Fairness-Aware Adaptive Resource Allocation Scheme in Multihop OFDMA Systems

We investigate a fairness-aware adaptive resource allocation scheme for the downlink of multihop OFDMA systems. Assuming that the base station has all the channel information, we formulate an optimization problem for an adaptive subchannel-, path- and power-allocation scheme that maximizes system capacity while guaranteeing minimum resources for each user. Since the optimization should be performed in real time, we propose an efficient heuristic algorithm composed of subchannel-allocation, load-balancing and power-distribution steps. The proposed algorithm is simple in that the iterative computations are removed, and accurate in that it performs similarly to the optimum solution     

OFDM系统中多业务间子载波借调自适应资源分配方法

该文研究了衰落信道条件下的无线资源分配问题。提出了一种适用于多用户OFDM系统中的多业务间子载波借调的自适应资源分配机制。该机制能够联合考虑信道衰落情况和业务的服务质量要求,在不同的业务间调整和借用子载波分配来最大化系统的容量和性能。仿真结果表明,该文提出的分配机制能改善OFDM系统的性能。     

MIMO-OFDM系统自适应资源分配研究

MIMO-OFDM系统中动态资源分配能够有效地利用系统发射功率和频谱资源,提高系统性能.文章重点讨论了MIMO-OFDM技术、基于信道状态信息物理层自适应传输和跨层自适应资源管理及MIMO-OFDM自适应算法,并指出热点研究方向.     

多小区OFDMA系统的分布式资源分配方案

该文研究了多小区OFDMA系统中下行链路的资源分配问题,主要考虑同信道干扰和频率选择性衰落对资源分配的影响,提出一种基于基站的分布式分配方案,同时考虑用户的服务质量要求(QoS)及公平性,完成子载波和功率的联合分配。算法只要求基站间简单的子载波使用计数的信息交换,不会给系统带来很大的信令负载。仿真表明,通过调整参数,该算法可以取得不同性能间的折衷。     

多用户MIMO-OFDM系统中一种子载波分配算法

介绍了多用户MIMO-OFDM系统中的Hungarian子载波分配算法,然后针对其计算复杂度过高的缺陷,提出一种局部最优的子载波分配算法,并与Hungarian子载波分配算法进行仿真比较。结果表明,该算法使系统总数据速率仅下降1．7％,而其计算复杂度却大幅减小,提高了资源分配的效率,符合高速无线系统资源实时分配的要求。     

基于资源因子的电力线通信系统自适应资源分配

本文分析了电力线通信系统在每时隙内的最大总功率、各实时用户固定比特和非实时用户最小比特、各子载波允许最大功率和特定比特数的约束下,多用户多业务在多子载波上的自适应资源分配的多层多目标最优模型,并提出一种基于资源因子和用户优先级的功率和速率自适应相结合的资源分配算法。在典型电力线信道环境下其仿真结果表明,本文算法的性能忧于已有的多用户资源分配算法且能满足多用户多业务电力线通信资源分配的多目标要求。     

Resource Allocation Scheme for Minimizing Power Consumption in OFDM Multicast Systems

This letter introduces a resource allocation scheme in orthogonal frequency division multiplexing(OFDM) multicast systems which focuses on minimizing power consumption. By allocating the resource optimally, the number of OFDM symbols that each mobile station(MS) receives can be minimized, resulting in the reduced power consumption of MSs. A heuristic algorithm for allocating resources suboptimally with low complexity is also proposed, and is shown to achieve almost optimal performance.     

多用户OFDM系统中一种新颖的自适应功率分配方案

针对多用户正交频分复用(OFDM)系统自适应资源分配的问题,提出了一种新的自适应子载波分配方案。子载波分配中首先通过松弛用户速率比例约束条件确定每个用户的子载波数量,然后对总功率在所有子载波间均等分配的前提下,按照最小比例速率用户优先选择子载波的方式实现子载波的分配;在功率分配中提出了一种基于人工蜂群算法和模拟退火算法(ABC-SA)相结合的新功率分配方案,并且通过ABC-SA算法的全局搜索实现了在所有用户之间的功率寻优,同时利用等功率的分配方式在每个用户下进行子载波间的功率分配,最终实现系统容量的最大化。仿真结果表明,与其他方案相比,所提方案在兼顾用户公平性的同时还能有效地提高系统的吞吐量,进而证明了所提方案的有效性。     

