GPRS/UMTS无线数据接入的控制与优化*

提出了一种新的基于代理的协议框架以提高在GPRS/UMTS网络中进行无线数据接入的性能。在此框架下研究了延时阻塞调度策略。该策略利用数据业务对延时不敏感的特性,在不增加带宽的前提下显著改善系统的响应性能,为实现该策略下的无线信道资源管理,设计了最优信道分配和自适应信道分配两种算法。理论分析和仿真表明,新的机制和算法可以显著地提高网络利用率并缩短系统的平均响应时间。     

A uplink radio resource allocation scheme for localized SC-FDMA transmission in LTE network

The radio resource allocation is one of the most important issues to achieve effective wireless communication. In Long Term Evolution (LTE) network, single carrier frequency division multiple access (SC-FDMA) is applied as the transmission technology for uplink traffic. Most researches focus on maximizing the system throughput of SC-FDMA under changeable channel condition. However, users may require different quality of services (QoS) for different applications. This paper studies radio resource allocation for QoS users in localized SC-FDMA system. The proposed scheme divides allocation process into matching algorithm and radio resource assignment algorithm. The Gale–Shapley algorithm is applied to find the optimal matching between resource blocks (RB) and user equipment (UE) by considering channel conditions and the desired QoS. Then the resource assignment algorithm heuristically allocates bandwidth to UE by referring the matched RB under the constraint of carrier continuity. This paper modified the Recursive Maximum Expansion (RME) algorithm to effectively assign radio resource for UEs with different bandwidth demands. The performance of our proposed scheme is compared with the modified RME scheme through exhaustive simulations. The video streaming, VoIP, and FTP traffic types were adopted for simulations. Our simulation results show that the proposed scheme achieves better QoS satisfaction and system throughput than the RME-modified scheme.     

Resource allocation for physical-layer security in OFDMAdownlinkwith imperfect CSI

We investigate the problem of resource allocation in a downlink orthogonal frequency-division multiple access (OFDMA) broadband network with an eavesdropper under the condition that both legitimate users and the eavesdropper are with imperfect channel state information (CSI). We consider three kinds of imperfect CSI: (1) noise and channel estimation errors, (2) feedback delay and channel prediction, and (3) limited feedback channel capacity, where quantized CSI is studied using rate-distortion theory because it can be used to establish an informationtheoretic lower bound on the capacity of the feedback channel. The problem is formulated as joint power and subcarrier allocation to optimize the maximum-minimum (max-min) fairness criterion over the users’ secrecy rate. The problem considered is a mixed integer nonlinear programming problem. To reduce the complexity, we propose a two-step suboptimal algorithm that separately performs power and subcarrier allocation. For a given subcarrier assignment, optimal power allocation is achieved by developing an algorithm of polynomial computational complexity. Numerical results show that our proposed algorithm can approximate the optimal solution.     

基于负载均衡的无线虚拟网络映射算法

针对网络僵化的问题,目前多采用网络虚拟化（NV）方法进行解决,其关键技术是虚拟网络映射（VNE）。为解决无线VNE过程中功率和带宽资源使用不均衡的问题,基于负载均衡原理提出一种联合资源分级的无线VNE算法。首先,采用新的节点资源排序方式,其中将节点功率和平均链路带宽作为排序依据;其次,对资源进行分级,以动态调整虚拟网络请求对功率和带宽资源的需求;最后,改进功率和带宽资源的单位成本,并以最小化成本为目标函数选择资源分配方案。与原有的无线VNE算法WVNE-JBP相比,所提算法的总体接受率提高了11.7个百分点,平均功率利用率提高了4.4个百分点,平均带宽利用率提高了1.6个百分点。实验结果表明,所提算法能有效提高虚拟网络接受率和资源利用率。     

基于HAGA的D2D-NOMA资源分配优化算法

针对无线系统带宽资源有限、基站负载压力大、传输时延长等问题,提出一种基于非正交多址接入技术的D2D系统吞吐量最大化资源分配算法。在不同用户的服务质量约束条件下,建立D2D系统吞吐量最大化资源分配模型。该模型的优化目标是一个混合整数非线性规划问题,将其解耦为信道匹配与功率分配2个子问题并分别进行处理,利用自适应惩罚函数法处理约束条件并提出一种基于爬山策略的自适应遗传算法以对问题进行求解。仿真结果表明,与GA、AGA算法相比,该算法能够有效提高D2D系统的吞吐量,且收敛性能更好。     

