基于补偿式CSI的分布式跨层联合资源分配算法

为消除过时信道状态信息(CSI)对分布式无线多跳网络环境下跨层资源分配效率的影响,提高跨层联合资源分配的准确性,基于信道相关性提出了一种补偿式跨层联合资源分配算法。利用瞬时和过时信道状态信息之间的条件概率密度函数,基于瑞利衰落信道模型求得信噪比(SINR) 模型下条件容量的闭式解。为补偿部分网络性能的损失,提出了一种考虑过时信道状态信息的联合拥塞控制、信道分配和功率控制的算法,在此过程中网络被建模成一个NUM 问题,可变的链路数据率和功率等资源限制作为约束条件。运用拉格朗日对偶分解技术,NUM问题被分布式求解。实验对比分析表明：在确保较低复杂度的前提下,该算法有效改善了分布式多跳网络资源分配的合理性,使其网络总体效用得到提升,降低了能耗。     

联合速率控制与功率分配的多信道无线网络跨层优化

本文基于凸优化方法,以提升网络效用与降低网络总功耗为目标,针对多无线多信道(Multi-radio Multi-channel)的多跳无线网络提出了一种联合速率控制与功率分配的跨层优化模型,并利用对偶分解方法设计了优化模型对应的分布式算法,证明了该分布式算法收敛性.该算法通过改变本征权的取值能够在网络效用与网络功耗之间取得折衷,并能根据速率要求动态调整各条链路的注入速率与发射功率使得网络达到效用与功耗的联合最优.通过仿真实验验证了该分布式算法可有效的调节网络效用与总功耗之间的平衡.     

无线多跳网络快速跨层资源优化分配算法

针对背压路由算法容易造成大量队列积压和收敛速度慢的缺陷,该文研究了无线多跳网络中节点功率受限情况下的联合拥塞控制、路由和功率分配的跨层优化问题。以最大化网络效用为目标,以流平衡条件、功率等为约束条件建模,基于牛顿法提出了一种具有超线性收敛性能的算法,并运用矩阵分裂技术使该算法能够分布式实施。仿真结果表明,该算法在实现网络效用最大化的同时,能够有效提高网络中的能量效用,且能将网络中的队列长度稳定在一个较低水平,降低包传输延时。     

无线mesh网络中基于效用最优的联合信道分配和功率分配算法

该文针对多信道无线mesh网络,采用基于效用最优的定价机制,提出了一种功率-干扰价格模型,并基于该模型提出了一种分布式联合信道分配和功率分配算法。每个节点根据自己所消耗功率状况合理地定功率价格,并根据自己所受干扰状况合理地定干扰价格。通过功率价格和干扰价格来调节链路的信道分配和功率分配,使网络效用最大化。仿真结果表明:所提出的算法能够快速、平稳地收敛到近似最优解。同时还仿真了网络可用信道数目、节点射频数目和功率对系统性能的影响,可以为网络配置提供参考。     

Ad Hoc网络基于簇的多信道MAC协议研究

介绍了一种适用于Ad Hoc网络的基于簇的多信道媒体接入控制协议。在该协议中,整个网络被划分成使用不同频道的若干个簇,每个节点配置有3个独立的无线收发信机,由簇首节点负责簇的维持功能,由簇首和簇成员节点通过共同执行信道重配置算法来完成信道分配工作。仿真结果表明,该协议可以很好地适应网络拓扑结构的频繁变化,在充分利用多信道优势工作的同时,解决了普遍存在于多跳无线移动网络中的隐藏终端和暴露终端问题。     

认知无线多跳网中结合QoS查找的跨层多信道MAC协议

针对认知无线多跳网中频谱资源具有较大时变性及差异性的问题,设计了一种结合QoS查找的跨层多信道MAC协议。该协议将按需QoS查找与动态频谱分配跨层相结合,仅让参与传输的节点执行频谱分配并按QoS要求获取频谱资源。此外,协议使用频分双工收发机实现了对公共控制信道的不间断监听,并设计了一套支持不同数量收发机节点间混合通信的接入算法。大量仿真结果表明,该协议能有效保证对端到端传输的QoS要求的满足,并显著提高端到端吞吐量及时延。     

基于贪心算法的无线mesh时空域多信道分配研究

无线mesh网络多接口多信道分配算法中,信道分配与接口数目之间存在相互制约、相互依赖、“涟漪效应”,导致链路无效以及承载网络拓扑的主要业务节点存在时序关系,本文在基于多信道空间和时间联合信道分配算法的基础之上,考虑前一个子时序已分配信道对下一个子时序信道分配的影响,提出了基于贪心算法的无线mesh时空域多信道分配算法.根据贪心算法原理,尽量不改变已分配信道,减少信道切换时间,将剩余的未分配信道分配给要分配的接口,使信道能并行工作以提高整个网络的吞吐量.通过实验仿真,对比了能够抑制“涟漪效应”和链路无效的静态多接口多信道分配算法、空间与时间相结合的多接口多信道分配算法.结果表明,整个mesh网络的吞吐量有明显提高,且随着网络中业务节点变化的减小而增大,随着可利用信道数目的增加而增加.     

