Cloud gaming systems allow users to play games that require high-performance computational capability on their mobile devices at any location. However, playing games through cloud gaming systems increases the Round-Trip Time (RTT) due to increased network delay. To simulate a local gaming experience for cloud users, we must minimize RTTs, which include network delays. The speculative video transmission pre-generates and encodes video frames corresponding to all possible user inputs and sends them to the user before the user’s input. The speculative video transmission mitigates the network, whereas a simple solution significantly increases the video traffic. This paper proposes tile-wise delta detection for traffic reduction of speculative video transmission. More specifically, the proposed method determines a reference video frame from the generated video frames and divides the reference video frame into multiple tiles. We calculate the similarity between each tile of the reference video frame and other video frames based on a hash function. Based on calculated similarity, we determine redundant tiles and do not transmit them to reduce traffic volume in minimal processing time without implementing a high compression ratio video compression technique. Evaluations using commercial games showed that the proposed method reduced 40-50% in traffic volume when the SSIM index was around 0.98 in certain genres, compared with the speculative video transmission method. Furthermore, to evaluate the feasibility of the proposed method, we investigated the effectiveness of network delay reduction with existing computational capability and the requirements in the future. As a result, we found that the proposed scheme may mitigate network delay by one to two frames, even with existing computational capability under limited conditions.

This paper proposes a protocol verification tool where protocols are described in an extended Petri net and Horn clauses. The extended net model contributes to reduce state space in verification with hierarchical description. The model also includes timed and colored net. Horn clause enables protocol designers to grasp a protocol by the declarative semantics. They can describe non critical but mandatory portion of a protocol like error processing or abortion with Horn clauses. Protocols are verified through simulation. Protocol verification includes two methods, all-in-one and hierarchical methods. By the all-in-one method all description is translated into Prolong clause and simulated exhaustively, whereas by the hierarchical verification, simulation begins with the lowest layer and deduces sufficient conditions that give liveness and safeness of the net model. Then the layer is replaced by a simpler net model that is incorporated into the higher layer. The scheme is applied to an illustrative example of the Alternating Bit protocol to discuss its effectiveness.

Three custom LSIs for EB60, a direct wafer exposure electron beam system, have been developed using 0.8 µm BiCMOS and SST bipolar technologies. The three LSIs are i) a shot cycle control LSI for controlling each exposure cycle time, ii) a linear matrix computation LSI for coordinate modification of the exposure pattern data, and iii) a position calculation LSI for determining the precise position of the wafer. These LSIs allow the deflection corrector block of the revised EB60 to be realized on a single board. A new adaptive pipeline control technique which optimizes each shot period according to the exposure data is implemented in the shot-cycle control LSI. The position calculation LSI implements a new, highly effective 2-level pipeline exposure technique, the levels refer to major-field-deflection and minor-field-deflection. The linear-matrix computation LSI is designed not only for the EB60 but also for a wide variety of parallel digital processing applications.

A number of mobile hosts might be densely staying in an area caused by traffic congestions. The greater part of the mobile hosts will require commonly useful data, such as traffic information, parking information and other driving related information in such environment. Simultaneous data transmission broadcasts using a common link are regarded as a suitable means to distribute this location-dependent information. However, there is no guarantee that mobile hosts can finish receiving the information completely within a limited time. In this paper, we propose a data retransmission method for communications between a base station and mobile hosts and a data recovery processing method for use between base stations. The data retransmission method called "TOA" (The Order of Arrival) schedules retransmission data specified in the first NACK request received after retransmission processing. We have proposed "Advanced" Join system in which a base station makes consolidated join requests to a multicast group on behalf of mobile hosts. Applying the TOA method to resending in the Advanced Join system, data-receiving efficiency is higher than with the simple Advanced Join system and the absolute number of completed mobile host data reception is higher. Using the TOA method, even with the base station disposition rate of 50% the number of completed reception is higher than with the Advanced Join system at 80%. The proposed reliable multicasting system to the DSRC-based ITS network can realize an efficient base station arrangement in the ITS network infrastructure and contribute to the deployment of a superior ITS.

