Abstract—In the future communication applications, users may obtain their messages that have different importance levels distributively from several available sources, such as distributed storage or even devices belonging to other users. This scenario is the best modeled by the multilevel diversity coding systems (MDCS). To achieve perfect (information-theoretic) secrecy against wiretap channels, this paper investigates the fundamental limits on the secure Rate region of the asymmetric MDCS (AMDCS), which include the symmetric case as a special case. Threshold perfect secrecy is added to the AMDCS model. The eavesdropper may have access to any one but not more than one subset of the channels but know nothing about the sources, as long as the size of the subset is not above the security level. The question of whether superposition (source separation) coding is optimal for such an AMDCS with threshold perfect secrecy is answered. A class of secure AMDCS (S-AMDCS) with an arbitrary number of encoders is solved, and it is shown that linear codes are optimal for this class of instances. However, in contrast with the secure symmetric MDCS, superposition is shown to be not optimal for S-AMDCS in general. In addition, necessary conditions on the existence of a secrecy key are determined as a design guideline.
标签： Fundamental Limits Secure Class on of
上传时间： 2020-01-04
上传用户：kddlas
transimpedance linearization circuitry. This allows it to drive video loads with excellent differential gain and phase perfor mance on only 50 mW of power. The AD8001 is a current feedback amplifier and features gain flatness of 0.1 dB to 100 MHz while offering differential gain and phase error of 0.01% and 0.025°. This makes the AD8001 ideal for professional video electronics such as cameras and video switchers. Additionally, the AD8001’s low distortion and fast settling make it ideal for buffer high-speed A-to-D converters. The AD8001 offers low power of 5.5 mA max (VS = ±5 V) and can run on a single +12 V power supply, while being capable of delivering over 70 mA of load current. These features make this amplifier ideal for portable and battery-powered applications where size and power are critical. The outstanding bandwidth of 800 MHz along with 1200 V/µs of slew Rate make the AD8001 useful in many general purpose high-speed applications where dual power supplies of up to ±6 V and single supplies from 6 V to 12 V are needed. The AD8001 is available in the industrial temperature range of –40°C to +85°C.
上传时间： 2020-04-21
上传用户：su1254
From the transition of analog to digital communication along with seamless mobility and high computing power of small handheld devices, the wireless communications industry has seen tremendous changes leading to the integration of several telecommunication networks, devices and services over last 30 years. The Rate of this progress and growth has increased particularly in the past decade because people no longer use their devices and networks for voice only, but demand bundle contents such as data download/streaming, HDTV, HD video , 3D video conferencing with higher efficiency, seamless connectivity, intelligence, reliability and better user experience. Although the challenges facing service providers and telecommunication companies differ by product, region, market size, and their areas of concentration but time to market, efficient utilization of their assets and revenue expansion, have impacted significantly how to manage and conduct their business while maintaining sufficient margin.
标签： Convergence Networks Beyond 4G of
上传时间： 2020-05-26
上传用户：shancjb
The growing interest for high data Rate wireless communications over the last few decades gave rise to the emergence of a number of wideband wireless systems. The resulting scarcity of frequency spectrum has been forcing wireless system designers to develop methods that will push the spectral efficiency to its limit.
标签： Algorithms Baseband Receiver
上传时间： 2020-05-26
上传用户：shancjb
At present, there is a strong worldwide push toward bringing fiber closer to indi- vidual homes and businesses. Fiber-to-the-Home/Business (FTTH/B) or close to it networks are poised to become the next major success story for optical fiber com- munications. In fact, FTTH connections are currently experiencing double-digit or even higher growth Rates, e.g., in the United States the annual growth Rate was 112% between September 2006 and September 2007, and their presence can add value of U.S. $4,000–15,000 to the selling price of a home.
标签： Technologies Broadband Networks Access
上传时间： 2020-05-26
上传用户：shancjb
Emerging technologies such as WiFi and WiMAX are profoundly changing the landscape of wireless broadband. As we evolve into future generation wireless networks, a primary challenge is the support of high data Rate, integRated multi- media type traffic over a unified platform. Due to its inherent advantages in high-speed communication, orthogonal frequency division multiplexing (OFDM) has become the modem of choice for a number of high profile wireless systems (e.g., DVB-T, WiFi, WiMAX, Ultra-wideband).
标签： Broadband Wireless Networks
上传时间： 2020-05-26
上传用户：shancjb
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.
标签： Radio Cognitive Software Defined
上传时间： 2020-05-26
上传用户：shancjb
The rapid growth in mobile communications has led to an increasing demand for wide- band high data Rate communications services. In recent years, Distributed Antenna Systems (DAS) has emerged as a promising candidate for future (beyond 3G or 4G) mobile communications, as illustRated by projects such as FRAMES and FuTURE. The architecture of DAS inherits and develops the concepts of pico- or micro-cell systems, where multiple distributed antennas or access points (AP) are connected to and con- trolled by a central unit.
标签： Distributed Antenna Systems
上传时间： 2020-05-27
上传用户：shancjb
A series of features makes the mobile telecommunications industry an interesting field of investigation for economists: the industry is experi- encing veryfastmarketgrowthcombinedwithrapidtechnological change; regulatory design in setting market structure is playing a very important role; and oligopolistic competition is unfolding under various forms. The number of subscribers to mobile networks is growing at a rapid Rate on a worldwide basis, as shown in figure 1.1.
标签： Telecommunications Economics Mobile of
上传时间： 2020-05-27
上传用户：shancjb
During the past decade, many wireless communication techniques have been developedto achievevariousgoals suchas higherdata Rate,morerobustlink quality, and higher number of users in a given bandwidth. For wireless communication systems, depending on the availability of a feedback link, two approaches can be considered: namely open and closed loop. Open loop communication system that does not exploit the channel knowledge at the transmitter is now well understood from both a theoretical and practical point of view.
标签： Communication StRategies Feedback Wireless for
上传时间： 2020-05-27
上传用户：shancjb
