Citation
Abstract
Motivated by previous work of Li and Rimoldi for obtaining bandwidth-e–cient trellis-coded modulation (TCM) signals with finite decoding delay, we present an alternative representation for their encoder/signal-mapper transmitter structure that consists of merely a single filter (with complex impulse response) having an input equal to the (+1,¡1) equivalent of the (0,1) input data bits in their implementation. The filter impulse response is of duration (”+1)=T (” is the memory of the modb ulation, T is the bit time, and ”T is the decoding delay) and can be constructed b b by designing its ”+1 bit time partitions in terms of the waveform difierences that characterize the finite decoding delay conditions found by Li and Rimoldi. The advantage of this simpler transmitter structure is that it readily allows computation of the modulation’s power spectral density, from which one can determine the conditions that must be imposed on the signal design to produce an equivalent lowpass power spectral density. This in turn allows for a straightforward procedure for designing the optimum signals to produce maximum bandwidth e–ciency as measured by fractional out-of-band power. Such optimum signal designs are determined for memory-one and memory-two modulations and are presented as examples of the application of the general results.
Keywords
Details
- Volume
- 42-145
- Published
- May 15, 2001
- Pages
- 1–30
- File Size
- 516.9 KB