| 摘要 |
PROBLEM TO BE SOLVED: To provide a dynamic secure group mobile communication system that effectively utilizes a radio frequency so as to enhance the information concealment effect thereby reducing the communication quantity in the group mobile communication using a plurality of radio frequency zones. SOLUTION: When a terminal B in a group (a) shown in Figure 1 (a) moves from a radio zone I to a radio zone II and reaches a state shown in Figure 1 (b), the terminal B informs a base station that the terminal B moves to the radio zone II. The base station changes the group key of the terminal B into a group key of a group (b) in order to assign the terminal B to the group (b) in the radio zone II. The terminal B reaches a state shown in Figure 1 (c), grouping bridging over the radio zones is eliminated, the frequency can effectively be utilized, the concealing effect of information by the grouping cannot be deteriorated and the communication quantity between the radio zones is not increased.
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