The performance of multiuser systems employing coded continuousphase modulation (CPM) in frequency-division multiplexed (FDM) uplink satellite communications is investigated. The spectral efficiency is improved reducing the inter-carrier frequency spacing. Since severe inter-channel interference (ICI) occurs in such cases, a simple iterative ICI cancellation algorithm is applied in conjunction with a bank of single-user (SU) receivers to perform demodulation and decoding. When modulation and coding parameters are suitably chosen, such a receiver achieves a performance close to the non-interfering multiuser case. ICI causes further degradation since the SU receivers are not perfectly matched to the received signal model. Moreover, the SU receivers require a perfect knowledge of the channel state information (CSI) in order to perform optimal demodulation in additive white Gaussian noise. To reduce the degradation caused by ICI, a new heuristic method for estimating the optimal CSI values to provide to the SU receiver is proposed. The proposed method is based on an approximation of the CSI vector provided to each SU receiver. Such a method proves useful since it leads to significant performance improvements of the considered schemes and exhibits a negligible complexity.Introduction: Multiuser continuous-phase-modulation (CPM) systems wherein all carriers share a portion of spectrum have been recently studied [1 -5]. These studies show that multiuser CPM modulations, when used in FDM schemes with tight inter-carrier frequency spacing, achieve a high spectral efficiency (SE). However, optimal multiuser receivers for such schemes exhibit significantly high complexity [2][3][4]. In a previous contribution [6], the authors developed a lowcomplexity iterative method for inter-carrier interference (ICI) cancellation and used it in the design of adaptive multiuser FDM-CPM systems achieving a high spectral efficiency. In [6] it was shown that it is possible to obtain a significant improvement of the SE thanks to a simple iterative ICI cancellation technique applied at the receiver. Moreover, the complexity of the resulting receiver is slightly increased by the ICI canceller. In fact, it only grows linearly with the number of users.In this Letter, we show how to improve the performance of the receiver algorithm used in [6]. The issue of finding suitable values for the CSI vectors to be provided to the receiver during iterations is faced using a heuristic approach. A parametric exponential function is employed: optimal parameter values are found through extensive simulations, and the CSI vector elements are obtained sampling such a function. A multiuser FDM system with tight inter-carrier frequency spacing like in [6] is considered. In this Letter, we assess the performance of three coded CPM schemes with full response modulation and rectangular (REC) frequency pulse shape (see Table 1). In the studied system these modulation schemes are employed as the inner components of a coded modulation scheme consisting of an outer convo...

Research on canvases and wooden supports used by Caravagesques based on paintings in Polish collections.The research on Caravagesques paintings' grounds was conducted as part of an exploratory project: Technique and technology of caravaggisti paintings based on polish museum collections. The project was financed by National Science Centre (2013/09/N/ HS2/02116, PRELUDIUM V) and it is a subject of doctoral thesis carried out under prof. Jerzy Nowosielski's guidance.The new aesthetics emerging from the style of Michealangelo Merisi, popularly known as Caravaggio, started a trend of imitating the rules of luminism, new forms and themes among artistic communities of Italy, Spain, the Netherlands, Germany and France. The artists adopted Caravaggio's technique rules although some local Badania podobrazi malarskich caravaggionistów... MATEUSZ JASIŃSKI, JERZY NOWOSIELSKI