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We introduce the problem of reoptimizing the network after a link failure has been repaired as an effective way for reducing capacity usage and improving network performance. Numerical results show gains higher than 42%.

Max-min fairness (MMF) is a general objective of multi-criteria optimization with important and natural applications in communication network design. The notion of MMF and optimization models involving MMF seem not to be commonly known to network designers and therefore they are not used to an extent they deserve. Moreover, the MMF approaches are sometimes “reinvented”, in some cases not correctly

In this paper we consider time-division-duplex (TDD) reciprocity calibration of a massive MIMO system. The calibration of a massive MIMO system can be done entirely at the base station (BS) side by sounding the BS antennas one-by-one while receiving with the other BS antennas. With an M antenna BS, this generates M(M - 1) signals that can be used for calibration purposes. In this paper we study se

In this paper, we propose a telco cloud meta-model that can be used to simulate different infrastructure con- figurations and explore their consequences on the system performance and costs. To achieve this, we analyse current telecommunication and data centre infrastructure paradigms, describe the architecture of the telco cloud and detail the benefits of merging both infrastructures in a unified

In 2001, a paper published in Nature by Andrews et al postulated the use of six co-located antennas, namely three electric and three magnetic dipoles, to achieve up to a six-fold capacity increase in wireless channels, relative to that of a single antenna. In other words, six degrees of freedom (DOFs) can be supported in a wireless channel with co-located six-port transmit and receive antenna arra

A new version of the stream cipher Grain-128 is proposed. The new version, Grain-128a, is strengthened against all known attacks and observations on the original Grain-128, and has built-in support for authentication. The changes are modest, keeping the basic structure of Grain-128. This gives a high confidence in Grain-128a and allows for easy updating of existing implementations.

This paper presents a directional analysis of the on-body propagation channels using the high resolution space alternating generalized expectation (SAGE) maximization algorithm. The analysis has been done on data obtained through FDTD simulations, on a male and a female numerical phantom. For estimating the angle of arrival (AoA) at a four element square array located at the chest, two different p

Popular Abstract in Swedish Projektioner om framtida klimat i Arktis och subarktis tyder på att drastiska förändrinar väntar regionen under det närmaste århundradet. Inte bara temperaturen spås öka utan även nederbörd, och då framför allt nederbörden under vinterhalvåret. Dessa förändringar kommer sannolikt att ha stor inverkan på miljön i Arktis och subarktis, och stora forksningsansträngningar hClimate projections indicate that Arctic and sub-Arctic regions are facing a significant change in climate during the 21st century. With warmer temperatures precipitation is also expected to increase, and in particular winter precipitation. These changes are likely to have large impacts on the Arctic and subarctic environment, and extensive research has focused on ecosystem-climate interactions in

Wireless communication using very-large multiple-input multiple-output (MIMO) antennas is a new research field, where base stations are equipped with a very large number of antennas as compared to previously considered systems. Unlike the conventional small and compact antenna arrays, the very-large arrays may span many wavelengths in space, thus they can experience large-scale fading over the arr

Abstract in UndeterminedIn this paper, the orthogonality of dual-polarized MIMO channels with Rician fading is investigated in a measured urban macrocellular scenario. Overall, efficient two-stream MIMO communication can be achieved as more than 70% of the measured route achieves better channel orthogonality than the average performance of the reference IID Rayleigh channel. Furthermore, the study

Interference between femto-cell systems is a critical factor for the deployment of such systems in, e.g., resedential areas. In this paper we report on a residential channel measurement campaign focusing on the channel properties for femtocell systems. We characterize basic channel properties such as delay spread and interference levels between different furnished residential houses. In addition w

The current family of 802.11 protocols are based on the Carrier Sense Multiple Access (CSMA) mechanism which is a simple and robust means of sharing a channel. However, two current trends in wireless networks point towards a situation where CSMA fails to perform better than pure random access solutions such as ALOHA. The first trend is the ever increasing raw data rate in each generation of 802.11

One of the latest additions in defining the test process is the upcoming ISO/IEC 29119 standard, which aims to define a universally applicable generic test process model. However, currently the standard does not offer any support for the adoption process of the model. In this paper, we present our framework, which aims to combine a maturity level-based approach with the standard process. Our objec