The spectral efficiency(SE)and energy efficiency(EE)tradeoff while ensuring rate fairness among users in non-orthogonal multiple access(NOMA)systems is investigated.In order to characterize the SE-EE tradeoff with rat...The spectral efficiency(SE)and energy efficiency(EE)tradeoff while ensuring rate fairness among users in non-orthogonal multiple access(NOMA)systems is investigated.In order to characterize the SE-EE tradeoff with rate fairness,a multi-objective optimization(MOO)problem is first formulated,where the rate fairness is represented with theα-fair utility function.Then,the MOO problem is converted into a single-objective optimization(SOO)problem by the weighted sum method.To solve the converted non-convex SOO problem,we apply sequential convex programming,which helps to propose a general power allocation algorithm to realize the SE-EE tradeoff with rate fairness.We prove the convergence of the proposed algorithm and the convergent solution satisfies the KKT conditions.Simulation results demonstrate the proposed power allocation algorithm can achieve various levels of rate fairness,and higher fairness results in degraded performance of SE-EE tradeoff.A pivotal conclusion is reached that NOMA systems significantly outperform orthogonal multiple access systems in terms of SE-EE tradeoff with the same level of rate fairness.展开更多
In this paper, proportional fairness(PF)-based energy-efficient power allocation is studied for multiple-input multiple-output(MIMO) non-orthogonal multiple access(NOMA) systems. In our schemes, statistical channel st...In this paper, proportional fairness(PF)-based energy-efficient power allocation is studied for multiple-input multiple-output(MIMO) non-orthogonal multiple access(NOMA) systems. In our schemes, statistical channel state information(CSI) is utilized for perfect CSI is impossible to achieve in practice. PF is used to balance the transmission efficiency and user fairness. Energy efficiency(EE) is formulated under basic data rate requirements and maximum transmitting power constraints. Due to the non-convex nature of EE, a two-step algorithm is proposed to obtain sub-optimal solution with a low complexity. Firstly, power allocation is determined by golden section search for fixed power. Secondly total transmitting power is determined by fractional programming method in the feasible regions. Compared to the performance of MIMO-NOMA without PF constraint, fairness is obtained at expense of decreasing of EE.展开更多
To mitigate interference on celledge users and improve fairness of the whole system, dynamic inter-cell interference coordination(ICIC) is one of the promising solutions. However, traditional dynamic ICIC is considere...To mitigate interference on celledge users and improve fairness of the whole system, dynamic inter-cell interference coordination(ICIC) is one of the promising solutions. However, traditional dynamic ICIC is considered as an NP-hard problem and power variability further adds another dimension to this joint optimization issue, making it even more difficult to quickly reach a near-optimal solution. Therefore, we theoretically obtain the closed-form expression of the near-optimal power allocation ratio for users in adjacent cells paired in the same resource block and interfere each other, so that the total utility corresponding to α-fairness is maximized. Dynamic ICIC using this closed-form solution could improve user fairness without causing an increment of the computational complexity. Numerical results show that, compared with the schemes using identical power for different users, our method does not obviously degrade the system's average spectral efficiency.展开更多
协作频谱感知是认知无线电网络的基础和关键阶段,频谱检测过程中的节点分配策略将直接决定联合频谱感知的结果。介绍了多种分配认知终端的方法,旨在提高频谱感知的效率和公平性。针对不同子频带的感知效率,提出了一种称为由频点占用导...协作频谱感知是认知无线电网络的基础和关键阶段,频谱检测过程中的节点分配策略将直接决定联合频谱感知的结果。介绍了多种分配认知终端的方法,旨在提高频谱感知的效率和公平性。针对不同子频带的感知效率,提出了一种称为由频点占用导致的无效传输参数(inefficient transport parameter,ITP)指标来评估通信性能,给出了感知效率优化问题的闭式表达解,设计的场景包括终端对相同频带有不同的感知性能和相同的感知性能。针对不同子频带间的感知公平性,提出了两种分配算法:弓形分配算法和类划分分配算法。子频带间的公平性通过评估子带中最差的感知性能进行衡量。为了适用于实际场景,加入了频段属性参数来增强公平性,该参数考虑了主用户使用不同频段的优先级及抗干扰能力。仿真结果表明,所提出的策略显著改善了认知无线电网络中的ITP,特别是在子频带利用率不同的情况下,提出的弓形分配算法在公平性不明显降低的情况下,复杂度有明显改善。展开更多
