Research on energy-efficient physical-layer secure transmission mechanism in decode-and-forward cooperative networks

The maximization problem of secure energy efficiency (EE) in decode-and-forward relay networks was investigated considering the power and energy constraints in physical-layer secure transmission.An iterative algorithm for power allocation was proposed based on fractional programming and DC (difference of convex functions) programming.This algorithm jointly allocated power for source and relay nodes to achieve energy-efficient secure transmission,subject to the peak power constraint of each node and the minimum secrecy rate requirement of the system.Simulation results demonstrate that the propose algorithm can improve the secure EE significantly compared with the conventional secrecy rate maximization strategy.     

Systematic energy-balanced cooperative transmission scheme in wireless sensor networks

Energy efficiency is a critical issue in wireless sensor networks(WSNs).In order to minimize energy consumption and balance energy dissipation throughout the whole network,a systematic energy-balanced cooperative transmission scheme in WSNs is proposed in this paper.This scheme studies energy efficiency in systematic view.For three main steps,namely nodes clustering,data aggregation and cooperative transmission,corresponding measures are put forward to save energy.These measures are well designed and tightly coupled to achieve optimal performance.A half-controlled dynamic clustering method is proposed to avoid concentrated distribution of cluster heads caused by selecting cluster heads randomly and to get high spatial correlation between cluster nodes.Based on clusters built,data aggregation,with the adoption of dynamic data compression,is performed by cluster heads to get better use of data correlation.Cooperative multiple input multiple output(CMIMO) with an energy-balanced cooperative cluster heads selection method is proposed to transmit data to sink node.System model of this scheme is also given in this paper.And simulation results show that,compared with other traditional schemes,the proposed scheme can efficiently distribute the energy dissipation evenly throughout the network and achieve higher energy efficiency,which leads to longer network lifetime span.By adopting orthogonal space time block code(STBC),the optimal number of the cooperative transmission nodes varying with the percentage of cluster heads is also concluded,which can help to improve energy efficiency by choosing the optimal number of cooperative nodes and making the most use of CMIMO.     

A distributed cooperative relaying optimization scheme for secondary transmission in Cognitive Radio networks

In Cognitive Radio (CR) networks, cooperative communication has been recently regarded as a key technology for improving the spectral utilization efficiency and ensuring the Quality of Service (QoS) for Primary Users (PUs). In this paper, we propose a distributed joint relay selection and power allocation scheme for cooperative secondary transmission, taking both Instantaneous Channel State Information (I-CSI) and residual energy into consideration, where secondary source and destination may have different available spectrum. Specifically, we formulate the cognitive relay network as a restless bandit system, where the channel and energy state transition is characterized by the finite-state Markov chain. The proposed policy has indexability property that dramatically reduces the compu-tation and implementation complexity. Analytical and simulation results demonstrate that our pro-posed scheme can efficiently enhance overall system reward, while guaranteeing a good tradeoff between achievable date rate and average network lifetime.     

单兵电台网路MAC层节能方案设计

单兵电台作为战术互联网的末端通信设备,对续航能力有很高的要求。主要从减少通信模块的空闲侦听时间着手,设计了一种MAC层按需休眠与唤醒方案,并对方案进行了仿真。仿真结果表明,在全连通网络和三跳网络环境下,随着业务发送时间间隔的增大,网络在有休眠策略下所需的平均能耗比无休眠策略下的平均能耗明显降低,验证了方案的可行性。     

An energy-efficient optimization deployment scheme for wireless sensor networks

Most of the current deployment schemes for Wireless Sensor Networks (WSNs) do not take the network coverage and connectivity features into account, as well as the energy consumption. This paper introduces topology control into the optimization deployment scheme, establishes the mathematical model with the minimum sum of the sensing radius of each sensors, and uses the genetic algorithm to solve the model to get the optimal coverage solution. In the optimal coverage deployment, the communication and channel allocation are further studied. Then the energy consumption model of the coverage scheme is built to analyze the performance of the scheme. Finally, the scheme is simulated through the network simulator NS-2. The results show the scheme can not only save 36% energy averagely, but also achieve 99.8% coverage rate under the condition of 45 sensors being deployed after 80 iterations. Besides, the scheme can reduce the five times interference among channels.     

