. . . "BRIEF DESCRIPTION OF THE DRAWINGS [0031] The above objects and other features of the present invention will become more apparent by describing in detail a preferred embodiment thereof with reference to the attached drawings, in which: [0032]FIG. 1 is a view showing a protocol stack used in a Bluetooth group ad-hoc network; [0033]FIG. 2 is a view schematically showing a protocol stack of a Bluetoot" .