time of reception of a packet addressed to another station and the like the packet analysis unit 112 analyzes the packet signal which can be received from another station in the present embodiment the packet is composed of a first decoding portion and a second decoding portion the details of a packet decoding method will be described later the information storage unit 113 stores an execution procedure instruction of a series of access control operations to be executed by the central control unit 103 and information obtained from an analysis result of a reception packet as described above in a wireless network of the present embodiment there are two kinds of communication stations of conventional stations capable of the transmission and the reception of a packet modulated according to some limited modulation systems and high grade communication stations capable of the reception in conformity with a high grade system in addition to the modulation systems in which the conventional stations can perform receptions there is a coexistence problem in a communication system in which the ieee 802 11g and the ieee 802 11b using the same band intermix the present embodiment solves this problem by making the high grade communication stations provide the so called ad hoc compatibility to the conventional stations the details of the solution will.