OFDMA中继网络基于效用的资源分配

研究半双工正交频分复用（OFDMA）中继网络的资源分配。解决动态子信道分配,自适应功率分配,传输策略选择和中继选择的联合优化问题。为了公平利用中继用户的资源,把中继用户所能帮助的最大子信道数和每个子信道的功率设为常量。在此基础上,提出贪婪算法以最大化总效用。当算法每次分配资源时,把资源分配给潜在效用增长最大的用户。仿真结果表明所提算法与固定的资源分配策略相比,能更高效地利用资源,并且改善了用户间的公平性。     

基于自适应功率分裂的协作非正交多址接入无线携能通信网络性能分析

为了提高无线通信系统的频谱利用率、降低功耗,针对双向协作非正交多址接入携能网络,提出了一种自适应功率分裂的无线携能准则。中继利用译码转发协议和用户的距离信息执行串行干扰消除,检测用户的信息并从发送端收割能量。发送端设计自适应功率分裂准则,使中继可以成功检测用户的信息,然后把剩余的能量全部用于能量传输,进而中继可以收割到最多的能量并将所解码的信息转发给接收端。基于所提的自适应功率分裂准则,分析网络的全局中断概率、端到端中断概率,以及高信噪比条件下的分集增益。与基于固定功率分裂的协作三级正交多址接入携能网络相比,基于自适应功率分裂的协作两级非正交多址接入携能网络可以获得更优的中断性能。     

IMT—Advanced协作中继的网络编码技术

网络编码技术的本质是在中间节点上对多条输入链路的数据信息进行线性或非线性处理转发。网络编码技术应用于IMT—Advanced系统中时,不仅可用于提高中继转发效率,还可用于设计干扰利用传输策略,以节约小区内的时频资源。文章针对多址接入中继信道模型,讨论了几种可提高中继转发效率的网络编码传输策略,研究了基于网络编码的干扰利用传输策略,分析了网络编码标准化过程中所面临的各种问题,指出引入网络编码技术对中继传输协议、控制帧格式以及用户调度和资源管理算法等的影响。     

无线双向中继网络编码系统用户调度方法性能分析

提出了一种用于无线双向中继网络编码系统的用户调度方法,基站或中继在调度用户时,综合考虑基站与中继和用户与中继之间信道的影响,使得基站采用原有预编码算法时,具有了波束赋形增益。仿真表明,系统吞吐量和首次传输的正确率明显提升,且算法复杂度低、用户公平性好,便于在实际系统使用。     

基于PF调度的多源多中继协作网络节点选择

针对多源多中继协作网络模型,提出一种公平的节点选择与用户调度方案。出于优化平均信道质量的思想,每个传输时隙,选择信道条件差异最大的两个用户同时进行传输信息。中继节点选择基于PF比例公平调度算法,能保证中继节点处的负载均衡。然后在中继端采用一种网络编码传输方案。最后,与其他2种调度方案相比较仿真系统的误码率性能。     

网络编码在IMT-Advanced协作中继中的应用

在IMT-Advanced协作中继中引入网络编码技术,它可以进一步提升网络吞吐量、负载均衡、安全性和顽健性。针对多用户的上行多址接入中继信道模型,给出了基于网络编码的传输策略,在此基础上,分析了该策略下的系统可达速率及中断概率,并与传统机制进行了比较。实验结果表明,网络编码可有效提升系统性能并节约无线链路资源,从而表明了网络编码在IMT-Advanced协作中继中应用的巨大潜力和优势。     

多径下Turbo码IDMA网络编码中继合作系统性能分析

基于交织多址网络编码中继合作系统,分析了其采用Turbo编码后在多径信道环境下的系统性能。研究了该系统中利用不同交织器来实现多用户的多址接入方式以及网络编码的中继合作机制。将多径信道以及Turbo编码融入该系统中,搭建计算机仿真环境,通过仿真数据分析系统性能。仿真结果表明,在多径信道环境下,采用Turbo编码的交织多址网络编码中继合作系统的系统误码率有明显改善。     

公平性驱动的RSMA-SDMA预编码设计

针对在发射功率受限时系统最小用户速率与系统公平性问题,提出了一种联合速率分拆多址接入(RSMA)和空分多址接入(SDMA)的用户接入方式选择传输策略,并建模了最大化系统公平性预编码设计问题.为解决建模所形成的离散非凸优化问题,将其分解为求解外层用户接入方式选择与内层最优预编码设计2个非凸子问题.针对预编码设计优化,利用...     

面向用户体验的多小区混合非正交多址接入网络资源分配方法

该文研究了多小区混合非正交多址接入(MC-hybrid NOMA)网络的资源分配.为满足异构用户的服务体验,以最大化全网综合平均意见评分(MOS)累加和为目标,考虑基站选择、信道接入和功率资源分配的联合优化问题,该文提出一种用户、基站和信道3方的2阶段转移匹配算法,并根据用户MOS进行子信道功率优化.仿真结果表明所提多小区混合NOMA网络资源分配方案能有效提升全网用户服务体验和公平性.     

