Rapid growth of wireless communication services in recent decades has created a huge demand of radio spectrum. Spectrum scarcity and utilization inefficiency limit the development of wireless networks. Cognitive radio is a promising tech- nology that allows secondary users to reuse the underutilized licensed spectrum of primary users. The major challenge for spectrum sharing is to achieve high spectrum efficiency while making non-intrusive access to the licensed bands. This requires in- formation of availability and quality of channel resources at secondary transmitters, however, is difficult to be obtained perfectly in practice.
標(biāo)簽： Opportunistic Spectrum Sharing
上傳時間： 2020-05-31
上傳用戶：shancjb
Mobile operators must continuously pursue cost‐ effective and efficient solutions to meet the high data demand requirements of their subscribers. Limited spectrum allocations and non‐contiguous spectrum blocks continue to pose challenges for mobile operators supporting large data uploads and downloads across their networks. With the increase in video and social media content, the challenges have increased exponentially.
標(biāo)簽： qorvo-carrier-aggregation-fundame ntals
上傳時間： 2020-05-31
上傳用戶：shancjb
This paper presents a Hidden Markov Model (HMM)-based speech enhancement method, aiming at reducing non-stationary noise from speech signals. The system is based on the assumption that the speech and the noise are additive and uncorrelated. Cepstral features are used to extract statistical information from both the speech and the noise. A-priori statistical information is collected from long training sequences into ergodic hidden Markov models. Given the ergodic models for the speech and the noise, a compensated speech-noise model is created by means of parallel model combination, using a log-normal approximation. During the compensation, the mean of every mixture in the speech and noise model is stored. The stored means are then used in the enhancement process to create the most likely speech and noise power spectral distributions using the forward algorithm combined with mixture probability. The distributions are used to generate a Wiener filter for every observation. The paper includes a performance evaluation of the speech enhancer for stationary as well as non-stationary noise environment.
標(biāo)簽： Telecommunications Processing Signal for
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(biāo)簽： Multimedia Subsystem The IMS 3G IP
上傳時間： 2020-06-01
上傳用戶：shancjb
The Home Gateway Initiative (HGI) is a non-profit making organization which publishes guidelines, requirements documents, white papers, vision papers, test plans and other documents concerning broadband equipment and services which are deployed in the home.
標(biāo)簽： Evaluation Discussion Framework Document KPI
上傳時間： 2020-06-06
上傳用戶：shancjb
RFID (radio-frequency identification) is the use of a wireless non-contact system that uses radio-frequencyelectromagnetic fields to transfer datafrom a tag attached to an object, for the purposes of automatic identification and tracking [38]. The basic technologies for RFID have been around for a long time. Its root can be traced back to an espionage device designed in 1945 by Leon Theremin of the Soviet Union,whichretransmittedincidentradiowaves modulatedwith audioinformation. After decades of development, RFID systems have gain more and more attention from both the research community and the industry.
標(biāo)簽： Infrastructure RFID as an
上傳時間： 2020-06-08
上傳用戶：shancjb
I wrote this book so that students, hobbyists, and engineers alike can take advantage of the Arduino platform by creating several projects that will teach them about the engineering process. I also wanted to guide the reader through introductory projects so that they could get a firm grasp on the Arduino Language, and how to incorporate several pieces of hardware to make their own projects. This book offers so much information on the Arduino, not just the basic LED projects but it offers different peripherals such as Ultrasonic sensor, the Xbox? controller, Bluetooth, and much more. This book also teaches the non-engineer to follow a process that will help them in future project (not just Arduino projects).
標(biāo)簽： Engineering Practical Arduino
上傳時間： 2020-06-09
上傳用戶：shancjb
The main aim of this book is to present a unified, systematic description of basic and advanced problems, methods and algorithms of the modern con- trol theory considered as a foundation for the design of computer control and management systems. The scope of the book differs considerably from the topics of classical traditional control theory mainly oriented to the needs of automatic control of technical devices and technological proc- esses. Taking into account a variety of new applications, the book presents a compact and uniform description containing traditional analysis and op- timization problems for control systems as well as control problems with non-probabilistic models of uncertainty, problems of learning, intelligent, knowledge-based and operation systems – important for applications in the control of manufacturing processes, in the project management and in the control of computer systems.
標(biāo)簽： Modern_Control_Theory
上傳時間： 2020-06-10
上傳用戶：shancjb
The PW5300 is a current mode boost DC-DC converter. Its PWM circuitry with built-in 0.2? powerMOSFET make this regulator highly power efficient. The internal compensation network alsominimizes as much as 6 external component counts. The non-inverting input of error amplifierconnects to a 0.6V precision reference voltage and internal soft-start function can reduce the inrushcurrent. The PW5300 is available in the SOT23-6L package and provides space-saving PCB for theapplication fields
標(biāo)簽： pw5300
上傳時間： 2022-02-11
上傳用戶：jiabin
解讀 5G 八大關(guān)鍵技術(shù) 【摘要】5G 不是一次革命，5G 是 4G 的延續(xù)，我相信 5G 在核心網(wǎng)部分不會有太 大的變動，5G 的關(guān)鍵技術(shù)集中在無線部分。 在進入主題之前，我覺得首先應(yīng)該弄清楚一個問題：為什么需要 5G？不是因 為通信工程師們突然想改變世界，而炮制了一個 5G。是因為先有了需求，才有了 5G。什么需求？ 未來的網(wǎng)絡(luò)將會面對：1000 倍的數(shù)據(jù)容量增長，10 到 100 倍的無線設(shè)備連接， 10 到 100 倍的用戶速率需求，10 倍長的電池續(xù)航時間需求等等。坦白的講，4G 網(wǎng)絡(luò)無法滿足這些需求，所以 5G 就必須登場。 但是，5G 不是一次革命。5G 是 4G 的延續(xù)，我相信 5G 在核心網(wǎng)部分不會有 太大的變動，5G 的關(guān)鍵技術(shù)集中在無線部分。雖然 5G 最終將采用何種技術(shù)，目前 還沒有定論。不過，綜合各大高端論壇討論的焦點，我今天收集了 8 大關(guān)鍵技術(shù)。 當(dāng)然，應(yīng)該遠不止這些。 1.非正交多址接入技術(shù) （Non-Orthogonal Multiple Access,NOMA） 我們知道 3G 采用直接序列碼分多址（Direct Sequence CDMA ，DS-CDMA） 技術(shù)，手機接收端使用 Rake 接收器，由于其非正交特性，就得使用快速功率控制 （Fast transmission power control ，TPC)來解決手機和小區(qū)之間的遠-近問題。 而 4G 網(wǎng)絡(luò)則采用正交頻分多址（
標(biāo)簽： 5G
上傳時間： 2022-02-25
上傳用戶：20125101110
蟲蟲下載站版權(quán)所有 京ICP備2021023401號-1
