Joint subcarrier and power allocation for downlink cellular OFDMA systems by intercell interference limitation

This paper addresses resource allocation for sum throughput maximization in a sectorized two-cell downlink orthogonal frequency-division multiple-access (OFDMA) system impaired by multicell interference. It is well known that the optimization problem for this scenario is NP-hard and combinational, which is here converted to a novel sum throughput maximization problem in cellular OFDMA systems based on the intercell interference limitation. Then, three subclasses of this new problem are solved. By the first subclass, on the assumption that subcarrier allocation parameters are fixed, an algorithm for optimal power allocation is obtained. However, the optimal resource allocation requires an exhaustive search, including the optimal power allocation which cannot be implemented in practice due to its high complexity. By the second subclass, the problem is reduced to a single cell case where the intercell interference in each subcarrier is limited to a certain threshold. Based on the solution of the single cell problem, a distributed resource allocation scheme with the aim of small information exchange between the coordinated base stations is proposed. By the third subclass, the centralized resource allocation for two adjacent cells as a general problem is solved. Here, the algorithm allocates simultaneously the subcarriers and the power of the considered two cells while the resource allocation parameters of both cells are coupled mutually. The present study shows that distributed and centralized resource allocation algorithms have much less complexity than the algorithm used in the exhaustive search and can be used in practice as efficient multicell resource allocation algorithms. Simulation results illustrate the performance improvements of the proposed schemes in comparison to the schemes with no intercell interference consideration.     

基于改进遗传算法的C-RAN网络动态无线资源分配

针对云无线网络(Cloud Radio Access Network,C-RAN)中传统静态资源分配效率低下以及动态无线资源分配中资源种类单一的问题,提出了一种基于用户服务质量(Qulity of Service,QoS)约束的动态无线资源分配方案,对无线资源从无线射频单元(Remote Radio Head,RRH)选择、子载波分配和RRH功率分配三个维度进行研究.首先,根据传统的C-RAN系统传输模型和QoS约束在时变业务环境下建立了以发射功率为变量,以吞吐量最大为优化目标的优化问题;然后,基于改进的遗传算法,将原优化方案转变为通过优化RRH选择、子载波分配和RRH功率分配来达到提高系统吞吐量的目的;最后,将改进的遗传算法与其他智能算法在种群规模变化下进行了时间复杂度对比.实验结果表明,所提算法具有较低时间复杂度,所提资源分配方案下的平均吞吐量增益为17％.     

Joint resource allocation and base-station assignment for the downlink in CDMA networks

In this paper, we jointly consider the resource allocation and base-station assignment problems for the downlink in CDMA networks that could carry heterogeneous data services. We first study a joint power and rate allocation problem that attempts to maximize the expected throughput of the system. This problem is inherently difficult because it is in fact a nonconvex optimization problem. To solve this problem, we develop a distributed algorithm based on dynamic pricing. This algorithm provides a power and rate allocation that is asymptotically optimal in the number of mobiles. We also study the effect of various factors on the development of efficient resource allocation strategies. Finally, using the outcome of the power and rate allocation algorithm, we develop a pricing-based base-station assignment algorithm that results in an overall joint resource allocation and base-station assignment. In this algorithm, a base-station is assigned to each mobile taking into account the congestion level of the base-station as well as the transmission environment of the mobile.     

基于对偶分解的OFDMA系统资源分配算法

该文针对多业务OFDMA系统资源分配问题,建立了考虑业务服务质量、数据到达、系统约束的最优化问题。分析了不同业务的速率约束、延时约束和队列长度之间的关系,并利用对偶分解方法将原问题分解为若干独立子问题,分别得到了最优资源块与最优功率分配规则,进而提出了基于对偶分解的最优资源分配算法。仿真结果表明,该算法在业务违反概率较低、公平性较好、算法复杂度略有上升的情况下,可以实现非实时业务吞吐量最大化。     

QoS-based optimal and fair resource allocation for energy-efficiency uplink NOMA networks

The energy-efficiency(EE) optimization problem was studied for resource allocation in an uplink single-cell network, in which multiple mobile users with different quality of service (QoS) requirements operate under a non-orthogonal multiple access (NOMA) scheme. Firstly, a multi-user feasible power allocation region is derived as a multidimensional body that provides an efficient scheme to determine the feasibility of original channel and power assignment problem. Then, the size of feasible power allocation region was first introduced as utility function of the subchannel-user matching game in order to get high EE of the system and fairness among the users. Moreover, the power allocation optimization to the EE maximization is proved to be a monotonous decline function. The simulation results show that compared with the conventional schemes, the network connectivity of the proposed scheme is significantly enhanced and besides, for low rate massive connectivity networks, the proposed scheme obtains performance gains in the EE of the system.     

