high complexity as well as very narrow operation bandwidth,...
We consider the up- as well as downlink of a cellular network in which base stations (BSs) are supported by a large amount of relays spread over the entire area like a carpet. The BSs only see the static relays as the nodes they communicate with, which enables large antenna arrays at the BSs with sophisticated multi-user MIMO transmission. Together with a simple form of BS cooperation, the communication...
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