Mitigation of inter-cell interference in visible light communication

This paper proposes the orthogonal and nonorthogonal schemes in the interference environments for visible light communication（ VLC） systems. The proposed schemes pay attention to the case when different bit streams from multiple cells are simultaneously transmitted, which consequently causes inter-cell interference（ ICI） and greatly deteriorates the bit error rate（ BER） and channel capacity performance of the system. The performance of the newdeveloped multi-cell system in indoor VLC systems is evaluated. The bipolar phase shift keying（ BPSK） modulation scheme with orthogonal pulses（ OPs） for multiple cells environments is employed to mitigate the ICI problem and improve the BER and channel capacity performances. Since the use of different OPs in each cell requires more number of OPs, which requires high bandwidth, OPs are reused at certain distances. Three different schemes, which are OPs,orthogonal and non-orthogonal pulses（ NOP） reuse, are compared. This paper investigates the impact of using these schemes and compared their performances in the ICI environments. The BER and channel capacity using the proposed schemes are comprehensively examined. Simulation and theoretical results showthat the OPs schemes are more effective in the interference areas of the room and significantly outperform NOP.

Pricing Based Power Control for Inter-Cell UAV-Assisted Vehicle-to-Vehicle Underlay Communication

The high-capacity vehicle-to-vehicle(V2 V) communication provides a promising solution to support ubiquitous media streaming and content sharing among vehicles.To extend the V2 V links to multiple cells and manage the inter-cell interference,we proposed an UAV-assisted inter-cell V2 V communication model,in which a shared UAV node is placed in the center of V2 V users.By charging the V2 V users underlay spectrum access fee,the cellular network earn profit at the cost of encountering co-channel interference from V2 V links.A Stackelberg game is formulated to model the interactions between the V2 V links and the cellular links,which are the game follower and the leader respectively.Their utility functions are maximized in terms of accessing price as well as transmit power of V2 V users and UAV relays.Simulation evaluations verify that the power-price tradeoff between V2 V network and cellular network has significant potentials to enhance their utility.

COOPERATIVE DIRECTIONAL INTER-CELL HANDOVER SCHEME IN HIGH ALTITUDE PLATFORM COMMUNICATIONS SYSTEMS

A novel Cooperative Directional inter-cell Handover Scheme(CDHS) for High Altitude Platform(HAP) communications systems is proposed,in which the handover target cell and the two cells adjacent to this handover target cell work cooperatively to exploit the traffic fluctuation to improve handover performance.Users in the overlap area of the overloaded handover target cell will be forced to handover directionally before their optimal handover boundary in order to free up resources for the handover calls which would otherwise be dropped due to the shortage of resources and queue time out.Simulation results show that the handover call dropping probability is greatly reduced(at least 60%) compared with the general queue handover scheme,with little performance reduction to the call blocking probability,and the Not in the Best Cell(NBC) average time is only increased moderately.Moreover,an optimal cell radius can be achieved for a specific platform speed by minimizing the unified system performance,which is the linear combination of the handover call dropping probability and the NBC average time.

Congestion Relief in Downlink OFDMA Cellular System Using Inter-Cell Relay

This paper proposes the concept of inter-cell relay for downlink orthogonal frequency division multiple access(OFDMA) cellular systems, which uses multi-hop to relay calls from overloaded cells to light-load neighboring cells. It is shown that when using inter-cell relay, the number of calls in the congestion cell can be significantly increased. The congestion cell is divided into two parts. One is called non-relay area(NRA), in which a call directly communicates with the base station(BS) of a congested cell. The other is called relay area(RA), in which a call communicates with the BS of a neighboring cell through a relay station(RS). The two parts have different user-call densities. By adjusting the densities of two parts, we will maximize the number of supported calls inside a congested cell. The results show the benefits gained from inter-cell relay in congestion relief, which can reduce cell congestion by fully utilizing the available resources in the neighboring cells.

Inter-Cell Interference Cancellation Algorithm for Reverse Link TDD-CDMA Systems

This paper proposes a new inter-cell interference cancellation algorithm called subspace projection in order to eliminate the stronger inter-cell interference. This algorithm is designed for the reverse link of time division duplex-code division multiple access systems. The algorithm works by projecting desired users＇ signal vector onto the subspace orthogonal to the subspace that inferrers the users＇ signal. Link-level simulation results show that the scheme eliminates the inter-cell interference efficiently, improves the receiver performance, and increases the system capacity.

