A wireless communication system includes a base station capable of communicating with a plurality of subscriber stations. The base station can transmit control information and data to a subscriber stations. The base station also can identify a set of RS patterns to be used to communicate with the subscriber station, assign a subset of antenna port numbers within the set of RS patterns to the subscriber stations. The base station can indicate the assigned states in a Downlink Control Information (DCI) format transmitted in a Physical Downlink Control Channel (PDCCH). The base station transmits the data using a subset of antenna ports corresponding to the subset of antenna port numbers. The base station also can map reference signals corresponding to the subset of antenna ports according to at least one RS pattern within the set of RS patterns.