共查询到20条相似文献,搜索用时 156 毫秒
1.
针对OFDMA系统下行链路资源分配和调度问题,提出了一种基于跨层设计的时频二维分配算法(CLSA),在资源分配同时考虑用户物理信道状态信息以及MAC和数据链路层的用户速率要求、延时要求、分组差错率要求等QoS需求,以提高系统吞吐性能以及中断率性能做为算法的设计目标.通过大量的仿真实验验证算法的性能,并与现有的经典算法(OFDMA系统中的MPF算法和M-LWDF算法)性能进行了对比分析.仿真实验结果表明,CLSA算法在系统有效吞吐性能和中断率性能方面有较好表现. 相似文献
2.
3.
无线中继技术与OFDMA-MIMO技术相结合,能够大大提高系统的性能,是一种极具潜力的技术。本文结合无线中继网络中OFDMA的帧结构,以轮询调度算法和贪婪算法为参考,提出了多天线下的OFDMA无线中继网络的比例公平资源分配算法;并和无中继的OFDMA系统及单天线下的OFDMA无线中继网络资源分配算法相比较。通过仿真表明本文提出的资源分配算法在考虑每个用户数据速率的同时能够大大提高系统的传输速率,满足用户的多种业务需求。 相似文献
4.
研究了OFDMA/TDM系统的资源分配问题,基于最差信道用户优先原则,提出了一种新的跨层资源分配算法CRRA(Cross-layer Radio Resource Allocation)及其简化算法S-CRRA(Simplified CRRA).该算法利用用户数据队列长度动态变化的特性和多用户分集策略以实现在满足用户服务质量(Quality of Service,QoS)的基础上最大化系统吞吐量,并且将频谱和功率分配分开进行以降低计算复杂度.仿真结果表明,CRRA算法和S-CRRA算法在系统吞吐量上基本一致,两者较已有的OFDMA/TDM系统资源分配算法能提高10%-24%的系统吞吐量. 相似文献
5.
6.
7.
常规的无人机通信链路资源分配技术主要使用OFDMA(Orthogonal Frequency Division Multi-plexing Access)多址接入技术共享信道信息,易受分配自适应速率影响,导致链路资源分配归一化速率较低,因此需要基于改进粒子群算法,设计一种全新的无人机通信链路资源分配技术。即根据通信链路信道信息,规划了无人机通信链路资源分配容量,再利用改进粒子群算法构建了通信链路资源分配模型,并设计了资源分配算法,从而实现无人机通信链路资源分配。实验结果表明,设计的无人机通信链路资源改进粒子群算法分配技术在不同链路下的资源分配归一化速率均较高,证明设计的无人机通信链路资源分配技术的分配效果较好,具有可靠性,有一定的应用价值,为提高无人机通信性能作出了一定的贡献。 相似文献
8.
传统的OFDMA协作通信系统,中继经过一一对应的两跳子载波接收和发送数据信息,这一对称的资源分配模式限制了系统吞吐量的提高;本文放宽对称约束,研究了非对称模式下的资源分配问题。自由度的增加,增大了系统资源分配的复杂度,这是一个结合中继选择、子载波分配和功率控制等多维自由度的混合离散型优化问题,很难得到满足实时性要求的近似最优算法。针对该模型,本文提出基于拉格朗日松弛的联合优化算法,算法的关键在于OFDMA系统的渐进强对偶性,这个性质使得多项式时间算法的设计成为可能。算法的复杂度与子载波数目成线性关系。仿真结果表明,该算法的性能是近似最优的,而且与对称模式相比,非对称模式下的资源分配进一步提升了系统的吞吐量性能。 相似文献
9.
10.
11.
