Search

In this paper, an advanced duplex scheme called cross-division duplex (XDD) is proposed to enhance uplink (UL) coverage in time division duplex (TDD) carriers by utilizing self-interference cancellation (SIC) capability at a base station. With XDD, it is possible to combine TDD’s ability to efficiently handle asymmetric UL and downlink (DL) traffic with frequency division duplex’s coverage advantage. To do so, XDD simultaneously operates UL and DL on the same TDD carrier but on different frequency resources. Such operation leads to severe interference on the received UL signal at the base station which requires two levels of SIC implementation; antenna and digital SIC. More than 50 dB of interference is removed through the antenna SIC using electromagnetic barriers between the transmitting and receiving antennas. The remaining interference is removed by the digital SIC based on estimating the non-linear channel of the circuit at the receiver baseband. It is verified by simulation and analysis that with the proposed XDD, the UL coverage can be improved by up to 2.37 times that of TDD. To check the feasibility of XDD, a Proof-of-Concept was developed where it was observed that the benefits of XDD can indeed be realized using the proposed SIC techniques.

Battery life of mobile terminals has been a key performance indicator (KPI) for user experience since the early days of wireless communications. This KPI has become even more important for fifth generation (5G) cellular systems due to higher requirements such as the support of carrier frequency up to 100 GHz, carrier bandwidth up to 400 MHz, peak data rate up to 20 Gbps, latency as small as 1 ms, and enhanced receiver performance. In response, various power saving techniques have been studied and implemented so that devices can be used over a longer period without noticeable decrease in performance. In this article, we provide a comprehensive overview of the latest terminal power saving techniques which were specified in 5G New Radio (NR) over the last couple of years. The key feature and benefit of each power saving technique is analyzed with simulation results under various traffic scenarios. In addition, some of the candidate techniques for the next phase of NR on terminal power saving enhancement are proposed targeting not only conventional data services but also various vertical services.

In this paper, an advanced duplex (AD) scheme is proposed to use flexible downlink (DL) and uplink (UL) allocation in time division duplex (TDD) carrier in 6G. By utilizing self-interference cancellation (SIC) capability at a base station to handle the interference from DL signal to UL signal, the proposed duplex scheme enables to simultaneously operate UL and DL on the same carrier but on different frequency resources. To do so, both TDD’s ability to efficiently handle asymmetric UL and DL traffic and frequency division duplexing’s coverage advantage can be achieved together in the AD scheme. To verify the feasibility, a Proof-of-Concept is developed where it is observed that the benefits of AD scheme can indeed be realized using the proposed SIC techniques. In a system having a 100 MHz bandwidth in the 2.4 GHz band, a multi-level SIC is applied to suppress the self-interference to less than 1 dB without a guard band between DL and UL signals. Based on this technology, in 6G, various duplex techniques can be applied in a time-varying manner, so that a significantly higher resource utilization than the existing 5G will be possible.

In this paper, compressed sensing-based OTFS (Orthogonal Time Frequency Space) transmission is proposed for next generation cellular systems on millimeter-wave and terahertz spectrum. The proposed multi-dimensional sparse vector compression (M-SVC) scheme maps non-sparse transmit vector to sparse vector and then applies delay-Doppler domain spreading by using only a small portion of time-frequency resource grid. As a result of M-SVC, the transmit vector of the data packet can be acquired from compressed sensing-based energy detection without the need for conventional channel estimation or symbol decoding. From numerical evaluations, it is observed that the proposed scheme outperforms conventional sparse vector coding while using only a small portion (e.g., 10 - 40%) of frequency resources compared to conventional schemes. Furthermore, M-SVC shows robustness against phase noise and Doppler effect when communicating over millimeter-wave and terahertz spectrum.