无线Mesh网络一种以节点为单位的多信道分配

在无线Mesh网络中,利用无线多信道路由协议可以提高网络的性能,因此信道资源的分配与管理对于无线Mesh网的性能优化起着十分重要的作用。本文介绍了一种以节点为单位进行信道分配的算法。     

无线Mesh网络一种以节点为单位的多信道分配

在无线Mesh网络中,利用无线多信道路由协议可以提高网络的性能,因此信道资源的分配与管理对于无线Mesh网的性能优化起着十分重要的作用.本文介绍了一种以节点为单位进行信道分配的算法.     

无线Mesh网络关键技术

无线Mesh网络(WMN)是一种特殊的Adhoc网络,具有分层的网络结构,其传输骨干网具有多跳、拓扑稳定、无供电约束、业务流量相对汇聚等特性。提高WMN频谱空间复用度是增加网络容量有效的方法,而其设计的关键是有效控制无线链路间的干扰范围。基于多信道的组网技术是WMN关键技术之一,其核心是信道的分配,通过合理的信道分配以获得最大信道利用率。WMN中路由度量的选取需要考虑多跳无线链路间的相互干扰,而通过采用负载均衡路由技术可以均衡网络资源的使用,从而提高网络容量和节点的吞吐率。     

E-BEB: Enhanced Binary Exponential Backoff Algorithm for Multi-hop Wireless Ad-hoc Networks

Binary exponential backoff algorithm is the de-facto medium access control protocol for wireless local area networks, and it has been employed as the standard contention resolution algorithm in multi-hop wireless ad-hoc networks. However, this algorithm does not function well in multi-hop wireless environments due to its several performance issues and technical limitations. In this paper, we propose a simple, efficient, priority provision, and well performed contention resolution algorithm called enhanced binary exponential backoff (E-BEB) algorithm for impartial channel access in multi-hop wireless ad-hoc networks. We also provide a simple and accurate analytical model to study the system saturation throughput of the proposed scheme. Simulations are conducted to evaluate the performance of E-BEB algorithm. The results show that the E-BEB algorithm can alleviate the fairness problem and support multimedia transmission in multi-hop wireless environments.     

Environment-Driven Opportunity Forwarding Cross-Layer Optimization for Ubiquitous Wireless Networks

In this paper, an environment-driven cross-layer optimization scheme is proposed to maximize packet forwarding efficiency. The proposed algorithm is aimed to improve the performance of location-based routing protocol in respect of greedy forwarding and avoid void regions for ubiquitous wireless networks. In greedy forwarding mode, we use a new routing metric IAPS which can estimate the forwarding distance, link quality and the difficulty of channel access during the process of the next hop node selection. When the packet forwarding comes into a local minimum, the proposed scheme uses an opportunistic forwarding method based on competitive advantage to bypass the void regions. NS2 simulation results indicate that the proposed algorithm can improve network resource utilization and the average throughput, and reduce congestion loss rate of wireless multi-hop network comparison with existing GPSR algorithm.     

Deep and robust resource allocation for random access network based with imperfect CSI

A deep and robust resource allocation framework was proposed for the random access based wireless networks,where both the communication channel state information (C-CSI) and the interference channel state information (I-CSI) were uncertain.The proposed resource allocation framework considered the optimization objective of wireless networks as a learning problem and employs deep neural network (DNN) to approximate optimal resource allocation policy through unsupervised manner.By modeling the uncertainties of CSI as ellipsoid sets,two concatenated DNN units were proposed,where the first was uncertain CSI processing unit and the second was the power control unit.Then,an alternating iterative training algorithm was developed to jointly train the two concatenated DNN units.Finally,the simulations verify the effectiveness of the proposed robust leaning approach over the nonrobust one.     

