One or more quality indicators are established at a first communication device having antenna elements. The quality indicators indicate a quality of one or more communication links between the first communication device and one or more second communication devices. A modification is determined according to the quality indicators, where the modification describes at least one adjustment of one or more modulation features. A time boundary indicator indicating a boundary of a time period is received. At least some of a set of signals are modulated in accordance with the modification and in response to the time boundary indicator, where a signal is associated with an antenna element. The set of signals is sent from the antenna elements to yield a transmitted signal.