China
Africa
Explore chapters and articles related to this topic
Speech and Channel Coding for North American TDMA Cellular Systems
Published in Jerry D. Gibson, The Communications Handbook, 2018
mobile telephone service (AMPS), which uses analog frequency modulation for speech transmission and frequency shift keying for signalling. The two directions of transmission use frequencies some 45 MHz apart in the band between 824 and 894 MHz. AMPS employs one channel per conversation in each direction, a technique known as frequency division multiple access (FDMA). IS-54 employs time division multiple access (TDMA) by allowing three, and in the future six, simultaneous transmissions to share each frequency band. Because the overall 30-kHz channelization of the allocated 25 MHz of spectrum in each direction is retained, it is also known as a FDMA-TDMA system. In contrast, the later IS-95 standard employs code division multiple access (CDMA) over bands of 1.23 MHz by combining several 30-kHz frequency channels.
Introduction to Wireless Networking
Published in K.R. Rao, Zoran S. Bojkovic, Dragorad A. Milovanovic, Wireless Multimedia Communications, 2018
K.R. Rao, Zoran S. Bojkovic, Dragorad A. Milovanovic
Today’s most successful digital mobile cellular system is GSM (Global System for Mobile Communications).8,9 GSM is digital system in Europe. In Japan the PDC (personal digital cellular) system is operated. In the United States the digital market is divided into several systems, TDMA (time division multiple access)-based and GSM systems. This fragmentation has led to severe problems regarding coverage and service availability. Some mobile subscribers in United States and Canada still use analog AMPS (advanced mobile phone services) systems.10,11 2G mobile systems are still mainly used for voice traffic. The basic versions typically implement a circuit-switched service focused on voice, and only offer low data rates (9.6 to 14.4 kbps). Transitional data technologies between 2G and 3G have been proposed to achieve faster data rates sooner and at a lower cost than 3G systems. The evolved systems are characterized by higher data rates (64 to 384 kbps) and packet data mode.
Third-Generation Cellular Communications: An Air Interface Overview
Published in Jerry D. Gibson, Mobile Communications Handbook, 2017
Cellular communications systems have been developed and commercialized since the advent of the advanced mobile phone system (AMPS) [1], whose initial commercial deployments date back to 1981 but existed in the lab for nearly two decades prior. Since AMPS was intended to provide full terrestrial coverage for mobile users, a distributed network architecture using the cellular paradigm was employed. This meant that a large number of base stations (fixed location transceivers that are networked with each other), each with its own coverage area (or cell), to communicate with mobile equipment. The primary service offered was full-duplex voice telephony. AMPS is a primarily analog transmission system, using frequency-division multiple access (FDMA) as its underlying networking solution. These early analog cellular communications systems are also known as “first generation.”
A vision of 6G – 5G's successor
Published in Journal of Management Analytics, 2020
When Motorola launched the first-generation (1G) commercial mobile phone in 1968, it marked the advent of the era of mobile phones for communication. In the past, due to the long-term failure to solve the problem of wireless transmission, mobile communication could only be used for military, civil aviation, maritime, or emergency events. At that time, the transmission rate was only 2.4 kbps, and roaming was not possible. Connectivity was limited to certain regional places. As early as 1947, scientists proposed the concept of cellular communication. Its core technology was frequency reuse and switching. Based on this concept, the advanced mobile phone service (AMPS) was developed in 1978. 1G (Figure 1), based on analog modulation technology, had the problems of low spectrum utilization rate, limited service types, slow data service speed, poor confidentiality, vulnerability to eavesdropping and theft, high equipment, and large volume costs (Gawas, 2015; Gui, Liu, Tang, Kato, & Adachi, 2020; Tariq et al., 2019).