in this paper the problem of minimizing the total transmitting power subject to a fixedtotal bit rate in ofdm systems is considered. upper bounds on transmitting power and bit rate ofeach subcarrier can also be taken into account. in practice, the number of bits of each subcarriershould be integer and nonnegative. in this paper an analytical optimal solution is derived for thecase of assuming t...

This paper describes discrete multi-tone (DMT) line coding, which has become the standard asymmetric digital subscriber line (ADSL) modulation technique as selected by the American National Standards Institute (ANSI) T1E1 committee. Presented here is an overview of DMT ADSL including quadrature amplitude modulation (QAM) encoding, rate-adaptation, bitswapping as well as some of the overall adva...

Multicarrier modulation techniques have been proposed in the digital subscriber line (DSL) applications. In this paper, the performance of DMT (OFDM) and DWMT (DSBMT) techniques for single and multitone interference are investigated. It is shown that a DMT system is sensitive to the location of narrow band interference. DMT technique needs additional narrow band interference canceller before fo...

In recent history there has been an enormous development in the subject area of Power Line Communications (PLC), since it has become possible due to advanced digital communications and digital signal processing techniques to use power lines for data transmission. PLC allows the use of the dynamic and far-reaching power cables to support high speed communication capabilities. Discrete Multi-tone...

The Discrete Multi Tone (DMT) modulation is considered a viable technique for high-speed digital transmission over subscriber loop. It was selected as the standard for ADSL modems and it is also a strong candidate in the VDSL area. This paper investigates a programmable solution for the DMT based VDSL modems using Texas Instrument processor family TMS320C62xx. A structure for both transmitter a...

This paper presents the development of the physical layer for a Power Line Communications (PLC) system based on Discrete Multi-Tone (DMT) modulation. Simulation is migrated towards a real system by means of emulation. An introduction is given, followed by an overview of the proposed system. The methodology adopted is then discussed and a more detailed explanation of DMT is presented. Some simul...

In this paper, we experimentally demonstrate a 450-nm laser underwater optical wireless transmission system, in which comprehensive investigation is made to show the significant performance improvement of discrete Fourier transform spread multi-tone (DFT-S DMT) as compared conventional quadrature amplitude modulation (QAM-DMT) modulation. DFT-S DMT outperforms QAM-DMT terms bit error rate (BER)...

| Multi-tone modulation (DMT, Discrete Multitone, OFDM, Orthogonal Frequency Division Multiplex) has the disadvantage of a quite high peak-toaverage ratio. Clipping of the high amplitudes caused by the analog circuitry leads to additional noise. In this contribution we show that in principal so-called Analog Codes (Reed-Solomon Codes over complex numbers) can be used for eliminating this noise.

This paper presents a new algorithm for distributing bits to the subchannels of a DMT modem. The so-called Inverse Robin Hood algorithm converges rapidly and can effectively optimise the overall bit error rate in a non-Gaussian channel. Key-words: Discrete multi-tone modulation, adaptive bit-loading, DSL modems, non-Gaussian channels.

| Multi-tone modulation (DMT, Discrete Multitone, OFDM, Orthogonal Frequency Division Multiplex) has the disadvantage of a quite high peak-toaverage ratio. Clipping of the high amplitudes caused by the analog circuitry leads to additional noise. In this contribution we show that in principal, so-called Analog Codes (Reed-Solomon Codes over complex numbers) can be used for eliminating this noise.