共查询到20条相似文献,搜索用时 359 毫秒
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该文首次在多天线多信道802.11无线网状网中提出了时频信道的概念。时频信道是通过在时间和频率两个维度划分无线资源取得的。这种划分方法增加了信道数量,使信道划分更加精细,为提高系统的信道利用率做了准备。在时频信道的基础上,提出了准动态信道分配算法。该算法可以和现有的固定信道分配算法结合,实现准动态信道分配,根据链路上负载变化,取得最大的吞吐量。该算法先根据固定信道分配算法为各链路分配相同数量的时频信道,剩余部分当作公共信道。在通信过程中,各链路首先使用分配给自己的信道和空闲的公共信道。如果分配给一个链路的信道不够,且别的链路上的信道有空闲,该链路还可以暂时使用这些空闲信道。理论分析和仿真结果证明该算法可以有效提高系统的吞吐量。 相似文献
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信息年龄(AoI)是近年来针对时间敏感类应用所提出的一种描述数据交付及时性的度量标准,它是从网络中目标节点的角度出发,衡量其最新收到的数据包的新鲜程度。在信道资源受限的多信道无线网络场景中,基于信息年龄的链路调度问题需要考虑信道资源和链路冲突的约束。针对上述问题,该文提出一种逐时隙调度链路进行数据传输的调度方法,以最小化网络的平均信息年龄。该文首先将信息年龄的优化问题转化为李雅普诺夫优化问题,然后将冲突约束下的多信道分配问题转换为二分图匹配问题并采用Kuhn-Munkres(KM)算法进行求解,进而得到约束条件下的链路调度方法。仿真结果表明,所提方法有效地优化了网络中的平均信息年龄,提升了网络数据的新鲜度。 相似文献
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多信道无线 Mesh 网络可以有效解决在多跳无线网络中容量下降的问题。然而现有的路由协议大部分为单信道的多跳无线网络所设计,对于多信道 WMN 而言,会导致无效的路由路径。分析了现有无线 Mesh 网络的路由算法,详细讨论了基于 WCETT (Weighted Cumulative Expected Transmission Time)的两种路由度量,在此基础上提出了一种新的路由量度 WCETTR-LB,其对链路信道干扰的估算更加精确,能够感知周围链路对本信道的潜在干扰,并且考虑了节点负载度的概念,更加有助于实现负载均衡。 相似文献
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Interference has strong effect on the available bandwidth of wireless local area network (WLAN) based mesh networks. The channel
assignment problem for multi-radio multi-channel multihop WLAN mesh networks is complex NP-hard, and channel assignment, routing
and power control are tightly coupled. To mitigate the co-channel interference and improve capacity in multi-channel and multi-interface
WLAN mesh networks, a power-efficient spatial reusable channel assignment scheme is proposed, which considers both channel
diversity and spatial reusability to reduce co-channel interference by joint adjusting channel, transmission power and routing.
In order to assign channel appropriately, an efficient power control scheme and a simple heuristic algorithm is introduced
to achieve this objective, which adjust the channel and power level of each radio according to the current channel conditions
so as to increase the opportunity of channel spatial reusability. The proposed channel assignment scheme also takes load,
capacity and interference of links into consideration. Simulation results show the effectiveness of our approach and demonstrate
that the proposed scheme can get better performance than other approaches in terms of throughput, blocking ratio, energy consumption
and end-to-end delay. 相似文献
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To improve the capacity of wireless ad hoc networks by exploiting multiple available channels, we propose a distributed channel
assignment protocol that is based on a cross-layer approach. By combining channel assignment with routing protocols, the proposed
channel assignment protocol is shown to require fewer channels and exhibit lower communication, computation, and storage complexity
than existing channel assignment schemes. A multi-channel MAC (MC-MAC) protocol that works with the proposed channel assignment
protocol is also presented. We prove the correctness of the proposed channel assignment protocol. In addition, through a performance
study, we show that the proposed protocol can substantially increase throughput and reduce delay in wireless ad hoc networks,
compared to the IEEE 802.11 MAC protocol and an existing multi-channel scheme.
