The shallow water channel is an environment that is of particular interest to many research fields. An underwater acoustic channel is characterized as a multipath channel. Time-varying multipath propagation is one of the major factors that limit the acoustic communication performance in shallow water. This study conducts two underwater acoustic experiments in Tanjung Balau, Johor, Malaysia. A t...

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...

This paper presents a semi-blind algorithm for multiuser interference cancellation and fading amplitude estimation for downlink MIMO DS-CDMA systems with multipath fading channels. Taking advantage of the space-time information of the parametric multipath channel, the proposed algorithm first uses a space-time channel decoupler to suppress multiuser interference and then decomposes the channel ...

Multipath channels often exhibit sparse structures in multicarrier underwater acoustic (MC-UWA) communication systems. Conventional linear channel estimators, such as least squares (LS) and minimum mean square error (MMSE) are considered as optimal solutions under the assumption of rich multipath. However, they often result in low spectral efficiency due to neglect of the sparsity in multipath ...

We study the performance of a UMTS downlink, as achieved by a single-user (RAKE) and a multiuser (linear MMSE) receiver with adaptive modulation and multicode in the presence of multipath fading. We advocate an adaptive transmission scheme that varies the number of virtual users and the modulation spectral efficiency in order to optimize the system throughput. Two multipath channel models are c...

When transmitting a known signal over a multipath channel, the received waveform is a stochastic process due to the random nature of the multipath arrival times and gains. Any program aimed at linear estimation of the random waveform requires its correlation function. Explicit formulas are given for this correlation function when the multipath arrival times and gains are described by the recent...

Time delay estimation arises in many applications in which a multipath medium has to be identified from pulses transmitted through the channel. Various approaches have been proposed in the literature to identify time delays introduced by multipath environments. However, these methods either operate on the analog received signal, or require high sampling rates in order to achieve reasonable time...

In the mobile radio environment, signals are usually impaired by fading and multipath delay phenomenon. This work modeled and simulates OFDM in a wireless environment, it also illustrates adaptive modulation and coding over a dispersive multipath fading channel whereby simulation varies the result dynamically. Dynamic approach entails adopting probabilistic approach to determining channel alloc...

This dissertation is concerned with the propagation of ultrawideband (UWB) electromagnetic impulses in complex multipath environments. In the first part the distortion of a UWB signal as it propagates through frequency selective materials is examined. The potential degree of distortion is investigated through experimental measurements, then the effect of that distortion on UWB communication and...

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...