  The cognitive interference channel with unidirectional destination
cooperation (CIFC-UDC) is a variant of the cognitive interference channel
(CIFC) where the cognitive (secondary) destination not only decodes the
information sent from its sending dual but also helps enhance the communication
of the primary user. This channel is an extension of the original CIFC to
achieve a win-win solution under the coexistence condition. The CIFC-UDC
comprises a broadcast channel (BC), a relay channel (RC), as well as a
partially cooperative relay broadcast channel (PCRBC), and can be degraded to
any one of them. In this paper, we propose a new achievable rate region for the
dis-crete memoryless CIFC-UDC which improves the previous re-sults and includes
the largest known rate regions of the BC, the RC, the PCRBC and the CIFC. A new
outer bound is presented and proved to be tight for two classes of the
CIFC-UDCs, result-ing in the characterization of the capacity region.
