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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.


Papers
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Proceedings ArticleDOI
24 Oct 2007
TL;DR: While current methods of gathering the interference map may be appropriate for characterizing interference in one card networks, they are unscalable for multiple card networks when considering: 802.11 characteristics (card and channel asymmetries, time variation), required downtime, and complexity of the measurement procedure.
Abstract: The interference map of an 802.11 network is a collection of data structures that can help heuristics for routing, channel assignment and call admission in dense wireless networks. The map can be obtained from detailed measurements, which are time consuming and require network down time. We explore methods and models to produce the interference map with a reduced number of measurements, by identifying interference properties that help to extrapolate complex measurements from simple measurements. Actual interference in an 802.11a testbed is shown to follow certain regularities - it is linear with respect to packet rate of the source, packet rate of the interferer, and shows independence among interferers. When multiple cards are available, they behave differently, and even different channels of the same card have different performance. We find that while current methods of gathering the interference map may be appropriate for characterizing interference in one card networks, they are unscalable for multiple card networks when considering: 802.11 characteristics (card and channel asymmetries, time variation), required downtime, and complexity of the measurement procedure.

122 citations

Proceedings ArticleDOI
01 Nov 2014
TL;DR: Numerical results show that the non-orthogonal system based on the proposed successive interference cancelation amenable multiple access (SAMA) paradigm employing the iterative MPA achieves significant performances gain over the orthogonal one for the same spectral efficiency with affordable complexity.
Abstract: In this work, we introduce a novel multiple access scheme which is based on the joint design of the system signature matrix at the transmitter and the successive interference cancelation (SIC) based detector at the receiver. The symbols of the different users are judiciously spread in the frequency (space) domain, which can be effectively exploited by the SIC based technique, such as the iterative message-passing algorithm (MPA), to cancel the multi-user interference as well as to obtain diversity gain. Numerical results show that the non-orthogonal system based on the proposed successive interference cancelation amenable multiple access (SAMA) paradigm employing the iterative MPA achieves significant performances gain over the orthogonal one for the same spectral efficiency with affordable complexity.

121 citations

Journal ArticleDOI
TL;DR: In this article, the authors show that the optimal transmit beamforming vector has a simple structure with very intuitive properties and interpretations and provide a theoretical foundation for practical low-complexity beamforming schemes.
Abstract: Transmit beamforming is a versatile technique for signal transmission from an array of $N$ antennas to one or multiple users [1]. In wireless communications, the goal is to increase the signal power at the intended user and reduce interference to non-intended users. A high signal power is achieved by transmitting the same data signal from all antennas, but with different amplitudes and phases, such that the signal components add coherently at the user. Low interference is accomplished by making the signal components add destructively at non-intended users. This corresponds mathematically to designing beamforming vectors (that describe the amplitudes and phases) to have large inner products with the vectors describing the intended channels and small inner products with non-intended user channels. While it is fairly easy to design a beamforming vector that maximizes the signal power at the intended user, it is difficult to strike a perfect balance between maximizing the signal power and minimizing the interference leakage. In fact, the optimization of multiuser transmit beamforming is generally a nondeterministic polynomial-time (NP) hard problem [2]. Nevertheless, this lecture shows that the optimal transmit beamforming has a simple structure with very intuitive properties and interpretations. This structure provides a theoretical foundation for practical low-complexity beamforming schemes. (See this lecture note for the complete abstract/introduction)

121 citations

Journal ArticleDOI
TL;DR: The proposed Fabry-Perot interferometer exhibits a wavelength shift of the interference fringes that corresponds to a temperature sensitivity of 249 pm/°C and a pressure sensitivity of 1130 pm/MPa, respectively, around the wavelength of 1560 nm.
Abstract: We investigated a novel and ultracompact polymer-capped Fabry-Perot interferometer, which is based on a polymer capped on the endface of a single mode fiber (SMF). The proposed Fabry-Perot interferometer has advantages of easy fabrication, low cost, and high sensitivity. The variation of the Fabry-Perot cavity length can be easily controlled by using the motors of a normal arc fusion splicer. Moreover, the enhanced mechanical strength of the Fabry-Perot interferometer makes it suitable for high sensitivity pressure and temperature sensing in harsh environments. The proposed interferometer exhibits a wavelength shift of the interference fringes that corresponds to a temperature sensitivity of 249 pm/°C and a pressure sensitivity of 1130 pm/MPa, respectively, around the wavelength of 1560 nm.

121 citations

Journal ArticleDOI
TL;DR: A semidefinite relaxation-based alternating optimization (SDRAO) solution is proposed to approach the optimal solution of the problem, and a closed-form solution is further developed relying on the transmitter-side zero-forcing (TZF), which can be implemented in a distributed manner, with the lowest computational complexity and CSI exchanging overhead.
Abstract: This paper investigates simultaneous wireless information and power transfer (SWIPT) in $K$ -user multiple-input multiple-output (MIMO) interference channels. In particular, the power splitting (PS) technique is leveraged at each receiver to divide the received signal into two flows, for information decoding (ID) and energy harvesting (EH), respectively. As a whole system, our objective is to minimize the total transmit power of all transmitters by jointly designing transmit beamformers, power splitters, and receive filters, subject to the signal-to-interference-plus-noise ratio (SINR) constraint for ID and the harvested power constraint for EH at each receiver. Due to the coupling nature of all variables, the formulated joint transceiver design problem is nonconvex, and has not yet been well addressed in the literature. In this paper, we first propose a semidefinite relaxation-based alternating optimization (SDRAO) solution to approach the optimal solution of the problem. Then, we semidecouple the joint optimization by the derived diversity interference alignment (DIA) technique, and obtain a solution of lower complexity. Finally, a closed-form solution is further developed relying on the transmitter-side zero-forcing (TZF), which can be implemented in a distributed manner, with the lowest computational complexity and CSI exchanging overhead.

121 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202213
2021840
20201,221
20191,432
20181,351
20171,311