Channel assignment and power allocation for throughput improvement with PPO in B5G heterogeneous edge networks

In Beyond the Fifth Generation(B5G)heterogeneous edge networks,numerous users are multiplexed on a channel or served on the same frequency resource block,in which case the transmitter applies coding and the receiver uses interference cancellation.Unfortunately,uncoordinated radio resource allocation can reduce system throughput and lead to user inequity,for this reason,in this paper,channel allocation and power allocation problems are formulated to maximize the system sum rate and minimum user achievable rate.Since the construction model is non-convex and the response variables are high-dimensional,a distributed Deep Reinforcement Learning(DRL)framework called distributed Proximal Policy Optimization(PPO)is proposed to allocate or assign resources.Specifically,several simulated agents are trained in a heterogeneous environment to find robust behaviors that perform well in channel assignment and power allocation.Moreover,agents in the collection stage slow down,which hinders the learning of other agents.Therefore,a preemption strategy is further proposed in this paper to optimize the distributed PPO,form DP-PPO and successfully mitigate the straggler problem.The experimental results show that our mechanism named DP-PPO improves the performance over other DRL methods.

ZTE Communications Special Issue on Channel Measurement and Modeling for Heterogeneous 5G

While cellular networks have continuously evolved in re- cent years, the industry has clearly seen unprecedented chal- lenges to meet the exponentially growing expectations in the near future. The 5G system is facing grand challenges such as the ever-increasing traffic volumes and remarkably diver- sified services connecting humans and machines alike. As a result, the future network has to deliver massively increased capacity, greater flexibility, incorporated computing capabili- ty, support of significantly extended battery lifetime, and ac- commodation of varying payloads with fast setup and low latency, etc. In particular, as 5G requires more spectrum resource, higher frequency bands are desirable. Nowadays, millimeter wave has been widely accepted as one of the main communication bands for 5G.

ZTE Communications Special Issue on Channel Measurement and Modeling for Heterogeneous 5G

While cellular networks have continuously evolved in recent years, the industry has clearly seen unprecedented challenges to meet the exponentially growing expectations in the near future.

Virtual 5G Network Embedding in a Heterogeneous and Multi-Domain Network Infrastructure

The pursuit of the higher performance mobile communications forces the emergence of the fifth generation mobile communication(5G). 5G network, integrating wireless and wired domain, can be qualified for the complex virtual network work oriented to the cross-domain requirement. In this paper, we focus on the multi-domain virtual network embedding in a heterogeneous 5G network infrastructure, which facilitates the resource sharing for diverse-function demands from fixed/mobile end users. We proposed the mathematical ILP model for this problem.And based on the layered-substrate-resource auxiliary graph and an effective six-quadrant service-type-judgment method, 5G embedding demands can be classified accurately to match different user access densities. A collection of novel heuristic algorithms of virtual 5G network embedding are proposed. A great deal of numerical simulation results testified that our algorithm performed better in terms of average blocking rate, routing latency and wireless/wired resource utilization, compared with the benchmark.

User Selection Algorithms for Lowering Cross-Tier Interference in Heterogeneous Network

To lower the cross-tier intercell interference(ICI) between macrocell and microcell,three user selection algorithms for the heterogeneous network were proposed in this paper, assuming full knowledge of channelstate information at the transmitter. Algorithm 1 chooses microcell users whose interference channel matrix is parallel to that of a known user and targets at increasing user SINR. Algorithm 2 takes effect of chordal distance-channel norm balance on the system into account and predetermines the available user set from which it can choose service users. With comprehensive considerations to effect of interference signal and useful signal on system, Algorithm 3 set a weighting function as the objective function of user selection. Simulation results demonstrated that all three proposed algorithms could achieve user diversity gain while lowering cross-tier interference.

Performance-based intersection layout under a flyover for heterogeneous traffic

Flyovers are constructed to manage heavy through movement. However, traffic operations underneath a flyover remain unmanaged and often pose a major con- cern in developing countries with non-lane-based hetero- geneous traffic. This may reduce the overall benefit of a flyover. An alternative intersection layout is proposed to improve traffic operations at the intersection underneath a flyover. The proposed layout segregates the traffic move- ments through effective channelization. A traffic island is also proposed in the middle of the intersection to facilitate concurrent right-turning movements. This layout helps in eliminating a signal phase and cuts down traffic cycle time by 40 %. A microsimulation-based traffic simulation model is developed for the evaluation of the proposed layout. The simulation model demonstrates effectiveness of the proposed layout. Average delay and average queue length are compared to measure the effectiveness. Traffic volume sensitivity analysis is conducted to estimate the capacity of the proposed layout. An intersection underneath a flyover along the Eastern Expressway in Mumbai is considered for the case study. The effectiveness of the proposed layout at the study location for varying flow level is evaluated by comparing average delay, average stop delay, average number of stops per vehicle, average queue length, and maximum queue length.

