High-quality Transmission Research Articles

CRE: A novel QoT-aware routing and wavelength assignment algorithm in all-optical networks

In a transparent wavelength routed optical network, physical impairments degrade optical signal to noise ratio (OSNR) of a transmitted signal. Therefore, the quality of a lightpath must be checked during connection setup procedure. Since a lightpath setup may inject crosstalk on all previously established lightpaths with which it shares links or nodes, OSNR for those lightpaths should be checked as well as the OSNR of the tentative lightpath. On the other hand, by increasing the number of hops for a lightpath, the amount of OSNR degradation increases due to crosstalk. Therefore, long paths are subject to high quality of transmission (QoT) degradation due to crosstalk. In this paper, we enhance OSNR degradation for different lightpaths with different hop numbers in such a way that OSNR degradation for long-hop lightpaths becomes closer to short-hop lightpaths, i.e., a fair OSNR degradation. We provide a mechanism called Crosstalk Risk Estimation (CRE) by which we can find the nodes with positive crosstalk risk (i.e., the node in which generated crosstalk noise violates its crosstalk tolerance bound). Then, after establishing a lightpath, a rerouting mechanism is employed to reduce crosstalk risks of these nodes by migrating some of the lightpaths that pass through them. Actually, each node that is positive crosstalk risk decides to reroute some lightpaths traversing from itself. This algorithm tries to minimize the impact of establishing a new lightpath on the already established lightpaths. Our performance evaluations show that the CRE algorithm can provide better QoT and network access fairness because it can reduce the crosstalk risk and successfully mitigate crosstalk effects.

Adaptive Antenna for Wi-Fi System Enhancement

As the demand for wireless communications constantly grows, the need arises for better coverage, improved capacity, and higher transmission quality. Thus, a more efficient use of the radio spectrum is required. Smart antenna systems are capable of efficiently utilizing the radio spectrum and promise an effective solution to the present wireless system problems while achieving reliable and robust highspeed high-data-rate transmission.

Effect of environment on the propagation of electromagnetic waves in GRC 408E digital radiorelay devices

Effect of environment on the propagation of electromagnetic waves in GRC 408E digital radiorelay devices

Heuristic Algorithms for Constructing Interference-Free and Delay-Constrained Multicast Trees for Wireless Mesh Networks

In this paper, we study a problem that is concerning how to construct a delay-constrained multicast tree on a wireless mesh network (WMN) such that the number of serviced clients is maximized. In order to support high-quality and concurrent interference-free transmission streams, multiple radios are implemented in each mesh node in the WMNs. Instead of only orthogonal channels used for the multicast in the previous works, both orthogonal and partially overlapping channels are considered in this study. As a result, the number of links successfully allocated channels can be expected to be much larger than that of the approaches in which only orthogonal channels are considered. The number of serviced subscribers is then increased dramatically. Hence, the goal of this study is to find interference-free and delay-constrained multicast trees that can lead to the maximal number of serviced subscribers. This problem is referred as the MRDCM problem. Two heuristics, load-based greedy algorithm and load-based MCM algorithm, are developed for constructing multicast trees. Furthermore, two load-based channel assignment procedures are provided to allocate interference-free channels to the multicast trees. A set of experiments is designed to do performance, delay and efficiency comparisons for the multicast trees generated by all the approximation algorithms proposed in this study.

Combining FIB milling and conventional Argon ion milling techniques to prepare high‐quality site‐specific TEM samples for quantitative EELS analysis of oxygen in molten iron

This paper reports a procedure to combine the focused ion beam micro-sampling method with conventional Ar-milling to prepare high-quality site-specific transmission electron microscopy cross-section samples. The advantage is to enable chemical and structural evaluations of oxygen dissolved in a molten iron sample to be made after quenching and recovery from high-pressure experiments in a laser-heated diamond anvil cell. The evaluations were performed by using electron energy-loss spectroscopy and high-resolution transmission electron microscopy. The high signal to noise ratios of electron energy-loss spectroscopy core-loss spectra from the transmission electron microscopy thin foil, re-thinned down to 40 nm in thickness by conventional Argon ion milling, provided us with oxygen quantitative analyses of the quenched molten iron phase. In addition, we could obtain lattice-fringe images using high-resolution transmission electron microscopy. The electron energy-loss spectroscopy analysis of oxygen in Fe(0.94)O has been carried out with a relative accuracy of 2%, using an analytical procedure proposed for foils thinner than 80 nm. Oxygen K-edge energy-loss near-edge structure also allows us to identify the specific phase that results from quenching and its electronic structure by the technique of fingerprinting of the spectrum with reference spectra in the Fe-O system.

