Code Domain Research Articles

Failure location mechanism in long-reach PON based on OCDR

An efficient and unambiguous failure monitoring and protection mechanism is proposed in long-reach passive optical network (LR-PON). Optical code domain reflectometer by optical coding scheme is utilized. Improved optical encoders are placed centrally in optical distribution network and at both sides of each remote node to monitor all links and nodes in the network, which can make much simpler installation and smaller management costs. A reliable and robust protection system is designed and it can protect LR-PON from multiple fault cases. The network can achieve monitoring and protection process by network management system centrally. After locating fault, the system can also monitor the network continuously. The performance analysis of the monitoring system: signal-to-noise-plus-interference ratio, signal-to-interference-ratio and signal-to-noise-ratio are studied. Furthermore, the performance of data signals for protection system is investigated by bit error rate. The results obtained prove the feasibility and efficiency of the proposed network, and it can support high network capacity.

Enhanced Index Modulated OFDM Spread Spectrum

Index modulated OFDM spread spectrum (OFDM-IM-SS) is a recently proposed scheme, which transmits the additional bits (index bits) through the code domain. In this paper, we propose a novel variant of OFDM-IM-SS, called index modulated OFDM with in-phase/quadrature spread spectrum (OFDM-IM-SS-IQ), to increase the spectrum efficiency of OFDM-IM-SS. In OFDM-IM-SS-IQ, the transmitted symbols are divided into in-phase and quadrature parts, which are combined by the corresponding spreading codes selected by their respective index bits. A low complexity detection algorithm for OFDM-IM-SS-IQ is investigated to relieve the computational complexity of the optimal maximum-likelihood detection. A closed-form of the upper bound on the bit error rate is then derived to evaluate the error performance of OFDM-IM-SS-IQ. In addition, a diversity-enhancing scheme of OFDM-IM-SS, named index modulated OFDM spread spectrum enhancement (OFDM-IM-SS-E), is also designed to achieve a full diversity order. Computer simulation results validate the theoretical analysis and show that OFDM-IM-SS-IQ outperforms the conventional OFDM-IM-SS scheme. They also prove that the proposed OFDM-IM-SS-E obtains full diversity and achieves a better bit error rate performance than OFDM-IM-SS.

Outage Probability Region and Optimal Power Allocation for Uplink SCMA Systems

As a promising non-orthogonal multiple access scheme, sparse code multiple access (SCMA) technology has attracted much attention. Because inter-user interference is present in code domain and multi-user iterative detection is required, user capacity and outage probability analysis for uplink SCMA systems are challenging and have not been presented in the literature. In this paper, the capacity region for uplink SCMA systems is analyzed, based on which the common and individual outage probability regions are calculated. Optimizing the outage probability within the outage probability region can be casted as an Lagrangian duality problem and solved by an iterative descent algorithm, which however imposes high complexity since the expectation operation is required in each iteration. To reduce the computational complexity of solving this Lagrangian duality problem, an adaptive algorithm is developed, which is capable of providing the optimal outage probability and adaptively updating it. Furthermore, a power allocation policy is naturally obtained to achieve the optimized outage probability in the outage probability region.

Analysis and Design of N-Path RF Bandstop Filters Using Walsh-Function-Based Sequence Mixing

Impedance translation using passive N-path mixers has been used to achieve local oscillator (LO)-defined series bandstop and shunt bandpass filtering. In this paper, we generalize N-path filtering using a correlator-based approach and propose N-path passive mixers driven by orthogonal sequences. Such sequence-driven N-path filters can potentially reject or select signals based on their properties in the spectral, spatial, and code domains. Specifically, a Walsh-function (WF) sequence (WF-seq)-based N-path shunt filter is implemented, demonstrating the feasibility of shunt bandstop filtering using LO sequences other than nonoverlapping pulses. The WF-seq approach enables reconfigurable concurrent filtering at two different frequencies with shunt operation avoiding penalties due to the switch drive overlap. A 65-nm CMOS implementation achieves 20-dB rejection at one frequency and 14-dB rejection concurrently at two frequencies between 0.3 and 1.4 GHz. The reconfigurable bandstop filter is implemented using analog gyrators and consumes 35–62.5 mW and achieves 2.9-dB noise figure and −2.5–5-dBm IIP3.

