Neighbor discovery in wireless networks with sectored antennas

Directional antennas offer many potential advantages for wireless networks such as increased network capacity, extended transmission range and reduced energy consumption. Exploiting these advantages requires new protocols and mechanisms at various communication layers to intelligently control the directional antenna system. With directional antennas, many trivial mechanisms, such as neighbor discovery, become challenging since communicating parties must agree on where and when to point their directional beams to communicate.In this paper, we propose a fully directional neighbor discovery protocol called Sectored-Antenna Neighbor Discovery (SAND) protocol. SAND is designed for sectored-antennas, a low-cost and simple realization of directional antennas, that utilize multiple limited beamwidth antennas. Unlike many proposed directional neighbor discovery protocols, SAND depends neither on omnidirectional antennas nor on time synchronization. SAND performs neighbor discovery in a serialized fashion allowing individual nodes to discover all potential neighbors within a predetermined time. SAND guarantees the discovery of the best sector combination at both ends of a link, resulting in more robust and higher quality links between nodes. Finally, SAND reliably gathers the neighborhood information in a centralized location, if needed, to be used by centralized networking protocols. The effectiveness of SAND has been assessed via simulation studies and real hardware implementation.     

低占空比无线传感器网络邻居发现算法研究

低占空比(low duty cycle,LDC)无线传感器网络邻居发现算法是当前无线传感器网络领域的研究热点之一。当前LDC无线传感器网络的邻居发现算法大致可分为同步邻居发现算法和异步邻居发现算法,其中异步发现算法又可分为基于法定人数的调度算法（Grid quorum和 U-connect）和基于中国剩余定理的调度方法(Disco算法)。针对发现延迟和能量消耗,通过仿真实验对当前LDC无线传感器网络邻居发现领域里的典型算法进行了对比分析,在此基础上得出LDC无线传感器网络邻居发现算法新的研究方向。     

定向Ad hoc网络中一种带冲突避免的邻居发现算法

定向天线应用于ad hoc网络,一方面能显著提升网络性能,另一方面也需要新的MAC和路由协议来控制定向天线系统。邻居发现算法作为其中最重要的协议之一,是定向ad hoc网络组网的基础和前提,针对现有文献中提出的各种邻居发现算法大多没有考虑同一定向波束扇区内存在多个节点时的冲突情况,提出一种带冲突避免的定向邻居发现算法DAND/CA。DAND/CA通过随机选择发送控制消息占用的微时隙,能有效避免碰撞冲突的发生。仿真结果表明,提出的DAND/CA算法在邻居发现时间和成功率等方面明显优于现有算法。     

Secure neighbor discovery and wormhole localization in mobile ad hoc networks

Neighbor discovery is an important part of many protocols for wireless adhoc networks, including localization and routing. When neighbor discovery fails, communications and protocols performance deteriorate. In networks affected by relay attacks, also known as wormholes, the failure may be more subtle. The wormhole may selectively deny or degrade communications. In this article we present Mobile Secure Neighbor Discovery (MSND), which offers a measure of protection against wormholes by allowing participating mobile nodes to securely determine if they are neighbors, and a wormhole localization protocol, which allows nodes that detected the presence of a wormhole to determine wormhole’s location. To the best of our knowledge, this work is the first to secure neighbor discovery in mobile adhoc networks and to localize a wormhole. MSND leverages concepts of graph rigidity for wormhole detection. We prove security properties of our protocols, and demonstrate their effectiveness through extensive simulations and a real system evaluation employing Epic motes and iRobot robots.     

Low-latency neighbor discovery algorithm based on multi-beacon message in mobile low-duty-cycle sensor network

Neighbor discovery enables nodes in the networks to discover each other through simple information interaction,which was suitable for the new mobile low duty cycle sensor network (MLDC-WSN).However,because the nodes in MLDC-WSN can move randomly and sleep,the network topology was changed frequently,which results in that some nodes need a lot of energy and time to find their neighbors.How to realize fast neighbor discovery for all nodes in the network was a difficult problem in current research.To solve this problem,a new low-latency neighbor discovery algorithm based on multi-beacon messages was proposed.In this algorithm,the nodes were discovered by sending a short beacon message through their neighbor nodes,and by adjusting the time and frequency of beacon message sent,a lower neighbor discovery delay was obtained.Eventually,through quantitative analysis and simulation experiments,it is found that compared with existing algorithms,this algorithm can find all neighbor nodes in MLDC-WSN with less energy consumption,lower latency and greater probability.     

