20 research outputs found
Classic OFDM Systems and Pulse Shaping OFDM/OQAM Systems
No full textIn this report, we provide a comparative study of state-of-the-art in Orthogonal Frequency Division Multiplexing (OFDM) techniques with orthonormal analysis and synthesis basis. Two main categories, OFDM/QAM which adopts base-band Quadrature Amplitude Modulation (QAM) and rectangular pulse shape, and OFDM/OQAM which uses baseband offset QAM and various pulse shapes, are intensively reviewed. OFDM/QAM can provide high data rate communication and effectively remove intersymbol interference (ISI) by employing guard interval, which costs a loss of spectral efficiency and increases power consumption. Meanwhile it remains very sensitive to frequency offset which causes inter-carrier interference (ICI). In order to achieve better spectral efficiency and reducing combined ISI/ICI, OFDM/OQAM using well designed pulses with proper Time Frequency Localization (TFL) is of great interest. Various prototype functions, such as rectangular, half cosine, Isotropic Orthogonal Transfer Algorithm (IOTA) function and Extended Gaussian Functions (EGF) are discussed and simulation results are provided to illustrate the TFL properties by the ambiguity function and the interference function.QC 20111026A hard copy is available in ICT/ECS archive. Electronic copy is available on www.ee.kth.se/~jinfengNGFDM - small project of Wireless@KT
Swedish system-on-chip conference focuses on meter to nanometer scale electronics R&D
No full textLiLaS
No full textThis paper describes a generic link layer simulation environment for multiple antenna systems in MATLAB and OCTAVE, for both Windows and Unix/Linux operating systems: LiLaS. The simulator is functionally divided into modules, sub-modules and models with a common interface for the convenience of modification and reconfiguration. Currently, it accommodates a variety of transmission schemes, including single-carrier and multiple-carrier MIMO, Orthogonal Frequency-Division Multiplexing (OFDM), OFDM/Offset QAM, Wideband Code Division Multiple Access (W-CDMA), filtered multitone (FMT) and RFID which have extensive applications in modern communication technologies, e.g.. WLAN 802.11 a/b/g/n, WiMAX, UWB, 3G, LTE, LTE advanced, IMT advanced, xDSL, DVB, etc.</p
Effects of Noise and Jitter in Bandpass Sampling
No full textBandPass Sampling (BPS) is an undersampling technique by intentional aliasing. BPS enables one to have an interface between the IF stage and the ADC in a radio receiver. Conventional uniform BPS at Nyquist rate normally results in a low Signal-to-Noise Ratio (SNR) due to noise spectrum aliasing. The noise (e.g. kT/C noise introduced in a voltage-mode sampler) is combined in each of the Nyquist bands within the bandwidth of the sampling device. Also timing jitter causes a performance degradation in BPS. In this paper, signal spectrum aliasing, noise aliasing and jitter effects in BPS is analyzed. It is verified by simulation that NonUniform Sampling (NUS) has the potential to suppress signal spectrum aliasing and relax the requirement on the anti-aliasing (AA) filter. Jitter effects in BPS are compared to LowPass Sampling (LPS) case. However, a signal cannot be reconstructed from its nonuniform samples by using only ideal lowpass filtering (classic Shannon's reconstruction). Finally, signal reconstruction in the presence of noise and jitter are investigated for three Reconstruction Algorithms (RAs) aimed at NUS.</p
Single clock charge pump designed in 0.35μm technology
No full textAn on-chip novel design of a single clock charge pump for high voltage applications is being presented in this paper. The proposed charge pump is designed using AMS 0.35μm technology. Three stages of the proposed charge pump are being used for the results verification and comparing them with the six stages of Dickson charge pump designed with diode connected PMOS. The proposed charge pump gives an output voltage of 5.34V at no-load. The proposed charge pump gives maximum efficiencies of 89% on 1MHz frequency and 87.4% on 5MHz frequency using 1Mohm load resistance. The efficiency and the output voltage including voltage gain per stage of the proposed charge pump are higher than the Dickson charge pump measured under similar conditions mediating that the performance of proposed charge pump is better than the Dickson charge pump.</p
A highly linear 1.2 V 12bit 5-45 MS/s CMOS pipelined ADC with CM-sensing-and-input-interchanged OTA sharing
No full textA 1.2 V 12bit programmable pipelined ADC is presented and implemented in 0.13 mu m CMOS technology. A common-mode-sensing-and-input-interchanged OTA-sharing technique is proposed to address the non-resetting and successive-stage crosstalk issues in conventional OTA-sharing technique. Speed options of 5-45 MS/s are available with scalable power obtained by adjusting the bias currents for OTAs, comparators, and reference buffers, etc., or the global bias current. The measured signal-to-distortion-and-noise ratio is in range of 62.5-69.2 dB, and the peak spurious free dynamic range is 80.7 dB for all speed options, while the figure-of-merit is in the range of 0.26-0.49 pJ/conversion. The core area is 1.5 mm(2).</p
Development and deployment of document management technology into Rover : executive summary
No full textDocument Management is a technology that allows the input, storage,
management and control of an image under the supervision of a computer based
system. A document may be an electronically scanned image of a hard copy
document or an electronic image such as a word-processed file, sound file, video
file, or graphics file. Once the document has entered the system, a full history of
that document is maintained throughout its lifecycle.