Multicell power allocation method based on game theory for inter-cell interference coordination

As a new technology, coordinated multipoint （CoMP） transmission is included in LTE-Advanced study item. Moreover, the network architecture in LTE-Advanced system is modified to take into account coordinated transmission. Under this background, a novel power allocation game model is established to mitigate inter-cell interference with cellular coordination. In the light of cellular cooperation relationship and centralized control in eNodeB, the power allocation in each served antenna unit aims to make signal to interference plus noise ratio （SINR） balanced among inter-cells. Through the proposed power allocation game algorithm, the users＇ SINR can reach the Nash equilibrium, making it feasible to reduce the co-frequency interference by decreasing the transmitted power. Numerical results show that the proposed power allocation algorithm improves the throughput both in cell-center and cell-edge. Moreover, the blocking rate in cell-edge is reduced too.

Performance of power control in inter-cell interference coordination for frequency reuse

To mitigate inter-cell interference in 3G evolution systems, a novel inter-cell interference coordination scheme called soft fractional frequency reuse is proposed in this article, which enables to improve the data rate in cell-edge. On this basis, an inter-cell power control is presented for the inter-cell interference coordination, and the inter-cell balanced signal to interference plus noise ratio （SINR） among users is established for power allocation, which enables mitigation of inter-cell interference. Especially, the power control is based on a novel exponential kernel arithmetic kernel equations. Numerical results show that the proposed rate compared to the existing power control algorithms. equation at higher convergence speed than the traditional scheme improves the throughput and reduces the blocking

Approximate inter-cell interference modeling for cellular network

In this paper, we develop and analyze several inter-cell interference modeling methods for cellular network. The models can analyze multiple interfering signals under different fading scenarios. Incoherent addition of summing multiple interfering signals is assumed. We propose an approximate method that uses the generalized Gram-Charlier series to analyze the error of the reference model. The approximate method is not only simple but also with neglectable errors. The methods proposed could be very useful in practical system design and analysis.

室内VLC-WiFi异构网络中多色载波资源分配

可见光通信接入点(VLC AP)在室内密集部署的方式在扩大VLC-WiFi系统容量的同时,增加了覆盖的小区间干扰。为了降低小区间干扰,提高系统的吞吐量和平均用户满意度,本文设计了多色载波分配与功率控制(MCAPC)的资源分配方法。该方法依据VLC AP的部署位置和信道特性,采用软频率复用方法确定各VLC AP的无干扰的主载波和多色副载波,并设计基于匹配博弈的载波和子频带分配算法为用户分配异构网络的频带资源;最后,设计基于功率控制效用值的干扰抑制的载波功率控制算法进一步抑制小区间干扰。研究结果表明,所提MCAPC方法能够提高室内多色VLC-WiFi异构网的系统吞吐量和用户的平均满意度。

基于K-means聚类的超启发式跨单元调度方法

结合我国制造业实际生产状况,针对柔性作业车间跨单元调度问题,提出一种基于K-means聚类的超启发式算法。应用K-means聚类算法将相近属性的实体划入相应“工件簇”决策块中,采用蚁群算法为每个决策块选择启发式规则;对每个决策块内的实体运用相应的启发式规则产生调度解。仿真结果表明:该算法以决策块的形式适度增大了计算粒度,有效降低了算法时间复杂度,以聚类的方式将具有相近属性的被加工实体进行聚集,有利于为不同属性的实体选择合适的规则。该算法提高了计算效率,具有较好的优化性能,是解决柔性跨单元调度的一种有效算法。

