A wireless communication method and system for optimizing channel selection for an AP. A semiconductor device having a configuration that comprises a silicon substrate, a contact interlayer film, a first interconnect interlayer film, a first via interlayer film and a second interconnect interlayer film, all of which are sequentially formed in this order, comprises two protective diodes, which are coupled to a MOSFET via the second interconnect. If the cache memory contains data corresponding to one or more of the related addresses, a sequential workload may be occurring, and a read pre-fetch operation may be triggered. The encryption and decryption circuit is electrically connected to a portable storage device, receives the encryption and decryption command, reads the password stored in the storage element according to the encryption and decryption command, and encrypts or decrypts data stored in the portable storage device by utilizing the password according to whether the data have been encrypted. End electrodes are subsequently formed on the substrate in a manner connected to conductive portions of the discharge electrodes.