Decreasing transistor sizes and lower voltage swings cause two distinct problems for
communication in integrated circuits. First, decreasing inter-wire spacing increases
interline capacitive coupling, which adversely affects transmission energy and delay.
Second, lower voltage swings render the transmission susceptible to various noise
sources. Coding can be used to address both these problems. So-called crosstalk-avoidance
codes mitigate capacitive coupling, and traditional error-correction codes introduce
resilience against channel errors.
Unfortunately, crosstalk-avoidance and error-correction codes cannot be combined in
a straightforward manner. On the one hand, crosstalk-avoidance encoding followed by
error-correction encoding destroys the crosstalk-avoidance property. On the other
hand, error-correction encoding followed by crosstalk-avoidance encoding causes the
crosstalk-avoidance decoder to fail in the presence of errors. Existing approaches
circumvent this difficulty by using additional bus wires to protect the parities generated
from the output of the error-correction encoder, and are therefore inefficient.
In this work we propose a novel joint crosstalk-avoidance and error-correction coding
and decoding scheme that provides higher bus transmission rates compared to existing
approaches. Our joint approach carefully embeds the parities such that the crosstalk-avoidance
property is preserved. We analyze the rate and minimum distance of the proposed scheme.
We also provide a density evolution analysis and predict iterative decoding thresholds
for reliable communication under random bus erasures. This density evolution analysis
is nonstandard, since the crosstalk-avoidance constraints are inherently nonlinear.