An incentive energy-efficient routing for data gathering in wireless cooperative networks

Because of energy-constraint, it is an attractive problem to select energy-efficient paths from source nodes to sink for data gathering in wireless ad hoc networks. Cooperative communication is a promising mechanism to reduce transmit energy in such kind of case. One of the fundamental assumptions for cooperative communication is that each node should be unselfish, responsible, and willing to forwarding data he has received. However, in energy-constrained environment, because of limited energy, each node hates participating in data transmission without any incentive and tries to avoid forwarding data (this behavior is selfish). In this paper, a utility function is proposed to stimulate nodes to behave unselfishly. We prove that it is a Nash Equilibrium when nodes work in an unselfish manner. Also, we show that the selection of forwarding nodes and relay nodes for data transmission is a NP-hard problem even when nodes behave unselfishly. A heuristic algorithm (Algorithm for Node Selection Problem, ANSP) is provided to solve this selection problem. We also prove the convergence of this algorithm. The analysis shows that this algorithm can reach the approximate performance ratio of 2?(1+α), where α is the maximal ratio of two power consumptions on two adjacent links in the network. The numerical results show that in a 100 node network, if nodes behave unselfishly, they will obtain a better utility, and more energy will be saved. The average saved energy when each node takes a selfish behavior, is 52.5% less than the average when nodes behave in an unselfish manner.     

WSN中基于乱序多项式对偶密钥的攻击方案

针对Guo等的WSN中基于乱序对称多项式的对偶密钥方案提出一种攻击方案。通过构造黑盒的方式,对多项式进行攻击,通过整体求解多项式集合,而不是求解单个多项式的方式,使多项式的排列顺序在多项式的破解中失去作用,从而实现乱序多项式的破解。定理证明和实例分析表明Guo等的方案不能抵御大规模节点俘获攻击,未能突破多项式的容忍门限,是一种不安全的方案。     

Efficient multihop transmission scheme for error‐free relay forwarding in cooperative networks

Multihop cooperative communication is emerging as a key concept to extend the coverage area of the network and potentially increase the capacity. The spectral efficiency of such networks can be improved by adapting the transmission to time‐varying channel conditions, referred to as incremental relaying. Although such incremental relaying concepts are progressively being studied, many challenges, such as erroneous transmissions by intermediate nodes and end‐to‐end delay of the network, limit its practical use due to lack of an efficient implementation. This paper proposes an efficient multihop incremental relaying technique. In this method, erroneous relay forwarding is mitigated, and the overhead for coordination among nodes is reduced by exploiting the implicit feedback channel available due to the broadcast nature of wireless transmissions. The proposed scheme fully leverages the benefit of overhearing and eliminates the additional feedback slots required for validation. Further, it ensures reliable forwarding of information, which optimizes the throughput of multihop networks. Thorough analysis of the proposed scheme is performed under different deployment environments, and the theoretical analyses presented in this paper are supported with results from extensive simulation studies. Copyright © 2013 John Wiley & Sons, Ltd.     

Optimal multi-threshold quantization scheme for bioinformatics inspired cooperative spectrum sensing in cognitive radio networks

Hard decision combination provides bandwidth efficiency but the results produced are unreliable while soft decision combination has better results but at the expense of much consumption of bandwidth. An acceptable trade-off is achieved between the two in case of quantized decision combination. In this paper an optimal quantization scheme is proposed in which the local sensing information is quantized so the maximum detection probability is met while the false alarm probability remains under a certain constraint. The proposed optimal scheme works on the basis of energy detection and the local quantization thresholds are found through iterative search. Smith–Waterman algorithm (SWA) is used to compare the local sensing reports of the CR users and similarity indexes are found for the CR users. The local sensing decisions of the CR users below a certain calculated threshold are rejected and are not included in the final decision combination at the FC. For detailed analysis, SWA-based rules of decision combination with optimal quantization thresholds are compared with a scheme that employs SWA-based rules of decision combination with heuristically selected quantization thresholds and a conventional majority combination scheme. Simulation results show that the proposed scheme performs better than the other two schemes.     