定向天线的Ad hoc网络邻居发现

在Ad hoc网络中邻居节点发现（Neighbor Discovery）是网络初始化中的重要步骤之一,节点邻居的信息对于几乎所有的链路选择和路由算法都有着重要的影响,特别是在采用方向性天线时邻居发现不仅难度更大而且其影响作用也更明显。通过分析在采用方向性天线时的Ad hoc网络中的邻居发现算法,总结出了其一般步骤,即首先通过判断网络规模来进行天线收发模式选择算法和扫描图案的选择,然后再设计相应的通信握手协议。     

基于Ka/Ku相控阵天线的空基自组网协议设计

针对空基自组织网络的大容量通信需求,首先提出了基于频分复用的定向MAC协议,在邻居发现过程中将测距算法与多维尺度变换定位算法相结合得到每个节点的相对位置,并设计了双预约资源分配算法,完成定向数据传输;然后提出了定向路由协议,解决了次佳路由问题和路由应答风暴,并加入相邻搜索、链路质量评估和备用路由,降低了协议开销。空基自组网基于Ka/Ku相控阵天线的定向传播特性以及Ka/Ku频段频谱资源丰富的特点,使用频分复用、空分复用技术实现多个信道的高速并行传输,从而极大地提高网络的吞吐量。     

Agent‐based secure routing for underwater acoustic sensor networks

The underwater networks have severe security implications and are vulnerable to various types of attacks such as selective forwarding, wormhole, and sinkhole. Neighbor discovery, a fundamental requirement for routing is vulnerable to wormhole attack, which enables false neighbor acceptance, thereby degrading the routing performance. The proposed agent‐based secured routing scheme enhances the quality of service by discovering the wormhole resilient secure neighbors and route the information through the secure path. This scheme uses 4 agencies, namely, security, routing, underwater gateway, and vehicle, which are embedded with static and mobile agents. (1) Agents in security agency of a node discover secured neighbors by using the direction of arrival estimation and authentication, (2) agents in routing agency of a node establish secured routes from source to surface gateway, (3) agents in Underwater Gateway Agency communicate with Autonomous Underwater Vehicles (AUVs) and underwater nodes for key distribution, and (4) vehicle traversing agency in AUV coordinates with Underwater Gateway Agency for changing AUVs traversal to cover the isolated network area. The proposed scheme depicts the improved performance compared to basic neighbor discovery and channel aware routing protocol in terms of failure detection, energy consumption, and overheads.     

采用定向天线的MANET邻居发现算法研究

在无线多跳移动自组织网(MANET)中采用定向天线(特别是波束成形天线)有一系列优点。这一技术能增加单跳传输的距离、减小干扰、提高空间复用度,从而能显著增大系统容量。然而,适应于采用全向天线的传统MANET的媒质接入控制(MAC)、功率控制、邻居发现、路由等方法必须作相应的修改。在分析前人相关研究的基础上,针对MANET使用定向天线情况下的邻居发现机制及算法进行了深入研究,提出了2种采用定向天线的MANET的邻居发现算法———非辅助TD模式的定向邻居发现算法与非辅助TRD模式的定向邻居发现算法。这2种算法与目前已提出的其他定向邻居发现算法的最大区别是,它们不需要依赖GPS或其他辅助信息就能独立实现邻居发现。     

NSMTSEP: Neighbor Supported Modified Threshold Sensitive Stable Election Protocol for WSN

The way by which we select a cluster head critically affects the overall futuristic structure in the network. Cluster head wastes more energy for long distance transmission in the network. Sometimes, due to incomplete information of neighbor nodes, a proper cluster head is not selected and deplete energy quickly. This paper, presents a clustering protocol (NSMTSEP) based on neighbor support. Support of the neighbor node is used to calculate the threshold. Neighbor nodes are labeled based on dynamically changing parameters. The total energetic value of different nodes, cluster heads degree, the summative information of distances of member nodes, etc. is dynamically changing parameters. The label of a node is used to calculate the weight of that particular node. Weight is finally used to formulate equations for threshold calculation. The fundamental target is to increase the stable time, throughput, and network lifespan by reducing the cost incurred in intra-cluster communication. Neighbor supported labeled method is suitable for increasing longevity in the network. NSMTSEP upgrades stability by 8.6%, 36.9% as compared to enhanced threshold sensitive stable election protocol (ETSSEP) and threshold sensitive stable election protocol (TSEP). NSMTSEP is three times more stable than stable election protocol (SEP) and low energy adaptive clustering hierarchy protocol (LEACH). Improvement in the lifespan of NSMTSEP is recorded by 11.98%, 3.43% and 24.9% over ETSSEP, TSEP, and LEACH respectively whereas more than twice in comparison with SEP. The throughput enhanced by 32.2% and 55.7% respectively over TSEP and LEACH, twice over SEP and ETSSEP respectively.