A New Multiple Access Technique for 5G: Power Domain Sparse Code Multiple Access (PSMA)

In this paper, a new approach for multiple access in the fifth generation (5G) of cellular networks called power domain sparse code multiple access (PSMA) is proposed. In PSMA, we adopt both the power domain and the code domain to transmit multiple users’ signals over a subcarrier simultaneously. In such a model, the same sparse code multiple-access (SCMA) codebook can be used by multiple users, where, for these users, the power domain non-orthogonal multiple access (PD-NOMA) technique is used to send signals non-orthogonally. Although the signal of different SCMA codebooks can be detected orthogonally, the same codebook used by multiple users produces interference over these users. With PSMA, a codebook can be reused in the coverage area of each base station more than one time, which can improve the spectral efficiency. We investigate the signal model as well as the receiver and transmitter of the PSMA method. In the receiver side, we propose a message passing algorithm-based successive interference cancellation detector to detect the signal of each user. To evaluate the performance of PSMA, we consider a heterogeneous cellular network. In this case, our design objective is to maximize the system sum rate of the network subject to some system level and QoS constraints such as transmit power constraints. We formulate the proposed resource allocation problem as an optimization problem and solve it by successive convex approximation techniques. Moreover, we compare PSMA with SCMA and PD-NOMA from the performance and computational complexity perspective. Finally, the effectiveness of the proposed approach is investigated using numerical results. We show that by a reasonable increase in complexity, PSMA can improve the spectral efficiency about 50% compared with SCMA and PD-NOMA.

A 79-GHz 2 $\times $ 2 MIMO PMCW Radar SoC in 28-nm CMOS

In this paper, the concept of phase modulated MIMO radars is explained and demonstrated with a 28-nm CMOS fully integrated 79-GHz radar SoC. It includes two transmitters, two receivers, and the mm-wave frequency generation. The receivers' outputs are digitized by on-chip ADCs and processed by a custom designed digital core, which performs correlation and accumulation with a pseudorandom sequence used in transmission. The SoC consumes 1 W to achieve 7.5 cm range resolution. A module with antennas allows for 5° resolution over ±60° elevation and azimuth scan in 2 × 2 code domain MIMO operation. A 4 × 4 MIMO system is also demonstrated by means of two SoCs mounted on the same module.

Classroom practice for understanding pointers using learning support system for visualizing memory image and target domain world

Pointers are difficult learning targets for novice learners of C programming. For such difficult targets, introducing a system visualizing program behaviors is generally expected to support learners to understand the targets. However, visualization in existing systems often conceals the concrete value of variables such as pointers; the way in which each visualized object is located on the memory is not made explicit. In order to address this issue, we focused on a program visualization system called TEDViT. It visualizes simultaneously and synchronously the memory image that is the field that presents the concrete value of variables and the target domain world that is the field that presents logically the data structures processed by the program. We consider that observing and comparing program code, memory image, and target domain world with TEDViT could work for understanding pointers. TEDViT visualizes the status of the target domain world according to the visualization policy defined by the teacher in order to allow teachers to set their instruction content based on the growing variety of learner background knowledge. We also consider that this feature could support teachers’ instructions and class managements appropriately, and improving teachers’ performance by TEDViT’s support would bring improvement of learners’ understanding. We conducted classroom practice for understanding pointers in connection with a memory model, thus introducing TEDViT to a real class. Analysis of answered scores in a questionnaire conducted after the practice suggests that our practice using TEDViT provided useful supports for participants to understand pointers. It also suggests our practice had a certain effect to reduce uneven levels of understanding among participants. Based on these results, we describe that classroom practices in our framework could support learners to understand pointers and support teachers to manage the class.