Heterogeneous of potassium currents in free wall myocytes from the infarcted rabbit ventricle and regression effects of imidapril

Objective To define the heterogeneous changes of ion channels in the noninfarcted myocardium after myocardial infarction in rabbit and effects of imidapril.Mehods Rabbits with left coronary artery ligation were prepared and allowed to recover for 8 wk.Myocytes were isolated from subendocardial,midmyocardial and subepicardial regions of the noninfarcted left ventricular free wall.Ion currents were recorded with whole-cell patch clamp way.Results The densities of the transient outward K^(+)currents(I_(to))and the inward rectifier K^(+)currents(I_(K1))were greatly reduced in midmyocardium and subepicardium while two currents reduced gently in subendocardium.The densities of the delayed rectifier K^(+)currents(I_(K))were reduced in noninfarcted three layers similarly.Imidapril could reverse the changes of membrane currents in healed myocardial infarction cells and depress the dispersion of repolarization.Conclusions The heterogeneities of K currents are enhanced in noninfarcted area.Normalization of heterogeneous changes of repolarization after treatment with imidapril was observed.

Robust resource allocation for NOMA-assisted heterogeneous networks

As a promising technology to improve spectrum efficiency and transmission coverage,Heterogeneous Network(HetNet)has attracted the attention of many scholars in recent years.Additionally,with the introduction of the Non-Orthogonal Multiple Access(NOMA)technology,the NOMA-assisted HetNet cannot only improve the system capacity but also allow more users to utilize the same frequency band resource,which makes the NOMA-assisted HetNet a hot topic.However,traditional resource allocation schemes assume that base stations can exactly estimate direct link gains and cross-tier link gains,which is impractical for practical HetNets due to the impact of channel delays and random perturbation.To further improve energy utilization and system robustness,in this paper,we investigate a robust resource allocation problem to maximize the total Energy Efficiency(EE)of Small-Cell Users(SCUs)in NOMA-assisted HetNets under imperfect channel state information.By considering bounded channel uncertainties,the robust resource optimization problem is formulated as a mixed-integer and nonlinear programming problem under the constraints of the cross-tier interference power of macrocell users,the maximum transmit power of small base station,the Resource Block(RB)assignment,and the quality of service requirement of each SCU.The original problem is converted into an equivalent convex optimization problem by using Dinkelbach's method and the successive convex approximation method.A robust Dinkelbach-based iteration algorithm is designed by jointly optimizing the transmit power and the RB allocation.Simulation results verify that the proposed algorithm has better EE and robustness than the existing algorithms.

Robust signal recognition algorithm based on machine learning in heterogeneous networks

There are various heterogeneous networks for terminals to deliver a better quality of service. Signal system recognition and classification contribute a lot to the process. However, in low signal to noise ratio（SNR） circumstances or under time-varying multipath channels, the majority of the existing algorithms for signal recognition are already facing limitations. In this series, we present a robust signal recognition method based upon the original and latest updated version of the extreme learning machine（ELM） to help users to switch between networks. The ELM utilizes signal characteristics to distinguish systems. The superiority of this algorithm lies in the random choices of hidden nodes and in the fact that it determines the output weights analytically, which result in lower complexity. Theoretically, the algorithm tends to offer a good generalization performance at an extremely fast speed of learning. Moreover, we implement the GSM/WCDMA/LTE models in the Matlab environment by using the Simulink tools. The simulations reveal that the signals can be recognized successfully to achieve a 95% accuracy in a low SNR（0 dB） environment in the time-varying multipath Rayleigh fading channel.

WiFi与ZigBee双向移动跨网通信方法研究

物联网设备的爆发式增长推进了异构无线设备互联互通的进程,跨网通信技术(Cross-Technology Communication,CTC)允许同一频段下遵循不同底层协议的无线设备在无需网关的前提下实现直联,但移动状态下的双向跨网通信方法仍缺乏系统的研究.本文提出了一种基于能量感知的跨网通信方案——MobiCTC,它支持WiFi与Zig‑Bee设备移动状态下的双向跨网通信.WiFi到ZigBee方向,该方案利用RSSI(Received Signal Strength Indicator)作为解码信息,基于能级映射实现信息解码;ZigBee到WiFi方向,该方案采用CSI(Channel State Information)作为解码信息,充分挖掘CSI的幅度与相位信息,利用机器学习方法实现分类解码.最后,本文使用TelosB节点和USRP X310平台对MobiCTC方案进行了实验验证.实验结果表明,移动状态下WiFi到ZigBee方向的系统吞吐量为139.535 bps,较WiZig提高了1.82倍,符号错误率为0.016,与WiZig基本持平;ZigBee到WiFi方向的系统吞吐量为250 bps,较FreeBee提高了15.7%,符号错误率为0.0516,较ZigFi下降了23.21%.

