A high-reliability relay algorithm based on network coding in multi-hop wireless networks

In multi-hop wireless networks, minimizing the transmission time is very important. In this paper, a high-reliability relay algorithm (HRRA) is proposed to decrease the transmission time based on the network coding in multi-rate environment. The HRRA includes the relay selection algorithm (RSA) and the block transmission algorithm (BTA). Based on the relay reliability of node, RSA chooses the neighbor with the higher link rate as the common relay node and creates more network coding opportunities at the common relay node. Thus, the network coding opportunities and the high-rate links associated with common node could both be exploited in the transmissions of BTA. Moreover, a comprehensive theoretical analysis of the transmission time of HRRA in a block is presented. Lastly, the simulation results show that HRRA can significantly reduce the transmission time compared with the shortest path algorithm and heuristic relay node selection algorithm and COPE.

     

Modeling throughput gain of network coding in multi-channel multi-radio wireless ad hoc networks

In this paper, we model the network throughput gains of two types of wireless network coding (NC) schemes, including the conventional NC and the analog NC schemes, over the traditional non-NC transmission scheduling schemes in multihop, multi-channel, and multi-radio wireless ad hoc networks. In particular, we first show that the network throughput gains of the conventional NC and analog NC are (2n)/(2n-1) and n/(n-1), respectively, for the n-way relay networks where n ges 2. Second, we propose an analytical framework for deriving the network throughput gain of the wireless NC schemes over general wireless network topologies. By solving the problem of maximizing the network throughput subject to the fairness requirements under our proposed framework, we quantitatively analyze the network throughput gains of these two types of wireless NC schemes for a variety of wireless ad hoc network topologies with different routing strategies. Finally, we develop a heuristic joint link scheduling, channel assignment, and routing algorithm that aims at approaching the optimal solution to the optimization problem under our proposed framework.     

An ant colony optimization based routing algorithm for extending network lifetime in wireless sensor networks

Reducing the energy consumption of network nodes is one of the most important problems for routing in wireless sensor networks because of the battery limitation in each sensor. This paper presents a new ant colony optimization based routing algorithm that uses special parameters in its competency function for reducing energy consumption of network nodes. In this new proposed algorithm called life time aware routing algorithm for wireless sensor networks (LTAWSN), a new pheromone update operator was designed to integrate energy consumption and hops into routing choice. Finally, with the results of the multiple simulations we were able to show that LTAWSN, in comparison with the previous ant colony based routing algorithm, energy aware ant colony routing algorithms for the routing of wireless sensor networks, ant colony optimization-based location-aware routing algorithm for wireless sensor networks and traditional ant colony algorithm, increase the efficiency of the system, obtains more balanced transmission among the nodes and reduce the energy consumption of the routing and extends the network lifetime.     

Relay-based cooperative MAC protocol with rate adaptation

The existing wireless cooperative MAC protocols rarely consider the impact of channel condition and node energy consumption.To this issue,a new wireless cooperative MAC protocol was proposed,which used the random linear network coding,and introduced a mechanism of request relay frame to solve the hidden terminal problem.Specifically,the proposed method adaptively adjusted the node rate according to RSSI,and determined the relay node based on the requirements of cooperative transmission.The simulation results show that the network performance can be improved through deploying the proposed protocol.     

基于深度强化学习的协作通信中继选择

协作通信是无线传感器网络(Wireless Sensor Network,WSN)实现数据可靠传输的关键技术,而协作通信技术的关键在于中继方案的选择。为此,提出了一种基于深度强化学习的协作通信中继选择算法(Deep Q-Learning Based Relay Selection Scheme,DQ-RSS)。首先,将WSN中具有中继选择的协作通信过程建模为马尔科夫决策过程,并采用Q学习在未知网络模型的情况下获取最佳中继选择策略;其次,针对高维状态空间下Q学习收敛时间长的问题,采用DQN(Deep-Q-Net)算法来加速Q学习的收敛。对比仿真实验结果表明,DQ-RSS在中断概率、系统容量和能耗方面均优于现有的中继选择方案,且能够有效节省收敛时间。     

