Multicarrier communications based on cosine modulated filter banks.

摘要

This dissertation concerns analysis and application of a class of multicarrier communication systems that use cosine modulated filter banks for signal modulation. The earlier publications on the subject have used the terminology "discrete wavelet multitone (DWMT)" to refer to this class of communication systems.; The first contribution of this dissertation is an in-depth study of DWMT. It is shown that, even though the past literature on DWMT has adopted equalizers that require over 20 taps per subcarrier, the actual number of parameters that need adjustment is actually only two per subcarrier.; Making this observation, the receiver of DWMT was modified in a separate work which is not part of this dissertation to allow adoption of a two-parameter equalizer in each subcarrier channel. To distinguish the proposed receiver structure and the attached equalizer from DWMT and its far more complex equalizer, the terminology "cosine modulated multitone (CMT)" is used throughout the dissertation. The rest of the dissertation builds on CMT and performs a number of studies of it. (1) An efficient implementation of CMT receiver is presented. (2) The property of CMT allows development of a blind equalization algorithm. The convergence of the blind equalizer is analyzed. A modified adaptation algorithm that avoids slow convergence is also proposed. (3) Prototype filter design is an important issue in filter bank based multicarrier systems. In this dissertation, a near PR (NPR) prototype filter design scheme that strikes a balance between minimizing residual intersymbol interference (ISI) plus interchannel interference (ICI) and maximizing the stopband attenuation is proposed. (4) A thorough study of application of CMT to very high-speed digital subscriber line (VDSL) is presented. I compare CMT with zipper discrete multitone (z-DMT) and filtered multitone (FMT) modulation schemes. Comparisons are made in terms of computational complexity, transmission latency, achievable bit-rate and resistance to radio ingress noise. In terms of computational complexity, z-DMT is found superior to CMT and FMT. CMT, on the other hand, offers the highest bit rate and also the least transmission latency. Both CMT and FMT outperform z-DMT significantly when channel is subject to radio ingress noise.