牙周炎与炎症性肠病相关研究进展

炎症性肠病(inflammatory bowel disease,IBD)是一组受多种因素影响的慢性非特异性胃肠道炎症性疾病,主要包括克罗恩病和溃疡性结肠炎。牙周炎是一类以牙菌斑生物膜为始动因子,牙槽骨慢性吸收破坏为表现的疾病。近年来越来越多的研究表明牙周炎与炎症性肠病二者之间存在相关性,但两者间的关系仍不明确。本综述从流行病学证据、生物学证据、关联治疗证据三个维度探究了两种疾病的内在关系:从流行病学证据来看,牙周炎与IBD患病风险增加相关,反过来IBD也影响牙周健康,其双向关联还需要进一步扩大数据源研究;从生物学证据来看,无论临床研究还是动物实验均说明IBD和牙周炎相互影响;从关联治疗证据来看,对IBD治疗有益的药物用于牙周炎的防治同样有效,对牙周炎改善有利的药物也可明显缓解IBD。IBD与牙周炎的相互作用机制包括微生物途径和免疫途径。微生物途径是指由于牙周炎患者口腔内机会致病菌的比例增加以及IBD影响了胃液分泌以及肠道菌群平衡,口腔细菌通过口腔肠道轴或血行传播异位定植于肠道的几率增大,这些微生物会通过释放毒力因子,破坏肠道黏膜屏障,引发炎症反应等方式进一步加重IBD炎症。免疫途径是指牙周炎激活口腔内适应性免疫,产生大量免疫细胞,特别是Th17细胞,其表面存在肠道归巢标记物α4β7整合素,IBD患者肠道黏膜上的α4β7整合素的配体表达增加,使得口腔Th17细胞加速转移至肠道从而加剧肠道炎症。研究表明,IBD患者口腔内细胞因子的表达量异常,如肿瘤坏死因子-α、白细胞介素-1β、白细胞介素-10、白细胞介素-6、白细胞介素-21、可溶性CD40配体(soluble CD40 ligand,sCD40L)、白细胞介素-23和干扰素-γ,提示IBD通过免疫途径影响牙周炎,以上细胞因子是治疗两种疾病的靶点所在,可为未来两种疾病的防治提供研究方向。

无蜂窝大规模MIMO的接入点间同步与空口校准技术

无线通信系统中多个天线单元相干协作发送(CJT)技术的性能严重依赖于发送端已知信道状态信息(CSI)。为了避免CSI反馈,通常假设系统工作在时分双工(TDD)模式。利用TDD空口上下行信道的互易性,根据上行探测信道获得下行CSI。但是,实际系统中由于节点(AP)间存在同步误差及通道的非理想因素,上下行整体信道并不互易。研究了面向无蜂窝大规模MIMO的网络侧时频同步以及空口(OTA)校准技术。基于现网商用远端天线单元(RRU)以及同步技术,给出了大规模组网的同步和空口校准方案。结合试验系统,探讨了CJT对同步和校准的性能的要求以及无蜂窝大规模MIMO实现方式和节点天线配置,给出了校准相位的预测性能。

帝迈DM79x血细胞分析仪的精密度和准确度情况分析

目的通过比对室内质控数据,评估4台DM79x血细胞分析仪在医院检验科每日室内质量控制中最宜工作状态下的精密度和准确度水平,提高检验结果准确性和一致性。方法统计2023年2月份(28天)实验室4台仪器使用原装低、中、高定值质控品以及每日检测一份随机门诊新鲜患者样本的室内质控数据,项目包括:白细胞(WBC)、红细胞(RBC)、血红蛋白(HGB)、血细胞比容(HCT)、血小板(PLT)、平均红细胞体积(MCV)、平均红细胞血红蛋白量(MCH)、平均红细胞血红蛋白浓度(MCHC),计算平均值(-X)、标准差(S)和变异系数(CV),以变异系数指数(CVI)和标准差指数(SDI)分别作为精密度和准确度评价指标。结果DM79x 4台仪器间室内质控比对,统计分析发现仪器对血细胞分析包括WBC、RBC、HGB、PLT、HCT、MCV、MCH、MCHC 8项参数,每台仪器的CVI不一,SDI室内质控测定结果<2.0,新鲜样本比对数据CVI、SDI的测定值均在要求范围内。结论医院检验科4台DM79x型全自动血细胞分析仪通过比对实验室间室内质量控制数据,具有良好的精密度和高准确度,仪器性能可满足临床实验室的工作需求,且通过患者新鲜样本比对,确保结果在不同仪器的准确性和一致性。

