一种基于比例公平的多跳OFDMA系统资源分配算法

为解决多跳OFDMA系统的资源分配问题,本文提出一种基于比例公平的资源分配算法,该算法将一个联合优化的问题分解为两个步骤,首先在等功率分配的条件下求出最优的子载波分配以及中继节点选择方案,然后再根据注水定理进行功率分配,以提高系统的性能.仿真结果表明,该算法能够在保障不同用户间公平性的条件下,有效地提高系统的容量.     

LTE-A多小区中继网络两跳速率匹配资源分配算法

针对中继网络的两跳特性,提出一种多小区中继网络两跳速率匹配资源分配算法。首先,在第一个子时隙内各小区独立地为小区中所有用户分配子载波,并根据子载波分配结果,建立基于非合作博弈的功率分配模型;然后,由第一跳资源分配结果对第二跳速率匹配,自适应地为中继分配资源以满足边缘用户的速率需求。仿真结果表明,该算法在满足边缘用户速率需求的前提下,进一步提高了中心用户的吞吐量,同时降低了系统的发射功率,从而提升了系统性能。     

基于比例速率约束的OFDMA-DF中继系统上行链路资源分配算法

针对正交频分多址接入解码转发(OFDMA-DF)中继上行链路通信系统,提出了一种基于比例速率公平约束的资源分配算法.新算法主要分为两个步骤:首先在假定平均功率分配下,按照速率约束比越小的用户越优先选择子载波和中继这一准则进行载波分配和中继选择;然后在此基础上进行子载波上的优化功率分配,并给出了功率分配结果.分析结果显示,新算法在获得较高系统容量的同时能很好地保证用户之间的公平性.     

OFDMA协同通信系统子载波和功率联合分配算法

针对OFDMA协同通信系统资源分配仅考虑平均功率下的子载波分配,中继存在未用功率情况,研究子载波分配后中继剩余功率分配问题。提出一种既满足业务QoS需求又兼顾用户间公平性的子载波和功率联合分配算法,并设计一种基于二分法的功率注水分配方案。测试表明,该算法能在满足业务QoS需求及用户公平性的同时,提升系统容量。     

基于子载波配对的多用户协作中继系统资源分配算法

针对多用户协作中继系统中的功率最小化问题,提出了一种基于联合子载波配对及分配的资源分配算法。首先根据不同用户的目标速率要求及平均信道增益进行子载波数目的分配;然后以信道条件最佳为准则,提出了一种联合子载波配对及分配的多用户迭代算法,以实现对每个用户的中继链路和直传链路分别进行子载波配对及虚拟配对;最后利用注水算法对子载波进行功率分配,从而保证各用户以最小功率进行传输。仿真结果表明,该算法在满足用户目标速率的情况下,能够进行有效的子载波配对及分配,从而最小化系统的发射功率。     

认知网络中基于中继的频谱资源分配

根据无线认知中继网络上、下行链路子载波的信道特性,研究认知网络的频谱资源分配,提出一种上、下行链路子载波联合优化的分配算法。该算法根据子信道增益差值因子的大小分配下行链路子载波,以源节点和中继节点功率最小化为优化目标配对上行链路子载波,以用户的实时需求分配子载波的比特和功率,有效降低了系统的发射功率,提高了系统吞吐量。仿真结果表明,与启发—集中式和分布式辅助反馈传输功率分配算法比较,该联合优化算法的单位比特功耗降低了1.5~3 dBμW,误比特率性能提高了1个数量级左右。     

中继网中基于QoS保证和比例公平的资源分配

中继系统下的众多资源分配策略很少同时考虑多用户情形下的子载波配对和不同用户需求。针对这一问题,提出了一种基于QoS(服务质量)保证和比例公平的多用户子载波配对和功率分配算法,该算法既能保证QoS用户的最小速率要求,又能满足BE(尽力而为)用户之间速率比例公平的准则。该算法首先根据不同用户需求分配第二跳的子载波,然后利用匈牙利配对算法得到两跳子载波的最佳配对,最后用类似注水算法进行功率分配。仿真结果表明,所提算法在满足用户QoS保证和比例公平准则的同时有效提升了系统的吞吐量。     

基于保密度的OFDMA中继网络资源分配研究

考虑到异构双向中继网络中存在窃听者的安全资源分配问题,为了提高中继安全性,该文研究了受限于子信道分配和功率约束的用户安全保密度问题模型,与传统的保密容量模型相比,安全保密度模型更侧重于反映用户本身的安全程度。基于此保密度模型,该文进一步考虑了不同用户的安全服务质量(Quality of Service, QoS)需求和网络公平性,联合优化功率分配、子信道分配、子载波配对,并分别通过约束型粒子群、二进制约束型粒子群优化算法和经典的匈牙利算法找到最优解,实现资源的最优分配,提高网络中合法用户的保密度。仿真结果验证了所提算法的有效性。     

