To sustain dense user equipment (UE) deployments, one of the difficult issues is to provide a proficient way to various channel access in the cellular communication networks, such as long-term evolution-Advanced (LTE-A) networks. In LTE-A, random access (RA) is the necessary process to set up the wireless connection between a UE and an evolved node B (eNB). The performance of the RA straightforwardly influences the performance of the whole system. Currently, a discrete uniform distribution (DUD) is used to avoid the potential collision in the network, while multiple UEs try to access the channel resources. However, in a DUD, every UE has an equal chance to choose similar contention preamble near to the expected value of the DUD, which may cause an increase in a collision among the UEs. In this work, we propose a method based on the existing alternatives, such as continuous exponential distribution (CED). CED distributes the random values between two bounds in a poison point process, in which random variables occur continuously and independently with a constant average rate. In this way, our proposed method can distribute the UEs in a parametric set of the probability distribution. Our proposed mechanism is named as CED RA (CED-RA), which replaces the DUD mechanism in RA with CED to show enhanced reliability and lower latency.

Nonorthogonal multiple access (NOMA) is one of the few promising techniques that can ensure the achievement of benefits foreseen in next‐generation 5G wireless networks and beyond. By using superposition coding, NOMA allows multiple users to share the same time and frequency resources, thereby enhancing user connectivity, spectral efficiency, and a considerable increase in user throughput. Interference mitigation is an important consideration in NOMA and is considerably more influencing in multicellular environments. First, a brief description of the impairments that can arise in a NOMA cellular network along with responsible factors is provided. Second, different approaches adopted to minimize these impairments are discussed. Finally, a possible solution is proposed that consists of a coordinated approach between the individual cells in the NOMA domain to minimize interferences and improve user throughput. Adaptive fractional frequency reuse (FFR) is used to allocate distinct frequency resources to edge users of different cells to minimize intercell interference in NOMA. Simulation results prove that the proposed NOMA scheme plays an important role in minimizing impairment effects and enhancing the SINR and the throughput performance of edge users while ensuring fairness in its design.

In CPU, SOC, GPU, and PC-on-chip, I/O power consumption can be significant. To improve power efficiency, I/O bundles in group of 4, 8, or 16b, should scale their data rate according to the application requirements. However, clocking architecture imposes significant challenges to support different data rate simultaneously. In high bandwidth I/O, LC oscillators are preferred for low jitter, but the limited frequency range confines the data rate tuning. Multiple LC-PLLs are costly in area and power, and sometimes infeasible due to heavily congested I/O area. Worse still, couplings between inductors could lead to PLL pulling closing the sampling eye. In this paper, a reconfigurable 0.65-10GHz digital fractional-n clock generator using a single LC PLL, calibrated 0.75/1.25/1.75 digital fractional post dividers for serial I/O is presented. The architecture enables I/O driven by the same PLL to operate at different data rate, thereby reducing power. In addition, multiple LC-PLLs are replaced by one saving area, power, and coupling between LC oscillators. The PLL incorporates a staggered varactor, wide-tuning VCO, and a hysteretic redundant frequency acquisition for improved temperature stability. The prototype in a 32nm high-k metal gate process has a measured TX/RX jitter of 0.9/0.3 ps/σ and dissipates 36.2mW from 1.05V supply.

A cognitive radio (CR) is the most promising candidate for the successful deployment of dynamic spectrum access (DSA). To embed DSA in a wireless sensor network, a CR is required to be installed on each sensor node. Such a sensor network is known as a cognitive radio sensor network (CRSN). Spectrum sensing is a prerequisite for a CR. Therefore every node in the CRSN consumes energy for spectrum sensing. To achieve a high-sensing accuracy, the nodes share sensing results among themselves, which is known as cooperative spectrum sensing (CSS). CSS improves sensing; however it increases energy consumption and shortens the lifetime of the network. As a CRSN is characterised as an energy constraint network, to prolong the lifetime of the network, the number of cooperating nodes should be minimum. This study presents a user selection scheme to minimise the overhead energy consumed by CSS in a CRSN. On the basis of the binary knapsack problem and its dynamic programming solution, the proposed technique selects the best nodes among the potential nodes subject to the energy constraint of the CRSN. The simulation results indicate the advantages of employing the proposed method, depending on the desired performance-energy consumption tradeoff.