多小区OFDMA解码转发中继通信系统的分布式资源分配算法

现有的多小区OFDMA中继通信系统资源分配的研究主要集中在单个小区的场景下,而不考虑由相邻小区引起的共信道干扰的影响。然而,实际系统中更高的频率复用因子和较小的小区半径,会导致严重的小区间干扰。该文考虑了多小区OFDMA解码转发中继通信系统的资源分配,它是一个混合离散型优化问题,即使在单小区场景下也是NP-hard难解的。由于全局最优求解的复杂性,该文提出一种分布式的次优的资源分配算法。算法分成两步:首先基于较低的信道反馈系统开销,分配子载波以满足用户的QoS要求;然后,将功率控制问题进一步简化并分解为多个凸优化的子问题,由椭球算法不断收敛的对偶变量迭代调整各个子问题的最优求解。仿真结果表明,与参考算法相比,所提算法的系统容量和边缘用户的吞吐量性能都有很大的提升。     

Multicast resource allocation with min-rate requirements in OFDM systems

This article addresses the multicast resource allocation problem with min-rate requirement constraints in orthogonal frequency division multiplexing (OFDM) systems. Due to the prohibitively high complexity for nonlinear and combinatorial optimization, the original problem is relaxed and reformulated to form a standard optimization problem. By theoretical derivation according to the Karush-Kuhn-Tucker (KKT) conditions, two propositions are presented as the necessary criteria for optimality. Furthermore, a two-step resource allocation scheme, including subcarrier assignment and power allocation, is proposed on a basis of the propositions for practical implementation. With the min-rate based multicast group order, subcarriers are assigned in a greedy fashion to maximize the capacity. When subcarrier assignment is determined, the proposed power allocation can achieve the optimal performance for the min-rate constrained capacity maximization with an acceptable complexity. Simulation results indicate that the proposed scheme approximates to optimal resource allocation obtained by exhaustive search with a negligible capacity gap, and considerably outperforms equal power distribution. Meanwhile, multicast is remarkably beneficial to resource utilization in OFDM systems.     

中继增强的无线蜂窝多小区系统的联合调度与功率控制算法

针对采用全局频率复用的中继增强的无线蜂窝多小区系统,该文考虑多种通信模式并存的混合场景,提出了一种干扰感知的联合资源分配策略。以最大化系统总吞吐量为目标,同时考虑小区间干扰对中继节点与移动站点的影响,以及基站与中继节点各自的发射功率约束。为了降低计算复杂度,针对用户与中继节点配对问题提出了一种基于小区间干扰的调度算法;针对功率控制问题分别提出了一种基于符号规划的最优功率分配算法和一种次优的最小能耗功率分配算法。仿真结果表明,该文所提算法逼近最优资源分配,在系统吞吐量与能量效率等性能方面具有显著优势。     

Cross-layer resource allocation for QoS guarantee with finite queue constraint in multirate OFDMA wireless networks

Efficient radio resource allocation is essential to provide quality of service （QoS） for wireless networks. In this article, a cross-layer resource allocation scheme is presented with the objective of maximizing system throughput, while providing guaranteed QoS for users. With the assumption of a finite queue for arrival packets, the proposed scheme dynamically a/locates radio resources based on user＇s channel characteristic and QoS metrics derived from a queuing model, which considers a packet arrival process modeled by discrete Markov modulated Poisson process （dMMPP）, and a multirate transmission scheme achieved through adaptive modulation. The cross-layer resource allocation scheme operates over two steps. Specifically, the amount of bandwidth allocated to each user is first derived from a queuing analytical model, and then the algorithm finds the best subcarrier assignment for users. Simulation results show that the proposed scheme maximizes the system throughput while guaranteeing QoS for users.     