无线协作网络中的最优中继选择方案及中断概率分析

从物理层安全的角度出发,在含有协作中继的通信网络中,通过选择最优中继来传递信息可有效提升系统性能。讨论了在含有多个单天线窃听用户的多中继通信系统中对最优中继的选择方案,并对系统采用放大转发（amplify-and-forward,AF）协议和解码转发（decode-and-forward,DF）协议这两种不同的情况分别进行了讨论和比较,同时还对比了不含中继的直接传输情况。理论分析和仿真结果表明,最优中继选择方案可有效保障系统的安全性能。     

ECCE: Enhanced cooperative channel establishment for secure pair-wise communication in wireless sensor networks

This paper presents the ECCE protocol, a new distributed, probabilistic, cooperative protocol to establish a secure pair-wise communication channel between any pair of sensors in a wireless sensor network (WSN). The main contributions of the ECCE protocol are: to allow the set-up of a secure channel between two sensors (principals) that do not share any pre-deployed key. This feature is obtained involving a set of sensors (cooperators) in the channel establishment protocol; to provide probabilistic authentication of the principals as well as the cooperators. In particular, the probability for the attacker to break authentication check decreases exponentially with the number of cooperators involved; to trade off the memory space required to store the pre-deployed encryption keys with the number of cooperators involved in the protocol. Hence, memory storage can be used to store keys built with the ECCE protocol, which helps amortizing the (limited) overhead incurred in the ECCE key set-up; to be adaptive to the level of threat the WSN is subject to. We provide analytical analysis and extensive simulations of ECCE, which show that the proposed solution increases both the probability of a secure channel set-up and the probability of channel resilience with respect to other protocols.     

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.     

面向认知无线电网络能量高效协作感知的在线节点选择算法

面向认知无线电网络中能量高效协作感知任务需求,提出了面向单次协作感知过程的能量最小化节点选择问题EMNS和面向在线协作感知的能量高效节点选择问题OENS。证明了两问题均为NP-hard难题。针对EMNS问题,提出采用分枝定界算法BAB求最优解和贪婪节点选择算法GS求近似解。针对OENS问题,提出为每个节点引入考虑能量消耗负载均衡的动态权重系数,基于BAB和GS算法设计了启发式的在线节点选择算法OBAB、OGS1。仿真实验结果表明,提出的算法可显著增加网络完成的协作感知过程次数,可有效延长网络"生存期"。     

基于按对平衡设计的异构无线传感器网络密钥预分配方案

利用异构无线传感器网络中普通节点和簇头节点间的差异性,基于中心可分解型按对平衡设计构造了异构的节点密钥环,设计了2种密钥预分配方案DCPBD和VDCPBD.其中,DCPBD利用了中心可分解类型PBD,将普通区组作为普通节点的密钥环,将特殊区组作为簇头节点的密钥环.VDCPBD基于DCPBD进行了扩展,将单一核密钥替换为基于另一密钥池进行SBIBD设计出的簇间密钥环,减小了DCPBD由于单个簇头节点被俘后对整个网络抗毁性的影响.由于在设计时考虑了节点的异构特性,使用确定性方法构造了异构密钥环,使得在保持密钥连通率不变的前提下获得了更低的空间复杂度.仿真实验表明,2个方案都支持大规模网络,且单跳密钥连通率随网络规模增大而趋近于1,2跳连通率恒为1.VDCPBD还具备了更强的抗节点捕获能力和更好的网络可扩展性.     

On the cooperative MIMO communication for energy-efficient cluster-to-cluster transmission at wireless sensor network

Energy-efficient data transmission is one of the key factors for energy-efficient wireless sensor networks (WSN). Cooperative multiple input multiple output (MIMO) explores the wireless communication schemes between multiple sensors emphasizing the MIMO structure. In this paper, an energy-efficient cooperative technique is proposed for a WSN where selected numbers of sensors at the transmitting end are used to form a MIMO structure wirelessly connected with a selected number of sensors at the receiving end. The selection of nodes in the transmitting end is based on a selection function, which is a combination of channel condition, residual energy, inter-sensor distance in a cluster, and geographical location, whereas the selection in the receiving side is performed on the basis of channel condition. Data are sent by the sensors in a cluster to a data-gathering node (DGN) using a multihop transmission. We are concentrating our design on the intermediate hop, where sensors in a cluster transmit their data to the sensors in another cluster with MIMO communication. Energy models are evaluated for both correlated and uncorrelated scenarios. The delay model of the proposed cooperative MIMO is also derived. Experimental results show that the selected MIMO structure outperforms the unselected MIMO in terms of total energy consumption. They also show energy-efficient performance by around 20% over unselected MIMO when they are compared with single-input-single-output structure. Also, the proposed approach takes around 50 more rounds than the geographically selected approach before dying at distance d?>?20 m.     