基于能量定价的协作OFDM系统网络寿命优化算法

 本文研究两跳协作多中继正交频分复用(OFDM)系统的网络寿命优化问题.为使网络寿命最大化,基于对节点能量的定价提出一种穷举算法,即首先列举所有的子载波配对与中继选择联合决策;在每种决策下利用拉格朗日法求解最优功率分配,使得网络在满足一定吞吐量的前提下消耗能量总价值最小;然后选择损耗能量价值最小的联合决策.由于穷举算法受到计算复杂度的限制,进而基于子载波的单位信噪比(SNR)代价将中继选择与子载波配对分步优化,提出两种低复杂度算法.仿真结果表明,本文各算法的网络寿命性能比已有算法均有显著提高.     

全双工中继协作下的移动边缘计算系统能耗优化算法

为缓解终端设备处理大数据量、低时延业务的压力,该文提出一种基于全双工中继的移动边缘计算网络资源分配算法。首先,在满足计算任务时延约束、用户最大计算能力、用户和中继的最大发射功率约束条件下,考虑中继选择与子载波分配因子、用户任务卸载系数、用户与中继的传输功率的联合优化,建立了系统总能耗最小化问题。其次,利用交替迭代和变量代换的方法,将原非凸问题分解为两个凸优化子问题,并利用内点法和拉格朗日对偶原理分别进行求解。仿真结果表明,所提算法具有较低的能量消耗。     

基于两跳载波配对策略的非再生OFDM中继系统性能优化

该文针对非再生中继方式,分析了基于正交频分复用(OFDM)的两跳中继系统的容量,并推广到发送端具有两根天线采用空时块码(STBC)的情形。以最大化端到端的信息速率为优化准则,提出了非再生两跳载波配对定理,并结合注水定理分别在频域、空域,以及空频二维进行了资源联合优化。仿真结果表明,资源联合优化与传统的平均资源分配相比,显著提高系统容量,且STBC-OFDM能获得更高性能增益。通过子载波配对方案能进一步增强系统性能。     

Subcarrier pairing for amplify-and-forward and decode-and-forward OFDM relay links

We consider a two-hop relay link in which orthogonal frequency division multiplexing (OFDM) is used on both hops. Under a joint sum-power constraint, our aim is to allocate power over subcarriers on the two hops such that the instantaneous rate of the relay link is maximized. Ordered subcarrier pairing (OSP) has been proposed in the literature to further improve the relay link rate; however, the optimality of OSP has been proven only for equal power allocation and the proof of its optimality under optimal power allocation has not been available yet. In this letter, we will provide our proof which verifies that OSP is optimal for both amplify-and-forward (AF) and decode-and-forward (DF) relay links when optimal power allocation is applied.     

QoS-Driven Jointly Optimal Subcarrier Pairing and Power Allocation for Decode-and-Forward OFDM Relay Systems

In this paper, we investigate the quality-of-service (QoS) driven subcarrier pairing and power allocation for two-hop decode-and-forward (DF) OFDM relay systems. By integrating the concept of effective capacity, our goal is to maximize the system throughput subject to a given delay-QoS constraint. Based on whether the destination can receive the signal transmitted by the source, we consider two scenarios, i.e. OFDM DF relay systems without diversity and OFDM DF relay systems with diversity, respectively. For OFDM DF relay systems without diversity, we demonstrate that the jointly optimal subcarrier pairing and power allocation can be implemented with two separate steps. For OFDM DF relay systems with diversity, we propose an iterative algorithm to achieve jointly optimal subcarrier pairing and power allocation. Furthermore, we find that the analytical results show different conclusions for the two types of OFDM relay systems. For OFDM relay systems without diversity, the optimal power allocation depend on not only the channel quality of subcarriers but also the delay QoS constraints, while the optimal subcarrier pairing just depends on the channel quality of subcarriers. For OFDM relay systems with diversity, both the optimal subcarrier pairing and power allocation depend on the channel quality of subcarriers and the delay QoS constraints. Simulation results show that our proposed scheme offers a superior performance over the existing schemes.     