The author was responsible for the introduction, development and deployment of
Document Management technology into Rover Group. The task given to the
author was to implement Document Management technology purely as a
repository and distribution management system for engineering drawings.
However, by adopting an innovative approach to the application of Document
Management technology, substantial benefits were realised.
As the author became more conversant with Document Management technology,
greater benefits became apparent. Following detailed analysis of Rover's existing
`Engineering drawing release process' the author re-engineered the process to
allow electronic paperless release of all engineering drawings. This re-engineering
provided Rover with substantial tangible and intangible benefits including cost
reduction, improved quality of data, reduced `time to market', improved access,
improved cycle time and reductions in manual labour.
Three projects detailed in the portfolio demonstrate how this technology was
applied to existing systems and processes. In particular, the `Hams Hall' project
clearly demonstrates innovation in the way in which the author used the
technology to manage working practices and data structure for a multi-disciplined
team located in different countries.
With changes implemented by the author, Rover now hold substantially more
digital data than before the implementation of Document Management
technology. Following research work by the author into both the types of data
held and the use to which that data was put, the legality of that data came into
question. This prompted a detailed analysis of the legal requirements of digitally
stored data that allowed the author to advise Rover Group of their current status
and make recommendations to ensure legal admissibility.
The work reported shows how a combination of technical expertise and an
appreciation of business issues and drivers, is crucial to the effective and
successful implementations of information systems. Other organisations have
shown considerable interest in the improved Document Management technology
enabled business processes, developed by the author
Partial Dissociation and Hydration Quantitatively Explain the Properties of Aqueous Electrolyte Solutions and hence Empirical Activity Concepts are Unnecessary
No full textThe author shows that Arrhenius's theory of partial electrolytic dissociation was immaturely displaced about eight decades ago by the empirical concept of ionic activities and the assumption of complete dissociation of electrolytes at all concentrations. The latter brought the theory of electrolytes over the next decades into a complicated state without any physical significance. Therefore, the author started a systematic investigation of the available data and could completely restore the original theory of partial dissociation. Now solution properties can be easily understood and quantitatively explained in terms of absolute concentrations and volumes of ions and ion pairs and hydration
D teams of portfolio entrepreneurs and management controllers to innovate: Implications of algorithmic decision-making
No full textWe focus on how international research and development (R&D) teams of portfolio entrepreneurs and their management controllers can help to innovate and sustain entrepreneurial activities. An algorithmic decision-making model is implemented that indicates how such portfolio entrepreneurs build complex business structures and create a context for management accounting controllers’ information that is suggestive of R&D internationalization challenges. A case study is utilized to compare one large and one medium-sized business conglomerate. Open interviews were conducted with portfolio entrepreneurs and their management controllers. We found that the international R&D teams of portfolio entrepreneurs and their management controllers have different mindsets when assessing sustainable innovative approaches for the existing business and for future expansion through acquisitions. Our findings assert the importance of context when understanding the challenges of management controllers dealing with the internationalization of such R&D efforts. © 2021 The Author(s)</p
