Orthogonal Frequency Division Multiplexing (OFDM) systems are commonly used to mitigate frequency-selective multipath fading and provide high-speed data transmission. In this paper, we derive new union bounds on the error probability of a coded OFDM system in wireless environments. In particular, we consider convolutionally coded OFDM systems employing single and multiple transmit antennas over...

At wideband frequencies the channel impairments are more severe since the coherent bandwidth of the transmitted signal is smaller than that of the channel. As the characteristic of the channel is found to be time varying, the mitigation methods are too fragile against such impairments like fading, attenuation, noise, etc. So it is mandatory that the methods to be used in broadband systems to co...

The water-filling algorithm enables an energy-efficient OFDM-based transmitter by maximizing the capacity of a frequency selective fading channel. However, this optimal strategy requires the perfect channel state information at the transmitter that is not realistic in wireless applications. In this paper, we propose opportunistic error correction to maximize the data rate of OFDM systems withou...

Abstract MC-CDMA, a multicarrier modulation scheme based on code division multiple access (CDMA) is the most likely candidate for the next generation of mobile radio communications. Rate compatible punctured turbo coded hybrid ARQ (RCPT HARQ) has been found to give improved throughput performance in a DS-CDMA system. In this paper, we apply RCPT HARQ to an MC-CDMA system and evaluate by compute...

We propose a subband spreading technique to average a frequency selective fading channel which produces different signal-to-noise ratios (SNR) per subcarrier in orthogonal frequency division multiplexing (OFDM) systems. Data symbols are spread over a subband using orthogonal codes and transmitted. Each subband is composed of a group of subcarriers. Received symbols in a subband have the same re...

Transmit antenna diversity has been exploited recently to develop high-performance space–time coders and simple maximum-likelihood decoders for transmissions over flat fading channels. Relying on block precoding, this paper develops generalized space–time coded multicarrier transceivers appropriate for wireless propagation over frequency-selective multipath channels. Multicarrier precoding maps...

This paper presents an iterative bit and power allocation algorithm for OFDM Multiple-Input Multiple-Output (MIMO) system in frequency selective fading channels and uses V-BLAST as a detection algorithm. Assuming knowledge of the instantaneous channel gains for all spatial channels at all the subcarriers in the receiver, bit and power is assigned to each spatial channel to minimize the total tr...