一种高效的无线自组网全网可靠广播协议

现有大部分的无线自组网广播协议采用最小虚拟骨干子网进行全网广播,能最小化广播的总发送次数。但是,由于未考虑无线链路的不可靠性,这些协议在实际网络中的广播效率并不高。为此,提出了一种高效的全网可靠广播协议（ENWRB）,该协议采用网络编码技术减少单跳广播的重传次数,并通过一种基于链路感知的虚拟骨干网选择算法产生更高效的广播骨干网。仿真结果表明,在确保所有节点成功接收广播消息的相同前提下,ENWRB协议的效率显著高于HCA(Hierarchical CDS-based Algorithm)协议。     

基于粒子群优化的ad hoc网络最小能耗多播路由算法

在无线ad hoc网络中,设备使用电池提供能量,随着多播应用日益广泛,如何构造最小能耗多播树是一个重要问题。针对选择不同的中继节点集对构造最小能耗多播树的影响,提出了一种优化最小能耗多播树构造的离散粒子群算法。为了避免离散粒子群算法早熟收敛,引入惯性权重策略,以平衡算法的全局搜索能力和局部搜索能力。模拟实验结果表明改进后的离散粒子群算法具有较强的优化能力,有效地优化了最小能耗多播树的构造。     

Lifetime evaluation in energy‐efficient rectangular ad hoc wireless networks

Ad hoc wireless network nodes are typically battery‐powered, therefore energy limit is one of the critical constraints of ad hoc wireless networks' development. This paper evaluates the network lifetime of a rectangular network model that achieves energy efficiency by optimizing the node radio range based on the geographical adaptive fidelity (GAF) topology management protocol (Proceedings of ACMMobil'01, July 2001; 70–84). We derive the optimal transmission range of nodes and analyze both static and dynamic traffic scenarios in both equal‐grid and adjustable‐grid rectangular GAF models, where the results show that the adjustable‐grid model saves 78.1% energy in comparison with the minimum energy consumption of equal‐grid model. The impact of node density on both equal‐grid and adjustable‐grid models is investigated to achieve grid‐lifetime balance among all grids to optimize the entire network lifetime. The lifetime estimation results show that without node density control the adjustable‐grid model prolongs the entire network lifetime by a factor of 4.2 compared with the equal‐grid model. Furthermore, the adjustable‐grid model with node density control is able to prolong the entire network lifetime by a factor of 6 compared with the equal‐grid model. Copyright © 2010 John Wiley & Sons, Ltd.     

QoS-aware minimum energy multicast tree construction in wireless ad hoc networks

Energy conservation is a critical issue in wireless ad hoc networks since batteries are the only limited-life energy source to power the nodes. One major metric for energy conservation is to route a communication session along the routes which require the lowest total energy consumption. Most recent algorithms for the MEM (Minimum Energy Multicast) problem considered energy efficiency as the ultimate objective in order to increase longevity of such networks. However, the introduction of real-time applications has posed additional challenges. Transmission of video and imaging data requires both energy and QoS-aware routing in order to ensure efficient usage of the networks. In this paper, we only consider “bandwidth” as the QoS in TDMA-based wireless ad hoc networks that use omni-directional antennas and have limited energy resources. We present a constraint formulation model for the QoS-MEM (QoS-aware Minimum Energy Multicast) problem in terms of mixed integer linear programming (MILP), which can be used for an optimal solution of the QoS-MEM problem. Experiment results show that in a typical static ad hoc network with 20 nodes, the optimal solutions can always be solved in a timely manner.     

Probabilistic reliable multicast in ad hoc networks

When striving for reliability, multicast protocols are most commonly designed as deterministic solutions. Such an approach seems to make the reasoning about reliability guarantees (traditionally, binary, “all-or-nothing”-like) in the face of packet losses and/or node crashes. It is however precisely this determinism that tends to become a limiting factor when aiming at both reliability and scalability, particularly in highly dynamic networks, e.g., ad hoc networks. Gossip-based multicast protocols appear to be a viable path towards providing multicast reliability guarantees. Such protocols embrace the non-deterministic nature of ad hoc networks, providing analytically predictable probabilistic reliability guarantees at a reasonable overhead.