Opportunistic Video Communication over Cooperative Decode-Forward Networks

An opportunistic automatic repeat request (ARQ) scheme was developed to support high-quality video transmission over cooperative decode-forward networks. The opportunistic ARQ is implemented in the form of distributed space-time block codes (STBCs) and the desired STBC for a certain channel state is determined by the diversity-multiplexing tradeoff principle. With good channel states, the source and relay may jointly retransmit the lost video packets using high-rate low-diversity codes while with bad channel states they will retransmit the lost video packets using low-rate high-diversity codes. Furthermore, an adaptive packet dropping mechanism was introduced by considering the delay constraint and layer dependency characteristics of scalable video streaming. Test results show that the scheme significantly improves the throughput and video quality compared with other schemes. Tests also indicate that the source-relay link condition plays an important role in affecting the scheme performance.

Frequency assignment problem in satellite communications using differential evolution

Satellite communications technology has a tremendous impact in refining our world. The frequency assignment problem is of a fundamental importance when it comes to providing high-quality transmissions in satellite communication systems. The NP-complete frequency assignment problem in satellite communications involves the rearrangement of frequencies of one set of carriers while keeping the other set fixed in order to minimize the largest and total interference among carriers. In this paper, we present a number of algorithms, based on differential evolution, to solve the frequency assignment problem. We investigate several schemes ranging from adaptive differential evolution to hybrid algorithms in which heuristic is embedded within differential evolution. The effectiveness and robustness of our proposed algorithms is demonstrated through solving a set of benchmark problems and comparing the results with a number of previously proposed techniques that solve the same problem. Experimental results show that our proposed algorithms, in general, and hybrid ones in particular, outperform the existing algorithms both in terms of the quality of the solutions and computational time.

A 0.13 .MU.m CMOS Bluetooth EDR Transceiver with High Sensitivity over Wide Temperature Range and Immunity to Process Variation

A 2.4 GHz 0.13 μm CMOS transceiver LSI, supporting Bluetooth V2.1 + enhanced data rate (EDR) standard, has achieved a high reception sensitivity and high-quality transmission signals between ―40°C and +90°C. A low-IF receiver and direct-conversion transmitter architecture are employed. A temperature compensated receiver chain including a low-noise amplifier accomplishes a sensitivity of ―90 dBm at frequency shift keying modulation even in the worst environmental condition. Design optimization of phase noise in a local oscillator and linearity of a power amplifier improves transmission signals and enables them to meet Bluetooth radio specifications. Fabrication in scaled 0.13 μm CMOS and operation at a low supply voltage of 1.5 V result in small area and low power consumption.

Performance Analysis of an Optical Gigabit Ethernet

The optical fiber is a very attractive communication medium since it offers a large bandwidth and low attenuation, and can therefore facilitate demanding services such as high-quality video transmission and others in computer networks. In this paper, a performance analysis of an optical gigabit ethernet performance using longer wavelength (C-Band) instead of O and E bands, and high Extinction Ratio (Er) value is presented. This performance analysis is represented by decrease the bit-error rate (BER), increase the number of nodes in the network, and increase the backbone cable length. Simulation results show improvement in the performance of the network when using 1550nm wavelength over the 1330nm wavelength for 1Gbps and 10Gbps. In addition, the results are compared for different values of Er where, higher values of Er give better performance. The work is software implemented using optical system simulator packet (OPTSIM 3.6).

C-SPECT - a Clinical Cardiac SPECT/Tct Platform: Design Concepts and Performance Potential.