面向混合业务的无线传感器网络能量有效接入策略

研究了在实时业务和非实时业务同时存在的混合背景下,非实时业务的无线传感器节点自适应侦听和睡眠的动态接入机制。网络节点处于睡眠状态时所需的能量很低,节约了无线传感器网络节点的平均能量消耗;但是,过长的睡眠时间可能使得网络节点错失传输机会。因此,根据信道的使用情况,合理地设定无线传感器网络节点的睡眠时间,能够在网络能量消耗和传输效率之间进行调整,从而最大化无线传感器网络的能量传输效率。首先,利用连续时间 Markov 方法对问题进行建模,并利用基于摄动分析理论对系统模型进行分析,获得求解无线传感器网络能量效率最大化的最优睡眠时间梯度算法。最后通过理论结果和计算机仿真模拟的对比,验证了推荐方法的可行性。     

A fuzzy decision scheme for relay selection in cooperative wireless sensor network

In energy‐constrained military wireless sensor networks, minimizing the bit error rate (BER) with little compromise on network lifetime is one of the most challenging issues. This paper presents a new relay selection based on fuzzy logic (RSFL) scheme which provides balance between these parameters. The proposed scheme considers node's residual energy and path loss of the relay‐destination link as the input parameters for the selection of the relay node. The relay node selection by fuzzy logic is based on prioritizing higher residual energy and minimum path loss. To evaluate the performance on wireless sensor network, we compare the proposed scheme with the three existing relay selection strategies, ie, random, maximum residual energy based relay selection (MaxRes), and minimum energy consumption based relay selection (MinEnCon). The simulation results of the proposed scheme in terms of network lifetime, BER, Network Survivability Index (NSI), and average energy of network nodes have been presented and compared with different relay selection schemes. The simulation results show that the proposed RSFL scheme has the lowest BER, moderate network lifetime, average energy, and NSI.     

On the Minimization of Communication Energy Consumption of Correlated Sensor Nodes

Minimizing the sensor-node energy consumption is an important consideration when designing wireless sensor networks. In this paper, we focus on the energy consumption issues related to communication of data from correlated sensor nodes. An optimization algorithm is proposed for minimizing the overall energy consumption of the hardware and the physical link. We perform a detailed trade-off analysis of the circuit energy consumption, the transmission energy consumption, the transmission time, the modulation symbol size, and the channel coding rate, over a wide range of transmission distances and correlation values. Thus, a new optimized communication schedule with much lower energy consumption than our benchmark scheme of optimized uncorrelated uncoded transmission is obtained. Compared to this scheme, the total energy consumption may be reduced by more than 83.5% for a correlation value of 0.6 and a transmission distance of 100 m when using the results from the proposed optimization. This is significant with respect to increasing the lifetime of a wireless sensor network.     

Optimized mobile sink based grid coverage-aware sensor deployment and link quality based routing in wireless sensor networks

Mobile sink (MS) has been used in wireless sensor networks (WSN) to increase the network lifetime by changing the location over time. The major quality of service given by WSN is coverage energy consumption (EC) and network lifetime. There are many methods implemented for enhance the coverage hole restoration and reduce the EC. We propose a novel MSCOLER (MS based Coverage Optimization and Link-stability Estimation Routing) protocol for Optimal Coverage restoration and Link stability Estimation. An optimization algorithm is used to optimize the coverage hole and move the redundant node besides the hole. During the routing process, link quality based routing is used to discover the relay nodes with the estimation of link stability to enhance the entire network lifetime and practically make the perfect transmission distance for energy saving. Experimental results demonstrate that proposed protocol can solve the coverage restoration problem, decrease the EC and reduce the network lifetime. The performance is evaluated regarding Average of residual energy (ARE), Receiving packets ratio (RPR), Moving energy consumption (MEC), Network lifetime (NL), Percentage of coverage (%C) and Average Energy Consumption (AEC).     

Transmission scheduling in a multi‐channel wireless network with bidirectional relaying links

Using network coding in a wireless network can potentially improve the network throughput. On the other hand, it increases the complexity of resource allocations as the quality of one transmission is affected by the link conditions of the transmitter to multiple receivers. In this work, we study time slot scheduling and channel allocations jointly for a network with bidirectional relaying links, where the two end nodes of each link can exchange data through a relay node. Two scenarios are considered when the relay node forwards packets to the end nodes. In the first scenario, the relay node always forwards network‐coded packets to both end nodes simultaneously; in the second scenario, the relay node opportunistically uses network coding for two‐way relaying and traditional one‐way relaying. For each scenario, an optimization problem is first formulated for maximizing the total network throughput. The optimum scheduling is not causal because it requires future information of channel conditions. We then propose heuristic scheduling schemes. The slot‐based scheduling maximizes the total transmission rate of all the nodes at each time slot, and the node‐based scheduling schedules transmissions based on achievable transmission rates of individual nodes at different channels. The node‐based one has lower complexity than the slot‐based one. Our results indicate that although the node‐based scheduling achieves slightly lower throughput than the slot‐based one, both the proposed scheduling schemes are very effective in the sense that the difference between their throughput and the optimum scheduling is relatively small in different network settings. Copyright © 2015 John Wiley & Sons, Ltd.     