In order to further reduce the transmission rate of multi-channel satellite broadcast signals, whose carrier-to-noise ratio (CNR fluctuates due to rainfall attenuation, we propose a novel digitized radio-over-fiber (DRoF) -based optical re-transmission system based on adaptive combination compression for ultra-high definition (UHD) broadcasting satellite (BS)/communications satellite (CS) broadcast signals. The proposed system reduces the optical re-transmission rate of BS/CS signals as much as possible while handling input CNR fluctuations. Therefore, the transmission rate of communication signals in time-division multiplexing (TDM) transmission is ensured, and network sharing of communication signals and broadcast signals via passive optical network (PON) is realized. Based on the ITU-R P.618-13 prediction model, an experimental evaluation is performed using estimates of the long-term statistics of attenuation due to rainfall. The attenuation is evaluated as a percentage of the time that long-term re-transmission service is available. It is shown that the proposed system is able to accommodate a wide range of rainfall attenuation and achieve a 99.988% time percentage for the duration of service provision. In order to show the rate reduction effect of the proposed system, the quantization bit reduction effect as a function of the input CNR, which depends on rainfall attenuation, is experimentally confirmed. Experiments show that service operation time of 99.978% can be achieved by 3-bit transmission. This means a 62.5% reduction in transmission rate is realized compared to conventional fixed quantization. Furthermore, the average quantization bit number in our system for service operation times is 3.000, indicating that most service operation times are covered by just 3-bit transmission.

The development of multi-view video has paved the way for emerging 3D applications. In general multi-view video streaming, video frames for all viewpoints, i.e., cameras, must be transmitted to viewers because the view-switching demands of all viewers are unpredictable. However, existing transmission schemes are highly vulnerable to frame loss. Specifically, frame loss in one viewpoint can induce a collapse in decoding for other viewpoints. To improve loss-resilience, this paper proposes a multi-path based multi-view video transmission scheme. Our scheme encodes video frames into multiple versions that are independent of each other, using inter-view prediction. The scheme then transmits each version using multiple transmission paths. Our scheme makes three contributions: 1) it reduces video traffic even for a large number of cameras, 2) it prevents an increase in the number of undecoded video frames caused by single-frame loss, and 3) it conceals frame loss by taking video frames from other paths. Evaluations show that our proposed scheme improves video quality by 3 dB, as compared to existing transmission schemes in loss-prone environments.

The goal of this study was to design a practical fuzzy controller of the cycle-to-cycle control for multi-joint movements of swing phase of functional electrical stimulation (FES) induced gait. First, we designed three fuzzy controllers (a fixed fuzzy controller, a fuzzy controller with parameter adjustment based on the gradient descent method, and a fuzzy controller with parameter adjustment based on a fuzzy model) and two PID controllers (a fixed PID and an adaptive PID controllers) for controlling two-joint (knee and ankle) movements. Control capabilities of the designed controllers were tested in automatic generation of stimulation burst duration and in compensation of muscle fatigue through computer simulations using a musculo-skeletal model. The fuzzy controllers showed better responses than the PID controllers in the both control capabilities. The parameter adjustment based on the fuzzy model was shown to be effective when oscillating response was caused due to the inter-subject variability. Based on these results, we designed the fuzzy controller with the parameter adjustment realized using the fuzzy model for controlling three-joint (hip, knee, and ankle) movements. The controlled gait pattern obtained by computer simulation was not significantly different from the normal gait pattern and it could be qualitatively accepted in clinical FES gait control. The fuzzy controller designed for the cycle-to-cycle control for multi-joint movements during the swing phase of the FES gait was expected to be examined clinically.

A new CCD linear image sensor with 2,048 elements has been developed by introducing photodiode processed by selective oxidation and ion implantation technologies. This construction provides high quantum efficiency at visible light with smooth spectral response, an output non-uniformity of1.5% and a dark current saturation time of 20 s. A transfer efficiency of 99.999% is achieved from a two-phase buried channel CCD. Transfer loss mechanism at a transfer gate was examined and the minimum aperture time of the gate proved to be as low as 1 µs. Spatial resolution of the device is superior to conventional sensors because of sharp sensitivity profile of the photoelement.

A simple, low reflection, and highly-efficient pilot-plant scale microwave irradiation reactor for woody biomass pretreatment was fabricated. Pretreatment is an essential process for effective bioethanol production. The fabricated reactor consists of 8 microwave irradiators which are attached to a metal pipe. The woody biomass mixture which contains water and organic acid flows through the metal pipe and is heated by microwaves at a total power of 12,kW. To design the microwave irradiators, we used a 3D Finite Element Method (FEM) simulator, which was based on the measured complex permittivity data of the woody biomass mixture. The simulation results showed that the reflection coefficient $|S_{11}|$ from the reactor was less than -30,dB when the woody biomass mixture temperature was between 30$^{circ}$C and 90$^{circ}$C. Finally, we experimentally confirmed that the fabricated irradiation reactor yielded a microwave absorption efficiency of 79%.