基于双向中继和网络编码的NOMA网络性能分析

针对实际场景中存在的具有上下行双向传输任务的通信系统,本文提出了一种双向中继协作非正交多址接入(NOMA, non-orthogonal multiple access)传输方案,基于解码转发(DF, Decode and Forward)协议研究信号的上行和下行双向传输技术,与现有NOMA方案不同,本方案为近端用户分配较大的功率,利用网络编码(NC, network coding)原理在两个时隙内实现基站和用户之间的双向信息交换。进一步考虑不完美信道状态信息(CSI, Channel State Information)条件,分析系统的传输性能并推导了系统中断概率以及遍历和速率闭合表达式。仿真结果表明,在完美CSI和不完美CSI条件下,相比于现有文献所提方案、单向中继(OWR,One-Way Relay)和正交多址(OMA, Orthogonal Multiple Access)网络,本文所提方案有效降低了系统的传输中断概率,提高了系统的遍历和速率以及系统吞吐量。      

改进的多用户OFDM系统子载波和比特分配算法

针对多用户正交频分复用（OFDM）系统资源分配问题,提出了一种改进的基于边缘自适应（MA）准则的子载波和比特分配算法。在采用比例公平准则为每个用户分配子载波集合基础上,以用户速率最大者-最小者（Max-Min）子载波交换为原则进行子载波调整,使用户功率递减同时兼顾用户的公平性;通过对信道状态信息进行判断,利用贪婪算法将用户子载波分配的比特取整,以实现系统功率最小化。实验结果表明,本文提出的改进次优算法的计算复杂度较传统分步算法稍高,但仍远低于最优算法,其系统性能得以提升,且接近最优算法。     

Proportional fair scheduling with superposition coding in a cellular cooperative relay system

Many works have tackled on the problem of throughput and fairness optimization in cellular cooperative relaying systems. Considering firstly a two-user relay broadcast channel, we design a scheme based on superposition coding (SC) which maximizes the achievable sum-rate under a proportional fairness constraint. Unlike most relaying schemes where users are allocated orthogonally, our scheme serves the two users simultaneously on the same time-frequency resource unit by superposing their messages into three SC layers. The optimal power allocation parameters of each SC layer are derived by analysis. Next, we consider the general multi-user case in a cellular relay system, for which we design resource allocation algorithms based on proportional fair scheduling exploiting the proposed SC-based scheme. Numerical results show that the proposed algorithms allowing simultaneous user allocation outperform conventional schedulers based on orthogonal user allocation, both in terms of throughput and proportional fairness. These results indicate promising new directions for the design of future radio resource allocation and scheduling algorithms.     

Performance analysis of user fair-based relay adaptive power allocation in physical-layer network coding cooperation

Network Coding (NC) is an effective technology to enhance the cooperative system spectral efficiency. However, since it is network-oriented, the existing performance metric of single-user outage can not comprehensively evaluate its gain and the impact to the entire network, which affect the user fairness. This paper proposes two novel user fair-based adaptive relay power allocation algorithms in single-relay NC cooperative multiple access channels. Firstly, common outage probability is employed as the performance metric, and to minimize it, a specific condition is deduced. On this basis, the instantaneous channel information-based adaptive relay power allocation scheme and the channel statistic information-based one with lower complexity are designed respectively, which make users?? signals superimposed at accurately calculated proportion to maintain fairness. Simulation results show that compared with other existing schemes, the proposed schemes can best maintain user fairness, and effectively improve the common outage performance of the whole system, at the expense of small spectral efficiency.     

Resource allocation with proportional rate fairness in orthogonal frequency division multiple access relay networks

We address the problem of subchannel and transmission power allocation in orthogonal frequency division multiple access relay networks with an aim to maximize the sum rate and maintain proportional rate fairness among users. Because the formulated problem is a mixed‐integer nonlinear optimization problem with an extremely high computational complexity, we propose a low‐complexity suboptimal algorithm, which is a two‐step separated subchannel and power allocation algorithm. In the first step, subchannels are allocated to each user, whereas in the second step, the optimal power allocation is carried out on the basis of the given subchannel allocation and the nonlinear interval Gauss–Seidel method. Simulation results have demonstrated that the proposed algorithm can achieve a good trade‐off between the efficiency and the fairness compared with two other existing relevant algorithms. In particular, the proposed algorithm can always achieve 100% fairness under various conditions. Copyright © 2012 John Wiley & Sons, Ltd.     

