Commercial Communication Systems Research Articles

Comparison and Design of Decoder in B3G Mobile Communication System

Turbo code has been shown to have ability to achieve performance that is close to Shannon limit. It has been adopted by various commercial communication systems. Both universal mobile telecommunications system (UMTS) TDD and FDD have also employed turbo code as the error correction coding scheme. It outperforms convolutional code in large block size, but because of its time delay, it is often only used in the non-real-time service. In this paper, we discuss the encoder and decoder structure of turbo code in B3G mobile communication System. In addition, various decoding techniques, such as the Log-MAP, Max-log-MAP and SOVA algorithm for non-real-time service are deduced and compared. The performance results of decoder and algorithms in different configurations are also shown.

A CPW‐fed two‐arm spiral slot antenna

AbstractA wideband coplanar waveguide (CPW)‐fed two‐arm spiral slot antenna without a balun circuit is presented in this article. Phase progressions at arm ports are realized through the coplanar waveguide excitations. A detailed characterization of all antenna components and parameters is provided along with guidelines and recommendations for broad bandwidth and small reflection. Variations of the impedance matching due to the turn numbers, the ground width separated between two neighboring turns and the slot width are tested and studied. The measured impedance bandwidth of a S11 ≤ 10 dB ranges from 1.63 to 8 GHz and covers most of the commercial wireless communication systems, such as DCS, PCS, IMT‐2000, WLAN, Bluetooth, and HIPERLAN. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 222–225, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23947

Multiband Electromagnetic-Bandgap Structures for Applications in Small Form-Factor Multichip Module Packages

The design and implementation of package-level electromagnetic-bandgap (EBG) structures is presented. By using spiral-based inductance-enhanced electromagnetic-bandgap structures (IE-EBGs), the relative periodicity for achieving bandgap at extremely low frequencies is substantially reduced in comparison to traditional EBGs. Using both full-wave electromagnetic simulation and experimental characterization, it is demonstrated that this type of structure can exhibit multiple bandgaps, which are individually tunable through variation of the inductance per unit area and/or the unit cell periodicity. Sample structures with dimensions compatible with today's microprocessor packaging technology are designed and fabricated in a multilayer organic flip-chip ball-grid array package substrate. These package-embedded IE-EBGs have unit cell dimensions less than 750 mum and exhibit the first forbidden bandgaps for electromagnetic wave propagation below 10 GHz, which is a frequency band of interest for commercial wireless communication systems.

Hierarchical Space-Time Block Code Recognition Using Correlation Matrices

The blind recognition of communication parameters is a key research issue for commercial and military communication systems. The results of numerous investigations about symbol timing estimation, modulation recognition as well as identification of the number of transmitters have been reported in the literature. But, to our knowledge, none of them have dealt with the recognition of the Space-Time Block Codes (STBC) used in multiple transmitter communications. In order to blindly recognize the STBC of a wireless communication, this paper proposes a method based on the space-time correlations of the received signals. Under perfect timing synchronization and under ideal conditions (full rank channel and a number of receivers greater or equal to the number of transmitters), it shows that the Frobenius norms of these statistics present non-null values whose positions only depend on the STBC at the transmitter side. A classifier for the space-time code recognition of 5 linear STBC (Spatial Multiplexing, Alamouti Coding, and 3 Orthogonal STBC using 3 antennas) is presented. Simulations show that the proposed method performs well even at low signal-to-noise ratios.

EDA toolbox for VHF Data Link system simulation

Commercial communication systems design software is usually shipped with libraries and toolboxes covering standards like GSM or UMTS. For designing aeronautical communication systems such ready-to-use libraries are rare. Low-level elements and functional blocks have to be adopted and used instead. In this paper a toolbox consisting of system elements for the use with electronic design automation software was developed. It enables radiofrequency design engineers to perform system level simulations using specialised components dedicated to aeronautical communication. For this, functional blocks within the physical layer of VHF Data Link were defined and made available. They cover basic radio frequency (RF) baseband operations as well as modulation, demodulation and power-ramp functionality. The library was tested and verified with a VHF Data Link Mode 4 signal generation application as well as with a VHF Data Link Mode 2 system simulation set-up. While the toolbox presented in this paper is intended to speed up development cycles by providing ready-to-use VHF Data Link functional blocks to radiofrequency system engineers, it is also a useful tool in signal generation and receiver testing.