Adaptive channel and power allocation of downlink multi-user MC-CDMA systems

The Multi-Carrier Code Division Multiple Access (MC-CDMA) is becoming a very attractive multiple access technique for high-rate data transmission in the future wireless communication systems. This paper is focused on the joint channel and power allocation in the downlink transmission of multi-user MC-CDMA systems and considers the throughput maximization problem as a mixed integer optimization problem. For simple analysis, the problem is divided into two less complex sub-problems: power allocation and channel allocation, which can be solved by a suboptimal Adaptive Power Allocation (APA) algorithm and an optimal Adaptive Channel Allocation (ACA) algorithm, respectively. By combining APA and ACA algorithms, an adaptive channel and power allocation scheme is proposed. The numerical results show that the proposed APA algorithm is more suitable for MC-CDMA systems than the conventional equal power allocation algorithm, and the proposed channel and power allocation scheme can significantly improve the system throughput performance.     

混合共享认知无线网络信道分配算法

混合频谱共享是适应认知用户不同地理分布的有效频谱共享模式。信道分配是无线通信网络中关键的问题之一,近年来得到了广泛研究。集中式信道分配算法是最常用的算法形式,但在认知无线电网络这种分布式系统中,集中式算法不易实现。将混合共享认知无线网络的信道分配问题构建为一对一的匹配博弈,提出了分布式用户-信道匹配算法。该算法数学复杂度低,且能够达到稳定匹配。仿真结果表明,算法收敛时间短,稳定匹配状态下的平均传输速率与使用匈牙利算法的最优分配算法所获得传输速率相接近,远优于随机分配算法的传输速率。     

异构无线网络负载均衡研究*

针对异构网络中的带宽分配及网络的负载均衡问题,提出了一种异构无线网络负载均衡的联合优化模型,该模型在一定条件下利用用户的带宽进行负载成本和网络效用的建立,并通过求解网络与用户的关联矩阵来得到带宽在网络中的优化分配方案,使异构无线网络达到负载均衡。仿真结果表明,联合优化模型的结果在最小化负载成本以及优化网络总效用性能之间,它让用户通过在不同网络间的切换使网络带宽优化分配、网络负载达到均衡。     

基于合作博弈的认知卫星网络信道分配与上行功率控制算法

随着通信业务需求的不断增长,频谱资源的有限性使得卫星通信网络和地面网络都面临着严重的频谱危机。认知无线电技术的出现,使得卫星网络与地面网络共用频率资源以提升网络效用成为可能。文中对认知接入分配给地面网络作为主用户的同一频谱资源的认知卫星网络的功率控制和信道分配问题进行了研究。根据卫星网络和地面网络的特性构建了合理的系统模型,并利用中断概率门限表征了信道估计误差对系统容量的影响。为了保护主基站的通信性能,在考虑信道估计误差、信道资源约束、认知卫星用户最大发射功率和微波基站干扰约束的条件下,根据议价博弈理论设计了优化函数。其次,根据凸优化理论推导了最优发射功率和信道分配的闭式解,并在此基础上设计了一种对偶迭代算法来求解该优化问题。最后,根据卫星网络的特性设置了合理的网络参数,并根据参数利用Matlab仿真平台对提出的算法进行了仿真实验。仿真结果表明:所提方法在不同到达速率的条件下均具备良好的收敛性;信道估计误差会降低网络的总容量;所提方法在波束数多于15个时,相比比例公平性算法容量提升超过50 bps/Hz,相比最大容量法公平性能提升超过一倍,因此,相较于这两种方法,该方法能在系统容量和用户间公平性之间获得较好的折中。     

Joint subcarrier,code, and power allocation for parallel multi-radio access in heterogeneous wireless networks

In the heterogeneous wireless networks, it has been proved that the joint spectrum and power allocation can achieve network diversity gains for parallel multi-radio access in theory. This article aims to develop an effective and practical algorithm of joint subearrier, code, and power allocation for parallel multi- radio access of the downlink in heterogeneous wireless networks （e.g., CDMA and OFDMA）. Firstly, we propose a unified framework to formulate the subcarrier, code, and power allocation as an optimization problem. Secondly, we propose a resource element （subcarrier and code） scheme based on the threshold type. Simulation results show that the proposed scheme outperforms the existing algorithm for considered wireless scenarios.     

