共查询到20条相似文献,搜索用时 15 毫秒
1.
在基于正交频分多址(OFDMA)的中继系统中,为了满足用户的QoS要求,保证系统的吞吐量最大的同时又保证用户公平性,给出了一种面向业务服务质量的资源分配算法。先根据用户在队列中的等待时延和用户对速率的需求引入时延优先级因子和速率优先级因子,以此计算用户的优先级。然后分别在回程链路和接入链路进行动态资源调度与分配。仿真结果表明,新算法能够兼顾中继用户和直传用户的性能,实现低丢包率、较好地满足 GBR需求,实现较高的系统吞吐量和公平性。 相似文献
2.
3.
4.
This paper proposes a bargaining game theoretic resource(including the subcarrier and the power) allocation scheme for wireless orthogonal frequency division multiple access(OFDMA) networks.We define a wireless user s payoff as a function of the achieved data-rate.The fairness resource allocation problem can then be modeled as a cooperative bargaining game.The objective of the game is to maximize the aggregate payoffs for the users.To search for the Nash bargaining solution(NBS) of the game,a suboptimal subcarrier allocation is performed by assuming an equal power allocation.Thereafter,an optimal power allocation is performed to maximize the sum payoff for the users.By comparing with the max-rate and the max-min algorithms,simulation results show that the proposed game could achieve a good tradeoff between the user fairness and the overall system performance. 相似文献
5.
6.
Subcarrier and power allocation for OFDMA-based multicast cellular networks using a coalitional game
The subcarrier and power allocation problem for orthogonal frequency-division multiple access (OFDMA)-based multicast cellular networks is investigated in this paper. Due to the intrinsic heterogeneity of the channel gains experienced by different multicast users, the conventional multicast schemes are highly conservative and spectrally inefficient. To address this issue, a novel multicast formulation is proposed where multiuser diversity inherent in OFDMA can be adaptively exploited by clustering users within a multicast group into smaller subgroups based on their channel gains. Subcarriers and power are then dynamically allocated to these subgroups to maximize the total multicast rate of the system. Coalitional game theory is adopted to model the group formation in which users can autonomously form coalitions with other users to compete for network resources. A low-complexity algorithm is proposed for the multicast coalitional game to reach multicoalitional equilibrium in which a sub-optimal performance can be obtained. Simulation results demonstrate that the proposed scheme outperforms the conventional unicast and multicast schemes while achieving a sub-optimal performance comparable to the exhaustive search scheme. 相似文献
7.
We consider all-optical Time Division Multiplexing (TDM)/Wavelength Division Multiplexing (WDM) broadcast and select networks with slotted operation. Each network access node is equipped with one fixed transmitter and one tunable receiver; tuning times are not negligible with respect to the fixed size slot time. We discuss efficient scheduling algorithms to assign TDM/WDM slots to multicast traffic in such networks. The problem is shown to be NP-hard; thus, heuristic algorithms based on the Tabu Search meta-heuristic are proposed, and their performance are assessed using randomly created request matrices based on two types of multicast traffic patterns. We show that significant advantages can be obtained by using these novel algorithms with respect to simpler greedy algorithms, even when restricting CPU times to realistic values to make the algorithms of practical use. 相似文献
8.
In recent years, multicast over wireless access networks has become a popular research topic. However, if relay nodes are supported in such a network, forming an efficient multicast topology becomes a challenging task. Since existing works fail to solve this problem satisfyingly, we in this paper propose a multi-hop multicast routing scheme for modern wireless relay networks. First, we formulate this important problem as Multi-Hop Multicast Maximization (MHMM), which involves forming a resource allocation of the base-station and relay stations in order to maximize the number of recipients with the given resource budget and channel conditions. To solve MHMM, we propose a heuristic called Multi-Hop Path Selection (MHPS). We prove that MHMM is NP-complete, and also analyze MHPS’s computational complexity and its worst-case performance. The results of simulations conducted to evaluate the heuristic’s performance demonstrate that, under variant conditions, MHPS utilizes bandwidth resources and relay nodes effectively such that it significantly outperforms all existing approaches. Moreover, its performance difference to the optimum is bounded. To the best of our knowledge, MHPS is the only scheme that focuses on this important issue and achieves such a satisfactory performance. 相似文献
9.