Associations of ERAP1 coding variants and domain specific interaction with HLA-C∗06 in the early onset psoriasis patients of India

Interferon-γ-induced aminopeptidase ERAP1 trims peptides within the endoplasmic reticulum so that they can be loaded onto MHC class I and presented to the CD8+ T-cells. ERAP1 association and its interaction with HLA-C∗06 is controversial across different populations. We have investigated the association and possible functional role of non-synonymous SNPs at different exons of ERAP1 (rs26653: Arg127Pro, rs30187: Lys528Arg and rs27044: Gln730Glu) and their interactions with HLA-C∗06 in psoriasis. Significant associations of HLA-C∗06 (OR=5.47, P<2.2×10−16), rs30187 (OR 1.35, P=7.4×10−4) and rs27044 (OR=1.24, P=5.8×10−3) were observed. All three ERAP1 SNPs showed significant association only for HLA-C∗06 positive patients, while rs30187 and rs27044 showed significant association only for early onset patients (rs30187: OR=1.47, P=9.6×10−5; rs27044: OR=1.36, P=3.3×10−4). No differential expression of ERAP1 was observed either between paired uninvolved and involved skin tissues of psoriasis patients or between non-risk and risk variants in the involved skin. Significant epistatic interaction was observed between HLA-C∗06 and the SNP (rs27044) located at the peptide-binding cavity of ERAP1. Evolutionary conservation analysis among mammals showed confinement of Lys528 and Gln730 within highly conserved regions of ERAP1 and suggested the possible detrimental effect of this allele in ERAP1 regulation.

Palmprint Recognition Based on Complete Direction Representation.

Direction information serves as one of the most important features for palmprint recognition. In the past decade, many effective direction representation (DR)-based methods have been proposed and achieved promising recognition performance. However, due to an incomplete understanding for DR, these methods only extract DR in one direction level and one scale. Hence, they did not fully utilize all potentials of DR. In addition, most researchers only focused on the DR extraction in spatial coding domain, and rarely considered the methods in frequency domain. In this paper, we propose a general framework for DR-based method named complete DR (CDR), which reveals DR by a comprehensive and complete way. Different from traditional methods, CDR emphasizes the use of direction information with strategies of multi-scale, multi-direction level, multi-region, as well as feature selection or learning. This way, CDR subsumes previous methods as special cases. Moreover, thanks to its new insight, CDR can guide the design of new DR-based methods toward better performance. Motived this way, we propose a novel palmprint recognition algorithm in frequency domain. First, we extract CDR using multi-scale modified finite radon transformation. Then, an effective correlation filter, namely, band-limited phase-only correlation, is explored for pattern matching. To remove feature redundancy, the sequential forward selection method is used to select a small number of CDR images. Finally, the matching scores obtained from different selected features are integrated using score-level-fusion. Experiments demonstrate that our method can achieve better recognition accuracy than the other state-of-the-art methods. More importantly, it has fast matching speed, making it quite suitable for the large-scale identification applications.

A novel multi-scale domain overlapping CFD/STH coupling methodology for multi-dimensional flows relevant to nuclear applications

A novel multi-scale domain overlapping coupling methodology designed to couple a computational fluid dynamics (CFD) code with a system thermal hydraulic (STH) code was developed and its performance was investigated. The methodology has been implemented in the coupling infrastructure code Janus, developed at the University of Michigan, providing methods for the on-the-fly data transfer through memory between the commercial CFD code STAR-CCM+ and the US NRC best-estimate thermal hydraulic system code TRACE. Coupling between these two software packages is motivated by the desire to extend the range of applicability of TRACE to scenarios in which local momentum and energy transfer are important, such as three-dimensional mixing of localized slugs of deborated or cold water in the downcomer and lower plenum of a reactor pressure vessel. The intra-fluid shear forces necessary to correctly capture these effects are neglected in the TRACE equations of motion, but are readily calculated from CFD solutions. CFD/STH coupling implementations therefore have applications in reactor transients such as boron dilution scenarios, Anticipated Transient Without SCRAM (ATWS) and Main Steam Line Break (MSLB).The proposed method is based on aliasing all spatial sources and sinks of momentum in the CFD domain as frictional losses in the system code domain. The internal velocity fields and, consequently, the inertial component of the pressure field are maintained consistent between the CFD and STH domains through a complementary velocity-matching interface. In this paper, coupled simulations are performed on Cartesian and cylindrical geometry with emphasis on consistency, convergence, and stability during transient scenarios. Results show that the presented domain overlapping coupling method is capable of adjusting pressure and velocity profiles of multi-dimensional system code solutions to match CFD solutions accurately. Important characteristics of transient simulations were found to include the background flow rate, specifically the stabilizing effect of viscous forces, as well as the time derivative of the flow rate. Under certain adverse conditions, the basic coupling method is found to produce unstable behavior. A stabilization method for adjusting CFD data is laid out and found to significantly improve the method’s performance under the most challenging conditions. Recommendations are laid out for further improving the coupling via advanced time stepping methods.

