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Orthogonal frequency division Multiplexing (OFDM) is a popular method for high data-rate wireless transmission. It converts a frequency selective channel into a set of parallel flat fading sub-channels, which makes the receiver simpler. Thereby, the bandwidth of the sub-carriers becomes small compared with the coherence bandwidth of the channel, wh...
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Citations
... In other words OFDM converts a frequency selective channel into a set of parallel flat fading sub channels, which makes the receiver simpler. Thereby, the bandwidth of the sub-carriers becomes small compared with the coherence bandwidth of the channel, which allows simple equalization [6]. In this paper an algorithm was simulated & the result was plotted as water filling algorithm which assigns more power to sub channels which experience good condition and may assign no power to bad conditioned sub channels. ...
A mobile radio channel is characterized by a multipath fading environment. Due to reception of multiple copies of transmitted signal ISI results. OFDM technology promises to be a key technique for achieving the high data capacity and spectral efficiency requirements for wireless communication systems. The purpose of this paper is to use a Mat-lab simulation of OFDM to see how the Bit Error Ratio (BER) of a transmission varies when M-PSK and M-QAM modulation scheme is used in different channel. Further depending upon the carrier to noise ratio of dm transmitter allocates different power to strong and weak channels using water-filling algorithm.
... A new ultra wide band antenna is proposed by the authors for UWB applications in [15]. Modern UWB systems use other modulation techniques, such as Orthogonal Frequency Division Multiplexing (OFDM)1617, to occupy these extremely wide bandwidths. In addition, the use of multiple bands in combination with OFDM modulation can provide significant advantages to traditional UWB systems. ...
Ultra-Wideband (UWB) has the potential to become a viable and competitive wireless technology for short-range high rate Wireless personal area networks (WPANs) as well as lower-rate and low power causing low cost devices and networks. This paper discusses properties of Gaussian pulses and derivatives thereof used for UWB signalling. The power spectral density(PSD) of signals sent into channel appear as discrete components resembling spikes with amplitudes that could adversely interfere with established communication systems. In this, mathematical model for the analysis of PSD in the channel is introduced. PSD for Time Hopping UWB (TH-UWB) signals using PPM (Pulse Position Modulation) technique is derived and simulated in the MATLAB 7.0 environment. Results show that TH-UWB PPM is a potential candidate for the fourth generation broadband wireless networks. Finally, it is established that the introduction of randomness into transmitted signal has the effect of decreasing the amount of interference power.
The article presents the results of measurements and simulations of intrasystem compatibility of the wireless networks operated in accordance with technical documentation IEEE 802.11g and IEEE 802.11n. Simulations were carried out using an advanced model of the MIMO-OFDM system. The simulations have been preceded by measurements in the anechoic chamber. The results of these measurements were used to define the input parameters of the simulator. The results of analyzes confirmed the usefulness of presented MIMO-OFDM system simulator to performance prediction of the wireless networks in the absence and presence of interference from other networks.