In this paper, we propose a new data transmission scheme called interference-aware cascade modulation (IA-CM) for advanced duplex (AD) in Beyond-5G cellular systems where downlink (DL) and uplink (UL) signals are transmitted and received simultaneously within a carrier bandwidth. In IA-CM, self-interference due to simultaneous operation of DL transmission and UL reception in a base station is handled by adapting the modulation and coding scheme (MCS) level of the UL data transmission according to the level of self-interference that has a gradual decaying profile in the frequency domain. Consequently, unlike conventional scheme where a single MCS level is used for UL data transmission throughout the assigned UL bandwidth, multiple MCS levels are used in IA-CM based UL data transmission. In the process, the base station evaluates signal-to-interference-plus-noise ratio (SINR) in frequency selective manner taking into account the interference leakage generated from non-linearity of DL transmission, coupling with UL, and self-interference cancellation capability. in Fig. 1, two-dimensional resource allocation The benefits of IA-CM are verified from evaluations and it is observed that IA-CM achieves a 30% throughput gain over the conventional scheme when AD is used.

In this paper, we propose a novel statistical beamforming (SBF) method called the partial-nulling-based SBF (PN-SBF) to serve a number of users that are undergoing distinct degrees of spatial channel correlations in massive multiple-input multiple-output (MIMO) systems. We consider a massive MIMO system with two user groups. The first group experiences a low spatial channel correlation, whereas the second group has a high spatial channel correlation, which can happen in massive MIMO systems that are based on fifth-generation networks. By analyzing the statistical signal-to-interference-plus-noise ratio, it can be observed that the statistical beamforming vector for the low-correlation group should be designed as the orthogonal complement for the space spanned by the aggregated channel covariance matrices of the high-correlation group. Meanwhile, the spatial degrees of freedom for the high-correlation group should be preserved without cancelling the interference to the low-correlation group. Accordingly, a group-common pre-beamforming matrix is applied to the low-correlation group to cancel the interference to the high-correlation group. In addition, to deal with the intra-group interference in each group, the post-beamforming vector for each group is designed in the manner of maximizing the signal-to-leakage-and-noise ratio, which yields additional performance improvements for the PN-SBF. The simulation results verify that the proposed PN-SBF outperforms the conventional SBF schemes in terms of the ergodic sum rate for the massive MIMO systems with distinct spatial correlations, without the rate ceiling effect in the high signal-to-noise ratio region unlike conventional SBF schemes.

In this paper, the scaling laws of scheduling gain and the feasibility of user scheduling for uplink massive multiple input&ndash, multiple output (MIMO) systems are investigated by analyzing the second moment of mutual information. We consider two well-known linear receivers of matched filter (MF) and zero-forcing (ZF). The exact distribution of the signal-to-interference-plus-noise ratio (SINR) and its moment-generating function are first obtained, and the approximated variance of the mutual information for a user is derived as a closed form with a function of the number of antennas. The achievable scheduling gain under the optimal user scheduler is then derived using the Gaussianity of the sum rate. From the analyses and simulation results, it is found that the scheduling gain for the MF receiver increases with the number of base station (BS) antennas, while that for the ZF receiver decreases as the number of BS antennas increases, for most cases (except some impractical scenarios). Therefore, it is verified that user scheduling is still beneficial for the MF receiver while random user selection is sufficient for the ZF receiver in massive MIMO systems.

As the automotive and AI industries are expanding rapidly, global-shutter (GS) image sensors are playing a more significant role in the perception system. More specifically, GS image sensors are required in various fields involving IR, including the face-ID in mobile devices, the driver monitoring system in automotive applications, and factory automation. GS image sensors are necessary for these applications because they can capture freeze-frame images without motion distortion due to their advantage in the pixel operation method. The simultaneous pixel exposure and in-pixel storing capability allow GS image sensors to achieve high-quality imaging, while the sequential pixel exposure and readout of rolling-shutter (RS) image sensors results in image distortion known as the jello effect. For mobile and automotive applications, a small form factor while maintaining a low parasitic light sensitivity (PLS) and low noise is crucial. In conventional backside illuminated (BSI) charge-domain GS image sensors, a light-shielding structure over the storage area must be formed in order to suppress the influence of parasitic light during the readout operation. Therefore, the introduction of such a light-shielding structure reduces the effective photodiode area, which results in a loss of full-well capacity (FWC), light sensitivity of the sensor, and pixel scalability.

