Item movement is determined via wireless tracking using RFID data from at least one RFID reader. The RFID data associates RFID tag information with each antenna of the RFID reader that receives the tag information. At least one processer is configured to identify a first appearance of unique tag information in the RFID data. Items may be grouped when their first appearance in RFID data and their antenna association indicates that they first appear in a location within a predetermined amount of time, as indicated by RFID data, and/or when they have all moved from a previous location within a predetermined amount of time, as indicated by different RFID data. A group designation comprises the relevant unique tag information, which may be stored in memory along with a time stamp.