We utilized machine learning to obtain vertical profiles of specific humidity (q) in the troposphere by combining measurements from the Equatorial Atmosphere Radar (EAR) and its Radio Acoustic Sounding System (RASS). This study focuses on features derived from EAR-RASS measurements, including virtual temperature (Tv), signal-to-noise ratio (SNR), and Doppler spectral width (σ). Regularized linear models outperformed tree-based models, as evidenced by their strong performance during testing and validation in both trainingtest splits and nested cross-validation. Predictions forqlevels aligned well with observed data; however, the models encountered challenges at higher altitudes, particularly above 6 km.Tvemerged as the most significant predictor in the 2–4 km and 4–6 km layers, while other features had minimal impact. The performance of all variables declined above 6 km due to reduced moisture andSNR.

As mobile multimedia services have significantly evolved and diversified with the spread of smartphones and Internet of Things (IoT) devices, low-delay multimedia cloud computing is the need of the hour. To address this demand, in this study, we introduce an edge cloud system that equips a multimedia service function chaining capability. A prototype implementation of the proposed edge cloud system has three main features: 1) edge computing deployment by using OpenStack, 2) multimedia service slicing and chaining, and 3) efficient resource management in edge networks. Based on these features, the proposed system achieves lower multimedia processing delay compared to a conventional cloud computing platform. We deploy the proposed system in our laboratory and validate the system performance by using typical multimedia application, such as human detection in video surveillance.

To provide energy-efficient (i.e., longer lifetime of sensors) and network-friendly (i.e., reducing network traffic) field sensing, we propose an edge-centric field monitoring system which applies efficient sensors and camera control. The proposed system detects conditions in a monitoring area and controls sensing frequency (sampling rate) of sensors, and capture rate and encoding rate of surveillance cameras, according to the detected conditions. In addition, the system applies a Multi-access Edge Computing (MEC) platform to provide fast feedback control to the sensors and cameras. In performance evaluations, we assume that the monitoring target is landslide detection and create a miniature “artificial landslide generation” environment in our laboratory. By using the environment, we evaluate the system performance, and evaluation results indicate that the proposed system can reduce network traffic and save energy consumption efficiently.

In this article, we leverage Network Function Virtualization(NFV) and Multi-Access Edge Computing (MEC) technologies, proposing a system which integrates ICN (Information-Centric Network) with CDN (Content Delivery Network) to provide an efficient content delivery service. The proposed system combines the dynamic CDN slicing concept with the NDN(Named Data Network) based ICN slicing concept to avoid core network congestion. A dynamic CDN slice is deployed to cache content at optimal locations depending on the nature of the content and the geographical distributions of potential viewers. Virtual cache servers, along with supporting virtual transcoders, are placed across a cloud belonging to multiple-administrative domains, forming a CDN slice. The ICN slice is, in turn, used for the regional distribution of content, leveraging the name-based access and the autonomic in-network content caching. This enables the delivery of content from nearby network nodes,avoiding the duplicate transfer of content and also ensuring shorter response times. Our experiments demonstrate that integrated ICN/CDN is better than traditional CDN in almost all aspects, including service scalability, reliability, and quality of service.

For the first time, the performance of the range imaging technique of the very high frequency band middle and upper atmosphere (MU) radar (Shigaraki observatory, Japan), when using frequency diversity, is assessed. This is done by the detection of unmanned aerial vehicles (UAVs) operated near the radar during the Shigaraki UAV radar experiment campaign, carried out from June 1, 2015 to June 14, 2015. During this campaign devoted to the measurements of fine-scale turbulence and stability in the lower troposphere using the turbulence sensors on the DataHawk UAV and the MU radar, the detection of the small UAV by the MU radar provided an excellent opportunity for taking stock of the range imaging technique in the presence of a single hard target. It was found that range imaging reproduces a faithful image of the aircraft position and its displacements with an excellent accuracy (of the order of ~10 m), giving extra credence to the thin echo layers and their vertical displacements generally observed from the range imaging technique in stably stratified conditions.

Disaster detection is an important research topic and draws great attentions from both industry and academia. In this paper, we study the hybrid landslide detection system, which utilizes the video surveillance camera and multiple kinds of sensors and can detect the landslide automatically. Edge processing is adopted in this hybrid system to fuse the sensor data based on the Dempster-Shafer (D-S) theory, i.e. utilizing multiple sensors' information to calculate the possibility of the landslide. Edge processing can make faster decisions than the control center, the results of the edge processing are then used to schedule the sensor's transmission frequency and video transmission under the network constraints in this system. The simulation results show that the proposed scheme outperforms the competing schemes in typical network scenarios.