An Efficient Resource Allocation Mechanism for LTE–GEPON Converged Networks

Optical–wireless convergence is becoming popular as one of the most efficient access network designs that provides quality of service (QoS) guaranteed, uninterrupted, and ubiquitous access to end users. The integration of passive optical networks (PONs) with next-generation wireless access networks is not only a promising integration option but also a cost-effective way of backhauling the next generation wireless access networks. The QoS performance of the PON–wireless converged network can be improved by taking the advantages of the features in both network segments for bandwidth resources management. In this paper, we propose a novel resource allocation mechanism for long term evolution–Gigabit Ethernet PON (LTE–GEPON) converged networks that improves the QoS performance of the converged network. The proposed resource allocation mechanism takes the advantage of the ability to forecast near future packet arrivals in the converged networks. Moreover, it also strategically leverages the inherited features and the frame structures of both the LTE network and GEPON, to manage the available bandwidth resources more efficiently. Using extensive simulations, we show that our proposed resource allocation mechanism improves the delay and jitter performance in the converged network while guarantying the QoS for various next generation broadband services provisioned for both wireless and wired end users. Moreover, we also analyze the dependency between different parameters and the performance of our proposed resource allocations scheme.     

Cross-layer resource allocation in wireless multi-hop networks with outdated channel state information

The cross-layer resource allocation problem in wireless multi-hop networks （WMHNs） has been ex-tensively studied in the past few years. Most of these studies assume that every node has the perfect channel state information （CSI） of other nodes. In practical settings, however, the networks are generally dynamic and CSI usually becomes outdated when it is used, due to the time-variant channel and feedback delay. To deal with this issue, we study the cross-layer resource allocation problem in dynamic WMHNs with outdated CSI under channel conditions where there is correlation between the outdated CSI and current CSI. Two major contributions are made in this work： （1） a closed-form expression of conditional average capacity is derived under the signal-to-interference-plus-noise ratio （SINR） model; （2） a joint optimization problem of congestion control, power control, and channel allocation in the context of outdated CSI is formulated and solved in both centralized and distributed manners. Simulation results show that the network utility can be improved significantly using our proposed algorithm.     

Bandwidth allocation in UWB WPANs with ECMA-368 MAC

The new ECMA-368 MAC for UWB WPANs consists of two channel access methods: the distributed reservation protocol (DRP) and prioritized contention access (PCA). The exact method of medium access slot (MAS) allocation in DRP is not specified in the standard. The contribution of this paper is twofold. First, the paper describes a distributed resource allocation method in which a number of interference–avoidance rules are used to reserve slots for devices. Devices maintain sending and receiving tables to track activities in the neighbourhood. The proposed method is a simple, effective solution to the DRP MAS allocation problem, avoiding reservation conflicts and interference from hidden terminals. Secondly, for VBR MPEG-4 video traffic, we propose a bandwidth requirement calculation method based on traffic prediction. In the proposed scheme bandwidth is allocated based on accurate traffic predictions, therefore matching network resources to the traffic demand. Application QoS is maintained while network utilization is kept high. Furthermore, the simple, adaptive linear predictor does not incur much computation overhead. Simulation results have demonstrated the accuracy of the proposed prediction algorithm and effectiveness of the bandwidth allocation method.     

车联网D2D通信中最大化频谱资源利用率分配算法

无线通信技术快速发展,终端设备不断增多,为缓解这一现象,提升系统网络容量,针对车联网蜂窝D2D(device to device)通信资源分配问题,提出了一种最大化频谱资源利用率分配算法.该算法以最大化频谱资源利用率为优化目标,在满足车联网通信的基本服务质量(quality of service,QoS)下,通过V2V(vehicle to vehi-cle)和V2P(vehicle to people)共享信道资源来提高频谱资源利用率.首先利用信道状态信息定义的链路增益因子为终端用户找到潜在的通信链路集合;然后证明终端用户复用链路资源时功率分配问题为一个凸优化问题,利用凸优化理论求得最优传输功率;随后求解最优的信道匹配问题,此问题为多对一的加权匹配问题,为降低算法复杂度用KM(Kuhn Munkres)算法来求解.仿真结果表明,所提算法较其他算法能够有效地提升系统吞吐量、提高频谱资源利用率、提升网络性能,优化车联网通信资源分配问题.     

