Overlapped discrete multitone modulation for high speed copper wire communications

Abstract

| Multicarrier modulation possesses several properties which make it an attractive approach for high speed copper wire communications networks. Among these properties are the ability to e ciently access and distribute multiplexed data streams, and a reduced susceptibility to impulsive, as well as to narrowband channel disturbances. In digital implementations of multicarrier modulation, subcarrier generation and data modulation are accomplished digitally using orthogonal transformations of data blocks. These implementations are particularly e cient with regard to bandwidth utilization and transceiver complexity. In this paper, we present a form of digital multicarrier modulation which we refer to as overlapped discrete multitone, or discrete wavelet multitone (DWMT), modulation. For DWMT modulation, which is based on the application of M-band wavelet lters, the pulses for di erent data blocks overlap in time, and are designed to achieve a combination of subchannel spectral containment and bandwidth e ciency that is fundamentally better than with other forms of multicarrier modulation. We show that, as a result of the spectral containment feature, DWMT gives a high level of robustness with regard to noise environments and channel variations that are encountered in practice.

Cosine Modulated Multitone for Very High-speed Digital Subscriber Lines

“…We note that the CMT scheme that was proposed in this paper is nothing but an amended version of DWMT, a modulated scheme which has been known for a decade [22]. However, because of its relatively high computational complexity, which was a consequence of inappropriate selection of the receiver structure, DWMT was never accepted by the industry.…”

“…At this point, we shall make some comments about DWMT and clarify the difference between the proposed receiver and that of the DWMT [22]. In DWMT, the analyzed sub-carrier signals that are passed to the post-combiner equalizers are the outputs of F a k (z) filters, i.e., 2 {u k (n)}.…”

“…Equalizers are thus used to combat the channel distortion. As noted above, post-combiner equalizers that span across the adjacent sub-bands and along the time axis were originally proposed for this purpose [22]. Such equalizers are rather complex -typically, 20 or more taps per sub-carrier are used.…”

“…Moreover, the use of filter banks for realization of transmultiplexer systems [28] as well as their application to MCM [22] have been recognized by many researchers. In particular, the use of CMFB to multi-carrier data transmission in DSL channels has been widely addressed in the literature, under the common terminology of discrete wavelet multitone (DWMT), e.g., [20]- [27].…”

SIR-optimized DFT-bank transceivers for multipath fading channels

“…In particular, the filter bank approach [2] [3] [4] has drawn many attentions recently. In [2], the authors propose the so-called discrete wavelet multitone (DWMT) system, in which perfect reconstruction (PR) filter bank is used as the transceiver. For multipath channels, there is intraband as well as cross-band interference in these transceivers.…”