  We develop practical coding schemes for the cognitive overlay radios as
modeled by the cognitive interference channel, a variation of the classical two
user interference channel where one of the transmitters has knowledge of both
messages. Inspired by information theoretical results, we develop a coding
strategy for each of the three parameter regimes where capacity is known. A key
feature of the capacity achieving schemes in these regimes is the joint
decoding of both users' codewords, which we accomplish by performing a
posteriori probability calculation over a combined trellis. The schemes are
shown to perform close to the capacity limit with low error rate.