针对多用户OFDMA系统资源分配中已有算法对系统容量和公平性兼顾较差的情况,提出了一种满足比例公平性的系统容量最大化资源分配算法。首先选择合适的公平度门限范围,在子载波分配中,先将各个子载波分配给信道增益最大的用户,再在公平度门限约束下重新分配最大速率用户的信道增益最小的子载波,可以实现子载波利用率和公平度的折中。然后采用注水线法分配功率来调整用户间的比例公平性,最终找到使系统容量最大的公平度门限。仿真结果表明,该算法在保证了用户间比例公平性为1的同时提高了系统容量。 相似文献
10.
LIU Jian LONG KePing & XU Jie School of Communication Information Engineering University of Electronic Science Technology Chengdu China 《中国科学:信息科学(英文版)》2011,(7):1444-1455
In this paper,we propose a new media access control (MAC) protocol,which is compatible with the IEEE 802.16e-2005 Orthogonal Frequency Division Multiple Access (OFDMA) wireless interface.In this protocol,the same radio resource can be shared by neighboring cells in the wireless mesh network (WMN) and collisions can be reduced in the overlapping areas.This protocol consists of two schemes: a downlink transmission and an uplink transmission.For downlink transmission we use a cross layer adaptive radio resourc... 相似文献
11.
Carrier synchronization in OFDMA uplink systems comprises estimation and compensation of carrier frequency offsets (CFOs) corresponding to different users. We propose a null sub-carrier-based CFO estimation algorithm for OFDMA uplink systems, employing generalized or sub-band sub-carrier allocation scheme. We analyze the effect of location and number of null sub-carriers on the performance of the algorithm, in the presence of multi-user interference (MUI) and channel frequency selectivity. We calculate the acquisition range of the proposed estimation algorithm and prove that the identifiability of CFO estimation is guaranteed in the presence of MUI and channel nulls. We also evaluate the computational complexity and the performance of the proposed estimation algorithm and, compare it with some of the existing approaches in the literature. 相似文献
12.
针对OFMDA解码-转发中继系统的资源分配问题,提出了一种以系统总功率和用户间的数据速率比例公平为约束条件,以最大化系统总速率为目标的资源分配算法。该资源分配问题为非线性最优化问题,联合求解所有变量复杂度很高,通过次优化的方法降低计算复杂度。算法包括:子载波分配和功率分配。子载波分配是以功率平均分配为前提,对基站-中继站和中继站-用户链路的子载波按照信道条件进行配对,并根据比例公平约束将配对的子载波分配给相应的用户。功率分配是对每个用户利用Lagrange方法调整每个子载波的功率,进一步提高系统的数据速率。算法仿真分析表明,该算法既能同时满足多用户不同数据速率的要求,又能提高系统的数据速率。 相似文献
13.
14.
在正交频分复用技术和双向通信下,研究了携能通信网络中的资源分配问题。提出了一种面向子载波和传输功率的联合分配算法,该算法不依赖于现有的功率分割或时隙切换机制,可以在不同的子载波上分别传输信息和能量,简化了携能机制设计;此外,考虑到实际能量收集电路的饱和特性,该算法基于非线性能量采集模型,采用拉格朗日对偶和次梯度方法,研究了在满足用户传输速率阈值的前提下使系统的总能耗最小化的问题,降低网络能量开销。数值仿真实验证实了此联合分配算法的有效性和能量高效性。 相似文献
15.
This paper describes an agent-based approach for scheduling multiple multicast on wormhole switch-based networks with irregular
topologies. Multicast/broadcast is an important communication pattern, with applications in collective communication operations
such as barrier synchronization and global combining. Our approach assigns an agent to each subtree of switches such that
the agents can exchange information efficiently and independently. The entire multicast problem is then recursively solved
with each agent sending message to those switches that it is responsible for. In this way, communication is localized by the
assignment of agents to subtrees. This idea can be easily generalized to multiple multicast since the order of message passing
among agents can be interleaved for different multicasts. The key to the performance of this agent-based approach is the message-passing
scheduling between agents and the destination processors. We propose an optimal scheduling algorithm, called ForwardInSwitch to solve this problem. We conduct extensive experiments to demonstrate the efficiency of our approach by comparing our results
with SPCCO, a highly efficient multicast algorithm reported in literature. We found that SPCCO suffers link contention when
the number of simultaneous multiple multicast becomes large. On the other hand, our agent-based approach achieves better performance
in large cases. 相似文献
16.
