Abstract: Techniques for improved margin control in a data communication system are disclosed. In one aspect, margin is adjusted in response to a first subpacket error rate. In another aspect, margin is further adjusted in response to an overall packet error rate. In yet another aspect, the first subpacket error rate is adjusted in response to an overall packet error rate. Various other aspects are also presented. These aspects have the benefit of responsive margin control when the overall packet error rate is relatively low, resulting in improved data throughput and increased system capacity.