高压电脉冲破碎非均质花岗岩数值模拟

对高压电脉冲破碎机制的研究是提高钻井破岩效率和优化电脉冲电参数的关键。利用颗粒流离散元软件及Voronoi划分建立非均匀介电性质的花岗岩模型,从电流场、电路场、电击穿场进行等离子通道生长过程仿真,并分析非均质度对击穿路径的影响;对比不同花岗岩的电破岩效率和电脉冲破岩效果。结果表明:花岗岩的非均质度增大使得初始电场极值增大,相应地降低了电破岩的能量需求;等离子通道的生长方向存在优先发展区域,等离子通道的生长过程体现出通道尖端处电场集中现象强于通道躯干处;花岗岩非均质度的差异使得等离子通道的总长度和平均贯穿深度存在显著差异,在一定非均质度范围内电脉冲破碎效果和非均质度呈正相关;不同非均质度花岗岩的单脉冲电破岩效率差异不大,等离子通道的总长度越长,电破岩效率越高。

南海北部涠洲A油田储层非均质性对注气开发的影响分析

储层非均质性对油田注气开发的影响是提高采收率的重要因素。文章对涠洲A油田S井区涠四段三套砂体储层非均质性进行评价,并结合岩心驱油实验以及生产动态得出,层间非均质性、平面非均质性、层内非均质性均对注气开发效果存在较大影响。层间非均质性、层内非均质性较强时,注气井吸气不均匀,注气效果较差;平面非均质性较强时,注入气沿高渗通道驱替原油,导致在高渗通道上的生产井气油比上升较快,注气效果较差。

面向软件定义互连系统的多协议交换电路

为满足软件定义互连系统中异构协议融合互连的需求,提出一种两级多协议交换电路,该电路通过融合共享缓存与Crossbar这2种交换架构,实现对多种异构协议的报文转发需求的兼顾。同时,提出一种基于时隙的多级仲裁调度方法,实现调度过程中时间与空间的解耦。仿真结果表明,所设计的交换电路能够弹性适应绑定模式变化引起的交换规模及端口缓存、端口带宽需求变化,缓存资源利用率相较传统组合输入输出排队(CIOQ)架构最高提高87.5%,转发时延低至数十纳秒,不仅适用于RapidIO、光纤通道(FC)、Ethernet、外设部件互连快速总线(PCIe)单一协议交换,而且适用于多种协议组合的混合协议交换。

井—震结合曲流型储层构型研究及应用——以大庆长垣西部斜坡区为例

大庆油田西部斜坡区萨尔图油层萨Ⅰ组储层以曲流型河道砂体沉积为主,由于点坝砂体边界及其内部废弃河道识别精度低,制约着开发水平井的部署。为此,在高密度地震资料基础上,采用基于动态Q补偿的偏移处理技术,大幅提高了河道砂体的成像精度,明确了地震剖面上曲流型河道砂体点坝及其内部废弃河道的波组特征;平面上为进一步突出曲流型河道砂体内部非均质特征,利用楔状地震正演模型,建立了不同频率地震数据体可识别的极限砂体厚度,根据研究区砂体厚度分布值域,优选基于S变换的3个单频体采用RGB三色融合技术,实现了不同厚度级别砂体精准预测;同时,建立了点坝砂体边界及其内部废弃河道的岩心相-测井相-地震相的响应模式,明确了点坝及废弃河道的含油性。研究结果表明:基于动态Q补偿的偏移处理技术,提高了河道砂体在地震剖面上的识别精度;基于S变换的分频体RGB属性融合技术,能够在平面上精准预测废弃河道、点坝边界及其内部非均质性;建立的岩心相—测井相—地震相的响应模式,能够准确预测不同类型砂体的含油性。应用研究成果指导部署井位304口,其中188口直井钻井成功率98.0%,116口水平井平均实钻水平段长度387.8 m,平均含油砂岩钻遇率93.4%。