The aim of this study is to realize a simplified gait analysis system using wearable sensors. In this paper, a joint angle measurement method using Kalman filter to correct gyroscope signals from accelerometer signals was examined in measurement of hip, knee and ankle joint angles with a wireless wearable sensor system, in which the sensors were attached on the body without exact positioning. The lower limb joint angles of three healthy subjects were measured during gait with the developed sensor system and a 3D motion measurement system in order to evaluate the measurement accuracy. Then, 10 m walking measurement was performed under different walking speeds with a healthy subject in order to find the usefulness of the system as a simplified gait analysis system. The joint angles were measured with reasonable accuracy, and the system showed joint angle changes that were similar to those shown in a previous report as walking speed changed. It would be necessary to examine the influence of sensor attachment position and method for more stable measurement, and also to study other parameters for gait evaluation.

In this study, we aimed to realize a method of presenting dynamic electrocutaneous sensation patterns as a user interface for persons with disabilities. In this study, the previously used pulse width (200 µs) was used in pattern recognition testing on the forearm and was compared with the short pulse width (80 µs) used for stimulation. A cathodic pulse with a frequency of 100 pps, which was suggested to be suitable in our previous study, was used. Experimental results on neurologically intact subjects suggested that the previously used pulse width was suitable and that a short pulse width would not be effective for stabilizing the stimulation amplitude or for improving the pattern recognition ability of our method.

In this paper, we propose the architecture of BALANCE (Better Adaptive Load-balancing through Acquiring kNowledge of Characteristic of an Environment) in which users can submit their jobs without acquiring either a status of an environment or characteristics of jobs and servers even in a widely connected heterogeneous network. The architecture of BALANCE includes three types of information bases and two types of daemons. Information bases, namely job, resource, and environment information base, manage the knowledge of job characteristics, available resources for CPUs, and status of the environment, respectively, as a proxy for users. The dispatching daemon selects an adequate server for each job using knowledge stored in the information bases. A service daemon executes each job. On completing each job, a service daemon gets a statistic of the job and returns it to the dispatching daemon where the job came from so that the statistic will be available at the next dispatching time. BALANCE enables an environment (1) to balance the load, (2) to share software functions as well as hardware facilities, and (3) to learn a user's job characteristics. We have implemented a prototype with more than 50 heterogeneous UNIX workstations connected by different networks. Two simple experiments on this prototype are presented. These experiments show a load balancing scheme that takes the characteristics of each job into account.

We proposed a fuzzy control scheme to implement the cycle-to-cycle control for restoring swing phase of gait using functional electrical stimulation (FES). We designed two fuzzy controllers for the biceps femoris short head (BFS) and the vastus muscles to control flexion and extension of the knee joint during the swing phase. Control capabilities of the designed fuzzy controllers were tested and compared to proportional-integral-derivative (PID) and adaptive PID controllers in automatic generation of stimulation burst duration and compensation of muscle fatigue through computer simulations using a musculo-skeletal model. Parameter adaptations in the adaptive PID controllers did not significantly improve the control performance of the PID controllers. The fuzzy controllers were superior to the PID and adaptive PID controllers under several subject conditions and different fatigue levels. These results showed the fuzzy controller would be suitable to implement the cycle-to-cycle control of FES-induced gait.

Coexistence between ZigBee and Wi-Fi technologies, which operate within the same frequency band, is increasing with the widespread use of the IoT (Internet of Things). ZigBee devices suffer significant decreases in the sink arrival rate of packets in the presence of Wi-Fi interference. To overcome this problem, many channel control methods have been proposed. These methods switch only ZigBee channels to avoid interference with Wi-Fi. In contrast, we propose a cooperative channel control method for improving ZigBee packet arrival rate by controlling both the Wi-Fi and ZigBee channels. Specifically, the proposed method not only controls ZigBee devices and channels but also requests a temporary pause in the use of specific Wi-Fi channels. Finally, computer simulations show the effectiveness of the proposed method from the viewpoints of ZigBee's packet arrival rate and applications' satisfaction. In addition, the feasibility of the proposed method is also confirmed by experiments with prototyping.

When an access point transmits multi-view video over a wireless network with subcarriers, bit errors occur in the low quality subcarriers. The errors cause a significant degradation of video quality. The present paper proposes Significance based Multi-view Video Streaming with Subcarrier Allocation (SMVS/SA) for the maintenance of high video quality. SMVS/SA transmits a significant video frame over a high quality subcarrier to minimize the effect of the errors. SMVS/SA has two contributions. The first contribution is subcarrier-gain based multi-view rate distortion to predict each frame's significance based on the quality of subcarriers. The second contribution is heuristic algorithms to decide the sub-optimal allocation between video frames and subcarriers. The heuristic algorithms exploit the feature of multi-view video coding, which is a video frame is encoded using the previous time or camera video frame, and decides the sub-optimal allocation with low computation. To evaluate the performance of SMVS/SA in a real wireless network, we measure the quality of subcarriers using a software radio. Evaluations using MERL's benchmark test sequences and the measured subcarrier quality reveal that SMVS/SA achieves low traffic and communication delay with a slight degradation of video quality. For example, SMVS/SA improves video quality by up to 2.7 [dB] compared to the multi-view video transmission scheme without subcarrier allocation.