一种基于源端网络编码和交替传输的中继协作方案

针对源节点通过两个中继向目的节点发送数据的无线通信系统,为了减小传统中继协作方案的复用损失,提出了一种将源端网络编码和交替传输有效结合起来的新方案,称为交替源端网络编码(SSNC)。该方案在源端每三个时隙对发送数据进行一次网络编码,并且两个中继在相邻的时隙中交替的发送和接收数据,每个时隙中,一个中继接收源端数据的同时另一个中继转发上一个时隙其接收到的数据给目的端。通过对该方案的中断概率和分集复用折中性能的推导和分析,发现该方案相对于传统的重复编码和分布式空时码方案在获得相同分集阶数的情况下有更高的传输效率,在实际的通信系统中可以兼顾性能和效率。仿真结果证实了我们的结论。      

Multi relay node selection strategy for energy capture collaborative relay network

An energy capture cooperative relay network was studied.Unlike traditional cooperative relay networks,the relay nodes generally did not have a fixed energy supply but could carry out energy capture.For this network,a natural question was how to determine whether the relay nodes perform energy capture or data forwarding,and how to select the relay node to assist the information transmission between the source node and the destination node.Based on this problem,a multi-relay node selection scheme was proposed,which select the operation according to the energy of the current time slot of the relay node.In each time slot,the relay node that meet the battery threshold requirements was selected to assist in transmission.The Markov chain was used to model the charging and discharging process of the relay node battery,and the probability of interruption and throughput of the wireless network was obtained.And the value of the battery threshold when the throughput was maximized,that is,when the probability of network breakage was minimum was solved.Finally,the advantages of this scheme were verified by numerical experiments.     

复数域网络编码中最大似然解码算法的改进

针对复数域网络编码中继网络,提出一种改进的中继处的最大似然解码算法。当传统的最大似然解码算法使用在复数域网络编码中继网络中时,计算复杂度会随着信息星座图映射方式的改变而大大增加。为了降低计算复杂度,在前人研究的基础上提出一种改进的最大似然解码算法,该算法利用无线中继网络通信系统的非对称性,在解码时,先进行预判决,然后进行精确判决,这样可以大大降低计算复杂度,提高了系统性能。     

基于边缘云计算的光纤无线网络优化设计

为了提升网络边缘数据处理能力,满足终端大带宽和低时延的要求,构建了基于边缘基础设施的云计算平台,设计了具有动态带宽调整的光纤网络模型。提出了一种基于边缘云计算的时序优化算法,并将其应用于光纤无线网络。通过OPNET软件仿真分析了时序优化算法的传输时延均值,结果显示,优化后最大时延为43.1 ms,仅为传统方法的34.2%。实验对局域网内多个终端之间的数据通信进行分析,讨论了三种算法的传输能效、光纤信道利用率及传输能耗。实验结果显示,采用时序优化算法的测试结果具有明显改善,其传输能效提升了近1倍,边缘云数据传输时延均值信道利用率提升了约6.2%,网络传输能耗均值最优。该光纤无线网络模型及其优化算法在传输时延、信道利用率以及网络能耗方面具有明显提升。其在提升光纤通信链路选择及边缘端数据交互中具有一定的优势。     

基于机会式网络编码的高效广播传输算法

为了提高无线网络广播传输的效率,针对单跳无线网络提出了采用编码方法的广播传输算法。在传统的无线广播传输模型的基础上,分别实现了基于机会式网络编码的单组合分组广播传输算法和多组合分组广播传输算法。它们采用不同的策略选择多个丢失分组编码组合成重传分组,并通过从编码组合数据分组中恢复丢失分组的方式来提高广播传输的吞吐量。仿真结果表明,新算法在不同无线信道传输模型下相比已有的算法有效地降低了广播传输所需的传输带宽。     

