836 research outputs found
Performance Analysis of PCFICH and PDCCH LTE Control Channels
Control channels play a key role in the evaluation of mobile system performance. The purpose of our paper is to evaluate the performance of the control channels implementation in the Long Term Evolution (LTE) system. The paper deals with the simulation of the complete signal processing chain for Physical Control Format Indicator Channel (PCFICH) and Physical Downlink Control Channel (PDCCH) in the LTE system, Release 8. We implemented a complete signal processing chain for downlink control channels as an extension of the existing MATLAB LTE downlink simulator. The paper presents results of PCFICH and PDCCH control channel computer performance analysis in various channel conditions. The results can be compared with the performance of data channels
The Laboratory of Wireless and Mobile Communications
The paper presents the basic information about establishing of the laboratory for Mobile Communications on the Dept. of Radio Electronics, Brno University of Technology. This information allows to experts from the practice to obtain the general notion about the extent of theoretical knowledge and practical experiences of our students in this field. This information can be also useful for the specialists from universities comparing simple their pedagogical activity in this field respecting the activity in another institute
Comparison of Fuzzy Logic and Genetic Algorithm Based Admission Control Strategies for UMTS System
CDMA systems have so-called soft capacity, so the total number of possible sessions has not an exact value. The capacity of CDMA system depends on the interference level in the system. There are therefore RRM (Radio Resources Management) functions, which are responsible for supplying optimum coverage, ensuring efficient use of physical resources and providing the maximum planned capacity. This paper presents and compares several algorithms that are used for admission control purposes in UMTS system. Several versions of fuzzy logic based algorithms, load factor based algorithm and genetic based algorithm are mutually compared via simulations
Enhanced Receivers for Interference Cancellation in 3G Systems
Interference cancellation and multiuser detection in CDMA systems are still actual research topics. These techniques enable us to deal with interference and to increase system capacity. In this paper, a so-called Generalized RAKE receiver, an Uplink generalized multiuser detection and a Blind adaptive multiuser detection are described. These algorithms are compared with conventional receivers and their properties are verified via simulations. The results imply that some of these algorithms are able to overcome the performance of the conventional receivers
Bluetooth and IEEE 802.11b/g Coexistence Simulation
This paper deals with the coexistence simulation of Bluetooth and Wi-Fi physical layers. Bluetooth and Wi-Fi systems share the same ISM 2.4 GHz frequency band and therefore using both systems in the same area may cause interference. A model of Bluetooth and IEEE 802.11b/g physical layers was made in Mathworks Matlab Simulink environment. A new simulation of Bluetooth and Wi-Fi coexistence is presented. The results in graphical form are introduced as a dependence of BER on Eb/N0 and BER on power ratio of Bluetooth and Wi-Fi systems
UMTS Network Model for Interference Analysis - Optimization of Spreading Codes Order
This article deals with mathematical modeling of UMTS network. The presented model is designed for interference analysis in this network. The paper presents the set of simulations based on an idea of a specific order of Walsh codes. In the first part the mathematical model is presented. This model is designed for Matlab and is based on 3GPP specifications. The second part describes the method of specific ordering of Walsh spreading codes. The specific order can decrease the interference level in the radio network of UMTS which is caused by multipath propagation. The simulation results are presented, too
Algorithms for Fast Computing of the 3D-DCT Transform
The algorithm for video compression based on the Three-Dimensional Discrete Cosine Transform (3D-DCT) is presented. The original algorithm of the 3D-DCT has high time complexity. We propose several enhancements to the original algorithm and make the calculation of the DCT algorithm feasible for future real-time video compression
An analytical and experimental study of heat transfer in a simulated Martian atmosphere Final report, 1 Nov. 1968 - 15 Oct. 1969
Convective heat transfer in simulated Martian atmospher
Combining Static and Dynamic Contract Checking for Curry
Static type systems are usually not sufficient to express all requirements on
function calls. Hence, contracts with pre- and postconditions can be used to
express more complex constraints on operations. Contracts can be checked at run
time to ensure that operations are only invoked with reasonable arguments and
return intended results. Although such dynamic contract checking provides more
reliable program execution, it requires execution time and could lead to
program crashes that might be detected with more advanced methods at compile
time. To improve this situation for declarative languages, we present an
approach to combine static and dynamic contract checking for the functional
logic language Curry. Based on a formal model of contract checking for
functional logic programming, we propose an automatic method to verify
contracts at compile time. If a contract is successfully verified, dynamic
checking of it can be omitted. This method decreases execution time without
degrading reliable program execution. In the best case, when all contracts are
statically verified, it provides trust in the software since crashes due to
contract violations cannot occur during program execution.Comment: Pre-proceedings paper presented at the 27th International Symposium
on Logic-Based Program Synthesis and Transformation (LOPSTR 2017), Namur,
Belgium, 10-12 October 2017 (arXiv:1708.07854
Near-infrared observations of active asteroid (3200) Phaethon reveal no evidence for hydration
Asteroid (3200) Phaethon is an active near-Earth asteroid and the parent body
of the Geminid Meteor Shower. Because of its small perihelion distance,
Phaethon's surface reaches temperatures sufficient to destabilize hydrated
materials. We conducted rotationally resolved spectroscopic observations of
this asteroid, mostly covering the northern hemisphere and the equatorial
region, beyond 2.5-micron to search for evidence of hydration on its surface.
Here we show that the observed part of Phaethon does not exhibit the 3-micron
hydrated mineral absorption (within 2-sigma). These observations suggest that
Phaethon's modern activity is not due to volatile sublimation or
devolatilization of phyllosilicates on its surface. It is possible that the
observed part of Phaethon was originally hydrated and has since lost volatiles
from its surface via dehydration, supporting its connection to the Pallas
family, or it was formed from anhydrous material
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