状态相关衰落信道下异构工业物联网系统的最优无线控制

随着工业4.0的发展,移动智能体系统(Mobile agent system,MAS)与多回路无线控制系统(Wireless control system,WCS)被部署到工厂中,构成异构工业物联网(Industrial internet of things,IIoT)系统,协作执行智能制造任务.在协作过程中,MAS与WCS紧密耦合,导致状态相关衰落,两者性能相互制约.为解决这一问题,研究异构工业物联网系统的最优控制问题,满足WCS控制性能约束与MAS安全生产约束的同时,最小化系统平均通信成本.首先,利用有限域系统描述MAS在不同阴影衰落程度工作区间的转移,刻画MAS与WCS耦合下的状态相关衰落信道模型.基于此,利用矩阵半张量积理论,通过构建受限跟随者状态转移图(Follower state transition graph,FSTG),建立最优控制问题可行性图判据,给出关于受限集合镇定的充分必要条件.其次,基于加权跟随者状态转移图的最小平均环理论,建立领航-跟随MAS最优控制序列的构造算法,并证明其最优性.最后,通过仿真验证算法的有效性.

习题内外表示异质融合的知识追踪模型

现有知识追踪研究大多使用习题蕴涵的知识点等内隐信息或历史交互数据等外显信息建模习题表示,没有注意到内外信息的异质性特征,缺乏对习题内外信息的异质融合。针对上述问题,提出了融合内外异质信息的知识追踪模型。首先,基于知识点等内隐信息,计算历史知识点与当前知识点之间的相关程度,刻画历史知识点对当前知识点的影响,建模习题的内隐表示;其次,基于交互数据等外显信息,计算历史习题与当前习题之间的相关程度,获取历史习题对当前习题的影响,建模习题的外显表示;再次,基于上述习题的内外表示,使用通道注意力机制融合得到习题的内外异质表示,从而预测学习者的作答表现。为了验证提出模型的性能和有效性,选取了四个相关的基线模型,在三个真实数据集上进行了对比实验。实验结果表明:在性能方面,提出的模型在多个评价指标上均取得较好的效果;在有效性方面,消融实验证明了提出的模型可以更好地根据内外信息建模习题表示;在应用方面,设计智慧学习环境证明了提出的模型在实际教学场景中的可用性。

异质性服务平台直营、转销或混合渠道结构选择

考虑异质性服务质量努力与两部定价佣金合同,构建制造商和平台构成的博弈模型,研究异质性服务平台渠道结构,识别直营、转销和混合3种渠道结构成为平台、制造商及系统最佳选择的条件。研究表明,当平台向制造商收取一定范围的固定管理费用时,异质性服务平台选择混合渠道;制造商入侵平台形成的混合渠道会提高批发价格,加剧双重边际效应;制造商服务质量努力系数增大能够减弱服务异质性,使得混合渠道中的批发价格降低,销量增加,促进制造商提升服务质量。并通过设计有效的两部定价佣金合同,使得混合渠道实现Pareto最优。

非正交多址接入异构网络用户公平性问题研究

针对5G非正交多址接入异构网络主要以传输总速率最大化为优化目标带来的资源分配不平衡,导致部分信道最小速率过低,造成用户服务质量下降,从而带来用户之间不公平问题,文中基于非正交接入异构网络模型,综合考虑传输总速率和用户最小速率,提出将整体优化问题解耦,利用最佳信道配对选择和优化用户功率分配方法最大化最小用户速率,解决用户公平性问题。仿真结果表明,提出的算法在较低的复杂度下,用户最小速率明显优于传统方法,用户公平性明显提升。

双渠道下异质品制造商的直销产品选择策略

考虑由单个零售商和单个异质品制造商组成的双渠道供应链,研究制造商直销渠道中的产品选择策略以及零售渠道中所供应的产品类型如何影响该策略。研究表明,当直销成本较低时,制造商的最优决策是在直销渠道同时销售高端产品和低端产品;当产品制造成本和直销成本都很高时,制造商的最优决策是仅直销高端产品。在零售渠道中只提供低端产品或同时提供两种产品情况下,当产品的制造成本较低但直销成本较高时,制造商选择仅直销高端产品;当产品的制造成本中等但直销成本较高时,制造商选择仅直销低端产品。在零售渠道中仅提供高端产品情况下,当制造成本较低时,制造商选择在直销渠道同时销售两类产品;当制造成本中等但直销成本较高时,制造商选择仅直销高端产品。

钙通道阻滞剂1,4-二氢吡啶类药物的绿色合成

心脏及心脑血管疾病是发达国家人群的第一死因,也是中国人死亡的首位原因.L-型钙通道是目前临床上主要使用选择性钙通道阻滞剂1,4-二氢吡啶类药物.文章研究了在非均相催化剂离子交换树脂Amberlyst 15的催化以及无溶剂条件下,高效的合成了钙通道阻滞剂1,4-二氢吡啶类药物.该反应体系具有原料便宜、反应时间短、操作及后处理简单、催化剂可回收利用、反应可放大等优良特点.