基于非合作博弈的OFDMA-WLAN系统资源分配算法研究

为满足无线局域网中基于正交频分多址技术(OFDMA-WLAN)的多用户通信需求,提出了一种基于非合作博弈的资源分配策略,利用博弈论这一有效工具对无线网络服务质量的资源分配问题进行研究,同时将用户对信道质量的不同需求转化为多用户对不同信道资源分配的非合作博弈竞争问题。此外,还将纳什均衡问题(NEP)细分为数个变分不等式子问题,通过凸优化函数对这些子问题分别求解。数值分析结果表明,所提算法在资源分配的公平性和数据传输率方面达到了更好的折中。     

异构无线网络中基于非合作博弈论的资源分配和接入控制

对异构无线网络中无线资源分配和呼叫接入控制进行研究.基于非合作博弈理论,提出了不同无线资源的带宽和连接数量分配的理论模型.结合网络连接的效用函数,对非合作博弈的无线资源分配中的纳什均衡点的存在性和唯一性进行论证.而且,进一步对业务量与阻塞率之间的关系进行分析,提出了能够保证通信可靠性的接入控制算法.仿真结果表明,基于非合作博弈论的无线资源分配机制能够有效地解决带宽和连接数量的分配问题,并能在整体上保证分配的合理性和公平性.接入控制算法根据需要能够动态地调整在某一区域分配的连接数量,从而保证通信的可靠性.     

OFDMA系统中的一种资源分配算法

在OFDMA系统中,通过为每个用户分配不同的子载波可以实现并行数据传输.资源分配是OFDMA系统资源调度中的一个重要研究问题.本文时OFDMA无线网络系统的下行链路,考虑了资源分配的问题.重点研究了功率和子载波在用户之间的分配问题,以往的分配算法通常是非线性的迭代算法,复杂度非常高.本文的资源分配算法降低了运算复杂度,与其它算法相比考虑了信道估计的误差问题,更加符合实际情况.仿真结果表明,该算法获得了较好的分集增益.     

全双工无线携能通信速率最大化波束赋形研究

针对全双工无线携能通信系统,提出了一种基于系统和速率最大化准则的波束赋形联合优化方案。该方案以系统和速率最大化为目标,在保证上行/下行链路的最大发射功率约束及最小能量收获需求的同时,实现了信息速率和频谱效率的同步改善。由于速率问题为非凸问题,首先采用半定松弛及一阶泰勒近似方法将其转换为凸优化问题,然后结合基于逐次凸近似的迭代算法分别求解最优的信息波束赋形矢量和能量波束赋形矢量。仿真结果表明,所提方案相比传统方案性能更优,实现了系统和速率的有效提高。     

OFDMA系统的一种资源分配方法

针对OFDMA下行链路发送端只能获得部分信道信息的情况,提出了一种基于部分信道信息的资源分配算法.该算法通过建立部分信道信息模型,考虑传输的中断概率,保证分配的数据速率、子载波等资源与真实的信道条件匹配.仿真结果表明,该方法实现了较好的多用户分集增益和实际吞吐量性能.     

认知网络中基于博弈论的联合功率控制与速率分配算法

针对认知无线网络上行链路中的资源分配问题,提出了一种适应于多小区认知无线网络的基于功率控制与速率分配的博弈算法。为了更加合理地控制用户的功率和速率,减小各次用户间的干扰,首先,在效用函数中分别给功率和速率设置了不同的代价因子,使其能够更加合理地控制用户,避免用户过度增加发射功率。其次,从理论上证明了该算法纳什均衡的存在性、唯一性以及算法的收敛性。最后,为了解决发射功率和传输速率的最优化问题,给出了联合功率控制和速率分配的迭代更新算法流程图。理论分析及仿真结果表明,与同类博弈算法相比,在保证通信质量的前提下,所提算法可以使得用户以较小的发射功率获得较大的传输速率和较高的信干噪比（SINR）,并且减小了用户间的干扰,提高了次用户系统容量。     

一种基于端系统竞价博弈的网络资源分配模型

随着网络流量以指数形式急剧增长,各种应用对网络资源的需求随之增加,特别是需要严格QoS保证的实时网络多媒体应用要求更多的网络资源.资源分配是QoS分配的最终实现,QoS分配目的是为了进行合理的资源分配,因而有效的资源分配十分重要.在描述资源分配问题的基础上,对资源分配博弈进行了深入研究,提出了能够反映供求关系的基于竞价的网络资源定价机制,并设计了端系统的效用函数,论证了资源分配博弈中Nash均衡点的存在性和唯一性以及实现Nash均衡解端系统的竞价策略.最后,为完善上述资源分配博弈模型,对该模型中的资源价格和相同竞价问题进行进一步讨论.该研究为基于竞价的资源分配算法的设计提供了理论上的支持.     