Resource Allocation and Adaptive Modulation in Uplink SC-FDMA Systems

In this paper, we study joint power and sub-channel allocation, and adaptive modulation in Single Carrier Frequency Division Multiple Access (SC-FDMA) which is adopted as the multiple access scheme for the uplink in the 3GPP-LTE standard. A sum-utility maximization problem is considered. Unlike OFDMA, in addition to the restriction of allocating a sub-channel to one user at most, the multiple sub-channels allocated to a user in SC-FDMA should be consecutive as well. This renders the resource allocation problem prohibitively difficult and the standard optimization tools (e.g., Lagrange dual approach widely used for OFDMA, etc.) can not help towards its optimal solution. We propose a novel optimization framework for the solution of this problem which is inspired from the recently developed canonical duality theory. We first formulate the optimization problem as binary-integer programming problem, and then transform this binary-integer programming problems into a continuous space canonical dual problem that is a concave maximization problem. Based on the solution of the continuous space dual problem, we derive joint power and sub-channel allocation algorithm whose computational complexity is polynomial. We provide conditions under which the proposed algorithms are optimal. We also propose an adaptive modulation scheme which selects an appropriate modulation strategy for each user. We compare the proposed algorithm with the existing algorithms in the literature to assess their performance. The results show a tremendous performance gain.     

MIMO-OFDM系统自适应资源分配算法研究

针对MIMO—OFDM系统的自适应调制问题,在完全已知信道状态和满足固定速率以及给定的误比特率的约束下以最小化发射功率为目的,文中提出了一种新的低复杂度的自适应算法,即M—P算法。该算法是对Hughes—Hartogs算法和变步长算法进行功率分配和步长加栽的改进。仿真结果表明,该算法在降低复杂度的同时提高了系统的性能。     

小蜂窝网络中不活跃用户的最优能量效率资源分配方案

针对5G网络中因小区重叠覆盖区域的干扰问题,为缓解密集小蜂窝网络中移动用户的业务连续性,提高频谱资源利用率,进而最大化整个网络平均能量效率问题。该文提出一种基于不活跃用户的最优能量效率资源分配方案(EEI)。首先,该方案依据不活跃用户通知区域,建立以用户为中心的虚拟小区,小区内小蜂窝基站可协作为用户提供通信服务,提高用户通信质量,缓解小蜂窝同层干扰,减少切换信令开销。其次,基于Lyapunov优化理论,该方案将整体网络平均能量效率优化问题,转换为用户最优传输资源分配和最优功率分配两个子问题,在最大化系统平均能量效率同时保证系统队列稳定性。由于该文将原优化问题进行了松弛,所得结果是局部最优解,而不是全局最优解。仿真结果表明,该文提出的基于不活跃用户的最优能量效率资源分配算法,其系统能量效率优于对比算法而计算复杂度较高。

     

Fair Adaptive Cross-Layer Resource Allocation Scheme for IEEE 802.16 Broadband Wireless Networks

In a WiMAX network, the Medium Access Control (MAC) protocol deals with resource allocation to different types of traffic. The key components that ensure Quality of Service (QoS) guarantees in a WiMAX network include Call Admission Control (CAC), Bandwidth and Burst allocation. In this Paper, a Cross-layer framework is designed to efficiently allocate resources to various classes of traffic. CAC and Bandwidth allocation are dealt in the MAC layer, while Burst allocation in the PHYsical layer. The predominant goal of this work is to reduce delay and Information Element (IE) overheads by efficiently utilizing the available frame space. The History based CAC (HCAC) proposed in this paper deals with call acceptance based on the Contention Window (CW) values. The History based Bandwidth Allocation (HBA) scheme deals with allocating bandwidth based on Consumption and Equity measures. The proposed tightly coupled Delay Tolerance based Scheduler (DTS) and Bucket based Burst Allocator (BBA) allocate resources by prioritizing flows with least delay tolerance. It is seen that the proposed schemes offer better performance in contrast to the existing benchmarked schemes in terms of Throughput, Average Delay and Packet Loss Ratio (PLR).

     

速率比例公平下多用户OFDM系统的自适应资源分配

在多用户正交频分复用(MU-OFDM)系统中,考虑各个用户之间具有比例数据传输速率限制条件下的一种公平的自适应资源分配方案的最优算法计算量巨大,为此,提出了一种将子信道分配和功率分配相分离的次优算法.首先,在假设相同功率分配的情况下进行子信道的分配,然后在保持一定比例公平条件下使总容量最大时进行最优功率分配.对该算法的仿真表明,在用户数为2、子信道数为10的系统中,所提算法的容量性能接近最优算法,而计算量由指数增长变为线性增长.所提资源分配算法的总容量比以前的算法在用户间的分配更公平也更灵活.     