相似文献
Shiwen MaoEmail: |
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Ji-Hoon Yun 《Wireless Personal Communications》2013,68(3):671-678
This paper quantitatively investigates the relationship between physical transmission rate and network capacity in multi-radio multi-channel wireless mesh networks by using mixed-integer linear programming to formulate the joint channel assignment and routing problem. The numerical results show that the rate lower than the highest available one can improve the network capacity due to increased connectivity. It is also shown that the lower transmission rate is able to utilize abundant channels more effectively due to the higher degree of freedom in channel assignment. Finally, it is shown that joint rate, channel assignment and routing improves the network capacity further. 相似文献
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Yan JinAuthor Vitae Weiping WangAuthor VitaeYingtao JiangAuthor Vitae Mei YangAuthor Vitae 《Ad hoc Networks》2012,10(3):401-420
Use of multiple orthogonal channels can significantly improve network throughput of multi-hop wireless mesh networks (WMNs). In these WMNs where multiple channels are available, channel assignment is done either in a centralized manner, which unfortunately shows a poor scalability with respect to the increase of network size, or in a distributed manner, where at least one channel has to be dedicated for exchanging necessary control messages or time synchronization has to be utilized for managing the duration of data packet transmission, causing excessive system overhead and waste of bandwidth resource. In this paper, we first formulate multi-channel assignment as a NP-hard optimization problem. Then a distributed, heuristic temporal-spatial multi-channel assignment and routing scheme is proposed, assuming every wireless node in the network is equipped with a single-radio interface. Here the gateway node is set to use all the channels sequentially in a round-robin fashion. This temporal scheme ensures all the nodes that need to directly communicate with the gateway node shall have a fair access to it. For those non-gateway nodes, a spatial scheme where channels are assigned based on their neighbors’ channel usage is adopted to exploit parallel communications and avoid channel interference among nodes. Furthermore, since the routing factors, including channel usage of neighbor nodes, node hop count, node memory size, and node communication history, are all considered along with the channel assignment, network performance, measured by packet delivery latency, channel usage ratio, and memory usage ratio, tends to be considerably enhanced. The simulation results have confirmed that, compared with a couple of well-known multi-channel assignment schemes, such as LCM [21] and ROMA [15], the proposed scheme shows substantial improvement in network throughput with a very modest collision level. In addition, the proposed scheme is highly scalable as the algorithm complexity is only linearly dependent on the total number of channels that are available in the network and the number of neighbors that a network node directly connects to. 相似文献
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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。 相似文献
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Currently most wireless sensor network applications assume the presence of single-channel medium access control (MAC) protocols. However, lower sensing range result in dense networks, single-channel MAC protocols may be inadequate due to higher demand for the limited bandwidth. In this paper we proposed a method of multi-channel support for DMAC in Wireless sensor networks (WSNs). The channel assignment method is based on local information of nodes. Our multi-channel DMAC protocol implement channel distribution before message collecting from source nodes to sink node and made broadcasting possible in DMAC. Analysis and simulation result displays this multi-channel protocol obviously decreases the latency without increasing energy consumption. 相似文献
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A non-cooperative game-theoretic approach to channel assignment in multi-channel multi-radio wireless networks 总被引:1,自引:0,他引:1
Rohith Dwarakanath Vallam Arun A. Kanagasabapathy C. Siva Ram Murthy 《Wireless Networks》2011,17(2):411-435
Channel assignment in multi-channel multi-radio wireless networks poses a significant challenge due to scarcity of number
of channels available in the wireless spectrum. Further, additional care has to be taken to consider the interference characteristics
of the nodes in the network especially when nodes are in different collision domains. This work views the problem of channel
assignment in multi-channel multi-radio networks with multiple collision domains as a non-cooperative game where the objective
of the players is to maximize their individual utility by minimizing its interference. Necessary and sufficient conditions
are derived for the channel assignment to be a Nash Equilibrium (NE) and efficiency of the NE is analyzed by deriving the
lower bound of the price of anarchy of this game. A new fairness measure in multiple collision domain context is proposed
and necessary and sufficient conditions for NE outcomes to be fair are derived. The equilibrium conditions are then applied
to solve the channel assignment problem by proposing three algorithms, based on perfect/imperfect information, which rely
on explicit communication between the players for arriving at an NE. A no-regret learning algorithm known as Freund and Schapire
Informed algorithm, which has an additional advantage of low overhead in terms of information exchange, is proposed and its
convergence to the stabilizing outcomes is studied. New performance metrics are proposed and extensive simulations are done
using Matlab to obtain a thorough understanding of the performance of these algorithms on various topologies with respect
to these metrics. It was observed that the algorithms proposed were able to achieve good convergence to NE resulting in efficient
channel assignment strategies. 相似文献
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现有的协作路由算法没有考虑多射频无线mesh网中的信道分配问题.为了给多并发业务流提供更优质的网络服务,本文结合多射频多信道技术和协作通信技术来降低同信道干扰并获得协作分集增益.基于协作通信模块虚拟化的方法,本文将联合协作路由和信道分配问题简化为联合直接路由和信道分配问题,将其建模为一个混合整数线性规划问题,并证明该问题为NP-hard问题.为了解决该问题,提出了一种宽松的联合协作路由选择和信道分配算法(Loose Joint Cooperative Routing and Channel Assignment algorithm,L-JCRCA).仿真实验结果表明,L-JCRCA可以有效提升网络整体吞吐量. 相似文献
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Using multiple channels in wireless networks improves spatial reuse and reduces collision probability and thus enhances network throughput. Designing a multi-channel MAC protocol is challenging because multi-channel-specific issues such as channel assignment, the multi-channel hidden terminal problem, and the missing receiver problem, must be solved. Most existing multi-channel MAC protocols suffer from either higher hardware cost or poor throughput. Some channel hopping multi-channel protocols achieve pretty good performance in certain situations but fail to adjust their channel hopping mechanisms according to varied traffic loads. In this paper, we propose a load-aware channel hopping MAC protocol (LACH) that solves all the multi-channel-specific problems mentioned above.LACH enables nodes to dynamically adjust their schedules based on their traffic loads. In addition to load awareness, LACH has several other attractive features: (1) Each node is equipped with a single half-duplex transceiver. (2) Each node’s initial hopping sequence is generated by its ID. Knowing the neighbor nodes’ IDs, a node can calculate its neighbors’ initial channel hopping sequences without control packet exchanges. (3) Nodes can be evenly distributed among available channels. Through performance analysis, simulations, and real system implementation, we verify that LACH is a promising protocol suitable for a network with time-varied traffic loads. 相似文献