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。     

基于TD-LTE系统的自适应调度技术研究

随着移动通信技术的飞速发展,LTE技术作为移动通信系统的主要演进方向,以其高速率、低时延的特点,越来越受到世界各大主流运营商和设备厂商的广泛关注。由于OFDM和MI-MO等先进技术的引入,使LTE系统的资源分配具有很大的灵活性,但是,面对这样灵活的系统,如何高效地利用这些时频资源,有效提高LTE系统的频谱效率,还有很多...     

Dynamic subcarrier and power allocation based on cooperative game theory in symmetric cooperative OFDMA networks

In order to improve the efficiency and fairness of radio resource utilization,a scheme of dynamic cooperative subcarrier and power allocation based on Nash bargaining solution(NBS-DCSPA) is proposed in the uplink of a three-node symmetric cooperative orthogonal frequency division multiple access(OFDMA) system.In the proposed NBS-DCSPA scheme,resource allocation problem is formulated as a two-person subcarrier and power allocation bargaining game(SPABG) to maximize the system utility,under the constraints of each user’s maximal power and minimal rate,while considering the fairness between the two users.Firstly,the equivalent direct channel gain of the relay link is introduced to decide the transmission mode of each subcarrier.Then,all subcarriers can be dynamically allocated to the two users in terms of their selected transmission mode.After that,the adaptive power allocation scheme combined with dynamic subcarrier allocation is optimized according to NBS.Finally,computer simulation is conducted to show the efficiency and fairness performance of the proposed NBS-DCSPA scheme.     

Resource allocation in downlink OFDMA distributed multipoint systems with incoherent and coherent transmitters

Distributed multipoint systems (DMS) are important and timely for the move to future broadband wireless communication systems.Traditional studies on DMS have mainly focused on the issues with the spatial division multiple access such as precoding techniques,which only consider a narrowband case.This paper addresses the downlink radio resource management of the orthogonal frequency division multiple access DMS (OFDMA-DMS),including power allocation between users or subcarriers,and distributed antenna selection.Signal models with incoherent and coherent transmitters are built.To maximize the system throughput,for the incoherent transmitter case,a strategy based on the iterative water-filling power allocation is proposed to approach the optimality.As for the coherent case,where coherent additions of the signal could occur at the users,the problem is transformed into an integer programming which is solvable.Numerical results show that the gain from the coherent transmitter is promising.And to achieve a near-optimal solution,only part of the DA ports will be used,which have better channel conditions.     

基于中继的OFDMA网络中可扩展编码视频流传输的权衡优化(英文)

To achieve an optimal trade-off between video quality and energy efficiency in the uplink streaming of multi-user Scalable Video Coding (SVC) videos in relay-based Orthogonal Frequency Division Multiple Access (OFDMA) cellular networks, a cross-layer design framework that jointly selects the Transmission Policy (TP) for SVC video frames, assigns OFDMA subcarriers, and allocates power for each subcarrier is proposed. We apply the dual decomposition method to the problem, and obtain a TP selection subproblem for each SVC video adaptation and a resource allocation subproblem of Joint Subcarrier, Relay and Power Allocation (JSRPA). A second level of dual decomposition is used to divide the JSRPA problem into independent subcarrier subproblems. The proposed Crosslayer Trade-off Optimization (CTO) algorithm is sub-distributed with significantly low complexity. A performance evaluation with typical SVC video traces demonstrates that the proposed algorithm is able to converge and efficiently achieve the optimal trade-off between the video quality and energy consumption at the MSs for uplink SVC streaming.     

Sequential frequency reuse with power control for OFDMA systems

Orthogonal frequency division multiple access (OFDMA) is a promising technique for high data rate communications in future cellular systems. Since frequency resources are universally reused in every cell in a system, a typical OFDMA system tries to maximize the spectral efficiency. Users located near the cell‐edge tend to have the weakest signal strength. So they might experience severe inter‐cell interferences (ICIs). In this paper, we propose a sequential frequency reuse (SqFR) that reduces ICIs by a sequential sub‐channel allocation. By giving more power to sub‐carriers allocated to cell‐edge users, our SqFR significantly enhances the performance of cell‐edge users. The performance of the proposed SqFR is investigated via the analysis and simulations. Simulation results show that proposed SqFR improves the performance of cell‐edge users in an OFDMA system under both homogeneous and heterogeneous traffic conditions. Copyright © 2011 John Wiley & Sons, Ltd.     

多小区OFDMA系统频偏补偿算法

针对OFDMA系统对频率偏移敏感的特性,在频率偏移估计的基础上重点研究了多小区OFDMA系统的频率偏移的补偿算法。就三个小区的情形,利用频域和时域两种补偿算法对其基站频率偏移做了小数位的补偿。仿真结果表明：频域补偿的效果比时域补偿好,而作为一种新的尝试,时域补偿所涉及的计算量减小了很多。     

OFDMA系统保证服务质量的分组调度算法

在正交频分多址接入系统中采用正比公平算法可以兼顾吞吐量和公平性,有效地提高系统性能。结合正比公平算法,该文提出一种应用于正交频分多址接入系统保证服务质量的分组调度算法。为防止需求速率高但瞬时信道状况差的用户分配过多的子载波,算法使用了动态变化的权重因子。在一次调度过程中,剩余子载波的权重因子可以随着子载波的分配而更新。仿真结果证明,在满足实时业务服务质量的前提下,该算法比正比公平算法具有更好的公平性。     

一种用于MIMO-OFDMA系统的调度和资源分配算法

该文提出了一种用于MIMO-OFDMA 系统下行链路的调度和资源分配算法,该方法能够优化利用空时频三维资源,为不同类业务提供QoS保证。该算法不仅结合了先进的物理层技术,同时从媒体接入控制(MAC)层考虑了业务特性、QoS 需求以及用户公平性等因素对资源进行分配。仿真结果表明,该算法在保证多业务传输质量的同时提高系统吞吐量。     

用于OFDMA系统的延迟公平资源调度方法

正交频分复用接入(OFDMA)具有传输速率高,带宽分配灵活等特点。文章提出了一种延迟公平资源调度算法。算法通过控制无线资源的分配来保证所有用户的等效延迟相等,从而使得所有用户在服务质量上保持公平。该算法不需要迭代计算,计算复杂度较低,适用于快速资源的分配应用环境。