A neural network approach to prediction of glass transition temperature of polymers

Polymeric materials are finding increasing application in commercial optical communication systems. Taking advantage of techniques from the field of artificial intelligence, the goal of our researc...

One-chip 고주파 단말기에의 응용을 위한 고집적 HBT 다운컨버터 MMIC

In this work, a highly integrated downconverter MMIC employing HBT(heterojunction bipolar transistor) was developed for application to one chip tranceiver solution of Ku-band commercial wireless communication system. The downconverter MMIC (monolithic microwave integrated circuit) includes mixer filter. amplifier and input/output matching circuit. Especially, spiral inductor structures employing SiN film were used for a suppression of LO and its second harmonic leakage signals. Concretely, they were properly designed so that the self-resonance frequency was accurately tuned to LO and its second harmonic frequency, and they were integrated on the downconverter MMIC.

SimpleDICOM Suite: Personal Productivity Tools for Managing DICOM Objects

Commercial picture archiving and communication systems (PACS) are adept at supporting mainstream radiology work flow, but radiologists frequently encounter situations requiring additional functionality. For example, the incorporation of foreign or nonradiologic images and the deidentification of examinations for research purposes are useful tasks that do not fall within the purview of most commercial PACS. A suite of free, downloadable, vendor-independent software programs designed as PACS add-ons, the SimpleDICOM (Digital Imaging and Communications in Medicine) Suite, has been developed to aid radiologists in performing these tasks. Clinically relevant software design and informed administrative decisions during deployment allow optimal function of this software suite, which is available for download from the Internet.

A neural network approach to prediction of glass transition temperature of polymers

Polymeric materials are finding increasing application in commercial optical communication systems. Taking advantage of techniques from the field of artificial intelligence, the goal of our research is to construct systems that can computationally design polymer formulations, including polymer optical fibers, with specified desirable consumer characteristics. Through the use of an extensive structure—property correlation database, properties of polymers can be predicted by an artificial network and the structure of novel polymers with desired properties can be optimized by a genetic algorithm. In this paper, we are focusing on one of the parameters, glass transition temperature (Tg) that influences a desired outcome in polymer optical fibers. Performance of such fibers can be optimized by engineering a polymer to exhibit a lower refractive index and Tg. This paper compares and discusses a neural network model and a linear model that have been developed to correlate Tg and repeating units of polymers. A neural network and multiple linear regression analysis were used in the study. A set of descriptors, chosen based on previous studies on the relations between Tg and polymer structure, were used to describe the structure of repeating units, individual bond energies, and intermolecular forces, especially hydrogen bonding, which is the strongest intermolecular force and exerts the greatest influence on Tg compared with other intermolecular interactions. A comprehensive neural network model with 28 descriptors was developed to predict Tg values of 6 randomly selected polymers from a database containing 71 polymers. The network was trained with the remaining 65 polymers and had a typical training root mean square error of 17 K (R2 = 0.95) and prediction average error of 17 K (R2 = 0.85). A linear regression model developed for comparison had an average error of 30 K (R2 = 0.88). © 2007 Wiley Periodicals, Inc.

Use of a Thin-Section Archive and Enterprise 3D Software for Long-Term Storage of Thin-Slice CT Data Sets

Rapid advances are changing the technology and applications of multidetector computed tomography (CT) scanners. The major increase in data associated with this new technology, however, breaks most commercial picture archiving and communication system (PACS) architectures by preventing them from delivering data in real time to radiologists and outside clinicians. We proposed a phased model for 3D workflow, installed a thin-slice archive and measured thin-slice data storage over a period of 5 months. A mean of 1,869 CT studies were stored per month, with an average of 643 images per study and a mean total volume of 588 GB/month. We also surveyed 48 radiologists to determine diagnostic use, impressions of thin-slice value, and requirements for retention times. The majority of radiologists thought thin slice was helpful for diagnosis and regularly used the application. Permanent storage of thin slice CT is likely to become best practice and a mission-critical pursuit for the health care enterprise.

