An opportunistic routing mechanism for real‐time voice service in mobile ad hoc networks

The opportunistic routing mechanism can use several lossy broadcast links to support reliable transmission. In this paper, a simple opportunistic routing mechanism for real‐time multimedia services is proposed. This mechanism is based on the dynamic source routing protocol with some modifications, multiple route request, and route reply messages are used to construct the forwarder list, and the nodes within the forwarder list forward the packets which they overhear. The forwarder list is placed on the packet header in the form of a Bloom filter, which will restrict the size of the forwarder list to a constant value. There are no strict scheduling mechanisms for the forwarding order of the forwarder nodes, thus our opportunistic routing mechanism can be scalable for multiple simultaneous flows. Simulations show that our mechanism can effectively decrease the transmission times and the amount of the control messages for each packet and reduce the end‐to‐end delay for real‐time voice service, the quality of service for these services can be supported well over the unstable wireless channel. Copyright © 2009 John Wiley & Sons, Ltd.     

Time‐aware and energy‐efficient opportunistic routing with residual energy collection in wireless sensor networks

In 1‐dimensional queue wireless sensor networks, how to balance end‐to‐end latency and energy consumption is a challenging problem. However, traditional best path routing and existing opportunistic routing protocols do not address them well because relay hop counts are usually much more, and the link appears more unreliable compared with general mesh topology. In this work, we formulate these 2 problems as a multiobjective optimization problem. Specifically, we first classify network packets into types of time tolerant and time critical and introduce a residual energy collection mechanism of neighboring nodes for forwarder set selection. We then propose a time‐aware and energy‐efficient opportunistic routing protocol (TE‐OR) to optimize energy consumption and to reduce latency for time‐critical packets. We evaluate TE‐OR by different parameters and compare it with existing protocols. The performance results show that TE‐OR achieves a trade‐off between energy consumption and time delay and balances energy consumption among nodes while guaranteeing the latency of time‐critical packets is minimized.     

QMOR: QoS-Aware Multi-sink Opportunistic Routing for Wireless Multimedia Sensor Networks

The energy efficiency and quality of service (QoS) provisioning of wireless multimedia sensor networks (WMSNs) are two major issues that impact the application of such networks. Recent studies demonstrate that network performance can be greatly improved by involving multiple sinks. However, mainstream WMSN routing protocols are generally designed to account for a single sink. This paper proposes a QoS-aware multi-sink opportunistic routing (QMOR) to efficiently deliver multimedia information under QoS constraints for WMSNs. We begin with an optimal nodes selection problem to reduce redundant multimedia data. Then, we focus on selecting and prioritizing forwarder list to enhance transmission efficiency. Finally, the multi-sink-aware operations are integrated into an optimization opportunistic routing framework, with an objective to minimize energy consumption subject to delay and reliability constraints. Our simulation results demonstrate that the QMOR performs better than typical WMSN QoS routing algorithm, in terms of the video transmission quality and energy utilization efficiency.     

Joint admission/congestion control for wireless CDMA systemssupporting integrated services

A new data traffic control scheme is developed for maintaining the packet error rate (PER) of real-time voice traffic while allowing nonreal-time data traffic to utilize the residual channel capacity of the multi-access link in an integrated service wireless CDMA network. Due to the delay constraint of the voice service, voice users transmit their packets without incurring further delay once they are admitted to the system according to the admission control policy. Data traffic, however, is regulated at both the call level (i.e., admission control) and at the burst level (i.e., congestion control). The admission control rejects the data calls that will otherwise experience unduly long delay, whereas the congestion control ensures the PER of voice traffic being lower than a specified quality of service (QoS) requirement (e.g., 10 ^-2). System performance such as voice PER, voice-blocking probability, data throughput, delay, and blocking probability is evaluated by a Markovian model. Numerical results for a system with a Rician fading channel and DPSK modulation are presented to show the interplay between admission and congestion control, as well as how one can engineer the control parameters. The tradeoff of using multiple CDMA codes to reduce the transmission time of data messages is also investigated     

Throughput oriented forwarders selection analysis for opportunistic routing in wireless mesh network

Opportunistic routing explicitly takes advantage of the broadcast nature of wireless communications by using a set of forwarders to opportunistically perform packet forwarding. A key issue in the design of opportunistic routing protocols is the forwarder list selection problem. This paper proposes a novel routing metric which shows the end-to-end throughput and a corresponding throughput oriented opportunistic routing forwarder-selecting algorithm throughput oriented forwarders selection (TOFS) through analyzing forwarding characteristics of forwarders. The algorithm puts forward a constraint mechanism that controls the number of forwarders by constraint of throughput for forwarders selection, achieving a better balance between number of forwarders and effective link stability by introducing the factor of transmission time. Simulation results show that the algorithm can improve the network end-to-end throughput effectively over existing methods.     

