In this paper, we study a joint spatial division multiplexing (JSDM) beamforming scheme, which enables large-scale spatial multiplexing gains for massive multi-input multi-output downlink systems. In ...contrast to the conventional JSDM, which employs a block diagonalization method as a pre-beamformer, we aim to maximize sum-rate by applying minimum-mean-squared error (MMSE) approaches when designing a pre-beamformer and a multi-user precoder sequentially. First, to suppress inter-group interference, we design the pre-beamformer, which minimizes an upper bound of the sum mean-squared-error in the large-scale array regime. Then, to mitigate same-group interference, we present the multi-user precoder based on the weighted MMSE (WMMSE) optimization method, which requires the same channel state information overhead as the conventional JSDM. Also, in order to reduce the computational complexity, we compute deterministic equivalents of the WMMSE beamforming parameters to generate the beamformers by employing asymptotic results of large system analysis. Through simulation results, we confirm that the proposed two-step beamforming methods bring substantial performance gains in terms of sum-rate over the conventional JSDM schemes especially in a low and medium signal-to-noise ratio regime with comparable complexity.
This letter studies a joint design of fronthaul compression and precoding for full-duplex (FD) cloud radio access networks (C-RAN). In this system, each radio unit (RU) takes the role of FD ...transmission and a control unit connected to all of the RUs via finite-capacity links performs co-operative interference management by centralized baseband processing. There exists non-negligible self-interference (SI) due to FD transmission even after analog SI cancellation (SIC) is applied at the RU. To efficiently alleviate the residual SI, we propose the implementation of additional digital SIC at each RU, which mitigates the SI in baseband and thus reduces the burden of the finite uplink fronthaul capacity. We then consider the problem of maximizing the sum rate of uplink and downlink users while satisfying the per-RU fronthaul capacity and power constraints. The problem is solved by the majorization minimization approach under a difference of convex structure. Through simulation results, we confirm that the proposed FD C-RAN system with SIC implemented at the RUs can achieve substantial gains compared to conventional schemes.
Simultaneous wireless information and power transfer (SWIPT) is a promising technique to transfer information and energy signals at the same time and frequency utilizing the multi-input multi-output ...(MIMO) beamforming. In this correspondence, the SWIPT MIMO technique is realized in the multicell cooperative transmission environment, namely, network-MIMO where the signals from different base-stations (BSs) to all the mobile users can be jointly designed based on the perfect knowledge of the downlink channels and transmit messages. To develop an efficient precoding matrix, we adopt the weighted minimum mean squared error criterion that can be generally applied to the sum-utility maximization of each receiver's information rate. In the SWIPT network-MIMO, a number of constraints arise including the power constraint at each BS, namely, the per-BS power constraints and the energy constraint at the energy harvesting users, which makes the problem challenging. A main contribution of the paper is to propose a simple bisection-based algorithm that finds a solution. The efficiency of the proposed algorithm is verified via computer simulation results.
This article introduces a 192-Gb 896-GB/s 12-high stacked third-generation high-bandwidth memory (HBM3 DRAM) with low power consumption and high-reliability traits. New design schemes and features, ...including internal low-voltage signaling, center strobe calibration, through-silicon via (TSV) auto-calibration, a symbol-correcting in-DRAM ECC, and machine-learning-based layout optimization, allow large amounts of data transfers among the vertically stacked base and core dies with limited delay mismatch or SI degradation, as well as reduced power consumption from low-voltage swings. Experimental results confirm 896-GB/s bandwidth operations at 1.0-V voltage conditions with up to 15% improved power efficiency.
In this paper, we study a joint spatial division multiplexing (JSDM) beamforming scheme which enables large-scale spatial multiplexing gains for massive MIMO downlink systems. In contrast to the ...conventional JSDM which employs a block diagonalization (BD) method as a pre-beamformer, we aim to maximize sum-rate by applying minimum-mean-squared error (MMSE) approaches when designing a pre-beamformer and a multi-user precoder sequentially. First, to suppress inter-group interference, we design the pre-beamformer which minimizes an upper bound of the sum mean-squared-error in the large-scale array regime. Then, to mitigate same-group interference, we present the multi-user precoder based on the weighted MMSE (WMMSE) optimization method, which requires the same channel state information overhead as the conventional JSDM. Through simulation results, we confirm that the proposed two-step beamforming method brings substantial performance gains in terms of sum-rate over the conventional JSDM schemes especially in low to medium signal-to-noise ratio (SNR) regime.
Ever since the introduction of high bandwidth memory (HBM DRAM) and its succeeding line-ups, HBM DRAM has been heralded as a prominent solution to tackle the memory wall problem. However, despite ...continual memory advancements the advent of high-end systems, including supercomputers, hyper-scale data centers and machine learning accelerators, are expediting requirements for higher-performance memory solutions. To accommodate the increasing system-level demands, we introduce HBM3 DRAM, which employs multiple new features and design schemes. Techniques such as an on-die ECC engine, internal NN-DFE I/O signaling, TSV auto-calibration, and layout optimization based on machine-learning algorithms are implemented to efficiently control timing skew margins and SI degradation trade-offs. Furthermore, reduced voltage swings allow for improved memory bandwidth, density, power efficiency and reliability.
