Fibre now being installed directly to subscribers. The area covered by a mobile-phone network is divided into cells, each of which contains a base station. When a mobile-phone user makes a call, he or she sends signals to the nearest base station. The radio-frequency band is shared by a multiple access scheme. A channel is divided into 8 time slots and uses binary modulation.
Frequency division is used between neighbouring base stations limiting channel interference.
Designed for 25-year lifetime. Transmit InGaAsP laser, 5mW output, can be modulated up to 2GHz. Detector InGaAs PIN photodiodes. Undersea networks now under construction will operate at 5 Gbps. These will use EDFAs.