In Wireless Communications, Diversity means the ability to receive radio signal from two or more antennas.
Many smart antennas are used to offer diversity, that greatly improves reception of radio signals. Such smart antennas are used in mobile phones, Differential GPS modules, IEEE802.11x WLAN routers, Bluetooth 2.0 ERIP etc.
in wireless communication systems which use multiple antenna we can use the Benefit of the multiple paths from the transmitter to the receiver and combining it in time of frequency to enhance the recieved signal.
Transmitting the replica of the signal is called diversity. It is common for wireless systems to employ both diversity techniques and channel coding for error detection and/or correction.