Distributed network embedded FEC for real-time multicast applications in multi-hop wireless networks

Multi-hop wireless networks are becoming popular because of their flexibility and low deployment cost. Emerging technologies such as orthogonal frequency division and multiple in and multiple out have significantly increased the bandwidth of a wireless channel. Further, as device cost decreases, a communication terminal can have multiple radios and transmit/receive data simultaneously, which improves the capacity of a wireless network. This makes the support of real-time multicast applications over multi-hop wireless networks viable and practical. Meanwhile, wireless links are prone to random and burst losses due to multipath fading and cross channel interference, real-time multicast over a wireless network remains a challenging problem. Traditional end-to-end FEC is less efficient in multi-hop wireless networks, as packets may suffer from random or burst losses in more than one hop before they arrive at their destination. In this paper, we advocate the deployment of distributed network-embedded FEC (DNEF) for real-time multicast distribution over multi-hop wireless networks. We first develop a packet loss model of multi-hop wireless networks using a system analysis approach. We then propose a distributed codec placement algorithm and evaluate its performance. Our simulation shows that multicast using DNEF significantly outperforms both traditional multicast and application-level peer-to-peer multicast that can be deployed over multi-hop wireless networks.     

认知无线多跳网中保证信干噪比的频谱分配算法

为解决无线多跳网络在固定频谱分配方式下所固有的信道冲突等问题,利用认知无线电的动态频谱分配技术,提出了一种适用于次用户组成的无线多跳网络的、underlay方式下的全分布式频谱分配算法。该算法将频谱分配问题建模成静态非合作博弈,证明了纳什均衡点的存在,并给出了一种求解纳什均衡点的迭代算法。大量仿真实验证明,该算法能实现信道与功率的联合分配,在满足主用户干扰功率限制的同时,保证次用户接收信干噪比要求。     

无线多跳Ad hoc网络中MAC机制的公平性与网络容量利用率

高效、公平的MAC协议是目前无线多跳Ad hoc网络研究的关键问题之一.该文在给出一种新的无线多跳Ad hoc网络的网络模型前提下,定义了MAC协议公平性、网络容量利用率两个性能参数.给出了一种能在竞争节点间公平共享无线信道并充分利用网络容量的MAC协议(FMAC),仿真比较了FMAC和IEEE 802.11 DCF的公平性和网络容量利用率.结果表明FMAC能在充分利用网络容量的前提下,实现无线信道在竞争节点间的公平共享.     

无线多跳网络的自适应容量感知优化与控制技术

In wireless multimedia communications, it is extremely difficult to derive general end-to-end capacity results because of decentralized packet scheduling and the interference between communi-cating nodes. In this paper, we present a state-based channel capacity perception scheme to provide sta-tistical Quality-of-Service (QoS) guarantees under a medium or high traffic load for IEEE 802.11 wire-less multi-hop networks. The proposed scheme first perceives the state of the wireless link from the MAC retransmission information and extends this information to calculate the wireless channel capaci-ty, particularly under a saturated traffic load, on the basis of the interference among flows and the link state in the wireless multi-hop networks. Finally, the adaptive optimal control algorithm allocates a net-work resource and forwards the data packet by tak-ing into consideration the channel capacity deploy-ments in multi-terminal or multi-hop mesh net-works. Extensive computer simulations demonstrate that the proposed scheme can achieve better per-formance in terms of packet delivery ratio and net-work throughput compared to the existing capacity prediction schemes.     

Efficient delay based scheduling with fairness in multi-hop wireless mesh networks

Some scheduling algorithms have been designed to improve the performance of multi-hop wireless mesh networks (WMNs) recently. However the end-to-end delay is seldom considered as the complexity of multi-hop topology and open wireless shared channel. This article proposes an efficient delay based scheduling algorithm with the concept of buffer-data- hops. Considering the demand satisfaction factor (DSF), the proposed algorithm can also achieve a good fairness performance. Moreover, with the interference-based network model, the scheduling algorithm can maximize the spatial reuse, compared to those graph-based scheduling algorithms. Detailed theoretical analysis shows that the algorithm can minimize the end-to-end delay and make a fair scheduling to all the links.     

Blocking probability and channel assignment in wireless networks

We consider a multi-hop wireless network with a connection-oriented traffic model and multiple transmission channels that can be spatially re-used. In such a network the blocking probability of a call that makes a channel request depends on (a) the channel assignment scheme and (b) the transmission radius of the nodes which affects the network link structure. In this work, we study these two aspects for simple wireless networks. Specifically, we develop blocking probability analysis for a wireless line and grid network and explore the tradeoff between transmission radius and blocking probability for multi-hop calls. We show that for a line network a larger transmission radius can substantially reduce the blocking probability of calls, while for a grid network with a more dense node topology using a smaller transmission radius is better. We then, investigate various channel assignment schemes and present a novel non-rearranging channel assignment algorithm for multi-hop calls in a general network. Our algorithm efficiently incorporates spatial channel re-use and significantly reduces call blocking probability when compared to other algorithms.