Coplanar waveguide‐fed band‐selective filter for wideband antenna

AbstractIn this study, a coplanar waveguide‐fed band‐selective filter and a spiral slot antenna have been designed, fabricated, and integrated for the applications of multisystem integration. The antenna module was fabricated on the same plane of the substrate, so that the circuit process and the position alignment could be simplified. The passband responses of the filter ranging below 2.6 GHz and from 5.0 to 6.0 GHz cover most of the commercial wireless communication systems. Simulated results are compared with measurements performed on the antenna module. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2264–2267, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21915

A joint source-channel distortion model for JPEG compressed images

The need for efficient joint source-channel coding (JSCC) is growing as new multimedia services are introduced in commercial wireless communication systems. An important component of practical JSCC schemes is a distortion model that can predict the quality of compressed digital multimedia such as images and videos. The usual approach in the JSCC literature for quantifying the distortion due to quantization and channel errors is to estimate it for each image using the statistics of the image for a given signal-to-noise ratio (SNR). This is not an efficient approach in the design of real-time systems because of the computational complexity. A more useful and practical approach would be to design JSCC techniques that minimize average distortion for a large set of images based on some distortion model rather than carrying out per-image optimizations. However, models for estimating average distortion due to quantization and channel bit errors in a combined fashion for a large set of images are not available for practical image or video coding standards employing entropy coding and differential coding. This paper presents a statistical model for estimating the distortion introduced in progressive JPEG compressed images due to quantization and channel bit errors in a joint manner. Statistical modeling of important compression techniques such as Huffman coding, differential pulse-coding modulation, and run-length coding are included in the model. Examples show that the distortion in terms of peak signal-to-noise ratio (PSNR) can be predicted within a 2-dB maximum error over a variety of compression ratios and bit-error rates. To illustrate the utility of the proposed model, we present an unequal power allocation scheme as a simple application of our model. Results show that it gives a PSNR gain of around 6.5 dB at low SNRs, as compared to equal power allocation.

Building the software radio

People have been working on software radio for about few years. Software radio is just what it sounds like - a radio that uses software to perform many of the signal processing tasks that analog circuits traditionally handle. Software radio could turn out to be a paradigm shift for communication systems. The US Defense Advanced Projects Research Agency (DARPA) kicked off research into software radios to solve military problems, but software radios can help solve some important problems in commercial communication systems as well. Software radio offers the advantage of putting many traditionally hard functions in modules whose characteristics can be changed while the radio is running.

Channel and source considerations of a bit-rate reduction technique for a possible wireless communications system's performance enhancement

In wireless commercial and military communications systems, where bandwidth is at a premium, robust low-bit-rate speech coders are essential. They operate at fix bit rates and those bit rates cannot be altered without major modifications in the vocoder design. A novel approach to vocoders, in order to reduce the bit rate required to transmit speech signal, is proposed. While traditional low-bit-rate vocoders code original input speech, the proposed procedure operates on the time-scale modified signal. The proposed method offers any bit rate from 2400 b/s to downwards without modifying the principle vocoder structure, which is the new NATO standard, Stanag 4591, Mixed Excitation Linear Prediction (MELP) vocoder. We consider the application of transmitting MELP-encoded speech over noisy communication channels by applying different modulation techniques, after time-scale compression is applied. Three different time-scale modification algorithms have been evaluated and waveform similarity overlap and add (WSOLA) algorithm has been selected for time-scale modification purposes. Computer simulation results, both source and channel, are presented in terms of objective speech quality metrics and informal subjective listening tests. Design parameters such as codec complexity and delay are also investigated. Simulation results lead to a possible wireless communications system, whose performance might be enhanced by using the spared bits offered by the procedure.