Because of scarcity of photons emitted from the heart, clinical cardiac SPECT imaging is mainly limited by photon statistics. The sub-optimal detection efficiency of current SPECT systems not only limits the quality of clinical cardiac SPECT imaging but also makes more advanced potential applications difficult to be realized. We propose a high-performance system platform - C-SPECT, which has its sampling geometry optimized for detection of emitted photons in quality and quantity. The C-SPECT has a stationary C-shaped gantry that surrounds the left-front side of a patient's thorax. The stationary C-shaped collimator and detector systems in the gantry provide effective and efficient detection and sampling of photon emission. For cardiac imaging, the C-SPECT platform could achieve 2 to 4 times the system geometric efficiency of conventional SPECT systems at the same sampling resolution. This platform also includes an integrated transmission CT for attenuation correction. The ability of C-SPECT systems to perform sequential high-quality emission and transmission imaging could bring cost-effective high-performance to clinical imaging. In addition, a C-SPECT system could provide high detection efficiency to accommodate fast acquisition rate for gated and dynamic cardiac imaging. This paper describes the design concepts and performance potential of C-SPECT, and illustrates how these concepts can be implemented in a basic system.

Teleteaching endoscopy: the feasibility of real-time, uncompressed video transmission by using advanced-network technologies

Teleteaching of endoscopy has been limited by the exorbitant cost and time inherent in high-quality digital endoscopy video transmission. The Digital Video Transport System (DVTS) transmitted over advanced networks, such as Internet2 and the Asia-Pacific Advanced Network (APAN), provides a unique infrastructure for sharing uncompressed digital videos of endoscopy. This may allow high-quality, real-time, international training of diagnostic and therapeutic endoscopy techniques at a low cost. To test the proof of concept of long-distance teaching through live, interactive, high-resolution video transmission by using advanced networks and the DVTS. We used teleteaching of image-enhanced endoscopy techniques as a model. Prospective multicenter pilot study. Trainees, faculty, and staff at 3 international endoscopy units. An image-enhanced endoscopy video lecture with advanced-network technologies. We compared image-based prelecture and postlecture test scores and secondarily assessed technical feasibility and quality. The DVTS transmitted over advanced networks successfully transmitted uncompressed, high-resolution, digital lectures with endoscopic video (digital video format 720 x 480 pixels). Postsession scores improved. Participants highly rated the technical and informational quality. The majority reported a definite interest in participating in future sessions, with a mean rating (out of 5 [scale 1-5]) of 4.7 +/- 0.5. Pilot study with a limited number of participants and sessions. The DVTS transmitted over advanced networks such as Internet2 and APAN can provide the infrastructure for transmission of high-resolution, uncompressed video endoscopy for the purpose of teleteaching endoscopy.

Tele-transmission of Stereoscopic Images of the Optic Nerve Head in Glaucoma via Internet

The objective was to describe an inexpensive system to visualize stereoscopic photographs of the optic nerve head on computer displays and to transmit such images via the Internet for collaborative research or remote clinical diagnosis in glaucoma. Stereoscopic images of glaucoma patients were digitized and stored in a file format (joint photographic stereoimage [jps]) containing all three-dimensional information for both eyes on an Internet Web site (www.trizax.com). The size of jps files was between 0.4 to 1.4 MB (corresponding to a diagonal stereo image size between 900 and 1400 pixels) suitable for Internet protocols. A conventional personal computer system equipped with wireless stereoscopic LCD shutter glasses and a CRT-monitor with high refresh rate (120 Hz) can be used to obtain flicker-free stereo visualization of true-color images with high resolution. Modern thin-film transistor-LCD displays in combination with inexpensive red-cyan goggles achieve stereoscopic visualization with the same resolution but reduced color quality and contrast. The primary aim of our study was met to transmit stereoscopic images via the Internet. Additionally, we found that with both stereoscopic visualization techniques, cup depth, neuroretinal rim shape, and slope of the inner wall of the optic nerve head, can be qualitatively better perceived and interpreted than with monoscopic images. This study demonstrates high-quality and low-cost Internet transmission of stereoscopic images of the optic nerve head from glaucoma patients. The technique allows exchange of stereoscopic images and can be applied to tele-diagnostic and glaucoma research.