一种全双工智能总线的研究

基于半双工非主从式和全双工主从式两种通信方式,研究了一种基于差分信号的非主从式全双工结构的智能总线,并设计了该总线系统的硬件结构和基本协议。总线数据由上行、下行方向两路独立工作的单向差分信号构成。总线设备通过独特的硬件和基本协议,实现了缓存-中继功能,实时中继传导上行、下行通信数据;或在有数据发送请求时抢占发送,缓存-中继传导上行、下行通信数据,从而实现较远距离、较多设备情况下的稳定传输。总线上任意设备之间的全双工通信兼顾了数据传输的效率和协调性,解决了一般半双工或全双工总线实时发送数据时的总线冲突问题。总线设备可以通过获取总线中的"位置"来得到唯一地址,并且通过周期性进入寻址状态,实现了总线断线检测和设备热插拔。     

基于无线携能通信的传感云系统Sink节点最优能效策略

无线携能通信能够提升传感器网络的能量效率和资源复用率,然而当前研究均优化无线携能通信参数以实现系统增益,忽略了信道质量变化对系统能量效率的影响.为了解决该问题,针对无线携能通信的传感云系统,提出基于最优停止理论的Sink节点能效优化策略.首先设计下行无线携能通信、上行信息传输的工作时序,其中下行阶段Sink节点采用机会调度策略,选择信道质量较好时刻开始下行链路传输.Sink节点能效定义为系统所实现的上行吞吐量与下行能耗之比.继而基于最优停止理论,建立Sink节点能效最优化问题并证明该问题存在最优停止规则.最后设计最优能效算法求解Sink节点最优下行无线携能传输时刻,从而制定相应的能效优化策略.通过仿真实验验证最优能效算法的有效性与性能,同时通过不同策略的对比验证所提策略在提升Sink节点能效方面的优势.     

分布式WLAN全双工链路加权调度算法

针对分布式无线局域网络带内全双工接入过程的链路调度公平性问题,提出一种基于节点调度权重的全双工链路调度算法(W-FD).通过节点调度权重实现链路负载均衡,从而提升全双工链路的吞吐量,减小节点接入时延.算法基于分布式网络结构,节点按自组织方式获取网络拓扑及邻居节点状态信息,依据节点间数据量、互扰关系和链路调度间隔等参数计...     

基于演化博弈的用户接入机制

用户接入问题就是无线终端选择接入某个服务基站的问题。用户接入可以看作无线资源管理的第一步,对于网络性能有着重要的影响,在实现负载均衡、控制干扰、提高频谱和能量效率等方面起着非常重要的作用。针对包含宏基站和全双工小基站的多层异构网络特点,考虑了分离多接入机制,即允许一个终端在上行和下行接入到不同的多个基站,从而实现性能的提升。在此基础上,将异构网络中的上行下行分离多接入的用户接入问题建模成一个演化博弈问题,其中用户是博弈方,相互之间进行资源的竞争,基站的接入选择就是博弈中的策略,每个用户希望能通过策略的选择实现自身效用的最大化。此外,基于演化博弈和强化学习设计了低复杂度自组织用户接入算法,用户可以根据当前的策略选择收益来进行策略调整,并最终达到均衡状态,实现了用户公平性。最后通过大量的仿真实验验证了所提方法的有效性。     

Using traffic asymmetry to enhance TCP performance

A wealth of recent work has gone into optimizing the performance of Transmission Control Protocol (TCP) on the downlink channel of wireless networks such as for example, honing its congestion awareness mechanism so that it is minimally affected by random wireless losses, and optimizing achieved fairness of the end-to-end TCP rates. Other work has gone into balancing the allocation of a shared resource between the downlink and uplink in order to optimize TCP performance. We build on such previous research by proposing a cross-layer algorithm for resource allocation in OFDMA systems aiming not only to achieve optimal throughput for competing TCP flows but also to allocate resources appropriately between the downlink and uplink. This is important due to the increasing number of Internet applications where the mobile terminal is the TCP sender (social networking, peer-to-peer, etc.). Therefore, our scheme makes use of the asymmetry in the traffic and by defining the boundary between downlink and uplink capacity dynamically, enhance the TCP performance. Through numerical investigations we show the performance of the proposed scheme in terms of achieved fairness to the receivers and efficient allocation of downlink to uplink ratios based on the TCP traffic.     

QoS scheduling of uplink resources in OFDMA networks

Orthogonal frequency division multiple access (OFDMA) transmission is the technology of choice for fourth generation (4G) wireless networks (802.16, 3GPP and 3GPP2). In both uplink and downlink directions, resources can be allocated in three dimensions, frequency, time and power. The uplink resource allocation problem is more complicated due to the limited transmission power of the subscriber stations (SS). In this paper we consider the uplink resource allocation problem for generic OFDMA wireless networks and derive the optimal scheduler taking into account constraints, such as quality of service (QoS), that were not considered in previous works.     