A novel physical downlink control channel (PDCCH) blind decoding method based on demodulation reference signal (DMRS) detection is proposed to reduce the power consumption at user equipment (UE) for 5G New Radio (NR). In the proposed scheme, a UE performs energy detection for the DMRS in the search space before PDCCH blind decoding. Based on the information of the time/frequency location where the DMRS is detected, the UE can dynamically adjust PDCCH monitoring configuration. Such adjustment helps UE to minimize unnecessary blind decoding attempts depending on the data traffic. Evaluations show a significant power saving gain over the conventional methods.

Today, as greenhouse gas reduction, environmental pollution, climate change response, and power outage are emerging as social issues, the energy industry is making various efforts to diversify its supply to adapt to these changes. However, since nuclear power is a safety issue after the Fukushima nuclear power plant, wind power, wave power, and geothermal power are difficult to be used because they are difficult to use due to their difficult conditions and installation conditions. Nowadays, solar energy that is easy to install and relatively free is attracting attention. However, since solar power generation is affected by the weather, power generation is not constant and it is difficult to link grid. Therefore, this study establishes a model for predicting solar power generation, and conducts basic research to link solar power generation system with system efficiently by managing it efficiently.1

New Radio (NR) is a new radio air interface developed by the 3rd Generation Partnership Project (3GPP) for the fifth generation (5G) mobile communications system. With great flexibility, scalability, and efficiency, 5G is expected to address a wide range of use-cases including enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), and massive machine type communications (mMTC). The physical downlink control channel (PDCCH) in NR carries Downlink Control Information (DCI). Understanding how PDCCH operates is key to developing a good understanding of how information is communicated over NR. This paper provides an overview of the 5G NR PDCCH by describing its physical layer structure, monitoring mechanisms, beamforming operation, and the carried information. We also share various design rationales that influence NR standardization., Comment: 8 pages, 5 figures, 1 table, submitted for publication

As energy supply changes become more important, interest in the field of efficient energy management is increasing. In this paper, demand forecasting is performed through time series analysis of power big data. And we measured the performance through predictive comparison of time series prediction model.

Recently, as the paradigm of the energy industry changes, energy consumption patterns forecasts of users are becoming important In this paper, we analyze power consumption based on time series in terms of improving prediction accuracy by data processing.

This paper analyzes the power allocation scheme to maximize the sum-rate for heterogeneous networks based on asynchronous time division duplex. We consider heterogeneous networks where a small cell exists in the macro cell coverage and the small cell and the macro cell share the same time-frequency resources. We formulate the optimization problem which maximizes the sum-rate of the heterogeneous network subject to the target signal-to-interference-plus-noise ratio. We analyze the feasible region in order for the optimal solution to exists and the optimal power allocation scheme for maximizing the sum-rate. Simulation results show that the proposed power allocation schemes outperform the maximum power transmission scheme.

A Switched Reluctance Motor and Generator (SRMG) has a simple double salient pole structure that uses reluctance torque and does not use a permanent magnet, making the unit price low. This kind of structure makes it mechanically tough, have outstanding output characteristics making it used as traction purpose. However the noise, vibration and torque ripple is bigger than other motors and because it does not have any magnetic flux in the rotor, it is not useful in regenerating.[[ In this paper, novel regenerating method with separate excitation driving technique is presented. It is different from the existing regenerating brake that uses the remnant flux on a separate excitation type by using a parallel switching base to redirect portion of the flux path to excitation and the rest to generation. The proposed method makes it able to use a larger portion in generating, there is no limitation in the excitation current in order to generate and the control of the output is simple. Because the proposed method is based on the parallel switching technique the number of switch per phase does increase. However in motor mode the division of current goes down making it easier to go in generating mode. The proposed method is generated upper 50% regenerating power rate more than general method. In order to prove the possibility, a simulation of flux flow using FEM is applied. The proposed method is also verified by experiment result.

