Today’s wireless services have come a long way since the roll out of the conventional voice-centric cellular systems. The demand for wireless access in voice and high rate data multi-media applications has been increasing. New generation wireless communication systems are aimed at accommodating this demand through better resource management and improved transmission technologies.
標(biāo)簽： radio Cognitive Software Defined
上傳時間： 2020-05-26
上傳用戶：shancjb
Wireless technology has been evolving at a breakneck speed. The total number of cell-phones in use (as of 2011) was over 6 billion for a 7 billion world population [1] constituting 87% of the world population. Additionally, with user convenience be- coming paramount, more and more functions are being implemented wirelessly.
標(biāo)簽： Front-Ends Cognitive Receiver radio
上傳時間： 2020-05-26
上傳用戶：shancjb
Cognitive radio has emerged as a promising technology for maximizing the utiliza- tion of the limited radio bandwidth while accommodating the increasing amount of services and applications in wireless networks. A cognitive radio (CR) transceiver is able to adapt to the dynamic radio environment and the network parameters to maximize the utilization of the limited radio resources while providing flexibility in wireless access. The key features of a CR transceiver are awareness of the radio envi- ronment (in terms of spectrum usage, power spectral density of transmitted/received signals, wireless protocol signaling) and intelligence.
標(biāo)簽： Cognitive Wireless Network
上傳時間： 2020-05-26
上傳用戶：shancjb
The capability of radio waves to provide almost instantaneous distant communications without interconnecting wires was a major factor in the explosive growth of communica- tions during the 20th century. With the dawn of the 21st century, the future for communi- cations systems seems limitless. The invention of the vacuum tube made radio a practical and affordable communications medium.
標(biāo)簽： Communications Receivers
上傳時間： 2020-05-26
上傳用戶：shancjb
The new digital radio system DAB (Digital Audio Broadcasting, nowadays often called Digital radio) is a very innovative and universal multimedia broadcast system which will replace the existing AM and FM audio broadcast services in many parts of the world in the future. It was developed in the 1990s by the Eureka 147/DAB project. DAB is very well suited for mobile reception and provides very high robustness against multipath reception. It allows use of single frequency networks (SFNs) for high frequency efficiency.
標(biāo)簽： Broadcasting Principles Digital Audio
上傳時間： 2020-05-27
上傳用戶：shancjb
The design and manufacturing of wireless radio frequency (RF) transceivers has developed rapidly in recent ten yeas due to rapid development of RF integrated circuits and the evolution of high-speed digital signal processors (DSP). Such high speed signal processors, in conjunction with the development of high resolution analog to digital converters and digital to analog converters, has made it possible for RF designers to digitize higher intermediate frequencies, thus reducing the RF section and enhancing the overall performance of the RF section.
標(biāo)簽： Transceivers Wireless Digital
上傳時間： 2020-05-27
上傳用戶：shancjb
This thesis is about wireless communication in shared radio spectrum. Its origin and motivation is ideally represented by the two quotations from above. In this thesis, the support of Quality-of-Service (QoS) in cognitive radio networks is analyzed. New approaches to distributed coordination of cognitive radios are developed in different spectrum sharing scenarios. The Wireless Local Area Network (WLAN) 802.11 proto- col of the Institute of Electrical and Electronics Engineers (IEEE) (IEEE, 2003) with its enhancement for QoS support (IEEE, 2005d) is taken as basis. The Medium Access Control (MAC) of 801.11(e) is modified to realize flexible and dynamic spectrum assignment within a liberalized regulation framework.
標(biāo)簽： Quality-of-Service Distributed Support
上傳時間： 2020-05-27
上傳用戶：shancjb
The General Packet radio Service (GPRS) allows an end user to send and receive data in packet transfer mode within a public land mobile network (PLMN) without using a permanent connection between the mobile station (MS) and the external network during data transfer. This way, GPRS opti- mizes the use of network and radio resources (RRs) since, unlike circuit- switched mode, no connection between the MS and the external network is established when there is no data flow in progress. Thus, this RR optimiza- tion makes it possible for the operator to offer more attractive fees.
上傳時間： 2020-05-27
上傳用戶：shancjb
When joining Siemens in 2001, I also extended my research interest towards radio net- work planning methodologies. This area of research brought together my personal interest in mobile communications and in the design of efficient algorithms and data structures. Between 2001 and 2003, I participated in the EU project Momentum, which was target- ing the performance evaluation and optimization of UMTS radio networks. I
標(biāo)簽： Efficient Methods WCDMA for
上傳時間： 2020-05-27
上傳用戶：shancjb
Following chapter introduces the mobile communication, gives a short history of wireless communication evolution, and highlights some application scenarios predestined for the use of mobile devices. Cellular and wireless based systems related to different generations of mobile communication, including GSM, IS-95, PHS, AMPS, D-AMPS, cdma2000 and WCDMA are also described by this Chapter. Much attention in this chapter is given to express the wireless based networks, such as Wi-Fi and WiBro/WiMax, and wireless broadcasting systems, including DMB, DVB-H, and ISDB-T. We conclude the chapter with the future vision of mobile communication evolution
標(biāo)簽： Technologies Enhanced Access radio
上傳時間： 2020-05-27
上傳用戶：shancjb
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