Block diagonalization with algebraic interference control, extension to precoding on OFDMA chunks

Block diagonalization is a linear precoding technique which allows to suppress multi-user interference at the transmitter side. However, the interference cancellation comes at the cost of reduced number of degrees of freedom for users. We present in this contribution a new block diagonalization extension that increases the number of degrees of freedom for a subset of preferred terminals using an algebraic parameter. We show how this extension can be used in resource allocation in order to provide a better rate for high priority users without increasing the transmit power. With this scheme, the new algebraic parameter is used in addition to the transmit power in order to provide different priorities to the served users. Also, we investigate two low complexity approaches to exploit block diagonalization techniques in OFDMA scenarios by calculating one precoder for a chunk of sub-carriers. We compare these two methods in terms of sum capacity and sensitivity to the new parameter.