Random Access Protocols with Collision Resolution in a Noncoherent Setting

Wireless systems are increasingly used for Machine-Type Communication (MTC), where the users sporadically send very short messages. In such a setting, the overhead imposed by channel estimation is substantial, thereby demanding noncoherent communication. In this paper we consider a noncoherent setup in which users randomly access the medium to send short messages to a common receiver. We propose a transmission scheme based on Gabor frames, where each user has a dedicated codebook of M possible codewords, while the codebook simultaneously serves as an ID for the user. The scheme is used as a basis for a simple protocol for collision resolution.Comment: 5 pages, 3 figures; EDIT: A version of this work has been submitted for publication in the IEEE Wireless Communication Letters Journa

Random Access in C-RAN for User Activity Detection with Limited-Capacity Fronthaul

Cloud-Radio Access Network (C-RAN) is characterized by a hierarchical structure in which the baseband processing functionalities of remote radio heads (RRHs) are implemented by means of cloud computing at a Central Unit (CU). A key limitation of C-RANs is given by the capacity constraints of the fronthaul links connecting RRHs to the CU. In this letter, the impact of this architectural constraint is investigated for the fundamental functions of random access and active User Equipment (UE) identification in the presence of a potentially massive number of UEs. In particular, the standard C-RAN approach based on quantize-and-forward and centralized detection is compared to a scheme based on an alternative CU-RRH functional split that enables local detection. Both techniques leverage Bayesian sparse detection. Numerical results illustrate the relative merits of the two schemes as a function of the system parameters.Comment: 6 pages, 3 figures, under revision in IEEE Signal Processing Letter

Non-coherent and semi-coherent schemes for physical-layer wireless network coding

We investigate non-coherent and semi-coherent schemes for physical-layer network coding in two-way relaying scenarios. We distinguish between scenarios without any channel knowledge requirements (non-coherent communication) and scenarios when either the relay or the users have receive channel knowledge (semi-coherent communication). We combine the paradigm of subspace-based communication originally developed for non-coherent point-to-point channels, with two-way relaying schemes based on physical-layer wireless network coding with denoise-and-forward (DNF). The aim is to demonstrate that denoising can be performed non-coherently and to investigate if these schemes offer an improvement over the schemes based on amplify-and-forward (AF)

DNA MICROSATELLITE INFORMATIVENESS, ALLELE FREQUENCIES AND THEIR DISTRIBUTION IN THE GENOME OF MACEDONIAN AUTOCHTHONOUS SHEEP POPULATIONS

As a result of natural selection, management system, environment pressure, different populations of Pramenka sheep in South East Europe developed distinctive productive and phenotype characteristics which are sufficient to distinguish them. In this study, the informativeness of fifteen DNA microsatellite markers in the genome of 105 individuals from three indigenous sheep populations in the country (Sharplaninian, Karakachanian and Ovchepolian) was analysed. In overall population, 281 different alleles were observed. The average number of alleles per locus in total population was 18.73, the mean He in overall population was 0.824, so all loci were highly polymorphic with PIC value higher than 0.5. Mean number of alleles per locus, at population level, were 12.13, 11.53 and 13.27 alleles in the genome of Sharplaninian, Ovchepolian and Karakachanian sheep populations, respectively. Results from this research will improve knowledge of the sheep genetic resources in the country at DNA level and will provide appropriate information for further conservation

Multicriteria model for application of underground gasification in coal deposites in Macedonia

With the increasing need for energy, both in quantitative and qualitative terms increasingly demands that natural energy raw materials are used techno - economically and in environmentally optimal way. This should be especially popular in our country does not have sufficient and structurally favorable supplies of energy raw materials. In this paper the aim is to introduce and implement new unconventional method of coal exploitation in order to minimize the emission of harmful gases. Specifically it comes to underground gasification of coal which is still a new and developing technology

USEFULNESS OF A LOCUS LEEF1Aa IN THE GENETIC DIFFERENTIATION OF TOMATO VARIETIES

The molecular techniques provide new possibilities to characterize advanced genetic materials for registration purposes and for the protection of breeders’ rights. The microsatellites appear as suitable molecular markers due to their highly polymorphic character. Such microsatellites may generate polymorphism useful for the analysis of genetic diversity and relationships within the genus Lycopersicon. The focus of the following study was usefulness of the locus LEEF1Aa in the genetic differentiation among six morphologically different tomato varieties of Lycopersicon esculentum Mill. The fragment analyses were done using Applied Biosystems DNA analyzer (ABI 3130) and GeneMapper®Software program. The obtained data were analyzed using the specific program Power Marker Software. The number of detected alleles for the microsatellites locus LEEF1Aa was six in estimated tomato varieties (219-221-223-225-227-229bp). The allele with the length of 229 bp was noticed only in Lycopersicon esculentum subsp. cultum var. grandifolium, while the alleles (221, 225 and 227 bp) in 4 varieties, the allele of 219 bp in 3 varieties and the allele of 223 bp in 2 varieties. The average PIC value for the locus LEEF1Aa was 0.7552 and it belongs to the group of high informative markers. Obtained results showed that the locus LEEF1Aais good choice for genetic differentiation of tomato varieties in combination with other polymorphic microsatellite loci

Defining the sliding plane in micro plan on rocky massif using geoelectrical method

The paper presents data from geoelectrical measurements of micro locations where there is a sliding rock mass. These studies have been conducted on location mountain Plackovica in the Eastern Macedonian zone. The observations were performed with an interval of two years. Method geoelectrical sounding was conducted. Measurements are performed multiple times on the same profile, in order to define the sliding plane, depending on the weather. From the data obtained from geoelectrical sounding it can be concluded that the specific electrical resistance of the rock masses decreases at a time of increased amount of rainfall. During dry periods of the year occur relatively high values of the specific resistance, especially in the surface layer. This phenomenon is normal to expect. The analysis of the specific electrical resistance in the investigated profile clearly indicates that the plane of the sliding rock masses characterized by reduced specific resistance in relation to the surrounding rock mass, especially in extremely wet weather. In these conditions comes to the intense activation of the process of sliding rock masses. The results obtained are consistent with the basic theoretical assumptions, i.e. the zone with increased amounts of water has a lower value of the intensity of the specific electrical resistance, although it is the same type of geological environment. The results of these studies indicate that geoelectrical methods can provide useful information when investigating the sliding plane in rock mass