为优化珠江地区中医类医疗机构的资源规划,本文利用聚集度分析评估地理与人口要素对医疗资源分配均等性作用的大小,2023年珠江地区中医药(traditional chinese medicine, TCM)类医疗机构共计55家,调查结果发现:珠江东部的中医类医疗机...为优化珠江地区中医类医疗机构的资源规划,本文利用聚集度分析评估地理与人口要素对医疗资源分配均等性作用的大小,2023年珠江地区中医药(traditional chinese medicine, TCM)类医疗机构共计55家,调查结果发现:珠江东部的中医类医疗机构平均地理集聚度为0.7,而中西部地区的平均地理集聚度仅为0.5。这表明在珠江东部,中医类医疗机构的分布相对较为均匀,而在中西部地区,某些地区的医疗机构分布相对较少。按人口配置的公平性,珠江中西部地区的中医类医疗机构平均人口集聚度为0.6,而东部地区的平均人口集聚度仅为0.4。这表明在中西部地区,中医类医疗机构的人口覆盖率相对较高,而在东部地区,某些地区的人口覆盖率较低。总的来说,珠江地区中医类医疗机构的资源配置在公平性和效率方面存在一定的差异。同时,珠江地区总体资源配置的综合效率处于弱DEA有效状态,但仍有许多地区需要进一步提高资源配置的效率和公平性。展开更多
To meet the communication services with diverse requirements,dynamic resource allocation has shown increasing importance.In this paper,we consider the multi-slot and multi-user resource allocation(MSMU-RA)in a downlin...To meet the communication services with diverse requirements,dynamic resource allocation has shown increasing importance.In this paper,we consider the multi-slot and multi-user resource allocation(MSMU-RA)in a downlink cellular scenario with the aim of maximizing system spectral efficiency while guaranteeing user fairness.We first model the MSMURA problem as a dual-sequence decision-making process,and then solve it by a novel Transformerbased deep reinforcement learning(TDRL)approach.Specifically,the proposed TDRL approach can be achieved based on two aspects:1)To adapt to the dynamic wireless environment,the proximal policy optimization(PPO)algorithm is used to optimize the multi-slot RA strategy.2)To avoid co-channel interference,the Transformer-based PPO algorithm is presented to obtain the optimal multi-user RA scheme by exploring the mapping between user sequence and resource sequence.Experimental results show that:i)the proposed approach outperforms both the traditional and DRL methods in spectral efficiency and user fairness,ii)the proposed algorithm is superior to DRL approaches in terms of convergence speed and generalization performance.展开更多
终端直通技术(Device-to-Device,D2D)引入LTE-A蜂窝网络虽然能够提高蜂窝系统性能,但是却带来了很大的干扰。为了降低干扰,提升系统性能,如何进行资源分配成为研究的重点。首先,为了降低资源分配算法的复杂度和干扰强度,提出了D2D通信...终端直通技术(Device-to-Device,D2D)引入LTE-A蜂窝网络虽然能够提高蜂窝系统性能,但是却带来了很大的干扰。为了降低干扰,提升系统性能,如何进行资源分配成为研究的重点。首先,为了降低资源分配算法的复杂度和干扰强度,提出了D2D通信限制区域和D2D用户限制复用蜂窝用户(Cellular User Equipmen,CUE)资源区域的概念。其次,为了保证蜂窝系统服务质量(Quality of Service,Qo S)需求并提升系统性能,提出了一种D2D资源分配算法。最后,使用非线性规划问题中的乘子法来确定D2D用户和CUE的最佳发射功率,以最大化系统吞吐量。仿真结果表明,所提算法与已有方案相比能够显著提升系统的吞吐量和公平性。展开更多
基金Supported by the Fundamental Research Funds for the Central Universities(2016RC055)
文摘The spectral efficiency(SE)and energy efficiency(EE)tradeoff while ensuring rate fairness among users in non-orthogonal multiple access(NOMA)systems is investigated.In order to characterize the SE-EE tradeoff with rate fairness,a multi-objective optimization(MOO)problem is first formulated,where the rate fairness is represented with theα-fair utility function.Then,the MOO problem is converted into a single-objective optimization(SOO)problem by the weighted sum method.To solve the converted non-convex SOO problem,we apply sequential convex programming,which helps to propose a general power allocation algorithm to realize the SE-EE tradeoff with rate fairness.We prove the convergence of the proposed algorithm and the convergent solution satisfies the KKT conditions.Simulation results demonstrate the proposed power allocation algorithm can achieve various levels of rate fairness,and higher fairness results in degraded performance of SE-EE tradeoff.A pivotal conclusion is reached that NOMA systems significantly outperform orthogonal multiple access systems in terms of SE-EE tradeoff with the same level of rate fairness.
基金supported by the National Natural Science Foundation of China (No. 61671252)
文摘In this paper, proportional fairness(PF)-based energy-efficient power allocation is studied for multiple-input multiple-output(MIMO) non-orthogonal multiple access(NOMA) systems. In our schemes, statistical channel state information(CSI) is utilized for perfect CSI is impossible to achieve in practice. PF is used to balance the transmission efficiency and user fairness. Energy efficiency(EE) is formulated under basic data rate requirements and maximum transmitting power constraints. Due to the non-convex nature of EE, a two-step algorithm is proposed to obtain sub-optimal solution with a low complexity. Firstly, power allocation is determined by golden section search for fixed power. Secondly total transmitting power is determined by fractional programming method in the feasible regions. Compared to the performance of MIMO-NOMA without PF constraint, fairness is obtained at expense of decreasing of EE.