一种基于RAN架构无线接入网系统容量最大化的功率分配算法

针对新型RAN架构无线接入网中功率分配问题进行研究, 建立系统容量最大化的最优化数学模型, 提出了一种基于RAN架构无线接入网的系统容量最大化的功率分配算法, 并且应用人工鱼群算法求解了算法中目标函数的全局最优解, 即一组使系统容量最大化的发射功率。仿真结果表明, 与现有的分布式网络架构中非合作的功率控制博弈算法相比, 新算法可以显著提高系统容量, 即证明了该算法的有效性。     

电力通信系统的宽带调节技术

当前利用分层网络结构对电力通信系统数字信道进行调节的方式,存在吞吐量性能差、宽带分配不均衡以及电力信息传输丢失严重等问题。提出利用遗传算法对电力通信系统宽带进行调节。对电力通信系统宽带中,每个OFDM符号内多个用户同时进行电力数据传输中的多种参数进行定义并计算,对最大的传输比特数以及最大功率进行计算,在电力通信资源分配速率的自适应和功率自适应的目标几乎一致理论基础上,建立电力通信多用户速率自适应宽带资源分配的数学模型,针对多用户的多目标特点,利用遗传算法中优良基因的注入,跨世代精英的保留以及迭代次数等,满足电力通信系统的多用户宽带资源分配需求。并通过实验证明,所提方法可实现电力通信系统宽带的有效调节。     

基于二分图的两级动态异构网络选择方案

通信技术的发展,使多种接入技术并存的异构网络成为未来通信网络的发展趋势,随着用户业务QoS需求的提高和传输带宽的增加,现有的网络选择算法已经不能满足用户高质量的通信需求。针对异构无线网络频谱资源日益紧缺的问题,提出了由用户端和网络端共同参与的两级动态网络选择方案。该方案包括灰度关联分析法和二分图联合优化匹配算法,通过用户端和网络端的共同决策,算法在有效满足移动用户业务服务质量需求的前提下,优化了系统吞吐量,均衡了网络负载。仿真实验表明,相对传统算法,该方案极大地提高了异构网络频谱资源利用率并降低了用户在无线网络间的切换概率,实现了用户需求和网络资源的合理配置。     

一种容量最大化的OFDMA资源分配算法

针对功率受限的多用户OFDMA系统,提出了一种简化的子载波和功率分配算法,此算法在最大化系统容量的同时兼顾了用户间的公平性。算法首先依据当前的信道状况计算出各用户所需的载波数量,并分配子载波,然后以注水算法对各载波上的功率进行分配。仿真结果表明,以此算法对OFDMA的系统资源进行分配可显著提高系统的多项性能。     

Interference aware resource allocation for hybrid hierarchical wireless networks

This paper addresses the problem of interference aware resource allocation for OFDMA based hybrid hierarchical wireless networks. We develop two resource allocation algorithms considering the impact of wireless interference constraints using a weighted SINR conflict graph to quantify the interference among the various nodes: (1) interference aware routing using maximum concurrent flow optimization; and (2) rate adaptive joint subcarrier and power allocation algorithm under interference and QoS constraints. We exploit spatial reuse to allocate subcarriers in the network and show that an intelligent reuse of resources can improve throughput while mitigating interference. We provide a sub-optimal heuristic to solve the rate adaptive resource allocation problem. We demonstrate that aggressive spatial reuse and fine tuned-interference modeling garner advantages in terms of throughput, end-to-end delay and power distribution.     

5G超密集异构网络带内无线回传资源分配方案

为实现5G超密集异构网络中无线回传链路和接入链路之间的最优资源分配,研究多用户场景下双层异构网络的联合用户调度和功率分配问题,在队列稳定和无线回传资源有限的情况下,综合考虑用户调度、功率分配和干扰控制等因素,对带内无线回传的最优资源分配问题进行数学建模并求解,基于李雅普诺夫优化理论提出联合用户调度和功率分配的优化算法。将优化问题解耦为网络内各个用户的调度以及宏基站和小基站的功率分配过程,采用MOSEK求解器和二分类方法获得用户调度向量,利用拉格朗日乘子法求解功率分配问题,并通过队列的时刻更新过程实现最优资源分配。仿真结果表明,在多用户场景下,该方案能够有效提升网络总吞吐量以及网络效用,并且毫米波频段的通信性能优于传统蜂窝网络频段。