电子信息工程专业英语导论PART4unit13.ppt

PART 4 Communication Technology UNIT 13 Mobile Wireless communications New words and Technical Terms cell pattern cop handoff preassign blocking roam hybrid alphanumeric pager Nordic MTSO (mobile telephone switching office) FDMA (frequency-division multiple access) FCC (Federal Communications Commission) full-duplex over-the-air TDMA (time-division multiple access) CDMA (code-division multiple access) DCC (digital control channel) SMS (short message service) GSM (Global System for Mobile) PN (pseudo random) Text Mobile Communications Evolution During the 1970s, Bell Telephone Laboratories, which was then part of ATT Corporation developed the first wireless transmission system to provide service to mobile subscribers. That system consisted of three major components that continue to form the infrastructure for more modem mobile systems to this day. Those components include base stations, a Mobile Telephone Switching Office (MTSO)，and cellular phones. Although significant technological developments have occurred in the field of mobile wireless communications since the 1970s, the basic components of a cellular system retain the same infrastructural relationship. In addition, the basic concept behind cellular systems has remained the same. Basic Mobile Communications Infrastructure In a mobile communications environment，a geographic area is subdivided into cells that support operations on distinct frequencies. To prevent interference between cells, the first type of mobile wireless communications system，which is referred to as the Analog Mobile Phone System(AMPS)，employed a seven-cell pattern, as illustrated in Fig.4-1. The cell pattern shown in Fig.4-1 ensures that no adjacent cells operate on the same frequency. In actuality, each cell consists of a base station and an antenna that