This study proposes an intelligent real-time odor monitoring system for monitoring odor problems, a new type of environmental problems, in real-time and for managing harmful substances. This system minimizes the measurement error of individual sensors by building a gas sensor array integrating 8 sensors, and applies a pattern recognition algorithm revised for accurate data analysis. The revised pattern recognition algorithm evaluates the similarity of patterns by combining ANN (Artificial Neural Networks) in testing the similarity and fitness of GA (Genetic Algorithm) in order to enhance the reliability of harmful gas pattern extraction. Moreover, the proposed system applies PCA (Principal Component Analysis) for the clustering of each gas pattern. What is more, this study designs a pattern matching algorithm and compares with data in the built DB in order to identify output malodorous substances. In addition, the outcomes are evaluated through the comparison of the ANN, GA and proposed ANN-GA algorithms. As the proposed system can enhance the reproducibility, reliability and selectivity of odor sensor output, it is expected to be applicable to diverse environmental problems including air pollution.

Disseminating data generated by sensors to users is one of useful functions of sensor networks. In probable real-time applications of sensor networks, multiple mobile users should receive data within their end-to-end delay constraint. In this paper, we propose a dynamic DElay-constrained minimum-Energy Dissemination (DEED) scheme. A dissemination tree (d-tree) is updated in a distributed way without regenerating the tree from scratch, such that energy consumption of the tree is minimized while satisfying end-to-end delay constraints. The d-tree is adjusted using delay estimation based on geometric distance. DEED increases the probability that packets arrive at users within an upper-bound end-to-end delay (UBED) and minimizes energy consumption in both building the d-tree and disseminating data to mobile sinks. Evaluation results show that DEED makes each node consume small energy resources and maintains fewer UBED misses when compared to Directed Diffusion and other baselines for sensor networks.

When a robot navigates in the unstructured environment, it frequently meets various objects capable of being represented as a simple geometrical primitives such as planes, spheres, cylinders, and their combinations. In this paper, we propose a method for the perception of the environment with a low cost two degree-of-freedom IR (infrared) scanner, which can be used for navigation of the quadruped walking robot. Our work is mainly focused on the development of an algorithm for real-time modeling of the environment and the shape reconstruction of the environment. Though the proposed algorithm is very simple, it is useful to determine the geometrical features of the object as well as provide sufficient information for navigation of the robot. Using the proposed method, a method for gait control of the quadruped walking robot can be generated. The validity of the proposed algorithms are demonstrated through experiments using a quadruped walking robot called "MRWALLSPECT III(Multifunctional Robot for WALL inSPECTion version 3)".

This paper describes an integrated approach for the design of a quadruped robot, called "MRWALLSPECT III (multifunctional robot for wall inspection version 3)", which walks in planes as well as climb walls with suction pads. Since the robot is expected to be able to move from wall to wall to plane including negotiating convex or concave corners, a comprehensive study is needed to develop the robot by performing intuitive and geometrical analysis, critical aspects of design such as joint ranges, design of ankles, and location of actuators are discussed. Environmental geometries are classified into several groups, and criteria for design are proposed for each case. The proposed criteria are applied to the actual design of MRWALLSPECT III designed to carry an ultrasonic NDT tool for inspection of the large surface of industrial utilities. By implementing the proposed idea on the robot its effectiveness is experimentally confirmed.

Data dissemination from sources to sinks is one of the main functions in sensor networks. In this paper, we propose SEAD, a Scalable Energy-efficient Asynchronous Dissemination protocol, to minimize energy consumption in both building the dissemination tree and disseminating data to mobile sinks. SEAD considers the distance and the packet traffic rate among nodes to create near-optimal dissemination trees. The sinks can move without reporting their location to the tree while receiving data updates successfully. Our evaluation results illustrate that SEAD consumes less energy on building and maintaining a dissemination tree to multiple mobile sinks compared to other approaches such as directed diffusion, TTDD, and mobile ad hoc multicast.

In this paper, a new communication network with high safety, maintainability, and user convenience for digital I and C systems of nuclear power plants are proposed based on integrated design concepts, such as simple structure, standardized protocol, hard real-time property, high-speed data rate, fault-tolerance, verification and validation, hierarchical architecture, data transfer control using data gateway, and enhanced network management. Components of the proposed communication network are three level networks such as a field network, a control network, and an information network, a data gateway between the control network and the information network, and data gateway between control divisions. A new data flow concept for enhancing independence and user convenience in the data gateway between the control network and the information network is proposed. The architectures of three level networks and both gateways are proposed.

This paper proposes a translation method for programmable logic controllers (PLCs) used in most automation systems. It describes detailed steps of the method that converts from a ladder diagram directly to a native code. A general-purpose DSP (digital signal processor) based PLC with the translation method is implemented. A benchmark test in an automotive manufacturing process shows that the proposed translation method fairly speeds up the execution in comparison with existing interpretation methods.