A communication device of the present invention includes channel compensations, an adaptive processor, a MAC and a controller. The first channel layer is composed of In1-xGaxAs and has an energy level of conduction band lower than that of the electron-supplying layer at the interface. Additionally, various techniques can be used to remove or reduce the functionality limitations of the computer . A switch on the housing is used to electrically connect the battery to the vibrator. Semiconductor module mount-surfaces 30B1, 30B2, 30C1, 30C2 are arranged in the first main surface 30B and the second main surface 30C in a zigzag pattern in cross-sectional view; and the semiconductor modules 20 are mounted onto some or all of the semiconductor module mount-surfaces 30B1, 30B2, 30C1, 30C2. The methods are simpler and more cost-effective.