The MME pool areas through which the mobile can move without a change of serving MME. Every MME pool area is controlled by one or more MMEs on the network.
The S-GW service areas served by one or more serving gateways S-GW, through which the mobile can move without a change of serving gateway.
The MME pool areas and the S-GW service areas are both made from smaller, non-overlapping units known as tracking areas (TAs). They are similar to the location and routing areas from UMTS and GSM and will be used to track the locations of mobiles that are on standby mode.