In order to provide high-quality and highly reliable video delivery services for mobile users, especially train passengers, we propose a proactive content caching scheme that uses transportation systems. In our system, we place content servers with cache capability [e.g., content centric networking/named data networking (CCN/NDN)] in every train and station. Video segments encapsulated by MPEG-Dynamic Adaptive Streaming over HTTP (MPEG-DASH) are distributed and pre-cached by the station servers before the trains arrive at the stations. The trains receive content via high-speed wireless transport, such as wireless LANs or millimeter waves, when they stop at the stations. We developed prototype systems based on hypertext transfer protocol and CCN/NDN protocol, evaluate their performance through two field experiments that uses actual trains, and compare with traditional video streaming over cellular networks. Such evaluations indicate that our system can achieve high-quality video delivery without interruption for up to 50 users simultaneously.

Providing robust content delivery along with efficient wireless resource usage is important for next generation wireless networks. To achieve this, we propose a proactive content caching scheme utilizing transportation systems, especially trains. In our system, we place content servers with CCN capability to every train and station. Segments of video contents are pre-cached by the station servers before trains arrive at stations. Trains receive the contents via high-speed wireless transport while they stop at the stations. We develop a prototype system based on IP and CCN Hybrid protocols. We evaluate its performance by field experiment and compare with traditional CDN scenarios using cellular networks. Evaluations conclude that our system can achieve high-speed and high-reliable video delivery without freezing.

The middle and upper atmospheric (MU) radar at Shigaraki, Japan, is an excellent system to carry out observation using a spaced antenna (SA) technique. Over several years, numerous scientific studies were reported using SAs. In most of the studies, a SA is used to derive wind information, and the array is divided in to three segments and is grouped with three or six channels to obtain the baselines in the form of an equilateral triangle. In previous work, the wind had been estimated by the SA up to a maximum height of 10-14 km. In general, a SA-based wind estimation could not give good height coverage due to a smaller aperture being used for received signals. In this paper, the observation has been conducted for full-array transmission and reception of signal with 25 receiver channels of the profiler. The receiver channels are divided into three equal segments to form the baselines suitable for deriving horizontal wind vector components using full correlation analysis (FCA). FCA is considered as a conventional SA technique. The identification of receive channels for grouping and its phase centers was critical to obtain the good correlation value and to determine the velocity. The grouping is repeated with four different orientations of the array group. In each case, the wind velocity is estimated. The horizontal wind vector components obtained from all orientations are averaged to obtain mean horizontal wind vector components. The results are compared with the wind velocity estimated using a Doppler beam swinging (DBS) technique and that observed by the GPS sonde. It is observed that the new approach adopted using spatially distributed array grouping has yielded higher height coverage up to 20 km and in good agreement with the results obtained using DBS and GPS-sonde observations with a temporal resolution of 1.3 min in clear air condition.

Software beam synthesis by postset beam steering (PBS) technique is used to derive the horizontal wind velocities from multireceiver phased-array radar data. In order to improve the efficiency of beam synthesis, the Capon beamforming method is used to synthesize time series signals in the desired line-of-sight angle within the radar transmit beam volume (3.6°beamwidth). This paper describes beam synthesizing in optimum directions to reduce the error in the measurement of horizontal wind velocities using the PBS technique. For this purpose, beams are synthesized at various tilt angles with multibeam configuration. From the synthesized beam, power spectral distribution is obtained by one of the subspace methods, i.e., eigenvector (EV). The mean Doppler frequency and radial wind velocity at the desired line-of-sight angle are derived by an adaptive-moment estimation method from an EV-produced power spectrum. Using the moments obtained in various radial directions, horizontal wind components are derived by the conventional method for wind profiler radars. Also, an analysis is done for the required number of beams to improve PBS-based wind estimation. The statistical comparisons of performances of various tilt angles and beam configurations are being studied using the data collected from a multireceiver phased-array radar system (middle and upper atmosphere radar, Shigaraki, Japan). The analyzed results show that beam synthesis at the tilt angle from 1.5°to 2.0°using a 16-beam configuration minimize the error in horizontal wind estimation by PBS technique.

This paper mainly focuses on the advantages of subspace-based eigenvector (EV) spectral estimator to improve the power spectrum and the quality of calculations in spectrum parameter estimation. In general, the spectrum produced by most of subspace methods is sharply peaked at the frequency of complex sinusoids. Although subspace methods exhibit the advantage of spectral resolution, the retrieval of the actual spectrum width is not well observed in many cases, compared with standard Fourier estimates. Several simulation works are carried out to determine the unknown order of the signal correlation matrix, which significantly helps in obtaining the equivalent Fourier spectrum using EV along with numerous advantages of the subspace method for better estimation of spectrum parameters. Such advantages are useful in precisely obtaining the atmospheric moments (Doppler frequency, spectrum width, etc.) from the synthesized beams required for wind estimation by the postset beam steering technique. In addition, the systematic improvements done in EV are much useful for complete wind profiling up to ~ 20 km with a temporal resolution of ~ 26 s, which is reported for the first time.

