Communications Blockset

Discrete Multitone Signaling Demo, Alternative Form

The model dmt_sim_alt illustrates an alternative way to model discrete multitone signaling. Because it uses fewer blocks, it loads and initializes more quickly. To see how the alternative version uses fewer blocks, compare the alternative DMT Modulator subsystem with the original DMT Modulator subsystem.

Original: 256 Modulator Blocks

In the original form, each of 16 Modulator Bank icons represents a set of 16 modulator blocks. The system has 256 modulator blocks in total. This arrangement closely resembles the definition of 256-channel DMT signaling.

Alternative: Ten Modulator Blocks

In the alternative form, ten modulator blocks implement the ten different signal constellations in this modulation scheme. The system sends selected bits to the modulator block that is appropriate for them. This approach deviates from the specified definition of frame-based signals, however, because a frame of bits that enters one of the modulator blocks is not a set of successive samples from a time series. If you use an approach like this in your own models, first be sure that you understand the possible implications. (Refer to the online documentation for the Communications Blockset for more information about the definition of frame-based signals.)

For more information about other aspects of dmt_sim_alt, see Discrete Multitone Signaling Demo and the original dmt_sim demo.

Selected Bibliography

[1]  Maxwell, Kim. "Asymmetric Digital Subscriber Line: Interim Technology for the Next Forty Years." IEEE Communications Magazine, October 1996. 100-106.

Discrete Multitone Signaling Demo

Iterative Decoding of a Serially Concatenated Convolutional Code (SCCC) - Demo