无线Ad hoc网络机会路由的实现与仿真

在无线自组织网络中,路由协议对网络的性能起着关键性作用。然而由于无线信道的不稳定性经常造成通信中断而需重建路由,使自组织网传统路由协议的效率大大降低。提出了一种应用于无线自组织网络的机会路由协议（WAOR）,利用无线信道的广播特性和多径传输来增强链路的可靠性。采用网络仿真器NS2的仿真结果表明,WAOR的性能优于传统的动态源路由协议（DSR）和自组织网按需平面距离矢量路由协议（AODV）。     

机会网络中一种低缓存占用的Epidemic 路由算法

由于机会网络中节点的缓存空间有限,容易导致数据分组丢失和时延增加。针对部分数据分组已经到达目的节点,但是该类分组仍在网络中其它节点存储、传输问题,提出一种低缓存占用的Epidemic路由算法(RBER)。该算法通过SV运算进行节点缓存清理,从而避免这类冗余数据分组对缓存的占用。理论分析和仿真结果表明,该机制能够降低网络开销、数据分组的发送和缓存占用。     

A QoS-aware routing mechanism for multi-channel multi-interface ad-hoc networks

To accommodate real-time multimedia application while satisfying application QoS requirements in a wireless ad-hoc network, we need QoS control mechanisms. In this paper, we propose a new routing mechanism to support real-time multimedia communication by efficiently utilize the limited wireless network capacity. Our mechanism considers a wireless ad-hoc network composed of nodes equipped with multiple network interfaces to each of which a different wireless channel can be assigned. By embedding information about channel usage in control messages of OLSRv2, each node obtains a view of topology and bandwidth information of the whole network. Based on the obtained information, a source node determines a logical path with the maximum available bandwidth to satisfy application QoS requirements. Through simulation experiments, we confirmed that our proposal effectively routed multimedia packets over a logical path avoiding congested links. As a result, the load on a network is well distributed and the network can accommodate more sessions than QOLSR. We also conducted practical experiments using wireless ad-hoc relay nodes with four network interfaces and verified the practicality of our proposal.     

应用于无线Mesh路由协议的研究

文章在研究应用于无线Mesh网络的DSR协议多播过程中发现会产生网络风暴问题,对此提出了一种均衡流量的距离门限动态源路由协议,对它进行仿真,仿真结果表明使用了该方法的路由算法在吞吐量上较原算法有较大改善。     

DSR路由协议的改进

DSR路由协议是移动Ad Hoc网络常用的按需路由协议之一。由于采用洪泛机制寻找和维护路由表,DSR路由协议能量开销高、分组交付率低。针对此问题,提出局部化路由查询方法,限制路由请求跳数,改进DSR路由协议的路由发现过程,有效地平衡了路由信息存储量、网络拥塞和能量消耗。分析表明,改进的DSR路由协议将路由请求分组控制在一定的网络范围内,减少数据传输时延、降低网络能量开销。仿真结果显示,在选择适当的最大跳数时,改进的DSR路由协议在分组交付率、路由载荷方面均优于传统的DSR路由协议。     

CPCA: An efficient wireless routing algorithm in WiNoC for cross path congestion awareness

Wireless network-on-chip (WiNoC) is a new paradigm to mitigate the long-distance transmission latency for conventional wired network-on-chip. The wireless routers in WiNoC have to handle a large number of packets which could cause data congestion, thus reducing the network performance. In this paper, we propose a novel wireless routing algorithm, called CPCA, which exploits the cross path congestion information as hints to route the packets. Under CPCA, the whole network is partitioned into sub-networks. In each subnet, the congestion information of the wireless router is propagated along the cross path. As a result, the routers in the same dimension can get the congestion degree of wireless router within the subnet. Based on the congestion information, CPCA can compute the suitable path for packets routing, which can prominently avoid the congestion aggravation in the wireless router. Experimental results show that our proposed method can effectively improve performance in terms of packets transmission latency and network throughput.     

TDM over IP的发展趋势及其应用

论述了TDM over IP技术出现的背景、实现过程以及实际应用方案.利用伪线路仿真技术实现在以太网上传送实时业务,将语音、图像等信息直接装入以太网(或IP网)数据包,然后依照IP路由进行简单高效的传送.此技术可广泛应用于PON、基站回传、接口转换以及传统业务线路的改造等方面.     

小卫星业务调度路由优化

针对小卫星通信链路交换频繁和低资源利用率的问题，提出了一种基于调度的小卫星路由优化策略。建立起小卫星星座模型，根据其运行方向(与赤道平面近似垂直)和所在维度确定链路的实时连接策略，优化其路由路径。面对持续增长的网络业务与有限的星上资源的矛盾，将业务数据包分类为实时性数据包和非实时性数据包，实行加权轮询调度保证其服务质量和资源的利用率。仿真结果证明，相比已有小卫星路由算法，优化的路由算法可以有效减小数据传输时延并增加系统吞吐量。     

A Performance Evaluation of a Dynamic Source Routing Discovery Optimization Protocol Using GPS System

Ad hoc networks are useful for providing communication support where no fixed infrastructure exists or the deployment of a fixed infrastructure is not economically profitable, and movement of communicating parties is allowed. Therefore, such networks are designed to operate in widely varying environments, from military networks to low-power sensor networks and other embedded systems. Frequent topology changes caused by node mobility make routing in ad hoc wireless networks a challenging problem. In this paper, we propose an optimization technique, which we refer to as GDSR, a reactive protocol that makes use of DSR scheme and the Global Positioning System (GPS). As opposed to the DSR protocol our GDSR scheme consists of propagating the route request messages only to the nodes that are further away from the query source. We discuss the algorithm, its implementation and present an extensive simulation and experimental results to study its performance. We also present a comparative study of GDSR protocol with the existing DSR protocol. Our results clearly indicate that the GDSR protocol outperforms the DSR protocol by significantly decreasing the number of route query packets thereby increasing the efficiency of the network load. Furthermore, we show that a careful GPS screening angle is an important factor in the success of GDSR ad hoc routing protocol.     