Degenerated-Inverse-Matrix-Based Channel Estimation for OFDM Systems

This paper addresses time-domain channel estimation for pilot-symbol-aided orthogonal frequency division multiplexing (OFDM) systems. By using a cyclic sinc-function matrix uniquely determined by transmitted subcarriers, the performance of our proposed scheme approaches perfect channel state information (CSI), within a maximum of 0.4 dB degradation, regardless of the delay spread of the channel, Doppler frequency, and subcarrier modulation. Furthermore, reducing the matrix size by splitting the dispersive channel impulse response into clusters means that the degenerated inverse matrix estimator (DIME) is feasible for broadband, high-quality OFDM transmission systems. In addition to theoretical analysis on normalized mean squared error (NMSE) performance of DIME, computer simulations over realistic nonsample spaced channels also showed that the DIME is robust for intersymbol interference (ISI) channels and fast time-invariant channels where a minimum mean squared error (MMSE) estimator does not work well.

Side-mode transmission diagnosis of a multichannel selectable injection-locked Fabry-Perot Laser Diode with anti-reflection coated front facet

Theory and experiments on the side-mode-suppression-ratio (SMSR) enhancement and the linewidth reduction of a Fabry-Perot laser diode (FPLD) side-mode-injection-locked by using another FPLD are demonstrated to realize its potential application as a DWDM transmitter source. The SMSR, the spectral linewidth and the linewidth enhancement factor are simulated to realize the limitation of the FPLD-FPLD link under side-mode injection-locking condition. A degradation of the linewidth enhancement factor from 1.5 to 2.1 is observed due to the slave FPLD injection-locked at principle- and side-mode conditions. Up to 22-channel selectability of the 2.5 Gbit/s directly modulated FPLD based transmitter under side-mode injection-locking is demonstrated with a SMSR >35 dB, a Q-factor 6.8-9.2, a locking range of 24 nm, a power penalty of -0.7 dB, and a BER of 10(-10) at -17 dBm. The side-mode injection-locked FPLD shows high-quality transmission performance and meet the demand for cost-effective and high-capability 2.5 Gbit/s WDM systems.

Adaptive Load Balancing MDP-Based Approach of Two-Dimensional Spreading for VSF-OFCDM in 4G Next-Generation Cellular Communications

The variable spreading factor-orthogonal frequency and code division multiplexing (VSF-OFCDM) system has been proposed as the forward link interface for achieving a high data rate in fourth-generation (4G) mobile communications. VSF-OFCDM allocates the orthogonal channelization codes of an orthogonal variable spreading factor (OVSF) code tree in 2-D spreading in the time and frequency domains but suffers from two disadvantages, namely, moderate utilization and low transmission quality. Moderate utilization is caused by code blocking, and the low transmission quality is due to the multicode interference from high channel loading in the time domain of the 2-D spreading. A tradeoff thus exists between code blocking and multicode interference. A lower code blocking means a higher interference. Achieving high utilization while also providing high transmission quality is a critical issue that should be addressed in 4G VSF-OFCDM. Therefore, this paper proposes a 2-D spreading approach that is based on an adaptive load balancing with Markov decision process (which is denoted by ALM). The ALM approach consists of three phases. First, for balancing the channel load, the adaptive 2-D spreading phase is proposed to select the 2-D spreading combinations, which have low channel load and high frequency diversity, as the candidates. Second, a dynamic recombination of the 2-D spreading is presented to decrease the channel load while supporting the transmission quality from high frequency diversity if the channel load of a time-domain code exceeds the defined channel load threshold. Third, the cost-based Markov decision process (MDP) code-selection approach is adopted to minimize the code blocking. The MDP models the state of the OVSF code tree as an MDP and then defines the costs for all the candidate channelization codes. The MDP phase selects the least-cost channelization code as the optimal solution if several 2-D spreading combinations can satisfy the channel load limitation. Additionally, the time complexity of the ALM is analyzed. The numerical results indicate that the proposed approach outperforms the other approaches in transmission quality ratio, fractional reward loss, and total number of reassignments.