The recent widespread use of high-performance terminals has resulted in a rapid increase in mobile data traffic. Therefore, public wireless local area networks (WLANs) are being used often to supplement the cellular networks. Capacity improvement through the dense deployment of access points (APs) is being considered. However, the effective throughput degrades significantly when many users connect to a single AP. In this paper, users are classified into guaranteed bit rate (GBR) users and best effort (BE) users, and we propose a network model to provide those services. In the proposed model, physical APs and the bandwidths are assigned to each service class dynamically using a virtual AP configuration and a virtualized backhaul network, for reducing the call-blocking probability of GBR users and improving the satisfaction degree of BE users. Finally, we evaluate the performance of the proposed model through simulation experiments and discuss its feasibility.

Recent works on enhancing the comfort and convenience of vehicles have revealed the advantage of various wireless sensor nodes for information collection. For the highly required reliability in vehicles, Reliable Wireless Communication based on Substitute Forwarding (RWCSF) has been proposed. It ensures that 99.999% of communications can finish within 20ms, which is the quality of communication equivalent to wired links. However, the performance was evaluated in very limited situations, where two or more communications never occurred simultaneously and no noise was present. In this paper, we enhance RWCSF to achieve the target communication quality even if two or more communications occur simultaneously. In addition, we evaluate the enhanced method in various types of vehicles that create internal noise.

With the widespread diffusion of Internet of Things (IoT), the number of applications using wireless sensor devices are increasing, and Quality of Service (QoS) required for these applications is diversifying. Thus, it becomes difficult to satisfy a variety of QoS with a single wireless system, and many kinds of wireless systems are working in the same domains; time, frequency, and place. This paper considers coexistence environments of ZigBee and Wi-Fi networks, which use the same frequency band channels, in the same place. In such coexistence environments,ZigBee devices suffer radio interference from Wi-Fi networks, which results in severe ZigBee packet losses because the transmission power of Wi-Fi is much higher than that of ZigBee. Many existing methods to avoid interference from Wi-Fi networks focus on only one of time, frequency, or space domain. However, such avoidance in one domain is insufficient particularly in near future IoT environments where more ZigBee devices and Wi-Fi stations transfer more amount of data. Therefore, in this paper, we propose joint channel allocation and routing in both frequency and space domains. Finally, we show the effectiveness of the proposed method by computer simulation.

A multicast (point-to-multipoint) protocol of a satellite broadcast channel by a source and many destinations is presented and its performance characteristics are analyzed. We propose a new time-domain multicast scheme for packet satellite channels, retransmission via collisions protocol (called RVCP). RVCP is classified to the automatic repeat request (ARQ) of the multi-selective-repeat scheme and does not require individual channels for each receiving station to request for broadcast packets that have been received incorrectly. Our analytical models show that RVCP performs considerably better than the other protocols, particularly in the situation that packet error rate is less than 10-4 or there are a large number of destinations. It is an excellent characteristic of RVCP that the equipment of the source station need not increase in proportion to the number of destinations, too. And since RVCP is a relatively simple protocol, it is easy to be implemented.

The cycling wheelchair “Profhand” was developed in Japan as locomotion and lower limb rehabilitation device for hemiplegic subjects and elderly persons. Functional electrical stimulation (FES) control of paralyzed lower limbs enables application of the Profhand to paraplegic subjects as a rehabilitation device. In this paper, simplified muscle stimulation control for FES cycling with Profhand was examined for practical application, because cycling speed was low and not stable in our preliminary study and there was a difficulty in setting stimulation electrodes for the gluteus maximus. First, a guideline of target cycling speed to be achieved by FES cycling was determined from voluntary cycling with healthy subjects in order to evaluate FES cycling control. The cycling speed of 0.6m/s was determined as acceptable value and 1.0m/s was as ideal one. Then, stimulation to the gluteus maximus and that to the dorsiflexor muscles in addition to the quadriceps femoris were examined for simple FES cycling control for Profhand with healthy subjects. Stimulation timing was adjusted automatically during cycling based on muscle response time to electrical stimulation and cycling speed, which was shown to be effective for FES cycling control. Simple FES cycling control with Profhand removing stimulation to the gluteus maximus was found to be feasible. Stimulation to the dorsiflexor muscles with the quadriceps femoris was suggested to be effective for practical, simple FES cycling with Profhand in case of removing the gluteus maximus stimulation.