A 144-kb/s digital subscriber loop (DSL) transmission system based on hybrid transmission with an echo cancelling method is described. It incorporates advanced LSI technology to obtain compactness, low cost, and high reliability. An echo canceller (EC) LSI has been developed using CMOS technology. Combined with the multiplexing processor (MXP) LSI, the EC LSI provides basic DSL equipment functions. A specially arranged frame format with a newly developed digital phase-locked loop (DPLL) circuit for stable timing extraction, an automatic balancing network, and a two-stage echo canceller characterize the system. Using this line termination circuit, the DSL equipment showed a reach of over 6 km when used with 0.5 mm diameter cable for 160-kb/s bidirectional digital transmission.>

This paper describes an LSI that was developed for wide application in digital video signal processing. The newly developed LSI consists of two independent 12-bit full adders/subtracters and a variable delay unit. The minimum arithmetic operation cycle time is 67 nsec and power dissipation is 250 mW. The LSI is packaged in a 135 pin RIT package. It has rather simple structure, but has very powerful applications in real time video signal processing. The application of this LSI for TV conference CODEC is also presented as an example.

This paper describes some results of analysis on an architecture focusing on the pipeline structure of multiplier. Throughput of a 16 bit multiplier with fixed point arithmetic was analyzed for a single cycle structure, a 2-stage pipeline structure and a 3-stage pipeline structure. Total efficiency which includes overheads inherent to a pipeline structure was examined for each structure based on the programs made for practical use such as a 32 kb/s ADPCM codec, echo canceler, 19 section filter banks for voice recognition etc. Each analysis showed that the 2-stage pipeline structure is a suitable choice from the view points of efficiency and simplicity of programming.

This paper describes the design of a highly efficient CMOS LSI circuit digital signal processor (FDSP3). To realize an operating cycle rate of 10 MHz and a throughput rate of 0.6 μs per second-order filter section, considerable care has been paid to the design of software structures and hardware circuitry. Basic program routines and some application examples are also shown. These examples illustrate the high efficiency of the developed DSP device.

This paper describes a newly developed CMOS LSI DSP (FDSP3). It has a powerful multiplier, which operates at a rate of 10 M-operations/s, almost twice as fast as the fastest existing LSI DSP's. Some key techniques to attain these high performance characteristics of the DSP are described. Suitable memory capacities of the RAM and ROM were analyzed as a function of the operational capability of the DSP. These were reflected in the design of the FDSP3. To assist in the development of the program, support tools have been developed. A Pascal based cross compiler and an on-line debugging tool are described in some detail.

This paper describes a newly developed CMOS LSI DSP and its application to a 32 Kbps ADPCM CODEC and a 4,800 bps data MODEM. The paper first analizes the required memory capacities of ROM and RAM as a function of arithmatic operation capability of DSP. Based on the results, the LSI DSP is developed, which has a proper amount of memory capacities. It has a multiplier which operates at a rate of 1.4 M operations/s. It is also equipped with a versatile I/O interface circuit which is suitable for multi-processors configuration of a system.

This paper describes a complete hardware implementation of an experimental two-wire digital subscriber loop transmission system using balanced pairs of wires. It is based on the time division burst mode transmission scheme (ping-pong), and provides two information channels, 64 kbits/s and 8 kbits/s, and a signaling channel both ways. The burst cycle is 2 ms and line transmission rate is 192 kbits/s. The salient feature of the system is that it is equipped with a powerful bridged tap equalizer which has the capability to compensate a large fraction of existing two-wire subscriber loops in Japan. It is realized by a fifth-order recursive filter using analog tapped delay lines, and a modified zero forcing algorithm is adopted for the adaptation of the tap coefficients. The experimental results showed that the combination of the\sqrt{f}AGC and the bridged tap equalizer enables the digital transmission up to 4 km on the 0.4 mm φ subscriber line with three bridged taps each of 400 m length.

This paper describes a fast data processing LSI unit tailored to the digital signal processing (DSP) applications in the field of electrical communications. The results of successful application to the 4800 bit/s modem are also given. The LSI processor discussed here adopts a firmware control scheme to enhance the flexibility and freedom of application and extensively utilizes the pipeline processing technique to attain high speed data handling capability. The various operations encountered in DSP systems are unified into one operation of the typeA \times B + C \rightarrow Dand the LSI processor is designed to continuously perform this operation, while the data to be operated are transferred sequentially into the processor controlled by exterior firmware. The developed LSI handles 8 bit data at the clock frequency of 1.152 MHz and manages 144 K operations per second (6.9 μs cycle time). The LSI is an N-MOS chip containing 1500 gates and packaged in a 40 pin DIP. The automatic equalizer for 4800 bit/s modem was implemented using two of the developed LSI processors and about 4 K ROM and 1 K RAM memory chips. The measurement on this modem gave the error rate of 10-5atS/N = 17.6dB and error free phase jitter allowance of 55° p-p. Application of the LSI processor to digital filters for roll-off spectrum shaping and timing signal extraction is also described.