Energy-Saving Resource Management for D2D and Cellular Coexisting Networks Enhanced by Hybrid Multiple Access Technologies

In this paper, we investigate the energy-saving resource management problem for a new device-to-device (D2D) and cellular coexisting network, where D2D users employ orthogonal frequency division multiple access (OFDMA) and cellular users employ sparse code multiple access (SCMA). This hybrid network can support massive connectivity by exploiting the degrees of freedom in code and space domains, however, the complicated spectrum sharing pattern also leads to serious interference, which further boosts the power consumption of mobile devices (MDs). To tackle this problem, we propose a unified resource management scheme to minimize the total transmit power of all MDs by jointly optimizing mode selection, resource allocation, and power control. First, we analytically get the optimal resource-sharing mode (dedicated mode or reuse mode) for cellular users and D2D users based on the mapping rule between SCMA codebooks and OFDMA resource blocks. For each resource-sharing mode, we reformulate the resource management problems as classical problems in graph theory, and then devise efficient algorithms leveraging the special structure of the constructed graphs. Finally, simulation studies indicate that the network capacity is upgraded with the hybrid multiple access technologies, and the energy efficiency performance is also enhanced through the unified resource management.

The information capacity of the genetic code: Is the natural code optimal?

We envision the molecular evolution process as an information transfer process and provide a quantitative measure for information preservation in terms of the channel capacity according to the channel coding theorem of Shannon. We calculate Information capacities of DNA on the nucleotide (for non-coding DNA) and the amino acid (for coding DNA) level using various substitution models. We extend our results on coding DNA to a discussion about the optimality of the natural codon-amino acid code. We provide the results of an adaptive search algorithm in the code domain and demonstrate the existence of a large number of genetic codes with higher information capacity. Our results support the hypothesis of an ancient extension from a 2-nucleotide codon to the current 3-nucleotide codon code to encode the various amino acids.

Molecular cloning and functional analysis of a novel phytoglobin gene from the alpine plant Stipa purpurea

Background: Stipa purpurea, the dominant species of the alpine steppe in the Tibetan Plateau, survives well under various abiotic stresses including drought, hypoxia and chilling.Aims: To understand the molecular mechanism by which alpine plants including S. purpurea adapt to the abiotic environmental factors of the Tibetan Plateau.Methods: We cloned the coding domain sequence of one Phytogb gene from S. purpurea using the rapid amplification of cDNA ends method and analysed its function by heterologous expression in Arabidopsis.Results: The Phytogb gene, which we named StipurPhytogb1, included 474 nucleotides and encoded a protein of 157 amino acids. Functional analyses showed that StipurPhytogb1 could improve the resistance of transgenic Arabidopsis to drought and hypoxia caused by waterlogging. Further analyses suggested that StipurPhytogb1 improved the above resistance by inhibiting nitric oxide accumulation and mediating the induction of antioxidant enzyme activities to scavenge reactive oxygen species.Conclusion: These findings indicate that StipurPhytogb1 may play an essential role in the adaptation of S. purpurea to drought and the hypoxic environment of the Tibetan Plateau and has potential as a candidate gene for genetic transformation to improve plant stress tolerance.

Single Carrier Frequency Domain Equalization with Space-Time Trellis Codes

Orthogonal Frequency Division Multiplexing (OFDM) is readily employed in wireless communication to combat the intersymbol interference (ISI) effect with limited success because as the capacity of MIMO systems increases, other destructive effects affect the propagation channels and/or overall system performance. As such, research interest has increased, on how to improve performance in the mediums where fading and ISI permeate, working on several combinatorial techniques to achieving improved effective throughput. In this study, we propose a combined model of the Space-Time Trellis Code (STTC) and Single-Carrier Frequency Domain Equalization (SC-FDE) to mitigate multiple-fading and interference effects. We present analytical performance results for the combined model over spatially correlated Rayleigh fading channels. We also show that it is beneficial to combine coding with equalization at the system’s receiving-end ensuring overall performance: a better performance over the traditional space-time trellis codes.

