Wireless is one of the most rapidly developing technologies in our time, with dazzling new products and services emerging on an almost daily basis. These developments present enormous challenges for communications engineers, as the demand for increased wireless capacity grows explosively. Indeed, the discipline of wireless communications presents many challenges to designers that arise as a result of the demanding nature of the physical medium and the complexities in the dynamics of the underlying network.
標(biāo)簽： Communications Wireless MIMO
上傳時(shí)間： 2020-05-28
上傳用戶：shancjb
Wireless metropolitan area networks (WirelessMANs) is emerging as a promising broadband wireless access (BWA) technology to provide high-speed, high bandwidth efficiency and high-capacity multimedia services for residential as well as enterprise applications. It is observed that WirelessMAN (e.g., WiMAX) is even regarded as a 4G technology. For the success of the WirelessMANs, international standardization organiza- tions are very actively specifying the standards IEEE 802.16, ETSI HiperMAN and Korea WiBro.
標(biāo)簽： BroadbanMobile WiMAX Toward Broadband Wirelessd Wireless Mobile Toward WiMAX
上傳時(shí)間： 2020-05-30
上傳用戶：shancjb
With the rapid growth of the wireless mobile applications, wireless voice has begun to challenge wireline voice, whereas the desire to access e-mail, surf the Web or download music (e.g., MP3) wirelessly is increasing for wireless data. While second generation (2G) cellular wireless systems, such as cdmaOne1, GSM2 and TDMA3, introduced digital technology to wireless cellular systems to deal with the increasing demand for wireless applications, there is still the need for more spectrally efficient technologies for two reasons. First, wireless voice capacity is expected to continue to grow. Second, the introduction of high-speed wireless data will require more bandwidth.
標(biāo)簽： Wireless Systems Mobile Beyond and 3G
上傳時(shí)間： 2020-05-30
上傳用戶：shancjb
The family of recent wireless standards included the optional employment of Multiple-Input Multiple-Output(MIMO)techniques.This was motivatedby the observationaccordingto the classic Shannon–Hartley law that the achievable channel capacity increases logarithmically with the transmit power. In contrast, the MIMO capacity increases linearly with the number of transmit antennas, provided that the number of receive antennas is equal to the number of transmit antennas. With the further proviso that the total transmit power is increased in proportion to the number of transmit antennas, a linear capacity increase is achieved upon increasing the transmit power, which justifies the spectacular success of MIMO systems.
標(biāo)簽： Multi-Functional Systems MIMO
上傳時(shí)間： 2020-05-31
上傳用戶：shancjb
Many wireless communications channels consist of multiple signal paths from the transmitter to receiver. This multiplicity of paths leads to a phenomenon known as multipath fading. The multiple paths are caused by the presence of objects in the physical environment that, through the mechanisms of propagation, alter the path of radiated energy. These objects are referred to as scatterers. In the past, researchers often looked at ways to mitigate multipath scattering, such as in diversity systems. Multiple-input, multiple-output (MIMO) systems, on the other hand, use multipath diversity to their advantage; a MIMO system has the ability to translate increased spatial diversity into increased channel capacity.
標(biāo)簽： Multiple-Output Multiple-Input Channel Models
上傳時(shí)間： 2020-05-31
上傳用戶：shancjb
The family of recent wireless standards included the optional employment of MIMO tyechniques. This was motivated by the observation according to the classic Shannon-Hartley law the achiev- able channel capacity increases logarithmically with the transmit power. By contrast, the MIMO capacity increases linearly with the number of transmit antennas, provided that the number of receive antennas is equal to the number of transmit antennas.
標(biāo)簽： Simulation Modeling Network and
上傳時(shí)間： 2020-05-31
上傳用戶：shancjb
Optical wireless communication is an emerging and dynamic research and development area that has generated a vast number of interesting solutions to very complicated communication challenges. For example, high data rate, high capacity and minimum interference links for short-range communication for inter-building communication, computer-to-computer communication, or sensor networks. At the opposite extreme is a long-range link in the order of millions of kilometers in the new mission to Mars and other solar system planets.
標(biāo)簽： Communication Wireless Optical Systems
上傳時(shí)間： 2020-05-31
上傳用戶：shancjb
Ever since ancient times, people continuously have devised new techniques and technologies for communicating their ideas, needs, and desires to others. Thus, many forms of increasingly complex communication systems have appeared over the years. The basic motivations behind each new one were to improve the transmission fidelity so that fewer errors occur in the received message, to increase the transmission capacity of a communication link so that more infor- mation could be sent, or to increase the transmission distance between relay sta- tions so that messages can be sent farther without the need to restore the signal fidelity periodically along its path.
標(biāo)簽： Communications Essentials Optical
上傳時(shí)間： 2020-05-31
上傳用戶：shancjb
Wireless networking is undergoing a transformation from what has been primarily a medium for supporting voice traffic between telephones, into what is increasingly becoming a medium for supporting traffic among a variety of digital devices transmitting media of many types (voice, data, images, video. etc.) Wireline networking underwent a similar transformation in the 1990s, which led to an enormous build-up in the capacity of such networks, primarily through the addition of new optical fiber, switches and other infrastructure.
標(biāo)簽： Multiusers Detection Wireless Networks
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
Wireless communications, together with its applications and underlying technologies, is among today’s most active areas of technology development. The very rapid pace of im- provements in both custom and programmable integrated circuits for signal processing ap- plications has led to the justfiable view of advanced signal processing as a key enabler of the aggressively escalating capacity demands of emerging wireless systems. Consequently, there has been a tremendous and very widespread effort on the part of the research community to develop novel signal processing techniques that can fulfill this promise.
標(biāo)簽： Communication Wireless Systems
上傳時(shí)間： 2020-06-01
上傳用戶：shancjb
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