基金supported by the National Natural Science Foundation of China under Grant No. 61501160supported by the Fundamental Research Funds for the Central Universities of China under Grant No. 2015HGCH0013
文摘To mitigate interference on celledge users and improve fairness of the whole system, dynamic inter-cell interference coordination(ICIC) is one of the promising solutions. However, traditional dynamic ICIC is considered as an NP-hard problem and power variability further adds another dimension to this joint optimization issue, making it even more difficult to quickly reach a near-optimal solution. Therefore, we theoretically obtain the closed-form expression of the near-optimal power allocation ratio for users in adjacent cells paired in the same resource block and interfere each other, so that the total utility corresponding to α-fairness is maximized. Dynamic ICIC using this closed-form solution could improve user fairness without causing an increment of the computational complexity. Numerical results show that, compared with the schemes using identical power for different users, our method does not obviously degrade the system's average spectral efficiency.
文摘协作频谱感知是认知无线电网络的基础和关键阶段,频谱检测过程中的节点分配策略将直接决定联合频谱感知的结果。介绍了多种分配认知终端的方法,旨在提高频谱感知的效率和公平性。针对不同子频带的感知效率,提出了一种称为由频点占用导致的无效传输参数(inefficient transport parameter,ITP)指标来评估通信性能,给出了感知效率优化问题的闭式表达解,设计的场景包括终端对相同频带有不同的感知性能和相同的感知性能。针对不同子频带间的感知公平性,提出了两种分配算法:弓形分配算法和类划分分配算法。子频带间的公平性通过评估子带中最差的感知性能进行衡量。为了适用于实际场景,加入了频段属性参数来增强公平性,该参数考虑了主用户使用不同频段的优先级及抗干扰能力。仿真结果表明,所提出的策略显著改善了认知无线电网络中的ITP,特别是在子频带利用率不同的情况下,提出的弓形分配算法在公平性不明显降低的情况下,复杂度有明显改善。
文摘为优化珠江地区中医类医疗机构的资源规划,本文利用聚集度分析评估地理与人口要素对医疗资源分配均等性作用的大小,2023年珠江地区中医药(traditional chinese medicine, TCM)类医疗机构共计55家,调查结果发现:珠江东部的中医类医疗机构平均地理集聚度为0.7,而中西部地区的平均地理集聚度仅为0.5。这表明在珠江东部,中医类医疗机构的分布相对较为均匀,而在中西部地区,某些地区的医疗机构分布相对较少。按人口配置的公平性,珠江中西部地区的中医类医疗机构平均人口集聚度为0.6,而东部地区的平均人口集聚度仅为0.4。这表明在中西部地区,中医类医疗机构的人口覆盖率相对较高,而在东部地区,某些地区的人口覆盖率较低。总的来说,珠江地区中医类医疗机构的资源配置在公平性和效率方面存在一定的差异。同时,珠江地区总体资源配置的综合效率处于弱DEA有效状态,但仍有许多地区需要进一步提高资源配置的效率和公平性。
基金supported by the National Natural Science Foundation of China(No.62071354)the Key Research and Development Program of Shaanxi(No.2022ZDLGY05-08)supported by the ISN State Key Laboratory。
文摘To meet the communication services with diverse requirements,dynamic resource allocation has shown increasing importance.In this paper,we consider the multi-slot and multi-user resource allocation(MSMU-RA)in a downlink cellular scenario with the aim of maximizing system spectral efficiency while guaranteeing user fairness.We first model the MSMURA problem as a dual-sequence decision-making process,and then solve it by a novel Transformerbased deep reinforcement learning(TDRL)approach.Specifically,the proposed TDRL approach can be achieved based on two aspects:1)To adapt to the dynamic wireless environment,the proximal policy optimization(PPO)algorithm is used to optimize the multi-slot RA strategy.2)To avoid co-channel interference,the Transformer-based PPO algorithm is presented to obtain the optimal multi-user RA scheme by exploring the mapping between user sequence and resource sequence.Experimental results show that:i)the proposed approach outperforms both the traditional and DRL methods in spectral efficiency and user fairness,ii)the proposed algorithm is superior to DRL approaches in terms of convergence speed and generalization performance.
文摘终端直通技术(Device-to-Device,D2D)引入LTE-A蜂窝网络虽然能够提高蜂窝系统性能,但是却带来了很大的干扰。为了降低干扰,提升系统性能,如何进行资源分配成为研究的重点。首先,为了降低资源分配算法的复杂度和干扰强度,提出了D2D通信限制区域和D2D用户限制复用蜂窝用户(Cellular User Equipmen,CUE)资源区域的概念。其次,为了保证蜂窝系统服务质量(Quality of Service,Qo S)需求并提升系统性能,提出了一种D2D资源分配算法。最后,使用非线性规划问题中的乘子法来确定D2D用户和CUE的最佳发射功率,以最大化系统吞吐量。仿真结果表明,所提算法与已有方案相比能够显著提升系统的吞吐量和公平性。