A Handoff, or Handover, is the process in which a cellular phone is handed from one cell to the next in order to maintain a radio connection with the network. The variables that dictate a handover depend on the type of cellular system. In CDMA (Code Division Multiple Access) based systems interference requirements are the limiting factor for handover. In FDMA (Frequency Division Multiple Access) and TDMA (Time Division Multiple Access) systems such as GSM the main limiting factor is the signal quality available to the MS (Mobile Station). Other factors include distance TA (Timing Advance), loading, and received power levels.