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本科毕业论文中英文翻译--Wireless-Communications无线通信.doc

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Wireless Communications*
by
Joshua S. Gans, Stephen P. King and Julion and standards. Section 4 surveys recent economic studies of the diffusion of mobile telephony. Finally, section 5 reviews issues of regulation and competition; in particular, the need for and principles behind access pricing for mobile phone networks.
2. Background
Marconi’s pioneering work quickly led to variety of commercial and government (particularly military) developments and innovations. In the early 1900s, voice and then music was transmitted and modern radio was born. By 1920, commercial radio had been established with Detroit station WWJ and KDKA in Pittsburgh. Wireless telegraphy was

first used by the British military in South Africa in 1900 during the Anglo-Boer war. The British navy used equipment supplied by Marconi to communicate between ships in

Delagoa Bay. Shipping was a major early client for wireless telegraphy and wireless was standard for shipping by the time the Titanic issued its radio distress calls in 1912.1
Early on, it was quickly recognized that international coordination was required for wireless communication to be effective. This coordination involved two features. First, the potential for interference in radio transmissions meant that at least local coordination was needed to avoid the transmission of conflicting signals. Secondly, with spectrum to be used for international communications and areas such as maritime safety and navigation, coordination was necessary between countries to guarantee consistency in approach to these services. This drove government intervention to ensure the coordinated allocation of radio spectrum.

2.1 Spectrum Allocation

Radio transmission involves the use of part of the electromagnetic spectrum. Electromagnetic energy is transmitted in different frequencies and the properties of the energy depend on the frequency. For example, visible light has a frequency betwee