Wei Wang Wenbo Wang Qianxi Lu Tao Peng 《International Journal of Communication Systems》2009,22(5):603-623
Cognitive radio makes it possible for an unlicensed user to access a spectrum unoccupied by licensed users. In cognitive radio networks, extra constraints on interference temperature need to be introduced into radio resource allocation. In this paper, the uplink radio resource allocation is investigated for OFDMA‐based cognitive radio networks. In consideration of the characteristics of cognitive radio and OFDMA, an improved water‐filling power allocation scheme is proposed under the interference temperature constraints for optimal performance. Based on the improved water‐filling power allocation, a simple subcarrier allocation algorithm for uplink is proposed. The subcarrier allocation rules are obtained by theoretical deduction. In the uplink subcarrier allocation algorithm, the subcarriers are allocated to the users with the best channel quality initially and then adjusted to improve the system performance. A cursory water‐filling level estimation method is used to decrease the complexity of the algorithm. Asymptotic performance analysis gives a lower bound of the stability of the water‐filling level estimation. The complexity and performance of the proposed radio resource allocation scheme are investigated by theoretical analysis and numerical results. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
12.
Multiuser multiple‐input multiple‐output orthogonal frequency division multiple access (MIMO‐OFDMA) is considered as the practical method to attain the capacity promised by multiple antennas in the downlink direction. However, the joint calculation of precoding/beamforming and resource allocation required by the optimal algorithms is computationally prohibitive. This paper proposes computationally efficient resource allocation algorithms that can be invoked after the precoding and beamforming operations. To support stringent and diverse quality of service requirements, previous works have shown that the resource allocation algorithm must be able to guarantee a specific data rate to each user. The constraint matrix defined by the resource allocation problem with these data rate constraints provides a special structure that lends to efficient solution of the problem. On the basis of the standard graph theory and the Lagrangian relaxation, we develop an optimal resource allocation algorithm that exploits this structure to reduce the required execution time. Moreover, a lower‐complexity suboptimal algorithm is introduced. Extensive simulations are conducted to evaluate the computational and system‐level performance. It is shown that the proposed resource allocation algorithms attain the optimal solution at a much lower computational overhead compared with general‐purpose optimization algorithms used by previous MIMO‐OFDMA resource allocation approaches. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
13.
In this paper, we propose a joint resource allocation, routing, and connection admission control (CAC) scheme for uplink transmission in orthogonal frequency division multiple access (OFDMA) relay networks with cooperative relaying. For cooperative relaying, relay station can relay uplink data from mobile station (MS) to base station with cooperation of the MS using transmit diversity. Transmit diversity can be achieved by virtual MISO via distributed space–time coding. The proposed scheme jointly allocates OFDMA resources and selects path for each user with CAC to maximize the upink throughput of cooperative OFDMA relay networks. The basic OFDMA resource unit is considered as a resource element which is one subcarrier over one OFDMA symbol. An efficient multi-choice multi-dimensional knapsack (MMKP) algorithm is presented for the proposed scheme. The proposed MMKP algorithm provides a unified framework which is applicable to OFDMA networks with and without cooperative relaying. We evaluate the performance of the proposed scheme with and without cooperative relaying in a hilly terrain with heavy tree density by using OPNET-based simulation. We show that the cooperative relaying improve the uplink system throughput compared with non-cooperative relaying, and the proposed scheme outperforms the conventional link quality-based scheme in both cooperative and non-cooperative relay networks. 相似文献
14.
In this paper, we present a heterogeneous network framework involved an orthogonal frequency division multiple access (OFDMA) network with an out-of-band Ad Hoc network, which maybe a promising architectural upgrade and has not been studied so far. In the heterogeneous system, the mobile stations (MSs) are dual-mode with both cellular OFDMA and Ad Hoc radios. And MSs communicate with the base station by cellular OFDMA mode, while they communicate with each other by Ad Hoc mode. An active MS can choose multiple inactive MSs as its relay stations (RSs). And each RS operates in a full duplex mode, that is, it can receive data through Ad Hoc network in the first hop and transmit data through the OFDMA network in the second hop, simultaneously. Based on this heterogeneous system, the problem of joint relay selection, subcarrier and power allocation with the objective of maximizing the system capacity under individual rate and transmit power constraints is addressed. We propose a dual-based resource allocation scheme to solve the problem fairly and efficiently, and then we propose a fully distributed resource allocation scheme to decrease the computational complexity. Simulation results show that the performance of the proposed dual-based resource allocation scheme, in terms of the system capacity and the outage probability, is better than that of the fully distributed resource allocation scheme. However, the performance improvement is at the expense of a high computational complexity. 相似文献
15.