A microstrip filter utilized in ultra‐wideband antennas

AbstractIn this paper, a microstrip filter has been designed, fabricated, and measured for application in ultra‐wideband antennas. By using the combination of a band‐stop filter and a low‐pass filter, the band‐selective characteristics can be demonstrated. In order to enhance the suppression of the out‐of‐band signals, a defected ground structure (DGS) with stopband performance is used. The passband responses of the filter, which range below 2.8 GHz and from 5.0 to 6.0 GHz, cover most commercial wireless communication systems. The LC‐lumped equivalent circuit of the filter has been extracted and simulated by using transmission‐line analysis. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 41: 248–251, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20107

Role of contemporary communications systems in the process of planning, organizing and realization of military operations

Fast progress in commercial communications systems development has made possibilities to fulfill communications needs in military organizations especially during the periods of peace. A reconnaissance system, based on specific military technology such as passive radar systems and acoustic sensors, available in commercial market, represents a possible realization of a simple and highly efficient system. Necessary communication with a higher command, also as actions that are made based on gathered information, could de supported through use of commercial communications systems employing adaptive modulation processes, direct sequence and freqyency hopping spread spectrum communications and code division multiple access. In this way organized systems completely fulfill communication needs of the Army of Serbia and Montenegro during peacetime, but the applicability of such systems expends partially or fully on cases of limited military interventions antiterrorist actions and nature disasters.

Studies of the novel CPW-fed spiral slot antenna

The design and analysis of a coplanar waveguide-fed spiral slot antenna, applied in most of the commercial wireless communication systems, have been proposed and presented in this paper. The spiral slot antenna and the feeding structure are fabricated on the same plane of the substrate so that the circuit process and the position alignment could be simplified. The comparisons of the measured initial operated frequency versus the substrate thickness, the turn number and the slot width are detailed and discussed.

EM design of broadband RF multiport toggle switches

Radio frequency (RF) MEMS is an emerging sub-area of MEMS technology that is revolutionizing RF and microwave applications. RF MEMS devices have a broad range of optional applications in military and commercial wireless communication, and navigation and sensor systems. This article presents the EM design of different multiport toggle switches. Such a multiport switch can be used in the compact designs of switching matrices, routing networks, or phase shifters. One application range is the creation of electronically steerable antenna arrays, which can be used for radar applications and satellite communication. The miniaturized switches are based on the single pole single throw (SPST) toggle switch and, in addition to their small size, they have an increased RF performance regarding losses and operation bandwidth (DC to 50 GHz). A 3D FDTD field solver has been used for the electromagnetic design of all the switches. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE 14: 329–337, 2004.

Channel and source considerations of a MELP derived vocoder operating at reduced bit rates

Robust low bit rate speech coders are essential in commercial and military communication systems. They operate at fixed bit rates and those bit rates cannot be altered without major modifications in the vocoder design. In this paper we introduce a scaled speech coder, which operates on time-scale modified input speech. The proposed method offers any bit rate from 2400 b/s to downwards without modifying the principle vocoder structure, which is the mixed excitation linear prediction (MELP) vocoder. We consider the application of transmitting MELP-encoded speech over noisy communication channels after time scale compression is applied. Computer simulation results, both source and channel, are presented in terms of objective speech quality metrics and informal subjective listening tests. A statistical tool called bootstrap is also used to determine the accuracy of these test results. Design parameters such as codec complexity and delay are also investigated.

Filmless radiology at the Baltimore VA Medical Center: a 9 year retrospective

The transition from conventional film based to filmless operation at the Baltimore VA Medical Center in 1993 was successful and has resulted in a number of clinical and economic benefits. The subsequent integration of the Department of VA hospitals in Maryland into a single network, the VA Maryland Health Care System, resulted in the opportunity to establish a ‘virtual’ radiology and nuclear medicine department. This integrated department is based upon a wide area network in which outlying medical centers utilize a central HIS/RIS and a central commercial Picture archival and communication system (PACS) as well as a VA ‘home grown’ image management and communication system, the VISTA imaging system. The creation of this virtual radiology/nuclear medicine department has resulted in additional savings and improvements in clinical care. The benefits of the PACS were made possible, to a large extent, by the high level of integration of the PACS and medical modalities with the hospital information and transcription systems. Our experience suggests that it is absolutely essential to integrate the PACS into the patient's electronic medical record in order to maximize efficiency and clinical effectiveness of the system.