Putative HIV and SIV G-Quadruplex Sequences in Coding and Noncoding Regions Can Form G-Quadruplexes.

The HIV virus is one of the most studied viruses in the world. This is especially true in terms of gene sequencing, and to date more than 9 thousand genomic sequences of HIV isolates have been sequenced and analyzed. In this study, a series of DNA sequences, which have the potential to form G-quadruplex structures, is analyzed. Several such sequences were found in various coding and noncoding virus domains, including the U3 LTR, tat, rev, env, and vpx regions. Interestingly, a homological sequence to the already well-known HIV integrase aptamer was identified in the minus-strand. The sequences derived from original isolates were analyzed using standard spectral and electrophoretic methods. In addition, a recently developed methodology is applied which uses induced circular dichroism spectral profiles of G-quadruplex-ligand (Thiazole Orange) complexes to determine if G-rich sequences can adopt G-quadruplex structure. Targeting the G-quadruplexes or peptide domains corresponding to the G-rich coding sequence in HIV offers researchers attractive therapeutic targets which would be of particular use in the development of novel antiviral therapies. The analysis of G-rich regions can provide researchers with a path to find specific targets which could be of interest for specific types of virus.

Precise Failure Location and Protection Mechanism in Long-Reach Passive Optical Network

In this paper, optical code domain reflectometer (OCDR) and optical time domain reflectometer (OTDR) are used for centralized monitoring and troubleshooting any fault occurring in the network. It combines the advantages of the OTDR scheme and the optical coding scheme, which can supervise the whole long-reach passive optical network in a cost-effective manner. Network management system in the central office can initialize monitoring, locating failure, and protection process by monitoring information. The scheme can locate the faulty point precisely by OTDR after determining the failed optical fiber link by the optical coding technique. The OTDR precise positioning and protection scheme can be carried out simultaneously, thus saving recovery time. Furthermore, network performance of OCDR and OTDR, recovery time, loss, cost, bit error rate of data signal transmission are also studied. The results obtained prove the feasibility and efficiency of the proposed network, and that it can support high network capacity.

General purpose multiplexing device for cryogenic microwave systems

We introduce and experimentally characterize a general purpose device for signal processing in circuit quantum electrodynamics systems. The device is a broadband two-port microwave circuit element with three modes of operation: it can transmit, reflect, or invert incident signals between 4 and 8 GHz. This property makes it a versatile tool for lossless signal processing at cryogenic temperatures. In particular, rapid switching (≤15 ns) between these operation modes enables several multiplexing readout protocols for superconducting qubits. We report the device's performance in a two-channel code domain multiplexing demonstration. The multiplexed data are recovered with fast readout times (up to 400 ns) and infidelities ≤10−2 for probe powers ≥7 fW, in agreement with the expectation for binary signaling with Gaussian noise.

On Novel Access and Scheduling Schemes for IoT Communications

The Internet of Things (IoT) is expected to foster the development of 5G wireless networks and requires the efficient support for a large number of simultaneous short message communications. To address these challenges, some existing works utilize new waveform and multiuser superposition transmission schemes to improve the capacity of IoT communication. In this paper, we will investigate the spatial degree of freedom of IoT devices based on their distribution, then extend the multiuser shared access (MUSA) which is one of the typical MUST schemes to spatial domain, and propose two novel schemes, that is, the preconfigured access scheme and the joint spatial and code domain scheduling scheme, to enhance IoT communication. The results indicate that the proposed schemes can reduce the collision rate dramatically during the IoT random access procedure and improve the performance of IoT communication obviously. Based on the simulation results, it is also shown that the proposed scheduling scheme can achieve the similar performance to the corresponding brute-force scheduling but with lower complexity.

