The first practical examples of mobile communications were used in many countries like the USA, the UK and Germany in military services, and played a significant role in the First World War to transfer important INformation from the front to headquarters to take further actions. Good and secure wireless communications were an important need for all military services – army, navy and air force. In this respect, the Second World War was a big experimental battlefield for the development and evolution of mobile radio. It was in the interests of governments that after the Second World War the military investment should be paid back by civilian use, and all western European countries started their so-called first generation of mobile communication networks.
标签： Multimedia Business Mobile The
上传时间： 2020-06-01
上传用户：shancjb
This book addresses the issues on the development of next generation CDMA technologies and contains a lot of INformation on the subject from both the open literature and my own research activities in the last fifteen years.
标签： Technologies Generation Next CDMA The
上传时间： 2020-06-01
上传用户：shancjb
Changes in telecommunications are impacting all types of user group, which include business users, traveling users, small and home offices, and residential users. The acceptance rate of telecom- munications and INformation services is accelerating significantly. Voice services needed approximately 50 years to reach a very high teledensity; television needed just 15 years to change the culture and lives of many families; the Internet and its related services have been penetrating and changing business practices and private com- munications over the last 2 to 3 years.
标签： Telecommunications Handbook The
上传时间： 2020-06-01
上传用户：shancjb
Recent advances in wireless communication technologies have had a transforma- tive impact on society and have directly contributed to several economic and social aspects of daily life. Increasingly, the untethered exchange of INformation between devices is becoming a prime requirement for further progress, which is placing an ever greater demand on wireless bandwidth. The ultra wideband (UWB) system marks a major milestone in this progress. Since 2002, when the FCC allowed the unlicensed use of low-power, UWB radio signals in the 3.1–10.6GHz frequency band, there has been significant synergistic advance in this technology at the cir- cuits, architectural and communication systems levels. This technology allows for devices to communicate wirelessly, while coexisting with other users by ensuring that its power density is sufficiently low so that it is perceived as noise to other users.
上传时间： 2020-06-01
上传用户：shancjb
The continuing explosive growth in mobile communication is demanding more spectrally efficient radio access technologies than the prevalent second generation (2G) systems such as GSM to handle just the voice traffic. We are already witnessing high levels of mobile penetration exceeding 70% in some countries. It is anticipated that by 2010 more than half of all communications will be carried out by mobile cellular networks. On the other hand, the INformation revolution and changing life habits are bringing the requirement of commu- nicating on a multimedia level to the mobile environment. But the data handling capabilities and flexibility of the 2G cellular systems are limited.
上传时间： 2020-06-01
上传用户：shancjb
The dictionary definition of telecommunications is ‘communication over long distance by cable, telegraph, telephone or broadcasting’, but since its initiation over 100yearsagothingshavemovedrapidly.Telecommunicationsisnowaverycomplex industrywithmanydifferentpressures,operatinginahighlydynamic environment.It is best viewed as part of a wider industry known as INformation and communication technology (ICT). The purpose of this chapter is to explain where telecommunication fits in, to highlight some of the complexities – hopefully to simplify them – and to position the industry in today’s dynamic business environment.
标签： Telecommunications Understanding Business
上传时间： 2020-06-01
上传用户：shancjb
The INformation age is exploding around us, giving us access to dizzying amounts of data the instant it becomes available. Smart phones and tablets provide an untethered experience that offers stream- ing video, audio, and other media formats to just about any place on the planet. Even people who are not “computer literate” use Facebook to catch up with friends and family, use Google to research a new restaurant choice and print directions to get there, or Tweet their reactions once they have sampled the fare. The budding Internet-of-things will only catalyze this data eruption. The infrastructure supporting these services is also growing exponentially, and the technology that facilitates this rapid growth is virtualization.
上传时间： 2020-06-01
上传用户：shancjb
Visible light communications (VLC) is the name given to an optical wireless communication system that carries INformation by modulating light in the visible spectrum (400–700 nm) that is principally used for illumination [1–3]. The communications signal is encoded on top of the illumination light. Interest in VLC has grown rapidly with the growth of high power light emitting diodes (LEDs) in the visible spectrum. The motivation to use the illumination light for communication is to save energy by exploiting the illumination to carry INformation and, at the same time, to use technology that is “green” in comparison to radio frequency (RF) technology, while using the existing infrastructure of the lighting system.
标签： Communication Visible Light
上传时间： 2020-06-01
上传用户：shancjb
Wavelength division multiplexing (WDM) refers to a multiplexing and transmission scheme in optical telecommunications fibers where different wavelengths, typically emitted by several lasers, are modulated independently (i.e., they carry independent INformation from the transmitters to the receivers). These wavelengths are then multiplexed in the transmitter by means of passive WDM filters, and likewise they are separated or demultiplexed in the receiver by means of the same filters or coherent detection that usually involves a tunable local oscillator (laser).
标签： Multiplexing Wavelength Division
上传时间： 2020-06-01
上传用户：shancjb
Notwithstanding its infancy, wireless mesh networking (WMN) is a hot and growing field. Wireless mesh networks began in the military, but have since become of great interest for commercial use in the last decade, both in local area networks and metropolitan area networks. The attractiveness of mesh networks comes from their ability to interconnect either mobile or fixed devices with radio interfaces, to share INformation dynamically, or simply to extend range through multi-hopping.
标签： Multi-hop Networks WiMAX WiFi Mesh LTE and
上传时间： 2020-06-01
上传用户：shancjb
