  The transmitter optimization (i.e., steering vectors and power allocation)
for a MISO Broadcast Channel (MISO-BC) subject to general linear constraints is
considered. Such constraints include, as special cases, the sum power, the
per-antenna or per-group-of-antennas power, and "forbidden interference
direction" constraints. We consider both the optimal dirty-paper coding and the
simple suboptimal linear zero-forcing beamforming strategies, and provide
numerically efficient algorithms that solve the problem in its most general
form. As an application, we consider a multi-cell scenario with partial cell
cooperation, where each cell optimizes its precoder by taking into account
interference constraints on specific users in adjacent cells. The effectiveness
of the proposed methods is evaluated in a simple system scenario including two
adjacent cells, under different fairness criteria that emphasize the bottleneck
role of users near the cell "boundary". Our results show that "active"
Inter-Cell Interference (ICI) mitigation outperforms the conventional "static"
ICI mitigation based on fractional frequency reuse.