Resource Allocation with Limited Feedback and Joint Coding Scheme for Wireless Multi-antenna Multicast System

In conventional multicast scheme (CMS), the total throughput of multicast group is constrained by the user with the worst channel quality. In order to overcome this problem of limited throughput, we introduce a resource allocation algorithm by exploiting layered coding combined with erasure correction coding for multicast services in the downlink of OFDMA-based multi-antenna system. To reduce the feedback overhead of uplink, we design a novel transmission scheme with limited feedback. Then, we formulate the joint subcarrier and power allocation problem for the data of base layer and enhancement layers, which is shown to be NP hard. Hence, in order to reduce the computational complexity, we propose a three-phase suboptimal algorithm. The algorithm is designed to maximize the system throughput while at the same time guarantee the quality of services (QoS) requirements of all multicast groups. It is composed of precoding scheme, proportional fairness subcarrier allocation algorithm and modified water-filling power allocation algorithm with QoS guarantees (MWF-Q). To further decrease the complexity of MWF-Q, a power allocation algorithm with increased fixed power allocation algorithm with QoS guarantees is introduced. Simulation results show that the proposed algorithms based on limited feedback scheme significantly outperform CMS and any other existing algorithm with full feedback. Moreover, the proposed scheme can efficiently reduce 50 % of the full feedback overhead.     

车联网中网络切片资源分配方案

为了满足车联网中不同应用的服务质量(Quality of Service, QoS)要求,提出了一种基于网络切片技术的车联网频谱资源分配方案。该方案考虑数据接入控制,通过联合优化频谱资源块(Resource Block, RB)分配和车辆信号发射功率控制,在安全服务切片低时延高可靠性的约束下,最大化信息娱乐服务切片的平均和吞吐量。将车联网资源管理建模为一个混合整数随机优化问题,利用李雅普诺夫(Lyapunov)优化理论将该优化问题分解为接入控制和RB分配与功率控制两个子问题,并分别对其进行求解,得到每个时隙的接入控制和资源分配方案。仿真结果表明,所提出的资源分配方案能够有效提高信息娱乐服务切片的平均和吞吐量,并且可以通过调整引入的控制参数值来实现吞吐量和时延的动态平衡。同时,与已有方案相比,该方案具有更好的时延性能。     

3D placement of unmanned aerial vehicles and partially overlapped channel assignment for throughput maximization

This paper investigates a wireless system with multi-Unmanned Aerial Vehicles (UAVs) for improving the overall throughput. In contrast to previous studies that optimize the locations of UAVs and channel assignment separately, this paper considers the two issues jointly by exploiting Partially Overlapped Channels (POCs). The optimization problem of maximizing network throughput is formulated as a non-convex and non-linear problem. In order to find a practical solution, the problem is decomposed into two subproblems, which are iteratively optimized. First, the optimal locations of UAVs are determined under a fixed channel assignment scheme by solving the mixed-integer second-order cone problem. Second, an efficient POC allocation scheme is determined via the proposed channel assignment algorithm. Simulation results show that the proposed approach not only significantly improves system throughput and service reliability compared with the cases in which only orthogonal channels and stationary UAVs are considered, but also achieves similar performance using the exhaustive search algorithm with lower time complexity.     

AG‐DPA: Assignment game–based dynamic power allocation in multibeam satellite systems

Dynamic power allocation is the key technology to maintain the link quality and improve the system throughput in multibeam satellite systems. Many numerical optimization algorithms have been proposed to optimize the power allocation schemes among beams. However, current metaheuristic algorithms, most of which are off‐line iterative methods, are not appropriate in nonuniform traffic demands and time‐varying channels due to the high computational complexity. To solve this problem, an assignment game–based dynamic power allocation (AG‐DPA) is proposed to achieve the suboptimality with low complexity in multibeam satellite systems. The key idea of the proposed AG‐DPA is to model the DPA problem into an assignment game model where the competitive equilibrium is achieved. Further, an adaptive price factor is introduced to make a trade‐off between algorithm performance and complexity. Simulation results show the effectiveness of the proposed AG‐DPA algorithm.     