Connected Vehicle research has emerged as one of the highest priorities in the transportation systems because connected vehicle technology has the potential to improve safety, mobility, and environment for the current transportation systems. Various connected vehicle based applications have been identified and evaluated through various measurements to assess the performance of connected vehicle applications. However, most of these previous studies have used hypothetical study areas with simple networks for connected vehicle environment. This study represents connected vehicle environment in TRANSIMS to assess the performance of V2V communication applications in the realistic urban network. The communication duration rate and spatial-temporal dispersion of equipped vehicles are investigated to evaluate the capability of V2V communication based on the market penetration rate of equipped vehicles and wireless communication coverage in the whole study area. The area coverage level is used to assess the spatial-temporal dispersion of equipped vehicles for two study areas. The distance of incident information propagation and speed estimation error are used to measure the performance of event-driven and periodic applications based on different market penetration rates of equipped vehicles and wireless communication coverage in both morning peak and non-peak times. The wireless communication coverage is the major factor for event-driven application and the market penetration rate of equipped vehicles has more impact on the performance of periodic application. The required minimum levels of deployment for each application are determined for each scenario. These study findings will be useful for making decisions about investments on deployment of connected vehicle applications to improve the current transportation systems. Notably, event-driven applications can be reliably deployed in the initial stage of deployment despite the low level of market penetration of equipped vehicles. Ph. D.

A 1.2-V 72-Mb double data rate 3 (DDR3) SRAM achieves a data rate of 1.5 Gb/s using dynamic self-resetting circuits [5]. Single-ended main data lines halve the data line precharging power dissipation and the number of data lines. Clocks phase shifted by 0 , 90 , and 270 are generated through the proposed clock adjustment circuits. The proposed clock adjustment circuits make input data sampled with optimized setup/hold window. On-chip input termination with the linearity error of 4.1% is developed to improve signal integrity at higher data rates. A 1.2-V 1.5-Gb/s 72-Mb DDR3 SRAM is fabricated in a 0.10- m CMOS process with five metals. The cell size and the chip size are 0.845 m2 and 151.1 mm2, respectively. Published version

This paper describes a digital impedance controller (DIC) [I] for high-speed signal interface. The proposed DIC provides the wide range impedance control covering from 23Ω to 140Ω with 3.29% maximum quantization error. The maximum quantization error of the proposed DIC is 2.26% with RQ ranging from 23 Q to 53 Ω, the same range covered by conventional scheme. The high resolution and wide range impedance control is implemented by using automatic gate voltage optimization. The amount of jitter caused by quantization error is 6.9 ps while 13.8 ps in conventional scheme. The data input valid window is 623 ps at 0.75±200 mV and maximum eye open is 641 mV meaning about 10% improvement at 1.5Gbps/pin DDR3 SRAM interface.

This paper describes memory interface circuits applicable to multi Gbit/s/pin chip-to-chip communication. To obtain the high linearity characteristics of the off-chip drivers (OCD) and the on-die terminators (ODT), a novel circuit structure is proposed. The linearity error of the designed OCD and ODT is 4.7% and 1.7% respectively when measured between 0.2V and 1V. The pull-up and pull-down impedance mismatch is reduced by adding a compensation impedance unit. The maximum pull-up and pulldown mismatch is 0.5 bit. An impedance update scheme without training sequence is designed to guarantee the signal integrity of the first data. The valid data window is 418ps at 2Gbit/s, Vref /spl plusmn/150mV. The proposed circuits are fabricated with 0.1/spl mu/m dual-oxide CMOS process technology.

This paper describes a digital impedance controller (DIC) for high-speed signal interface. The proposed DIC provides the wide range impedance control covering from 23/spl Omega/ to 140/spl Omega/ with 3.29% maximum quantization error. The maximum quantization error of the proposed DIC is +2.26% with RQ ranging from 23/spl Omega/ to 53/spl Omega/ the same range covered by conventional scheme. High-resolution and wide range impedance control are implemented by using automatic gate voltage optimization. The data input valid window is 623ps at 0.75/spl plusmn/200mV and maximum eye open is 641mV meaning about 10% improvement at 1.5Gbps/pin DDR3 SRAM interface.