Dynamic frame partitioning scheme for IEEE 802.16 mesh networks

The IEEE 802.16 mesh network is a promising next generation wireless backbone network. In the network, the allocation of minislots is handled by centralized scheduling and distributed scheduling, which are independently exercised. However, the standard does not specify how the frame can be partitioned among its centralized and distributed schedulers. Through efficient partitioning that dynamically adapts the partitioning based on demand, network can support more user applications. Although a dynamic frame partitioning scheme to use Markov model has been studied, the dynamic frame partitioning method has not been fully investigated. This paper proposes two novel and general dynamic frame partitioning scheme for IEEE 802.16 mesh networks so that the minislot allocation can be more flexible and the utilization is increased. The two schemes respectively use GM(1,1)‐Markov model and Grey–Verhulst–Markov model to predict efficient partitions for future frames according to the minislot utilization in current frames. Our study indicates that the two proposed schemes outperform the scheme of using Markov model. Copyright © 2012 John Wiley & Sons, Ltd.     

A robust security scheme for wireless mesh enterprise networks

In this paper, we address the security challenges for wireless mesh enterprise networks (WMENs). The topology and communication characteristics of WMEN include the following: (a) deployment of the network devices are not planar, rather, devices are deployed over three-dimensional space (e.g., office buildings, shopping malls, grocery stores, etc.); (b) messages, generated/received by a mesh client, traverse through mesh routers in a multihop fashion; and (c) mesh clients, being mostly mobile in nature, may result in misbehaving or be spurious during communications. We propose a security scheme for WMEN in order to ensure that only authorized users are granted network access. Particularly, our scheme includes: (a) a deterministic key distribution technique that perfectly suits the network topology, (b) an efficient session key establishment protocol to achieve the client–router and router–router communications security, and (c) a distributed detection mechanism to identify malicious clients in the network. Analytical and simulation results are presented to verify our proposed solutions.     

New dual-game-based cooperative bandwidth control scheme for ultra-dense networks

Wireless Networks - Future 5G cellular networks are being designed to address the explosive traffic growth of mobile users. In emerging new wireless system paradigms, the ultra-dense network (UDN)...     

Optimal energy-efficient scheme for two-way relay channel using physical layer network coding

Systems are always designed and optimized based on full traffic load in the current literatures.However,practical systems are seldom operating at full load,even at peak traffic hours.Instead of maximizing system rate to achieve the full load,an optimal energy-efficient scheme to minimize the transmit power with required rates is investigated in this article.The considered scenario is a two-way relay channel using amplify-and-forward protocol of physical layer network coding,where two end nodes exchange mess...     

A token circulation scheme for code assignment and cooperative transmission scheduling in CDMA-based UAV ad hoc networks

Code division multiple access (CDMA) ad hoc networks have been considered a promising multiple-channel networking architecture for connecting tactical platforms in battle fields. In this paper we consider a network of a swarm of unmanned aerial vehicles (UAVs) that are used in a tactical surveillance mission. The UAVs are assumed to have multiuser detection capability and form a CDMA-based ad hoc network. A token circulation scheme is proposed to conduct functions required at the medium access control layer including detection of hidden/lost neighbors, code assignment and schedule-based cooperative transmission scheduling. In the proposed scheme, a token continuously circulates around the network based on the “receive-forward” module. Through circulation of the token, each UAV can detect its hidden and/or lost neighbors in near real-time, assign codes enabling the spatial reuse of code channels without incurring code collision, and schedule data transmissions in a cooperative and distributed manner. In addition, the proposed scheme is able to take advantage of multiuser detection functionality and allows for simultaneous transmissions from multiple transmitters to a same receiver. The performance of the proposed token circulation scheme is evaluated, both analytically and through simulations. It is shown that the latency of the token is at most linearly proportional to the network size, and the average delay of a data packet increases with either the packet generation rate or the network size. The results also show that the proposed token circulation scheme is suitable for large-scale CDMA-based UAV ad hoc networks with even heavy network traffic load.