A dirty paper coding scheme for multiuser MIMO cognitive radio channel

In this paper, we propose a dirty paper coding (DPC) scheme for the cognitive radio channel where multiple cognitive users coexist with a primary user. The cognitive transmitter is assumed to know the primary signals non-causally and is equipped with two antennas, of which each transmits to a single-antenna receiver. In our proposal, zero-forcing DPC is employed to cancel the interference not only from the primary user but also from other cognitive users. The transmit power constraint is satisfied by the application of the multiuser trellis shaping. The optimal values of the power allocation parameter and the scaling factor are derived. The performance of this scheme is compared using simulations with that employing conventional trellis shaping.