Implementation Complexity and Communication Performance Tradeoffs in Discrete Multitone Modulation Equalizers
IEEE Transactions on Signal Processing
Several high-speed wireline and wireless communication standards modulate encoded data on multiple carrier frequencies using the inverse Fourier transform (FFT). The real part of the quantized inverse FFT samples form a symbol. The symbol is periodically extended by prepending a copy of its last few samples, a.k.a. a cyclic prefix. When the cyclic prefix is longer than the channel order, amplitude and phase distortion can be equalized entirely in the frequency domain. Prior to the FFT, a
... o the FFT, a time-domain equalizer, in the form of a finite impulse response filter, shortens the effective channel impulse response. Alternately, a bank of equalizers tuned to each carrier frequency can be used. In earlier work, we unified optimal multicarrier equalizer design algorithms as a product of generalized Rayleigh quotients. In this paper, we convert the unified theoretical framework into a framework for fast design algorithms. The relevant literature is reviewed and classified according to this framework. We analyze the achieved bit rate vs. implementation complexity tradeoffs in the original and fast design algorithms. The comparison includes multiple implementations of each of 16 different equalizer structures and design algorithms using synthetic and measured discrete multitone modulated data.