Optimal resource allocation for multiple network‐coded two‐way relay in orthogonal frequency division multiplexing systems

This paper studies optimal resource allocation for multiple network‐coded two‐way relay in orthogonal frequency division multiplexing systems. All the two‐way relay nodes adopt amplify‐and‐forward and operate with analog network coding protocol. A joint optimization problem considering power allocation, relay selection, and subcarrier pairing to maximize the sum capacity under individual power constraints at each transmitter or total network power constraint is first formulated. By applying dual method, we provide a unified optimization framework to solve this problem. With this framework, we further propose three low‐complexity suboptimal algorithms. The complexity of the proposed optimal resource allocation (ORA) algorithm and three suboptimal algorithms are analyzed, and it is shown that the complexity of ORA is only a polynomial function of the number of subcarriers and relay nodes under both individual and total power constraints. Simulation results demonstrate that the proposed ORA scheme yields substantial performance improvement over a baseline scheme, and suboptimal algorithms can achieve a trade‐off between performance and complexity. The results also indicate that with the same total network transmit power, the performance of ORA under total power constraint can outperform that under individual power constraints. Copyright © 2012 John Wiley & Sons, Ltd.     

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。     

基于合作中继的OFDM蜂窝网络的QoS感知资源调度算法

针对基于中继的OFDM蜂窝网络,该文考虑具有不同QoS要求的混合业务场景,引入合作传输机制,提出了一种基于合作中继的QoS感知资源调度算法,解决了合作中继节点选取,子载波分配以及功率控制等问题。以最大化系统效用为目标,在考虑QoS业务的速率要求与基站功率约束的同时,针对中继结构引入了中继节点的功率约束。为降低计算复杂度,将原非线性组合优化问题分解为子载波分配与功率控制两个子问题。仿真结果表明,该文所提算法在能量节约、系统效用,吞吐量等性能方面都有显著优势。     

Resource allocation scheme in two-way multi-relay OFDM system

A joint optimization scheme for power allocation and subcarrier pairing under high SNR in two-way multi-relay OFDM system was proposed.Unlike those schemes in which relays use subcarriers separately,all the relays were allowed to forward signal on each subcarrier pair for providing much space diversity.With the constraint of total system power,the proposed scheme firstly allocated each relay power with Cauchy inequality with the assuming that the total relay power was fixed.Then the dichotomy was used to calculate the power allocation between the source node and the relay node by maximizing the equivalent channel gain for different subcarrier pairs.Lastly,the power of different subcarrier pairs was allocated by convex programming,and the subcarriers were paired by Hungarian algorithm to obtain the maximum system capacity.There was no optimal power allocation method with low complexity because of the complexity of the power allocation algorithm in two-way multi-relay networks.This algorithm greatly reduces the complexity of power allocation and simulation results show that the proposed scheme outperforms the relay selection scheme and the relays use subcarriers separately scheme.     

Resource allocation for multiuser two-way OFDMA relay networks with user rate constraints

This paper studies the resource allocation for a multi-user two-way amplify-and-forward (AF) relay network over orthogonal frequency-division multiplexing (OFDM) technology,where all users communicate with their pre-assigned partners.Using convex optimization techniques,an optimal solution tominimize the total transmit power while satisfy each user-pair’s data rate requirements is proposed.We divide the resource allocation problem into two subproblems:(1) power optimization within user-pair and relay in each subcarrier.(2) optimal subcarrier allocation and sum power assignment among N parallel OFDM subcarriers.Closed-form expressions of the power among user-pair and relay can be obtained in subproblem (1),and so the proposed algorithm decreases the variable dimensionality of the objective function to reduce the complexity of this optimization problem.To solve it,a three-step suboptimal approach is proposed to assign the resources to user-pairs:Firstly,decompose each user-pair into two sub user-pairs which have one-way and two-way relaying transmission modes.Secondly,allocate the subcarriers to the new mode user-pairs and assign the transmit power to each carrier.Thirdly,distribute the assigned power to three nodes allocated in the subcarrier.Simulation results demonstrate the significant power is saved with the proposed solutions,as compared to a fixed subcarrier allocation.     

A joint subcarrier selection and power allocation scheme using variational inequality in OFDM‐based cognitive relay networks

Introducing orthogonal frequency division multiplexing (OFDM) into cognitive radio (CR) can potentially increase the spectrum efficiency, but it also leads to further challenges for the resource allocation of CR networks. In OFDM‐based cognitive relay networks, two of the most significant research issues are subcarrier selection and power allocation. In this paper, a non‐cooperative game model is proposed to maximize the system throughput by jointly optimizing subcarrier selection and power allocation. First, taking the direct and relay links into consideration, an equivalent channel gain is presented to simplify the cooperative relay model into a non‐relay model. Then, a variational inequality method is utilized to prove the existence and uniqueness of the Nash equilibrium solution of the proposed non‐cooperative game. Moreover, to compute the solution of the game, a suboptimal algorithm based on the Lagrange function and distributed iterative water‐filling algorithm is proposed. The proposed algorithm can jointly optimize the process of subcarrier selection and power allocation. Finally, simulation results are shown to demonstrate the effectiveness of the proposed joint subcarrier selection and power allocation scheme. Copyright © 2015 John Wiley & Sons, Ltd.