Wireless communications is one of the most active areas of research over the past and the current decades. In fact, the demand for wireless services has been changing from the regular voice telephony services to mixed voice, data, and multimedia services over the wireless media. Since the mid-1990s, the wireless industry has been advancing at an incredible speed. For example, the 2G cellular systems (such as GSM, D-AMPS, and IS-95) have significantly improved the spectral efficiency and network capacity to support wireless telephony services