     

Angular MAC: a framework for directional antennas in wireless mesh networks

Capacity of wireless mesh networks can be enhanced through the use of smart directional antennas, which not only enable nodes to have high quality links but also increase network throughput by allowing spatial reuse. This paper proposes a new MAC protocol and framework, called Angular MAC (ANMAC) that enables directional antennas in wireless mesh networks. The protocols and algorithms of the ANMAC framework fit well with the requirements of mesh networks such as neighbor discovery and self-configuration, while providing significant throughput enhancements. The throughput enhancements are proven by comprehensive simulations with realistic antenna patterns, including performance comparisons of ANMAC with directional schemes using a similar node architecture and omni 802.11. Also, the effect of contention window size is analyzed and a dynamic contention window adaptation algorithm is proposed to maximize the throughput of the self-configuring mesh network, by taking instantaneous traffic conditions into account.     

Optimal Block Design for Asynchronous Wake-Up Schedules and Its Applications in Multihop Wireless Networks

In this paper, we consider the problem of designing optimal asynchronous wake-up schedules to facilitate distributed power management and neighbor discovery in multihop wireless networks. We first formulate it as a block design problem and derive the fundamental trade-offs between wake-up latency and the average duty cycle of a node. After the theoretical foundation is laid, we then devise a neighbor discovery and schedule bookkeeping protocol that can operate on the optimal wake-up schedule derived. To demonstrate the usefulness of asynchronous wake-up, we investigate the efficiency of neighbor discovery and the application of on-demand power management, which overlays a desirable communication schedule over the wake-up schedule mandated by the asynchronous wake-up mechanism. Simulation studies demonstrate that the proposed asynchronous wake-up protocol has short discovery time which scales with the density of the network; it can accommodate various traffic characteristics and loads to achieve an energy savings that can be as high as 70 percent, while the packet delivery ratio is comparable to that without power management.     

Energy-efficient neighbor discovery protocol for mobile wireless sensor networks

Low energy consumption is a critical design requirement for most wireless sensor network (WSN) applications. Due to minimal transmission power levels, time-varying environmental factors and mobility of nodes, network neighborhood changes frequently. In these conditions, the most critical issue for energy is to minimize the transactions and time consumed for neighbor discovery operations. In this paper, we present an energy-efficient neighbor discovery protocol targeted at synchronized low duty-cycle medium access control (MAC) schemes such as IEEE 802.15.4 and S-MAC. The protocol effectively reduces the need for costly network scans by proactively distributing node schedule information in MAC protocol beacons and by using this information for establishing new communication links. Energy consumption is further reduced by optimizing the beacon transmission rate. The protocol is validated by performance analysis and experimental measurements with physical WSN prototypes. Experimental results show that the protocol can reduce node energy consumption up to 80% at 1–3 m/s node mobility.     

一种适于波束切换移动自组网的邻居发现改进算法

基于多波束切换的移动自组网系统在未来通信中具有广阔的应用前景,邻居发现是基于多波束切换的移动自组网系统的关键技术之一。现有基于多波束切换的移动自组网邻居发现算法在波束交叠情况下无法选择最优通信波束,为了解决基于多波束切换的移动自组网邻居发现过程中的最优通信波束选择问题,提出一种改进算法,在邻居发现过程中增加接收信号质量评估机制,增强网络的稳定性,提高网络吞吐量,并通过仿真验证了在波束交叠的情况下系统的累计平均接收电平优于传统方法。     

PND: a p‐persistent neighbor discovery protocol in wireless networks

In wireless communications research, a number of literature assume that every node knows all of its neighbor nodes. To this end, neighbor discovery research has been conducted, but it still has room for improvement in terms of discovery delay. Furthermore, prior work has overlooked energy efficiency, which is considered as the critical factor in wireless devices or appliances. For better performance with respect to the discovery delay and energy efficiency, we proposed a novel p‐persistent‐based neighbor discovery protocol and devised a simple and light algorithm estimating the number of neighbor nodes to support the proposed protocol. Our protocol requires a lower delay and a smaller number of messages for the discovery process than the existing protocols. For extensive performance evaluation, we adopted extra comparison targets from other research areas within the same context. Copyright © 2011 John Wiley & Sons, Ltd.     