基于多维资源自适应分配的协作认知传输机制

该文针对协作认知无线电网络提出一种时域、频域和空域资源联合分配的传输机制,在改善授权用户传输性能的前提下使参与协作的认知用户获得合理的回报。所提机制利用多天线认知节点担任中继,通过自适应的时隙划分与带宽分配,对两跳传输链路中的瓶颈予以消除;并在包含多个协作认知用户的场景中,给出一种考虑公平性的中继选择算法。该方法一方面采用比例公平的思想实现认知用户间的公平性,另一方面通过调整奖励因子,使中继获得合理的回报。仿真结果表明,所提算法能够改善授权与认知系统的数据速率,同时给予认知中继公平的回报。     

A Fair and QoS-Aware Resource Allocation Scheme in UWB WPANs with WiMedia Distributed MAC

Merits of distributed medium access control specified by WiMedia Alliance such as distributed nature and high data rate make it a favorite candidate standard for high rate wireless personal area network. However, the current WiMedia MAC standard has not considered supporting Quality of Service (QoS) even though QoS parameters such as a range of service rates are provided to each traffic stream (TS). Therefore, we propose a fair and QoS-aware resource allocation method that provides a fair and maximized QoS for all TSs according to the current traffic load condition and differentiates SoQ among different QoS classes while guaranteeing fairness of SoQ within a QoS class in a fully distributed manner. Even in case that the traffic load varies, each device independently recognizes the changes and calculates fair and maximum allowable service rates for TSs. From the simulation results, it is proven that the proposed method achieves high capacity of TSs and fair QoS provisioning under various traffic load conditions.     

多用户自适应调制OFDM系统的高效子载波分配方案

为保证用户的子载波分配的实时高效,该文给出了一种能够满足和适应未来移动多媒体通信要求的高效频带分配方案。它是基于自适应调制的OFDM系统的。该方案使用了一种基于贪婪算法的高效算法,这种算法简单易于理解,复杂度低,仿真结果表明其性能优良,接近于最优解。     

A Simple Superposition Coding Scheme for Optimizing Resource Allocation in Downlink OFDMA Systems

In this paper, we propose to apply a simple superposition coding strategy for downlink of OFDMA systems. The novelty of this paper consists on allowing at most two users to share the same subchannel. The main idea is to consider the subchannels allocated to the users with the weakest link, and allow these subchannels to be shared by some potential users who can transmit some number of bits with only a small amount of power. To decrease the overhead of the proposed OFDMA system, we restrict to use a predetermined superposition encoding|decoding scheme. We address the problem of resource allocation, which consists on finding the optimal subchannel assignment in the OFDMA system. A low complexity algorithm, denoted Share Specific Subcarrier Allocation (SSSA) is then proposed. It offers a fairness allocation among users. This can be done by taking into account all user’s buffer states information. Simulation results confirm that the proposed technique outperforms the classical algorithms in terms of total throughput and dropping probability.     

一种低复杂度的分簇多带超宽带系统动态资源分配算法

提出了一种用于多用户多带超宽带系统的低复杂度动态资源分配方案,该方案在满足所有用户数据速率请求和给定的误比特率前提下,可以最小化总的系统传输功率.分析和实验表明,提出的算法与现有方法相比,性能只有很少的损失,却可以显著降低运算的复杂度.复杂度的降低主要通过把一般性的限制性优化问题转化为线性编程问题,并在求解线性编程问题的过程中寻找更好的初始解.此外,还通过对相邻的副载波进行分簇,亦降低了算法的复杂度,并为系统设计提供了更多的灵活性.最后,还通过实验研究了簇的大小和用户数目对算法和系统的影响.     

一种多小区OFDMA系统中有效公平的资源分配方法

在多小区OFDMA系统中,一个主要的研究方向就是如何通过控制来自邻小区的同道干扰来优化系统性能。采用了联盟形成以及合作博弈中纳什讨价还价解(NBS)的方法,使小区内用户随机地结合成合作型双人联盟并对子载波的使用进权行讨价还价,从而换取有利于自己的子载波。所提出的算法不仅复杂度低而且能产生一个公平的解,另外还证明了这种机制下的帕累托最优性。仿真结果充分表明了所提算法的有效性与公平性。