On triplexer design for next generation Ethernet passive optical network systems

The standardisation effort targeting 10 Gbit/s EPON systems, together with the requirement for coexistence with the legacy IEEE 802.3ah compliant equipment, impose a set of very tight requirements in terms of wavelength allocation plan for future EPON systems and significant limitations in terms of triplexer design for optical network unit (ONU) modules, where two wavelength channels (or three, when an analogue video overlay is used on the downstream) must be properly separated with minimum power and quality loss, providing also a high quality transmission window for the upstream 1310 nm signal. In this paper, we look closer at the possible triplexer and filter design for emerging 10 Gbit/s EPON systems in the light of current IEEE 802.av Task Force activities and technical limitations of the wavelength division multiplexing (WDM) filter design process.

Optoelectronic Package Having Low-Loss Optical Waveguide Hole With Core–Clad Structure for Chip-to-Chip Interconnection

We have developed optoelectronic packages having optical waveguide holes with core-clad structures for chip-to-chip optical interconnection within computer systems. A rate of 10-Gb/s/ch chip-to-chip optical signal transmission has been demonstrated. The optoelectronic package we have developed consists of two guide pins and four-channel optical waveguide holes. The two guide pins are used to align an optical fiber connector with an optical device. The optical waveguide holes are used to transmit optical signals vertically through the optoelectronic package. Using the optical waveguide holes in the optoelectronic package, and high-quality signal transmission has been achieved.

3-4 スーパーハイビジョンの高品質・高信頼IP伝送に関する一検討(第3部門 放送方式)

3-4 スーパーハイビジョンの高品質・高信頼IP伝送に関する一検討(第3部門 放送方式)

An Energy-Efficient and High-Quality Video Transmission Architecture in Wireless Video-Based Sensor Networks.

Technological progress in the fields of Micro Electro-Mechanical Systems (MEMS) and wireless communications and also the availability of CMOS cameras, microphones and small-scale array sensors, which may ubiquitously capture multimedia content from the field, have fostered the development of low-cost limited resources Wireless Video-based Sensor Networks (WVSN). With regards to the constraints of videobased sensor nodes and wireless sensor networks, a supporting video stream is not easy to implement with the present sensor network protocols. In this paper, a thorough architecture is presented for video transmission over WVSN called Energy-efficient and high-Quality Video transmission Architecture (EQV-Architecture). This architecture influences three layers of communication protocol stack and considers wireless video sensor nodes constraints like limited process and energy resources while video quality is preserved in the receiver side. Application, transport, and network layers are the layers in which the compression protocol, transport protocol, and routing protocol are proposed respectively, also a dropping scheme is presented in network layer. Simulation results over various environments with dissimilar conditions revealed the effectiveness of the architecture in improving the lifetime of the network as well as preserving the video quality.

An Energy-Efficient and High-Quality Video Transmission Architecture in Wireless Video-Based Sensor Networks

Technological progress in the fields of Micro Electro-Mechanical Systems (MEMS) and wireless communications and also the availability of CMOS cameras, microphones and small-scale array sensors, which may ubiquitously capture multimedia content from the field, have fostered the development of low-cost limited resources Wireless Video-based Sensor Networks (WVSN). With regards to the constraints of video-based sensor nodes and wireless sensor networks, a supporting video stream is not easy to implement with the present sensor network protocols. In this paper, a thorough architecture is presented for video transmission over WVSN called Energy-efficient and high-Quality Video transmission Architecture (EQV-Architecture). This architecture influences three layers of communication protocol stack and considers wireless video sensor nodes constraints like limited process and energy resources while video quality is preserved in the receiver side. Application, transport, and network layers are the layers in which the compression protocol, transport protocol, and routing protocol are proposed respectively, also a dropping scheme is presented in network layer. Simulation results over various environments with dissimilar conditions revealed the effectiveness of the architecture in improving the lifetime of the network as well as preserving the video quality.