Distributed two‐hop proportional fair resource allocation in Long Term Evolution Advanced networks

In Long Term Evolution Advanced networks with Type I in‐band half‐duplex decode‐and‐forward relay nodes, proportional fair (PF) resource allocation is aiming at guaranteeing two‐hop match and optimising global proportional fairness. The two‐hop match is defined as equal data rates in the access links and the corresponding backhaul links. The global proportional fairness is between all the user equipments served by the evolved nodes B and the relay nodes. Existing centralised schemes achieve these targets at the cost of enormous channel state information (CSI) exchange. Existing distributed schemes focus on resource partitioning and employ a traditional single‐hop PF scheduling algorithm in access links, with less CSI exchange. The traditional PF scheduling algorithm maximises single‐hop proportional fairness between the data rates in the access links rather than two‐hop proportional fairness between the end‐to‐end data rates in the two hops. In order to reduce CSI exchange and at the same time to maximise the two‐hop proportional fairness, a distributed two‐hop PF resource allocation scheme is proposed. The proposed scheme includes two‐hop PF resource scheduling algorithms and adaptive resource partitioning algorithms, applied in different two‐hop transmission protocols. Simulation results demonstrate the proposed scheme is better than the existing distributed schemes in obtaining better proportional fairness and larger cell‐edge user equipment throughputs. Copyright © 2014 John Wiley & Sons, Ltd.     

无线供电混合多址接入网络的资源分配

无线供电技术是延长无线网络节点寿命的有效方案。该文研究一个由基站和多个分簇用户组成的无线供电混合多址接入系统。系统的传输分为两个阶段。在第1阶段,基站向用户广播能量;在第2阶段,用户向基站传输信息。用户簇和用户簇之间采用时分多址接入,分时传输;同一簇内多个用户采用非正交多址接入,同时传输。该文研究联合优化系统的各阶段的传输时间、基站的发射功率、用户的发射功率等资源,分别以优化网络频谱效率和用户簇之间的公平性为目的,提出最大化网络吞吐量和最大化用户簇的最小吞吐量的联合资源分配算法。研究结果表明所提的两种算法分别能有效提高系统的频谱效率和保证用户簇之间的公平性。     

协作系统中基于比例公平的资源分配方法

针对多用户协作中继系统中的资源分配问题,提出了一种在满足用户速率比例公平约束条件下的新算法。该算法先将由2个时隙组成的中继用户传输链路转换为一个等效信道链路,将涉及子载波分配、中继选择和功率分配的组合优化问题转化为分步的次优化问题。该算法在等功率分配情况下,根据各用户速率比例公平系数进行初步子载波数目分配;以瞬时信道增益最佳原则,进行剩余子载波数目分配及具体子载波分配,同时完成中继选择;在速率比例公平约束条件下推导出次优化功率分配的闭式表达式,从而完成各子载波上的功率分配。仿真结果表明,该算法在有效提高系统容量的同时,保证了各用户速率之间的比例公平性。     

Dynamic resource allocation algorithm in multi-user cooperative OFDMA systems: considering QoS and fairness constraints

Wireless transmission systems are constrained by several parameters such as the available spectrum bandwidth, mobile battery energy, transmission channel impairments and users’ minimum quality-of-service. In this paper, a new strategy is investigated that aims at improving the allocation of resources in a dual hop OFDMA cooperative network consisting in multi source–destination pairs and multiple decode-and-forward relays. First, the joint optimization of three types of resources: power, sub-channel and relay nodes, is formulated as a problem of subchannel-relay assignment and power allocation, with the objective of minimizing overall transmission power under the bit-error-rate and data rate constraints. However, the optimal solution to the optimization problem is computationally complex to obtain and may be unfair. Assuming knowledge of the instantaneous channel gains for all links in the entire network, an iterative three-step resource allocation algorithm with low complexity is proposed. In order to guarantee the fairness of users, several fairness criteria are also proposed to provide attractive trade-offs between network performance (i.e. overall transmission power, average network lifetime and average outage probability) and fairness to all users. Numerical studies are conducted to evaluate the performance of the proposed algorithm in two practical scenarios. Simulation results show that the proposed allocation algorithm achieves an efficient trade-off between network performance and fairness among users.     

认知无线电网络中基于协作中继的资源分配算法

在认知无线电网络的协作中继机制下,中继节点利用其和源节点以及目的节点的不同公共信道为二者的通信转发数据,可以有效解决次用户的通信需求和可用带宽之间的矛盾,提高频谱利用率和系统吞吐量。基于协作中继的认知无线电网络中,不同通信链路上可能存在公共可用信道,使信道和中继的分配问题变得复杂。本文研究了公共信道存在的情况下系统的资源分配问题,基于网络最大流理论提出了两种算法:并行算法和贪婪算法,并分析了算法复杂度。仿真结果表明,两种算法都能够更有效地分配资源,提高频谱利用率,改善网络吞吐量。并行算法可以得到最优解,但其复杂度随信道公用程度的上升增长迅速,受节点并行处理能力的限制,只适用于信道公用程度较低的情况。贪婪算法不一定能得到最优解,但其复杂度较低,并且信道公用程度高时接近最优解,因此超出节点的并行处理能力后,可以选择贪婪算法。