The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In this paper, we present a channel estimation method based on two-dimensional signal spreading applicable to orthogonal frequency multiple access multicarrier systems. Our method exploits a spreading of a transmitted data signal as well as a pilot signal over the assigned frequency range and time period. As a spreading sequence we exploited orthogonal Walsh–Hadamard sequences. When compared with...
This paper presents a study on the possibilities of dictionary implementation for a dictionary compression system in FPGA. The possibilities of creation of the dictionary using the registers and the RAM memory are described. For these implementations, the interdependence of hardware consumption and latency during basic dictionary processes like writing, reading and searching a match is described....
The paper presents the usage of global optimization methods for finding the suitable placement of transmitters and receivers of radar systems. The optimization criterion is maximum covered area. The following text describes using a genetic algorithm for placing elements of radar systems which have several transmitters and several receivers. The algorithm is searching for the optimum configuration...
This paper discusses indoor channel modeling for mobile communications. We apply multislope log-distance channel model and simulate indoor path loss distribution. The standard deviation value of normal and log-normal distribution describes various fading effects affecting the signal propagation. We defined the areal signal path loss distribution in a restricted indoor environment. The PSO-based process...
The paper deals with a new frame synchronization scheme for OFDM systems. The scheme is based on the computing of the detection window variance. The variance is computed in two delayed times, so a modified Early-Late loop is used for the frame position detection. The proposed algorithm has good properties regarding the choice of the algorithm's parameters since the parameters may be chosen within...
This paper describes methods which will be used in the separation of multiple secondary surveillance radar replies. Mainly the A/C mode is examined. The aim of this research is to examine several methods to apply correlation of signal with template to isolate transponder reply. Thoughts are to use a differentiation of signal to better the correlation response and avoid false reception.
In the paper, a synthesizable combinational integer number divider VHDL model is described that is suitable for implementation in the FPGA devices. The algorithm the divider is based on is briefly introduced. Along the model, testbench for its functional verification is presented. Results of implementation in Xilinx Spartan-3 and Spartan-6 devices — amount of FPGA resources used and maximum delay,...
This paper analyzes the crash factor (CF) for multicarrier code division multiple access (MC-CDMA) communication system. The CF (or peak to average power ratio - PAPR) is critical in multicarrier orthogonal systems (based on orthogonal frequency division multiplex - OFDM). The amplitude statistics for system are computed and gamma distribution is considered for amplitude distribution modeling. The...
This paper deals with issues related with implementation of Variable Spreading Factor Orthogonal Frequency and Code Division Multiplexing (VSF-OFCDM) systems using Universal Software Radio Peripheral (USRP). Comparison of simulated and with USRP hardware achieved results of VSF-OFCDM systems with various 2D spreading factors (SF) are being done. Simulation of complete communication chain is being...
This paper describes a new PAPR (peak to average power ratio) reduction approach in MC-CDMA (multicarrier code division multiple access) system (in so called M-modification). The spreading sequence introduces coherence among subcarriers. This is used for chip position formatting to PAPR minimization. The optimizations methods are used to get best chip interleaving sequence (namely genetic algorithm...
A lot of methods for peak to average power ratio (PAPR) reduction of OFDM signals have been proposed over the last few years. One of the main drawbacks of many of them is their complexity. In this paper, a new technique for reducing complexity of method based on Adaptive symbol selection principle is proposed and evaluated using simulation
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.