D2D辅助的窄带物联网中能耗和传输成功率的最优折中

在设备到设备(D2D)通信辅助的窄带物联网(NB-IoT)中,为了尽可能提高传输成功率,D2D接收端需要预留较多的通信时隙(可以允许多次重传)。然而,这显著地增加了用户设备(UE)的能耗,特别是在信道条件较差或者相邻D2D链路干扰较严重的情况下。该文基于中继和能耗模型构造了一个传输成功率和能耗折中的优化问题,进而提出一个基于二分法的通信时隙最优配置算法。数值结果表明较多的预留时隙数量极大地增加了UE的能耗,但是不会显著提高传输成功率,与多中继传输、随机中继传输和100%成功传输等其他算法相比,该文提出的预留时隙最优配置算法获得了最小的能耗和几乎最大的传输成功率(只比100%成功传输方案低)。     

基于改进蚁群算法的高能效WSN协作传输策略*

针对传统传感器网络分簇不均匀,数据传输能耗相对较高的问题,提出了I-CoopACO(Cooperative transmission scheme based improved Ant Colony Optimal algorithm)算法.该算法在协作LEACH (Low Energy Adaptive Clustering Hierar-chy)的技术基础上,改进了成簇过程,使得分簇规模更加均匀;在稳定传输阶段,利用节点剩余能量和传输功耗构建启发因子,通过改进的蚁群算法搜索下一跳中继节点获得最优节点,使得传输功耗更低,能耗更均衡.仿真结果表明,在随机分布的感知网络中,I-CoopACO算法减少了传输能耗,均衡了网络负载,延长了网络工作寿命,比协作LEACH算法延长了64.93％的工作寿命.     

无线多址接入网络编码中继的信道分配算法

无线多址接入中继网络中,用户可选择是否接入中继,同时中继也可选择所服务的用户。在中继处应用网络编码技术可使单个中继同时服务于2个用户共享同一时频资源进行无干扰信息传输。基站采用联合检测方法恢复原始信息,从而得到传输速率的提升。针对多用户多中继场景,为了进一步提升系统的吞吐量,需要为用户选择合适的中继协助其传输,考虑到多址网络编码中继的中继选择问题是一个复杂的优化问题,为了降低其求解复杂度,分别采用基于贪婪准则和考虑用户公平性的信道分配算法进行求解。仿真结果表明,所提信道分配算法相比于随机信道分配可获得较大的性能增益,并且基于贪婪准则的算法性能优于考虑用户公平性的算法。     

基于可再生能量协作的雾无线接入网络资源分配

针对雾无线接入网络(Fog Radio Access Network,F-RAN)中能耗开销巨大的问题,提出了一种基于能量收集(Energy Harvesting,EH)约束的资源分配算法,从联合模式选择与功率分配两个方面进行了研究.首先建立传输模型和能量采集模型,根据功率约束和电费支出约束建立最优化问题;再使用分枝定界法对通信模式进行选择,利用吞吐量注水法对不同传输模式下的发射功率进行分配.仿真结果表明,提出的基于可再生能量协作的F-RAN的吞吐量和电网能量效率均高于传统F-RAN,具有经济和环境双重效益.     

On combining network coding with duty-cycling in flood-based wireless sensor networks

Network coding and duty-cycling are two major techniques for saving energy in wireless sensor networks. To the best of our knowledge, the idea to combine these two techniques for even more aggressive energy savings, has not been explored. This is not unusual, since these two techniques achieve energy efficiency through conflicting means, e.g., network coding saves energy by exploiting overhearing (i.e., nodes are awake), whereas duty-cycling saves energy by reducing idle listening (i.e., nodes sleep). In this article, we thoroughly investigate if network coding and duty cycling can be used together for more aggressive energy savings in flood-based wireless sensor networks.Our main idea is to exploit the redundancy sometimes present in flooding applications that use network coding, and put a node to sleep (i.e., duty cycle) when a redundant transmission takes place (i.e., the node has already received and successfully decoded a sequence of network-coded packets). We propose a scheme, called DutyCode, in which a multiple access control (MAC) protocol implements packet streaming and allows the network coding-aware application to decide when a node can sleep. We also present an algorithm for deciding the optimal coding scheme for a node to further reduce energy consumption by minimizing redundant packet transmissions. Finally, we propose an adaptive switching technique between DutyCode and an existing duty-cycling MAC protocol. We investigate our proposed solutions analytically and implement them on mote hardware. Our performance evaluation results, obtained from a 42-node indoor testbed, show that our scheme saves 30–46% more energy than network coding-based solutions.