This paper presents the Route Driven Gossip (RDG) protocol, a gossip-based multicast protocol designed precisely to meet a more practical specification of probabilistic reliability in ad hoc networks. Our RDG protocol can be deployed on any basic on-demand routing protocol, achieving a high level of reliability without relying on any inherent multicast primitive. We illustrate our RDG protocol by layering it on top of the “bare” Dynamic Source Routing protocol, and convey our claims of reliability and scalability through both analysis and simulation.     

Scalable team multicast in wireless ad hoc networks exploiting coordinated motion

In this paper, we study a new multicast paradigm for large scale mobile ad hoc networks, namely team multicast. In team multicast the multicast group does not consist of individuals, rather, of member teams. For example a team may be a special task force that is part of a search and rescue operation. The message must be broadcast to each member of each team in the multicast group. Team multicast is very common in ad hoc networks set up to accomplish some collective tasks, such as for emergency recovery or battlefield applications. A key problem in several of the above applications is scalability to large membership size as well as network size. Our approach exploits motion affinity (more precisely, team members’ coordinated motion) which is typically present when the set of nodes has a commonality of interests. Each team can be viewed as a logical subnet. Within the team a landmark node is dynamically elected. The addresses of and the paths to the chosen landmarks are propagated into the whole network so that a source of a multicast group can route to the landmark of a subscribed team.Our protocol, Multicast-enabled Landmark Ad Hoc Routing (denoted as M-LANMAR), uses tunneling from multicast sources to each landmark of the subscribed team and restricted flooding within the motion group. Simulation study shows that M-LANMAR provides efficient and reliable multicast compared with the application of a “flat” multicast scheme (e.g., ODMRP) that does not exploit team coordinated motion.This paper contains three contributions: a new model for team multicast, with the definition of team dynamics (join, merge, split); the exploitation of team mobility and of landmarks in order to achieve scalable multicast, and; the implementation and performance evaluation of M-LANMAR, a landmark based team multicast scheme.     

Energy efficient broadcast routing in mobile ad hoc networks

In this paper, we address the problem of broadcast routing in mobile ad hoc networks from the viewpoint of energy efficiency. In an ad hoc wireless network, each node runs on a local energy source which has a limited energy lifespan. Thus, energy conservation is a critical issue in ad hoc networks. One approach for energy conservation is to establish routes which require lowest total energy consumption. This optimization problem is referred as the minimum‐energy broadcast routing problem (MEBRP). In this paper, we propose new efficient algorithms for the construction of energy‐efficient trees for broadcast in mobile ad hoc networks. These algorithms exploit the broadcast nature of the wireless channel, and address the need for energy‐efficient operations. Empirical studies show that our algorithms are able to achieve better performance than algorithms that have been developed for MEBRP. Copyright © 2004 John Wiley & Sons, Ltd.     

A network coding based interference cancelation scheme for wireless ad hoc networks

The performance of wireless networks is limited by multiple access interference (MAI) in the traditional communication approach where the interfered signals of the concurrent transmissions are treated as noise. In this paper, we treat the interfered signals from a new perspective on the basis of additive electromagnetic (EM) waves and propose a network coding based interference cancelation (NCIC) scheme. In the proposed scheme, adjacent nodes can transmit simultaneously with careful scheduling; therefore, network performance will not be limited by the MAI. Additionally we design a space segmentation method for general wireless ad hoc networks, which organizes network into clusters with regular shapes (e.g., square and hexagon) to reduce the number of relay nodes. The segmentation method works with the scheduling scheme and can help achieve better scalability and reduced complexity. We derive accurate analytic models for the probability of connectivity between two adjacent cluster heads which is important for successful information relay. We proved that with the proposed NCIC scheme, the transmission efficiency can be improved by at least 50% for general wireless networks as compared to the traditional interference avoidance schemes. Numeric results also show the space segmentation is feasible and effective. Finally we propose and discuss a method to implement the NCIC scheme in a practical orthogonal frequency division multiplexing (OFDM) communications networks. Copyright © 2009 John Wiley & Sons, Ltd.     