Dynamic Resource Allocation for Downlink Multiuser MIMO-OFDMA/SDMA Systems

In this paper, new dynamic resource allocation algorithms are investigated for the downlink of multiuser multiple-input multiple-output orthogonal frequency-division multiple-access and space-division multiple-access (MU-MIMO-OFDMA/SDMA) systems. Firstly, a mathematical formulation of the optimization problem is presented with the objective of maximizing the total system throughput under the constraints of each user’s quality of service (QoS) requirement and the integer modulation orders available on each spatial subchannel. Secondly, since it is difficult to obtain the optimal solution to the joint optimization problem, the whole optimization procedure is divided into two steps, namely, the subcarrier-user scheduling and the resource allocation. In the first step, a new metric is proposed to measure the spatial compatibility of multiple users, each with multiple receive antennas, based on which a new scheduling algorithm is designed to identify the optimal sets of selected users over all subcarriers. In the second step, two dynamic resource allocation algorithms are developed to assign radio resources to the scheduled users subcarrier by subcarrier. Simulation results demonstrate that the proposed algorithms outperform the traditional allocation methods based on random scheduling scheme. Especially, the performance of the algorithm, combined with power reuse strategy, approaches closely to that of the optimal allocation method based on user selection.     

LTE-A异构网络下的高效资源分配算法

分析了OFDMA上行系统中,由宏基站(macrocell)和家庭式基站(femtocell)组成的双层网络,并提出了高效的资源分配算法。为避免严重的跨层干扰导致双层网络中的资源分配不协调,提出了一个跨层干扰控制算法。在基于干扰控制算法的结果上,提出包括功率分配和频谱分配的资源分配算法,以满足UE的目标速率,并获得较好的吞吐量性能。通过仿真,结果显示所提的资源分配算法相比较传统的算法,尤其在UE QoS保证和吞吐量性能的体现上,能获得明显的性能增益。     

Buffer-aware resource scheduling scheme for LTE-A uplink relay-assisted network

Due to the constraint of single carrier frequency division multiple access （SC-FDMA） adopted in long term evolution （LTE） uplink, subcarriers allocated to single user equipment （UE） must be contiguous. This contiguous allocation constraint limits resource allocation flexibility and makes the resource scheduling problem more complex. Most of the existing work cannot well meet UE＇s quality of service （QoS） requirement, because they just try to improve system performance mainly based on channel condition or buffer size. This paper proposes a novel resource scheduling scheme considering channel condition, buffer size and packet delay when allocating frequency resource. Firstly, optimization function is formulated, which aims to minimize sum of weight for bits still left in UE buffer after each scheduling slot. QoS is the main concern factor here. Then, to get packet delay information, this paper proposes a delay estimation algorithm. Relay node （RN） is introduced to improve overall channel condition. Specific RN selection strategy is also depicted in the scheme. Most important of all, a creative negotiation mechanism is included in the subcarrier allocation process. It can improve the overall system throughput performance in guarantee of user＇s QoS requirement. Simulation results demonstrate that the scheme can greatly enhance system performance like delay, throughput and jitter.     

Resource allocation and interference suppression with PCA for multicell MU-MIMO systems

Wireless Networks - This paper studies a resource allocation scheme and precoding design to increase the number of quality of service (QoS)-satisfied user equipments (UEs) for multicell multiuser...     

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 scheduling scheme with QoS support in two-hop relay-enhanced OFDMA systems

As the system performance is obviously improved by introducing the concept of relay into the traditional orthogonal frequency division multiple access(OFDMA)systems,resource scheduling in relay-enhanced OFDMA systems is worthy of being studied carefully.To solve the optimization problem of achieving the maximum throughput while satisfying the quality of service(QoS)and guaranteeing the fairness of users,a novel resource scheduling scheme with QoS support for the downlink of two-hop relay-enhanced OFDMA systems is proposed.The proposed scheme,which is considered both in the first time sub-slot between direct link users and relay stations,and the second time sub-slot among relay link users,takes QoS support into consideration,as well as the system throughput and the fairness for users.Simulation results show that the proposed scheme has good performance in maximizing system throughput and guaranteeing the performance in the service delay and the data loss rate.     

RFID系统中面向服务的动态资源配置优化机制

针对物联网中RFID(radio frequency identification)系统的tag和reader的速率不匹配及其资源受限问题,从理论上对tag和reader之间的协作通信上下文进行分析,提出一种面向服务的RFID系统资源配置优化机制,该机制利用tag与reader的组件QoS(quality of service)信息建立闭环控制框架,使用3种控制策略根据其资源状态和类型调节QoS参数。通过实验对机制进行了性能分析和验证,结果表明,该优化机制有效地提高RFID系统的吞吐量,高效地使用系统资源,减少了能量消耗和reader-to-reader干扰。