血清ITIH4和MCL-1水平与急性缺血性脑卒中患者病情程度及预后的关系

目的探究急性缺血性脑卒中(AIS)患者血清间α胰蛋白酶抑制因子重链4(ITIH4)、髓样细胞白血病因子-1(MCL-1)表达与病情程度及预后的关系。方法纳入2019年7月—2022年7月河南科技大学附属黄河医院神经内科诊治AIS患者128例为AIS组。根据入院时美国国立卫生研究院卒中量表(NIHSS)评分,分为轻度亚组(NIHSS<6分,n=42)、中度亚组(NIHSS 6~<14分,n=52)和重度亚组(NIHSS≥14分,n=34)。根据出院3个月时AIS患者改良Rankins评分,分为预后不良亚组(mRS评分>2分,30例)和预后良好亚组(mRS评分≤2分,98例)。另选取同期医院体检的健康人70例为健康对照组。酶联免疫吸附试验检测血清ITIH4、MCL-1水平。Pearson相关分析血清ITIH4、MCL-1水平与病情程度及预后的相关性;多因素Logistic回归分析影响AIS患者预后的因素;受试者工作特征曲线分析血清ITIH4、MCL-1对AIS患者预后的预测价值。结果AIS组患者血清ITIH4、MCL-1水平显著低于健康对照组(t/P=43.211/<0.001,43.191/<0.001);病情程度越重,AIS患者血清ITIH4/MCL-1水平越低(F/P=107.796/<0.001,297.976/<0.001);预后不良亚组梗死面积、入院24 h NIHSS评分高于预后良好亚组(t/P=9.637/<0.001,9.752/<0.001),血清ITIH4、MCL-1水平及出院3个月简易智能状态量表(MMSE)评分、蒙特利尔认知评估量表(MoCA)评分低于预后良好亚组(t/P=26.723/<0.001,11.709/<0.001,13.674/<0.001,10.782/<0.001);AIS患者血清ITIH4、MCL-1与梗死面积、入院24 h NIHSS评分呈负相关(r/P=-0.705/<0.001,-0.685/<0.001;-0.761/<0.001,-0.619/<0.001),与出院3个月MMSE评分、MoCA评分呈正相关(r/P=0.656/<0.001,0.632/<0.001;0.751/<0.001,0.789/<0.001);出院3个月MMSE评分高、出院3个月MoCA评分高是影响AIS患者预后不良的独立保护因素[0.622(0.446~0.868),0.606(0.427~0.861)],血清ITIH4低、MCL-1低、梗死面积大、入院24 h NIHSS评分高是危险因素[OR(95%CI)=1.467(1.150~1.870),1.415(1.094~1.829),1.605(1.168~2.205),1.765(1.233~2.526)];血清ITIH4、MCL-1及两项联合预测AIS预后不良的AUC分别为0.811、0.835、0.923,两项联合预测AIS预后不良的AUC大于单一指标,差异具有统计学意义(Z=4.258、4.119,P均<0.001)。结论AIS患者血清ITIH4、MCL-1表达下调,两者表达水平与病情严重程度有关,两者联合对AIS患者预后具有较高的预测价值。

5G抗干扰技术综述

5G技术不仅在以蜂窝网络为代表的移动互联网中占据主要角色,还正在积极地为工业场景提供技术变革的契机.目前,国内外已经开展了大量和5G抗干扰技术相关的工作,但仍缺乏对5G在授权和非授权频谱下抗干扰技术的系统性综述.本文分析了5G无线干扰的主要来源,指出了抗干扰研究的技术难点,并以授权频段5G蜂窝网络干扰与非授权频段异构系统间干扰两个关键问题为例,对现有的无线抗干扰方案进行了具体分析和归纳对比,最后对5G技术在授权频段和非授权频段抗干扰技术的未来研究方向进行了展望.

面向5G毫米波通信中基于深度图搜索的波束干扰协调

在毫米波(Millimeter Wave,mmWave)通信中,波束成形(Beam Forming,BF)技术使得小区间的干扰模型不同于工作在低频带的情况,小区间干扰(Inter-Cell Interference,ICI)的影响随着小区密度的增加而增加.为了解决毫米波小区间波束干扰研究中较多的信道状态信息反馈的开销和较高的计算复杂度问题,以时隙调度波束为基础设计了多个小区的波束调度算法.首先针对相邻的毫米波小区在同一时隙向同一边缘用户进行服务会产生较差的传输质量这一特征,构建了波束冲突矩阵.其次充分考虑用户需求的不同服务时隙数量,不同的小区波数数量,小区链路数有限等限制条件,提出了一种基于深度图搜索的波束干扰协调算法.仿真结果表明:所提算法能够明显降低波束碰撞的数量,提高信噪比,改善网络和速率.

聚光光伏系统太阳能电池散热技术及发展现状

低碳政策下新能源的高效利用势在必行,有效利用太阳能聚光光伏技术的核心为太阳能电池,太阳能电池对温度的变化非常敏感,高温会大幅降低太阳能电池的性能及寿命,因此,太阳能电池的有效散热是限制该技术发展的瓶颈。本文首先介绍了聚光太阳能电池散热的必要性及散热难题,随后根据电池结构和热沉装置之间是否存在壁面,从间壁式冷却和直接接触式冷却两个角度回顾了近年来国内外在电池冷却技术方面的研究现状及最新进展。最后,通过各冷却技术的冷却效果和电池性能增益对比分析了各冷却方式的优缺点和未来的研究重点,为聚光光伏系统太阳能电池的有效散热提供了参考与借鉴。