Assuming that a make-to-order manufacturing company has customer orders, the addressed capacity allocation problem is a due-date assignment problem for multiple manufacturing resources. The purpose of this study is to develop an intelligent resource allocation model using genetic algorithm and fuzzy inference for reducing lateness of orders with specific due dates. While the genetic algorithm is responsible for arranging and selecting the sequence of orders, the fuzzy inference module conveys how resources are allocated to each order. Experimental results showed that the proposed model has solved the capacity allocation problem efficiently. 相似文献
17.
This article treats the resource allocation problem for the downlink of a multi-cell, multiservice Wireless Mobile Communications System (WMCS) with heterogeneous architecture deployed into an urban environment using Long Term Evolution (LTE) and Orthogonal Frequency Division Multiple Access (OFDMA) in its physical level.The optimization model aims to satisfy services to users by making an efficient use of the available resources, and a fair frequency block allocation, using the Signal to Interference-plus-Noise Ratio (SINR). It is a Mixed Integer Nonlinear Programming (MINLP) model whose solution is complex to obtain directly. The proposed solution algorithm decouples the solution space of the problem and uses an iterative and semi-distributed approach to implement a frequency-domain scheduler in the medium term that uses a global vision of the system to allocate resources trying to obtain the SINR required for all users (the proposed goal). Since it is not always possible to achieve it, we take advantage of the elasticity of some of the services offered and incorporate a slack variable to solve it.The approach allows selecting the frequency allocation strategy, the exploration focus of the search space and the system administrator’s vision. The results obtained show that the implementation that uses a coordinated frequency allocation obtains better results in the amount of users with full satisfaction and in the use of power when compared to implementations using other frequency allocation strategies. In scenarios with heterogeneous architecture, the combined effect of picocells and coordinated frequency allocation improves the value for the defined performance metrics. 相似文献
18.
FEI ZeSong XING ChengWen LI Na HAN YanTao DANEV Danyo KUANG JingMing 《中国科学:信息科学(英文版)》2013,(4):99-108
In this paper,the capacity maximization and the spectrum utilization efficiency improvement are investigated for the Pico cells in broadband heterogeneous networks.In frequency-reuse model,the users attached to Macro base station are usually viewed as primary users,and those attached to Pico base station should be regarded as cognitive radio(CR) users.As both the primary users and the CR users communicate in parallel frequency bands,the performance of the system is limited by the mutual inter-carrier interference(ICI).In order to control ICI and maximize the achievable transmission rate of the CR users,an effective power allocation scheme is proposed to maximize the transmission rate of the CR users under a given interference threshold prescribed by the primary users.By transforming this suboptimal solution into an innovative matrix expression,the algorithm is easier to perform in practice.The simulation results demonstrate that the proposed algorithm provides a large performance gain in Pico cell capacity over the non-cooperative and equal power allocation schemes. 相似文献
19.
20.
The exponential growth of various services demands the increased capacity of the next-generation broadband wireless access networks, which is toward the deployment of femtocell in macrocell network based on orthogonal frequency division multiple access. However, serious time-varying interference obstructs this macro/femto overlaid network to realize its true potential. In this article, we present a macro services guaranteed resource allocation scheme, which can mitigate various dominant interferences and provide multiple services in macro/femto overlaid Third-Generation Partnership Project Long Term Evolution-Advanced networks. We model our multiple services resource allocation scheme into a multiobjective optimization problem, which is a non-deterministic polynomial-time (NP)-hard problem. Then, we give a low-complexity algorithm consisting of two layers based on chordal graph. Simulation results verify that the proposed scheme can achieve better efficiency than the previous works and raise the satisfaction ratio of Guaranteed Bit Rate (GBR) services while improving the average performance of non-GBR services. 相似文献