一种自适应的OFDMA系统下行分组调度算法 总被引:1,自引:0,他引:1
提出了一种适合于OFDMA(正交频分多址接入)系统的资源分配与调度算法,该算法利用物理层的信道信息和MAC层的队列状态信息,并综合考虑了数据分组传输的时延要求和业务的优先级,采取资源块与子载波分配相结合的资源分配方式。仿真结果表明,该算法在吞吐量和公平性方面都得到了较好的改善。 相似文献
16.
The existing works on resource allocation for OFDMA based cognitive radio networks are based on the assumption of Gaussian inputs whereas in practical systems the inputs are taken from a set of finite symbol alphabets. This paper considers a system with arbitrarily distributed finite power inputs and solve the resource allocation problem by employing the relationship between mutual information and minimum mean-square error. To protect the primary users’ links, constraint on interference power of the secondary users (SUs) is imposed. In OFDMA based CR networks, a tone can be assigned to one SU at most (exclusivity constraint), due to which the resource allocation problem becomes combinatorial and its solution becomes prohibitively difficult.In this paper, first, the exclusivity constraint on tones allocation is relaxed, the problem is convexified and an optimal solution is derived that provides an upper bound on the system performance. Then, an integer tone allocation and optimal power allocation (ITA–OPA) algorithm is developed that guarantees the assignment of each tone to a single SU with close-to-optimal performance. Finally, keeping in view the complexity of the optimal solution and ITA–OPA algorithm, a low-complexity suboptimal algorithm is devised that accounts for exclusive tone assignment. Simulation results show that the suboptimal algorithm also achieves near-optimal performance. The proposed algorithms outperforms the algorithms that assume Gaussian inputs. 相似文献
17.
Ronald Y. Chang Zhifeng Tao Jinyun Zhang C.‐C. Jay Kuo 《Wireless Communications and Mobile Computing》2013,13(1):12-27
A graph‐based framework is proposed in this paper to implement dynamic fractional frequency reuse (D‐FFR) in a multicell Orthogonal Frequency Division Multiple Access (OFDMA) network. FFR is a promising resource‐allocation technique that can effectively mitigate intercell interference (ICI) in OFDMA networks. The proposed D‐FFR scheme enhances the conventional FFR by enabling adaptive spectral sharing as per cell‐load conditions. Such adaptation has significant benefits in practical systems where traffic loads in different cells are usually unequal and time‐varying. The dynamic adaptation is accomplished via a graph framework in which the resource‐allocation problem is solved in two phases: (1) constructing an interference graph that matches the specific realization of FFR and the network topology and (2) coloring the graph by use of a heuristic algorithm. Various realizations of FFR can easily be incorporated in the framework by manipulating the first phase. The performance improvement enabled by the proposed D‐FFR scheme is demonstrated by computer simulation for a 19‐cell network with equal and unequal cell loads. In the unequal‐load scenario, the proposed D‐FFR scheme offers significant performance improvement in terms of cell throughput and service rate as compared to conventional FFR and previous interference management schemes. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
18.
19.
基于M2M终端组的资源分配策略可以有效提高M2M通信中的资源利用率.本文研究了M2M通信系统中基于组的保证不同组间传输速率的比例公平资源分配问题,提出了一种次优的能够保证不同终端组间传输速率比例公平的资源分配算法,并通过仿真对算法的性能进行了验证,给出了速率最大化算法与终端组比例公平算法的性能比较. 相似文献
20.
Two Inter-cell Interference (ICI) management algorithms: Primary Interference Balancing (PIB) algorithm and Interfering Bits Loading Avoidance (IBLA) algorithm are proposed for canceling the ICI effects which the existing efficient radio resource allocation algorithms do not consider. The efficient radio resource allocation algorithm, i.e., Pre-assignment and Reassignment (PR) algorithm, obtains the lowest complexity and achieves good throughput performance in single cell OFDMA system. However, in multi-cel... 相似文献