Orthogonal frequency division multiplexing (OFDM) provides an effective and low complexity means of eliminating intersymbol interference for transmission over frequency selective fading channels. In this paper investigation and comparison of various efficient pilot based channel estimation schemes for OFDM systems has been done. The channel estimation can be performed by either inserting pilot ...

This paper presents an analysis on the capacity and performance of MIMO-OFDM systems. The work is focused on the capacity of MIMO-OFDM systems over rician fading channel, in the case of the channel being known at the receiver only, which is more practical case of the channel. Simple expression for capacity is derived for the case of correlated rician fading. The performance of some MIMO-OFDM im...

In this paper, we address the problem of OFDM transmission over a time-varying, frequency-selective channel with high Doppler spread. This creates situations where the channel significantly evolves over the time span of one OFDM symbol. We analyze the CP-OFDM transmission mechanism, and the impairments due to the channel variations, using a decomposition of these variations over a base of sinus...

The capacity of OFDM systems can be achieved by channel estimation and adaptive transmission at each subcarrier. Therefore channel estimation techniques play a key role in the design of OFDM systems. In this paper, we propose a method to analyze and evaluate the performance of various channel estimation techniques. Using the developed optimization model, we can tune various parameters of channe...

The aim of this paper is to share novel paradigm of channel estimation for orthogonal frequency division multiplexing (OFDM) systems. OFDM is used to improve spectral efficiency and spatial diversity in wireless communications systems. This paper provides a review of channel estimation techniques (blind and pilot-aided) and its performance on data-aided channel. After comparison with known tech...

CogWave is a free and open-source software platform aiming at developing cognitive radio waveforms. Combining CogWave with USRP gives a rapid prototyping platform for physical layer design and algorithm validation through a realtime video, audio and text transmission. This paper presents the cognitive blind orthogonal frequency division multiplexing (OFDM) waveform implemented in the CogWave so...

MIMO-OFDM technology joins together the focal point of MIMO and OFDM and is generally utilized as a part of high information rate frameworks. Conventional channel estimation of MIMO-OFDM experiences a high cost of huge number of pilots. Channel estimation is discriminating to collector execution in the long term evolution (LTE) system. Reference signs are scattered with information indicators a...

OFDM has been proven to be a viable technique to overcome multipath fading in wireless channels. While OFDM systems convert a multipath fading channel into a series of equivalent flat fading channels they lack the inherent diversity available in multipath channels. Theoretically an uncoded OFDM system needs a simple receiver due to ISI free channel, but their performance deteriorates in the pre...

Recently time-frequency interferometry (TFI)OFDM has been proposed as a channel identification scheme. TFI-OFDM system can multiplex the same impulse response in twice on the time domain without overlapping to each other. In this case, the required pilot signal is only one. Moreover, by averaging of these impulse responses, the accurated channel impulse responses are obtained. However, if the t...

Orthogonal frequency division multiplexing (OFDM) provides an effective and low complexity means of eliminating intersymbol interference for transmission over frequency selective fading channels. This technique has received a lot of interest in mobile communication research as the radio channel is usually frequency selective and time variant. In OFDM system, modulation may be coherent or differ...