A system for mobile communication includes a mobile communication device that has a first plurality of antennas and a transmitter. The transmitter, in response to a requested bandwidth for a first packet not being greater than a bandwidth of a first transmit mode, is configured to encode and transmit the first packet from the first plurality of antennas. The first packet has a single-carrier frequency-division-multiple-access (SC-FDMA) modulation of the first transmit mode. In response to a requested bandwidth for a second packet being greater than the bandwidth of the first transmit mode, the transmitter is configured to encode and transmit the second packet from the first antennas. The second packet has a multiple-in-multiple-out orthogonal-frequency-division-multiplexing (MIMO-OFDM) modulation of a second transmit mode. A base station includes a second plurality of antennas and is configured to receive and decode the first packet and the second packet.