With mobile analog and TDMA cellular communications, as with WLANs, there is a scheme for transferring a moving user from one cell to an adjacent cell, when the signal in the current cell becomes too weak. This process is known as a handoff. The actual procedure used for a handoff varies, but is similar among the different cellular technologies. At any moment, each mobile device is located in one specific cell or cell sector and under the control of the base station of that cell, as shown in Figure . When a device leaves a cell, the base station notices the signal fading away and asks all the surrounding base stations how much power they are getting from the signal. The base station then transfers ownership to the cell receiving the strongest signal. The device is informed of the new base station, and if a call is in progress, it is instructed to switch to a new channel or frequency. This handoff process takes about 300 msec. Actual channel assignment is done by the MTSO, since the base stations are really just radio relays. The devices involved in this handoff are said to be roaming.

The handoff to an adjacent cell occurs on a channel of a different frequency to reduce the possibility of interference. This type of handoff is called a hard handoff and can take place between different cell sites or different sectors of one cell site.

In mobile CDMA cellular communications, the moving user can be connected to multiple cells at one time, adding and dropping connections as required as the mobile moves about the coverage area of the system. Each cell is typically operating on the same channel but using different spread spectrum codes, and handoffs between cells on the same channel are called soft handoffs. Handoffs between different sectors of a cell are called softer handoffs. If a CDMA handoff involves different channels or bands, it is a hard handoff. In a soft or softer handoff process, there is no time delay as the new connection is added before the old one is lost.

The handoff to an adjacent cell occurs on a channel of a different frequency to reduce the possibility of interference.