Driven by the desire to boost the quality of service of wireless systems closer to that afforded by wireline systems, space-time processing for multiple-input multiple-output (MIMO) wireless communications research has drawn remarkable interest in recent years. Excit- ing theoretical advances, complemented by rapid transition of research results to industry products and services, have created a vibrant and growing area that is already established by all counts. This offers a good opportunity to reflect on key developments in the area during the past decade and also outline emerging trends.
標簽： Space-Time Processing
上傳時間： 2020-06-01
上傳用戶：shancjb
The radio spectrum is one of the most precious resources which must be managed to ensure efficient access for the wireless communication services which use it. The allocation and management of spectrum are administered by the regulatory authorities. Traditionally, spectrum allocation is carried out exclusively of its use in large geographic areas and assigning frequency bands to specific users or service providers is proved to be inefficient. Recently, substantial knowledge about dynamic spectrum access scheme has been accumulated to enable efficient spectrum sharing.
標簽： Management Spectrum Access and
上傳時間： 2020-06-01
上傳用戶：shancjb
Radio frequency spectrum is a scarce and critical natural resource that is utilized for many services including surveillance, navigation, communication, and broadcast- ing. Recent years have seen tremendous growth in the use of spectrum especially by commercial cellular operators. Ubiquitous use of smartphones and tablets is one of the reasons behind an all-time high utilization of spectrum. As a result, cellular operators are experiencing a shortage of radio spectrum to meet bandwidth demands of users. On the other hand, spectrum measurements have shown that much spectrum not held by cellular operators is underutilized even in dense urban areas. This has motivated shared access to spectrum by secondary systems with no or minimal impact on incumbent systems. Spectrum sharing is a promising approach to solve the problem of spectrum congestion as it allows cellular operators access to more spectrum in order to satisfy the ever-growing bandwidth demands of commercial users.
標簽： Spectrum Sharing Between Radars
上傳時間： 2020-06-01
上傳用戶：shancjb
The use of mobile devices now surpasses that of traditional computers: wireless users will hence soon be demanding the same rich multimedia services on their mobile devices that they have on their desktop personal computers. In addition, new services will be added, especially related with their mobile needs, such as location-based information services.
標簽： Communications Technology Wireless Trends in
上傳時間： 2020-06-01
上傳用戶：shancjb
Regulation is a pervasive feature of the telecommunications services industry today. Government-appointed regulators and judicial or quasi-judicial bodies oversee it in countries at all stages of economic development. Its primary purpose is to encourage, nourish and maintain competition in national and international telecommunications services markets. It is, therefore, a fundamental feature of the legal and commercial landscape within which network owners and service providers operate. The modern development of regulation may be traced to the liberalisation of the industry from national monopolies from the 1980s onwards.
標簽： Telecommunications Regulation
上傳時間： 2020-06-01
上傳用戶：shancjb
Rapid progress in information and communications technology (ICT) induces improved and new telecommunications services and contributes greatly to society in general and to vendors and network and service providers. In addition to existing services such as telephony or leased line services, spread of the Internet, the Internet Protocol (IP) phone, and new communications services like IPTV are making great progress with the development of digital subscriber lines (DSL) and high - speed communications technologies like fi ber to the home (FTTH).
標簽： Telecommunications Networks
上傳時間： 2020-06-01
上傳用戶：shancjb
When 3GPP started standardizing the IMS a few years ago, most analysts expected the number of IMS deploymentsto grow dramatically as soon the initial IMS specifications were ready (3GPP Release 5 was functionallyfrozenin the first half of 2002and completedshortly after that). While those predictions have proven to be too aggressive owing to a number of upheavals hitting the ICT (Information and Communications Technologies) sector, we are now seeing more and more commercial IMS-based service offerings in the market. At the time of writing (May 2008), there are over 30 commercial IMS networks running live traffic, addingup to over10million IMS users aroundthe world; the IMS is beingdeployedglobally. In addition, there are plenty of ongoing market activities; it is estimated that over 130 IMS contracts have been awarded to all IMS manufacturers. The number of IMS users will grow substantially as these awarded contracts are launched commercially. At the same time, the number of IMS users in presently deployed networks is steadily increasing as new services are introduced and operators running these networks migrate their non-IMS users to their IMS networks.
標簽： Multimedia Subsystem The IMS 3G IP
上傳時間： 2020-06-01
上傳用戶：shancjb
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.
標簽： Multimedia Business Mobile The
上傳時間： 2020-06-01
上傳用戶：shancjb
Long-TermEvolution(LTE)isarguablyoneofthemostimportantstepsinthecurrentphaseof the development of modern mobile communications. It provides a suitable base for enhanced services due to increased data throughput and lower latency figures, and also gives extra impetus to the modernization of telecom architectures. The decision to leave the circuit- switched domainoutofthescope ofLTE/SAEsystem standardization might soundradical but itindicatesthatthetelecomworldisgoingstronglyfortheall-IPconcept----andthedeployment of LTE/SAE is concrete evidence of this global trend.
標簽： Deployment Handbook LTE-SAE The
上傳時間： 2020-06-01
上傳用戶：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.
標簽： Telecommunications Handbook The
上傳時間： 2020-06-01
上傳用戶：shancjb
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