AbstractsEngineering

The multicarrier communication is studied. Two special forms -OFDM multicarrier communication and wavelet-packet based multicarrier communication are presented. Multicarrier communication is the principle of transmitting data by divid ing the stream into several parallel bit streams, each of which has a much lower bit rate, and by using these sub-streams to modulate several carriers. It tends to be more robust against time domain impulse interference due to long symbol time. However, the sub-carriers may lose their mutual orthogonality if rapid time-variations frequency error of the channel occurs. OFDM multicarrier communication has densely spaced sub-carriers and overlapping spectra. Its time-domain waveforms are chosen such that mutual orthogonality is ensured even though sub-carrier spectra may overlap. OFDM with raised cosine filter multicarrier communication use steep bandpass filters that completely separate the spectrum of individual sub-carriers. Wavelet-packet based multicarrier communication employs wavelet-packets to be the pulse-shaping filters for sub-channels. The spectra overlap both in frequency-domain and in time-domain but their discrimination at the receiving end is guaranteed due to the orthogonality of the wavelets-packet functions. The system models of the two forms are proposed, analytical probabilities of error with frequency dispersion and AWGN are given, and the results of simulation are presented.