In this paper we revisit hybrid analog-digital precoding systems with emphasis on their modelling and radio-frequency (RF) losses, to realistically evaluate their benefits in 5G system implementations. For this, we decompose the analog beamforming networks (ABFN) as a bank of commonly used RF components and formulate realistic model constraints based on their S-parameters. Specifically, we concentrate on fully-connected ABFN (FC-ABFN) and Butler networks for implementing the discrete Fourier transform (DFT) in the RF domain. The results presented in this paper reveal that the PerFormance and energy efficiency of hybrid precoding systems are severely affected, once practical factors are considered in the overall design. In this context, we also show that Butler RF networks are capable of providing better PerFormances than FC-ABFN for systems with a large number of RF chains.
標簽： Analog-Digital Precoding Hybrid
上傳時間： 2020-05-27
上傳用戶：shancjb
This research work aims at eliminating the off-chip RF SAW filters from fre- quency division duplexed (FDD) receivers. In the first approach, a monolithic passive RF filter was constructed using on-chip capacitors and bondwire inductors. The bond- wire characteristics were studied in details and the effect of mutual inductive coupling between the bondwires on the filter PerFormance was analyzed. Based on that, a bond- wire configuration was proposed to improve the frequency response of the filter. The filter was implemented in 0.18 μm CMOS process for WCDMA applications.
標簽： Interference Mitigation Techniques
上傳時間： 2020-05-27
上傳用戶：shancjb
Radio frequency (RF) power amplifiers are used in everyday life for many applica- tions including cellular phones, magnetic resonance imaging, semiconductor wafer processing for chip manufacturing, etc. Therefore, the design and PerFormance of RF amplifiers carry great importance for the proper functionality of these devices. Furthermore, several industrial and military applications require low-profile yet high-powered and efficient power amplifiers.
標簽： Introduction Amplifier Design Power to RF
上傳時間： 2020-05-27
上傳用戶：shancjb
This book presents millimeter wave communication system design and analysis at the level to produce an understanding of the interaction between a wireless system and its front end so that the overall PerFormance can be predicted. Gigabit wireless commu- nications require a considerable amount of bandwidth, which can be supported by millimeter waves. Millimeter wave technology has come of age, and at the time of writing the standards of IEEE 802.15.3c, WiGig, Wireless HD TM , and the European Computer Manufacturers Association have recently been finalized.
標簽： Communication Millimeter Systems Wave
上傳時間： 2020-05-28
上傳用戶：shancjb
Use of multiple antennas at both ends of wireless links is the result of the natural progression of more than four decades of evolution of adaptive antenna technology. Recent advances have demonstrated that multiple- input-multiple-output (MIMO) wireless systems can achieve impressive increases in overall system PerFormance.
標簽： Technology System MIMO
上傳時間： 2020-05-28
上傳用戶：shancjb
In general there are three different techniques for PerFormance evaluation of systems and networks: mathematical analysis, measurements, and computer simulation. All these techniques have their strength and weaknesses. In the literature there are plenty of discussions about when to use which technique, how to apply it, and which pitfalls are related to which evaluation technique.
標簽： Simulation Modeling Network Tools and for
上傳時間： 2020-05-31
上傳用戶：shancjb
Modeling and simulation of nonlinear systems provide communication system designers with a tool to predict and verify overall system PerFormance under nonlinearity and complex communication signals. Traditionally, RF system designers use deterministic signals (discrete tones), which can be implemented in circuit simulators, to predict the PerFormance of their nonlinear circuits/systems. However, RF system designers are usually faced with the problem of predicting system PerFormance when the input to the system is real-world communication signals which have a random nature.
標簽： Nonlinear_Distortion_in_Wireless_ Systems
上傳時間： 2020-05-31
上傳用戶：shancjb
This book is a result of the recent rapid advances in two related technologies: com- munications and computers. Over the past few decades, communication systems have increased in complexity to the point where system design and PerFormance analysis can no longer be conducted without a significant level of computer sup- port. Many of the communication systems of fifty years ago were either power or noise limited. A significant degrading effect in many of these systems was thermal noise, which was modeled using the additive Gaussian noise channel.
標簽： Communication Principles Simulation Systems of
上傳時間： 2020-05-31
上傳用戶：shancjb
The book is written for those concerned with the design and PerFormance of satellite communications systems employed in fixed point-to-point, broadcasting, mobile, radio- navigation,data-relay,computercommunications,andrelatedsatellite-basedapplications.The recentrapidgrowthinsatellitecommunicationshascreatedaneedforaccurateinformationon both satellite communications systems engineering and the impact of atmospheric effects on satellite link design and system PerFormance. This book addresses that need for the first time in a single comprehensive source.
標簽： Communications Satellite Systems
上傳時間： 2020-06-01
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.
標簽： Telecommunications Processing Signal for
上傳時間： 2020-06-01
上傳用戶：shancjb