无线自组网中基于离散粒子群优化的睡眠调度感知最小功率广播

针对当网络使用睡眠调度并且节点的传输功率连续可调节时的最小功率广播调度问题,首先给出了一种计算节点内部最优发送调度的递归方法,然后提出了一种构造最小功率广播调度的离散粒子群算法。该算法搜索最优广播树结构,并融合基于最小广播功率增量的贪心算法和基于启发式调整广播树结构的局部优化算法以提高收敛速度和求解质量。模拟实验结果表明所提算法能够有效地减少广播功率。     

无线自组织网络中流间网络编码机会发现方法的研究

编码机会对流间网络编码协议的性能具有重要影响,包括AODV在内的大多数距离向量路由协议仅知道针对某个目的节点的一跳邻居信息,无法有效地发现编码机会。针对该问题,从节点需要掌握的网络拓扑信息这一角度,提出了编码机会有效发现的条件并从充分性与必要性两方面进行了分析,然后基于AODV路由协议进行了实现,同时利用真实的网络实验与网络仿真对所提条件进行了验证。实验与仿真结果表明,所提条件是正确的,可以有效地提高无线自组织网络的性能。     

面向无线ad hoc网络的一种平面t-支撑图

拓扑控制算法的目标是为无线ad hoc网络确定合适的底层拓扑。在无线ad hoc网络中，几何路由协议是一类重要的路由协议，为了保证消息转发的可达性和限制路由长度，它要求底层拓扑满足连通性、平面性和稀疏性，并且是原拓扑的t-支撑图。本文提出了一种新的几何结构AUDel图，并提出了两种低通信开销的构造AUDel图的局部拓扑控制算法。理论分析表明，AUDel图满足上述要求，我们提出的拓扑控制算法的通信歼销小于其它构造平面t-支撑图的拓扑控制算法。模拟实验验证了以上结论。     

一种高效可靠的无人机自组网多跳TDMA协议

设计无人机自组网媒体接入控制(Medium Access Control,MAC)协议时,需要考虑其控制开销和数据传输的可靠性。鉴于此,结合现有无线自组网多跳时分多址接入(Time Division Multiple Access,TDMA)协议和无人机自组网特点,提出了一种高效可靠的无人机自组网多跳TDMA协议。首先采用高效负载均衡的时隙请求信息上传机制,选择一个负载较小的节点转发节点时隙请求信息;然后根据相互通信的父节点删除重复节点的时隙请求信息,减少相同节点的时隙请求信息转发次数;最后通过实时更新节点时隙请求信息机制,提高节点时隙请求信息传输的可靠性。仿真结果表明,该协议在数据传输成功率、平均时延、控制开销方面优于现有协议,可较好地应用在无人机自组网中。     

A load‐balancing and coding‐aware multicast protocol for mobile ad hoc networks

In this paper, we propose a Load‐Balancing and Coding‐Aware Multicast (LCM) protocol for mobile ad hoc networks. In LCM protocol, a new route metric named Expected Transmission Time with Coding and Load Balancing (ETTCL) is presented at first, aiming at effectively selecting the path not only that has the possible coding opportunity but also where overflow due to network overload can be prevented. Then, we describe the route discovery phase by constructing the node‐disjoint multicast tree on the basis of ETTCL and employ network coding to encode the data flows for route maintenance. The effectiveness of LCM protocol is simulated and analyzed by NS‐2, which shows that this protocol has good performance in reducing average end‐to‐end delay and control overhead and can improve packet delivery ratio compared with the existing protocol. Copyright © 2015 John Wiley & Sons, Ltd.     

无线自组织网中VoIP性能研究

目前,VoIP技术及其业务迅速发展,在无线自组织网络中有广泛的应用,有必要对于VoIP在无线自组网中的传输进行分析研究。利用NS-2作为仿真工具对G.711编码标准下多跳无线自组织网中VoIP的传输进行仿真,使用802.11MAC层协议和AODV路由层协议。实验结果表明,无线自组织网络环境下VoIP系统性能(包括丢包率、时延等)受到多跳影响。     

An efficient reliable broadcasting protocol for wireless mobile ad hoc networks

The mobile ad hoc network (MANET) has recently been recognized as an attractive network architecture for wireless communication. Reliable broadcast is an important operation in MANET (e.g., giving orders, searching routes, and notifying important signals). However, using a naive flooding to achieve reliable broadcasting may be very costly, causing a lot of contention, collision, and congestion, to which we refer as the broadcast storm problem. This paper proposes an efficient reliable broadcasting protocol by taking care of the potential broadcast storm problem that could occur in the medium-access level. Existing protocols are either unreliable, or reliable but based on a too costly approach. Our protocol differs from existing protocols by adopting a low-cost broadcast, which does not guarantee reliability, as a basic operation. The reliability is ensured by additional acknowledgement and handshaking. Simulation results do justify the efficiency of the proposed protocol.     