Receiver-Oriented Multiple Access in Ad Hoc Networks with Directional Antennas

Directional antennas can adaptively select radio signals of interest in specific directions, while filtering out unwanted interference from other directions. A couple of medium access protocols based on random access schemes have been proposed for networks with directional antennas, using the omnidirectional mode for the transmission or reception of control packets in order to establish directional links. We propose a distributed receiver-oriented multiple access (ROMA) scheduling protocol, capable of utilizing multi-beam forming directional antennas in ad hoc networks. Unlike random access schemes that use on-demand handshakes or signal scanning to resolve communication targets, ROMA computes a link activation schedule in each time slot using two-hop topology information. It is shown that significant improvements on network throughput and delay can be achieved by exploiting the multi-beam forming capability of directional antennas in both transmission and reception. The performance of ROMA is studied by simulation, and compared with a well-know static scheduling scheme that is based on global topology information.     

Power-Controlled MAC Protocols with Dynamic Neighbor Prediction for Ad hoc Networks

1　IntroductionMobileadhocnetworksareasetofmobilenodeswhichformandself configurethenetworkwithoutthepre deployedcentraladministrativein frastructure (e.g .thebasestationofWLAN) .Thedemandforadhocnetworkshasbeenbloominginthepastyearsinthecommercialandmilitaryappli cations ,becauseonlyadhocnetworkscanbeappliedinthesituationswherethecentraladministrativein frastructurecan tbe pre installed (e .g .battlefields,disasterrescue)orisnoteconomicaltoinstallbecauseoftemporaryuse (e .g .ameetingintherent…     

Passive neighbor discovery with social recognition for mobile ad hoc social networking applications

Wireless Networks - Neighbor discovery is the cornerstone of the mobile social applications over mobile ad hoc networks. Most current neighbor discovery protocols adopt a carefully designed...     

A multiple relay‐based medium access control protocol in multirate wireless ad hoc networks with multiple beam antennas

The advanced technique of multiple beam antennas is recently considered in wireless networks to improve the system throughput by increasing spatial reuse, reducing collisions, and avoiding co‐channel interference. The usage of multiple beam antennas is similar to the concept of Space Division Multiple Access (SDMA), while each beam can be treated as a data channel. Wireless networks can increase the total throughput and decrease the transmission latency if the physical layer of a mobile node can support multirate capability. Multirate wireless networks incurs the anomaly problem, because low data rate hosts may influence the original performance of high data rate hosts. In this work, each node fits out multiple beam antennas with multirate capability, and a node can either simultaneously transmit or receive multiple data on multiple beams. Observe that the transmitting or receiving operation does not happen at the same time. In this paper, we propose a multiple relay‐based medium access control (MAC) protocol to improve the throughput for low data rate hosts. Our MAC protocol exploits multiple relay nodes and helps the source and the destination to create more than one data channel to significantly reduce the transmission latency. Observe that low data rate links with long‐distance transmission latencies are distributed by multiple relay nodes, hence the anomaly problem can be significantly alleviated. In addition, the ACK synchronization problem is solved to avoid the condition that source nodes do not receive ACKs from destination nodes. An adjustment operation is presented to reduce unnecessary relay nodes during the fragment burst period. Finally, simulation results illustrate that our multiple relay‐based MAC protocol can achieve high throughput and low transmission latency. Copyright © 2009 John Wiley & Sons, Ltd.     

QoS‐aware packet forwarding in MIMO sensor networks: a cross‐layer approach

Multiple‐input multiple‐output (MIMO) enabled wireless sensor networks (WSNs) are becoming increasingly important since significant performance enhancement can be realized. In this paper, we propose a packet forward strategy for MIMO sensor networks by jointly considering channel coding, rate adaptation, and power allocation. Each sensor node has multiple antennas and uses orthogonal space time block codes (OSTBC) to exploit both spatial and temporal diversities. The objective is to determine the optimal routing path that achieves the minimum symbol error rate (SER) subject to the source‐to‐destination (S‐D) energy consumption constraint. This SER‐based quality‐of‐service (QoS) aware packet forwarding problem is formulated into the framework of dynamic programming (DP). We then propose a low‐complexity and near‐optimal approach to considerably reduce the computation complexity, which includes state space partition and state aggregation techniques. Simulations indicate that the proposed protocol significantly outperforms traditional algorithms. Further still, the performance gain increases with tighter S‐D energy constraint. Copyright © 2009 John Wiley & Sons, Ltd.