P53 and HIC1 in Brain Cancer Gliomas

Hypermethylated in Cancer 1 (HIC1) is a novel tumor suppressor gene (TSG) which acts as a transcriptional enhancer and growth obliterator, identified by Baylin et al. more than 10 years back. HIC1 is found to be methylated in varieties of human cancers as seen in ductal carcinoma of the breast wherein promoter methylation and allelic loss of 17p13.3 chromosomal locus has been reported without any significant mutation in p53 gene. To determine the targets, Zhang et al. reported that Ephrin-A1 is one potential target for the TSG role of HIC1 in breast cancer cells. The region 17p13.3 consists of Variable Number of Tandem Repeats (VNTR) microsatellite markers such as YNZ22/D17S5/D17S30 and show intermittent DNA hypermethylation in neural cancer, colon cancer and lung cancer. Epigenetic silencing also is very commonly observed in liver cancer, breast cancer, gastric cancer, prostate cancer and is also seen in human male nonseminomatous germ cell tumors. The central coding domain of HIC1 exhibits elevated and eminent level of methylation in acute myeloid leukemia. Our laboratory had showed that 17p13.3 was preferentially affected in high grade primary human gliomas and the same was associated with increased p53 immunopositivity and proliferation within a particular tumor grade. Both HIC1 and p53 are catalogued as tumor repressors, HIC1 practically comply with p53 in cells cultures in laboratory as well as in genetically modified transgenic animals to repress/supress tumors and have binding sites on their promoters. Since P53 has binding site onto the promoter of HIC1 it transcriptionally up-regulates its expression. In corroboration, our result did showed an increased expression of HIC1 with wild type p53 containing U87MG cells whereas less or no expression with mutated cell lines (U373MG) or null p53 (SaOS-2) (Sanjay et al.). The ambiguity was previously reported that wild type P53 continuously being formed and degraded by ubiquitination and proteasomal mediated pathway in absence of stress signal. On contrary, mutant forms of P53 are usually stable and escape degradation from ubiquitination pathway. We observed almost no expression of p53 in U87MG and SaOS-2 cells whereas U373MG showed high level of mutated p53. Conventionally HIC1 is a tumour suppressor gene (TSG), hence the over expression of this gene leads to arrest of cell cycle. Since HIC1 plays the role of TSG, the activities like cell cycle regulation and p53 dependency is not known. We have done a research on the activity of HIC1 in cell cycle as well as during glioma cell line (U87MG) proliferation, that had the wild type p53 gene in both serum containing and serum deprived medium. Reduction in number of cells and cell proliferation was revealed during HIC1 knocking as compared to control siRNA of cells without any treatment with serum containing medium and serum free medium. Flow cytometry and FacsDiva software verified the arrest of the cell cycle at the G2-M phase without any significant increase in the number of cell death i.e., cell apoptosis in both the medium. An increase in the expression of p53 gene associated with the knockdown of the HIC1 was seen. Moreover, we observed an increase in p21, p27 along with p53 gene when compared to the controls. The expression level of another cell cycle regulatory protein p27 found to be very significantly high comparing to controls. This could be the cause of arresting the cell cycle even after knocking down a tumor suppressor gene like HIC1, which was quite unexpected and beyond the convention. The results revealed the significance of HIC1 in the normal progression of cell cycle and also its activity the at molecular level, affecting the homeostasis of p53 gene as well as a number of genes, which are directly or indirectly related to p53, taking part in the cell cycle process.

What recommendation systems for software engineering recommend: A systematic literature review

A recommendation system for software engineering (RSSE) is a software application that provides information items estimated to be valuable for a software engineering task in a given context. Present the results of a systematic literature review to reveal the typical functionality offered by existing RSSEs, research gaps, and possible research directions. We evaluated 46 papers studying the benefits, the data requirements, the information and recommendation types, and the effort requirements of RSSE systems. We include papers describing tools that support source code related development published between 2003 and 2013. The results show that RSSEs typically visualize source code artifacts. They aim to improve system quality, make the development process more efficient and less expensive, lower developer’s cognitive load, and help developers to make better decisions. They mainly support reuse actions and debugging, implementation, and maintenance phases. The majority of the systems are reactive. Unexploited opportunities lie in the development of recommender systems outside the source code domain. Furthermore, current RSSE systems use very limited context information and rely on simple models. Context-adapted and proactive behavior could improve the acceptance of RSSE systems in practice.