ABSTRACT
Cellular communications systems have been developed and commercialized since the advent of the advanced mobile phone system (AMPS), whose initial commercial deployments date back to 1981 but existed in the lab for nearly two decades prior. AMPS are a primarily analog transmission system, using frequency-division multiple access as its underlying networking solution. These early analog cellular communications systems are also known as “first generation.” Code Division Multiple Access (CDMA) 2000 came about as a response to the International Telecommunications Union's International Mobile Telecommunications-2000 effort for developing global third-generation wireless services. CDMA 2000 is backward compatible, which ensures that second-generation products could be easily evolved to meet third-generation requirements. Like cdma2000, Wideband CDMA is defined with respect to protocol layering. Digital cellular communications was a great advancement, in the 1980s many researchers started to examine CDMA as a method to increase capacity given the limited bandwidth available for transmission.