长链非编码RNA HOX转录反义RNA靶向miR-206对结直肠癌细胞迁移、侵袭的影响

目的探讨长链非编码RNA(lncRNA)HOX转录反义RNA(HOTAIR)靶向miR-206对结直肠癌细胞侵袭和迁移的影响。方法常规培养人结直肠癌HT-29细胞,将合成的HOTAIR si RNA和siRNA control转染于HT-29细胞,设置为si-HOTAIR组、si-con组,未进行转染的HT-29细胞设置为空白组。实时荧光定量聚合酶链反应测定转染效果,Transwell和划痕愈合实验检测HT-29细胞侵袭和迁移情况。生物信息学软件分析HOTAIR与miR-206区域结合位点,构建突变型(HOTAIR 3’UTR mut)和野生型(HOTAIR 3’UTR wt)萤光素酶报告载体,将HOTAIR 3’UTR wt、HOTAIR 3’UTR mut与miR-206 mimic或miR-NC载体共转染至HT-29细胞中,设为HOTAIR 3’UTRwt/miR-NC组、HOTAIR3’UTRwt/miR-206组、HOTAIR3’UTRmut/miR-NC组,HOTAIR3’UTRmut/miR-206组,培养48 h后检测萤光素酶活性。将HOTAIR si RNA和miR-206 inhibitor共转染于HT-29细胞,设置si-HOTAIR+anti-NC组和si-HOTAIR+anti-miR-206组,用Transwell和划痕愈合实验分析细胞侵袭、迁移水平。结果空白组与si-con组HT-29细胞中HOTAIR m RNA的表达水平比较,差异无统计学意义(P>0.05);与si-con组比较,si-HOTAIR组HT-29细胞中HOTAIR m RNA的表达水平降低(P<0.01)。空白组与si-con组HT-29细胞侵袭数目、细胞划痕愈合率比较,差异无统计学意义(P>0.05);与si-con组比较,si-HOTAIR组HT-29细胞侵袭数目减少,细胞划痕愈合率降低(P<0.01)。与HOTAIR 3’UTR wt/miR-NC组比较,HOTAIR 3’UTR wt/miR-206组中HOTAIR wt的萤光素酶活性下降(P<0.01);而HOTAIR 3’UTR mut/miR-NC组与HOTAIR 3’UTR mut/miR-206组萤光素酶活性比较,差异无统计学意义(P>0.05)。与si-HOTAIR+anti-NC组比较,si-HOTAIR+anti-miR-206组中miR-206的表达水平降低(P<0.01)。与si-HOTAIR+anti-NC组比较,si-HOTAIR+anti-miR-206组中HT-29细胞的侵袭和迁移率增加(P<0.01)。结论HOTAIR通过负调控miR-206促进HT-29细胞的侵袭和迁移能力。

基于深度强化学习的无人机小区间干扰抑制技术研究

无人机(UAV)辅助蜂窝网络的空中基站工作在频谱高度拥挤的场景中,会造成严重空中小区间干扰(Inter-Cell Interference, ICI)而大大降低网络性能。为解决该问题,研究了基于深度强化学习的无人机辅助蜂窝网络小区间干扰抑制技术。首先建立了无人机辅助蜂窝网络中基于联合波束成形与功率控制(Joint Beamforming and Power Control, JBPC)的抗干扰优化模型。然后提出了基于置信区间上界(Upper Confidence Bound, UCB) Dueling深度Q网络(Deep Q Network, DQN)的深度强化学习求解算法,并利用该算法设计了联合波束成形和功率控制的ICI抑制技术。仿真结果表明,基于UCB Dueling DQN学习的JBPC干扰抑制技术的收敛性优于DQN和Dueling DQN算法,且能达到穷举法的最优容量,有利于提高无人机辅助蜂窝网络性能。

大型基础设施项目融资风险动态评价体系研究

提出以＂融资风险阶段划分—分担—评价＂为主线的融资风险评价体系。基于＂新两阶段论＂把融资风险划分为缔约阶段融资风险和履约阶段融资风险;针对划分后的融资风险,构建灰色关联度和TOPSIS法相结合的分担模型;利用遗传算法优化支持向量机,在融资风险分担完成后,对融资风险展开评价;以青岛胶州湾海底隧道为例进行实证研究。研究表明：该评价体系实现了＂动态性＂＂针对性＂和＂准确性＂,是科学合理的,可以为大型基础设施项目中各利益攸关方及时准确地掌握各自的融资风险状况提供帮助。