With the emergence of large-language models (LLM) and generative AI, which require an enormous amount of model parameters, the required memory bandwidth and capacity for high-end systems is on an ...unprecedented increase. To meet this need, we present an extended version of the high-bandwidth memory-3 (HBM3 DRAM), HBM3E, which achieves a 1280GB/s bandwidth with a cube density of 48GB. New design schemes and features, such as all-around power-through-silicon via (TSV), a 6-phase read-data-strobe (RDQS) scheme, a byte-mapping swap scheme, and a voltage-drift compensator for write data strobe (WDQS), are implemented to achieve extended bandwidth and capacity with enhanced reliability. The overall architecture and specifications, such as bump map footprint, the number of channel and I/Os, and the operation voltage, are identical to the latest HBM3 1, 2; therefore, backward compatibility is provided, avoiding system modification.
The purpose of this paper is to analyze the effect of attitude toward food safety on the consumption of processed foods. The attitude is measured by two different approaches using consumer survey ...results. First, based on whether the consumers regard the safety as a relatively important factor, among others, when they purchase food, safety-sensitive and safety-nonsensitive consumer groups are divided. Second, based on whether consumers concern about safety information among the informations they are checking when they purchase food, safety-caring and safety-indifferent consumer groups are divided. For the division of consumer groups, K-Means Clustering is applied. By using a probit model and investigation of the marginal effect derived from the estimation results of the probit model, we analyze the purchase pattern of the consumer groups for the five different kinds of processed food. According to the estimation result, the purchasing experience for processed foods by the consumers who care about food safety is increasing. It is estimated that the consumers who care about food safety are more likely to buy imported and premium products.
고분자 수화젤을 이용한 이산화염소의 지속적 생성 시스템의 개발 전영현; 김범상; Jeon, Younghyun ...
Korean Chemical Engineering Research(HWAHAK KONGHAK), 50(1),
02/2012, Volume:
50, Issue:
1
Journal Article
Peer reviewed
Open access
Chlorine dioxide has an excellent ability to sterilize and deodorize and is harmless to humans. However, it is very unstable and explosive as it is highly concentrated, thus its use in the air clean ...filed has been limited. Therefore, there is a demand to develop the system to produce a low concentration of chlorine dioxide sustainedly. Here, for a first step in the development of the system on the sustained production of chlorine dioxide, the use of polymer hydrogels was investigated. P(MMA-co-HEMA) hydrogel particles were prepared via dispersion photopolymerization and sodium chlorite and citric acid were loaded respectively in the hydrogel particles. When sodium chlorite and citric acid were reacted with not loaded in the hydrogels, rapid production of chlorine dioxide occurred and the concentration of chlorine dioxide decreased over time. However, when sodium chlorite and citric acid were loaded respectively in the hydrogel particles and reacted, chlorine dioxide was produced slowly and sustainedly because the release of sodium chlorite and citric acid from the hydrogels delayed the reaction between them. The result shows that the use of P(MMA-co HEMA) hydrogels has the potential to develop the system on the sustained production of chlorine dioxide. 이산화염소는 우수한 살균력과 탈취력, 그리고 인체에 무해한 장점을 가지고 있으나, 과량 존재 시 불안정하고 폭발위험성이 존재하여 공기청정분야에서의 사용이 제한적이다. 따라서 본 연구에서는 고분자 수화젤 입자 내부에 아염소산나트륨과 시트르산을 각각 탑재시킨 후, 수화젤 입자로부터 방출된 두 물질이 반응하여 저농도의 이산화염소를 장시간 지속적으로 발생시킬 수 있는 시스템을 개발하고자 하였다. 분산광중합을 이용하여 P(MMA-co-HEMA) 수화젤 입자를 합성하였고, 수화젤 입자로부터 방출된 아염소산나트륨과 시트르산이 반응하여 생성된 이산화염소의 양과 수화젤에 탑재하지 않은 아염소산나트륨과 시트르산이 직접 반응하여 생성된 이산화염소의 양을 시간의 경과에 따라서 비교한 결과, 아염소산나트륨과 시트르산이 직접 반응하는 경우, 생성된 이산화염소가 시간이 경과함에 따라서 분해되어 그 양이 점차 감소하였으나 수화젤을 사용한 경우는, 아염소산나트륨과 시트르산이 수화젤로부터 방출된 후 반응을 하기 때문에 반응시간이 지연되어서 저농도의 이산화염소가 지속적으로 생성되는 것을 관찰할 수 있었다. 이러한 결과는 본 연구에서 목적으로 하는 저농도의 이산화염소를 장시간에 걸쳐서 지속적으로 생성할 수 있는 시스템을 고분자 수화젤을 이용하여 구현할 수 있음을 보여준다.
PDF