Efficient wireless packet scheduling in a non-cooperative environment: Game theoretic analysis and algorithms

In many practical scenarios, wireless devices are autonomous and thus, may exhibit non-cooperative behaviors due to self-interests. For instance, a wireless cellular device may be programmed to report bogus channel information to gain resource allocation advantages. Such non-cooperative behaviors are highly probable as the device’s software can be modified by the user. In this paper, we first analyze the impact of these rationally selfish behaviors on the performance of packet scheduling algorithms in time-slotted wireless networks. Using a mixed strategy game model, we show that the traditional maximum rate packet scheduling algorithm can cause non-cooperative devices to converge to highly inefficient Nash equilibria, in which the wireless channel resources are significantly wasted. By using a repeated game to enforce cooperation, we further propose a novel game theoretic algorithm that can lead to an efficient equilibrium.     

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。     

Slot allocation algorithms in centralized scheduling scheme for IEEE 802.16 based wireless mesh networks

In IEEE 802.16 based wireless mesh networks (WMNs), TDMA (Time Division Multiple Access) is employed as the channel access method and only TDD (Time Division Duplex) is supported and there are no clearly separate downlink and uplink subframes in the physical frame structure. As the uplink and downlink traffic has different characteristics in that the uplink traffic decentralizes in each MSS (Mesh Subscriber Station) and the downlink traffic centralizes in the MBS (Mesh Base Station), different scheduling methods should be taken in the uplink and downlink. This paper presents a uniform slot allocation algorithm which is suitable for both uplinks and downlinks. To achieve higher spatial reuse and greater throughput and to avoid switching frequently between receiving and transmitting within two adjacent time slots when a relay node forwards traffic, different link selection criteria are taken into account when allocating slots for uplinks and downlinks. A combined uplink and downlink slot allocation algorithm is proposed for further improving the spatial reuse and network throughput. The proposed algorithms are evaluated by extensive simulations and the results show that it has good performance in terms of spatial reuse and network throughput. To the best of the authors’ knowledge, this work is the first one that considers combined uplink and downlink slot allocation on the centralized scheduling scheme in IEEE 802.16 based WMNs.     

基于博弈资源分配的认知异构网络干扰协调算法

基于underlay频谱共享模式的认知异构网络可有效缓解频谱资源短缺问题,但同时会加剧网络中的干扰。针对该问题,提出了一种基于非合作博弈模型的动态频谱分配和功率控制算法进行干扰协调。首先,考虑频谱共享造成的干扰问题,引入认知用户优先等级,将问题构建为联合动态频谱分配与功率控制的频谱定价博弈模型;其次,通过两阶段动态博弈得到纳什均衡解,实现认知网络层频谱资源合理分配和发射功率控制。仿真表明,所提算法能够实现不同优先级用户频谱资源的合理分配和认知基站发射功率控制,有效抑制认知异构网络的跨层干扰和层内干扰。     

超密集网络中基于多基站博弈均衡的分布式无线资源管理算法

移动边缘计算和超密集网络技术在扩大移动设备计算能力和增加网络容量方面有明显的优势.然而,在两者融合的场景下,如何有效降低基站之间的同信道干扰,减少任务传输的时延和能耗是一个重要研究课题.本文设计了一个基于多基站博弈均衡的分布式无线资源管理算法.将小基站之间的无线资源管理问题转化为博弈问题,提出一种基于奖励驱动的策略选择算法.基站通过迭代不断更新其策略的选择概率,最终优化子信道分配和发射功率的调控.仿真结果表明,我们的算法在提高信道利用率和降低任务处理的时延和能耗方面具有优势.     

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.     

Utility-based downlink power allocation in multicell wireless packet networks

This paper introduces a utility-based radio resource management technique in multicell wireless packet networks. In terms of allocation of base station (BS) downlink transmit power and assignment of resource to users in each cell, we formulate a problem of maximizing system utility which is defined as the sum of cell utilities. The problem, however, is not solvable due to its non-convex property. Thus, we propose a heuristic algorithm based on an intuition obtained from analyzing a simple two-cell problem. Though the heuristic approach also incurs signaling overhead for power coordination between neighboring base stations, it is much less than that of the original approach. Simulation results show the performance of our proposed algorithm compared with two competitive schemes: optimal and maximum power allocation schemes. As expected, the optimal allocation scheme shows the best performance but can not be employed in a real network due to intractable complexity. Our heuristic algorithm performs reasonably well with very low complexity.