Even-Integer Interference Precoding for Broadcast Channels

In this paper, an improved precoding strategy for broadcast channels, i.e., the transmission from one central transmitter (e.g., base station) to a number of distributed receivers (e.g., mobile terminals), is presented. The new scheme is a generalization of Tomlinson-Harashima precoding applied to multiple-input/multiple-output (MIMO) channels and a translation of concepts from lattice-reduction-aided detection in MIMO communication systems to the broadcast scenario. The main idea is not to suppress the multi-user interference completely, but to shape them to values which solely contribute to the anyway present periodic extension of the signal set. Although the method is generally applicable, we concentrate on situations with 2 users and binary signaling per real dimension. Here, the interferences are allowed to be taken from the even integers, hence we call the new scheme “even-integer interference precoding”. Simulation results show that using the proposed technique, a considerable degree of diversity can be gained over linear preequalization, as well as conventional precoding.