支持网络编码的认知无线自组网拓扑控制算法

对认知无线自组网中有限的带宽进行研究,提出支持网络编码的拓扑控制算法。算法分为3个阶段：初始拓扑构建阶段,利用最短路径算法为单播业务构建拓扑,利用基于网络编码的最短路径算法为多播业务构建K冗余拓扑;拓扑优化阶段,通过逐条删除满足一定条件的链路优化拓扑;拓扑恢复阶段,针对关键点失效,利用与失效链路不在同一路径簇且开销最小的链路恢复网络连通。仿真结果表明,算法能够提高无线资源复用率,增强网络抗毁性。     

Scalable location guide overlay multicast in mobile ad hoc networks using tree partition scheme

Nodes mobility brings flinty challenges to multicast in Mobile ad hoc Networks (MANETs). To track nodes mobility, flooding messages are widely used for data delivery structure construction and maintenance in many multicast protocols. These periodic flooding messages significantly consume network resources, such as energy and bandwidth, and result in network collisions. To release data delivery structure maintenance onus, profited from GPS location service, a number of stateless location based multicast protocol were proposed, where a destination list is encapsulated into each data packet for data packet orientation. However, due to data packet capability limitation, the way of encapsulating a destination list in each data packet header restricts the protocol scalability. To solve the scalability issue of multicast protocols, we propose a Scalable Location Guide Overlay Multicast (SLGOM) for MANETs. Analysis and simulation results show that SLGOM achieves high performance in large multicast group and significantly improves the scalability of stateless multicast with respect to group size. Copyright © 2010 John Wiley & Sons, Ltd.     

Interference minimum network topologies for ad hoc networks

This paper investigates the topology control problem with the goal of minimizing mutual interferences in wireless ad hoc networks. It is known that interference is considered as a relationship between link and node in previous works. In this paper, we attempt to capture the physical situation of space‐division multiplex more realistically by defining interference as a relationship between any two bidirectional links. We formulate the pair‐wise interference condition between any two bidirectional links, and demonstrate that the interference condition is equivalent by employing the equal‐power allocation strategy and by employing the minimum‐power allocation strategy. Then we further study the typical interference relationship between a link and its surrounding links. To characterize the extent of the interference between a link and its surrounding links, a new metric, the interference coefficient, is given, and its property is explored in detail by means of analysis and simulation. Based on the insight obtained, a centralized algorithm, BIMA, and a distributed algorithm, LIMA, are proposed to control the network interference. Our simulation indicates that BIMA can minimize the network interference while conserving energy and maintaining good spanner property, and LIMA has relatively good interference performance while keeping low node degree, compared with some well‐known algorithms. Besides, both BIMA and LIMA show good robustness to additive noises in terms of interference performance. Copyright © 2010 John Wiley & Sons, Ltd.     

CAPACITY EVALUATION OF MULTI-CHANNEL WIRELESS AD HOC NETWORKS

In this paper, the capacity of multi-channel, multi-hop ad hoc network is evaluated.In particular, the performance of multi-hop ad hoc network with single channel IEEE 802.11 MAC utilizing different topologies is shown. Also the scaling laws of throughputs for largescale ad hoc networks and the theoretical guaranteed throughput bounds for multi-channel grid topology systems are proposed. The results presented in this work will help researchers to choose the proper parameter settings in evaluation of protocols for multi-hop ad hoc networks.     

On the construction of maximum residual energy resource broadcast trees with minimum diameter in static ad hoc wireless networks

Each node in a wireless ad hoc network runs on a local energy source that has a limited energy life span. Thus, energy conservation is a critical issue in such networks. In addition, it is in general desirable to construct routes with low hop counts as a route with a high hop count is more likely to be unstable (because the probability that intermediate nodes will move away is higher). In this paper, we address these two issues concurrently with energy conservation as the primary objective and low hop count as the secondary objective. One way of addressing the energy conservation issue is to construct routes that maximize the minimum residual battery capacity available among all nodes in each route. A broadcast tree with all routes satisfying this condition is referred to as a maximum residual energy resource broadcast tree. A maximum residual energy resource broadcast tree with the least diameter is referred to as a minimum diameter maximum residual energy resource broadcast tree and the problem of constructing such a tree is referred to as the minimum diameter maximum residual energy resource broadcast routing problem (MDMRERBRP). We propose an algorithm for MDMRERBRP and prove that MDMRERBRP is optimally solvable in polynomial time using the proposed algorithm. Copyright © 2005 John Wiley & Sons, Ltd.