Performance Evaluation of Routing Protocols for Ad Hoc Wireless Networks

A mobile ad hoc network is a collection of autonomous mobile nodes that communicate with each other over wireless links. Such networks are expected to play an increasingly important role in future civilian and military settings, being useful for providing communication support where no fixed infrastructure exists or the deployment of a fixed infrastructure is not economically profitable and movement of communicating parties is possible. However, since there is no stationary infrastructure such as base stations, mobile hosts need to operate as routers in order to maintain the information about the network connectivity. Therefore, a number of routing protocols have been proposed for ad hoc wireless networks. In this paper, we study and compare the performance of the following routing protocols AODV, PAODV (preemptive AODV), CBRP, DSR, and DSDV. A variety of workload and scenarios, as characterized by mobility, load and size of the ad hoc network were simulated. Our results indicate that despite its improvement in reducing route request packets, CBRP has a higher overhead than DSR because of its periodic hello messages while AODV's end-to-end packet delay is the shortest when compared to DSR and CBRP. PAODV has shown little improvements over AODV.     

一种基于WSN时变性与节点剩余能量均衡的机会路由算法

 为了解决数据报文在无线传感网络中动态路由以及网络内各节点剩余能量均衡问题,该文提出了一种机会路由算法。首先,利用热力学第2定律描述数据报文在无线传感器网络中动态路由的传输过程,其中,为了表征网络内各节点状态的时变性以及剩余能量,提出了机会熵模型;其次,以机会熵模型作为选择下一跳节点的理论依据,并结合蚁群优化(ACO)算法,设计并实现了考虑网络中各节点时变性与剩余能量均衡的机会路由算法(ACO for Time Dependent Opportunistic-routing Protocol, ATDOP),使得数据报文在转发过程时,能够有效地选择下一跳节点,从而使网络内各节点的通信资源和能量资源达到负载均衡。最后,通过实验证明,相对于已有的机会路由协议,ATDOP具有报文成功传输率高、网络有效吞吐量大以及网络工作寿命长等优点。     

MANET中基于DSR的一种最小能耗路由协议

如何高效地利用无线节点的有限能量是移动Ad Hoc网络(MANET)路由协议的一个重要考虑因素.鉴于动态源路由协议(DSR)没有考虑节点的能量限制,本文基于DSR协议提出了一种节能路由算法:MECP-DSR.它采用每报文能量消耗最小作为路由选取标准,并且在发送数据报文时对节点的发射功率进行控制.该文的仿真结果表明,MECP-DSR大大降低了节点的能量消耗,有效提高了移动Ad Hoc无线网络的生存期.     

无线传感器网中一种支持固定路由结构的协作机制

针对无线传感器网络中由于衰落信道等原因导致存在大量不可靠的链路,定义了机会节点集,在机会节点集里的节点可以协助完成数据的发送任务.机会节点集的协助机制,一方面利用无线传感网络的节点冗余度大,从而存在节点来协作;另一方面利用了无线信道的广播特性,从而使节点有机会来协助.定义了协助增益来评价协作机制带来的好处,推导出了解析表达式.基于机会节点集的协作机制可以用在大部分现有的路由协议中.仿真表明,采用协作机制后带来的协作增益可达1.18.     

基于网络编码的机会网络高效路由算法

针对采用Epidemic机制的机会网络路由算法在数据分组传送阶段存在通信冗余的问题,提出了一种基于网络编码的高效路由算法--NCBER(network-coding-based epidemic routing）。NCBER在传送数据分组的过程中使用主动异或网络编码和多播,并取消了 Request（请求）控制分组,从而减少数据分组的转发次数和控制分组数量,降低网络开销,缩短分组传输时延。理论分析和仿真结果表明,NCBER 算法在网络开销和数据分组端到端时延性能方面优于经典的Epidemic路由算法及其改进算法MRRMR（message redundancy removal of multi-copy routing）,并且使数据传送成功率保持在100%。     

A Delay-Aware Wireless Sensor Network Routing Protocol for Industrial Applications

With the rapid development of information communication technologies, industrial manufacturing environments and requirements have changed considerably. Since wireless sensor networks have become more and more popular, our production chains have improved with respect to efficiency, flexibility and security. On the other hand, building a secure, robust and fast network is an essential issue for enterprises. In the past, few experts focused on this issue of industrial applications and most of solutions proposed are not suitable for industrial environments. In this paper, we propose a real-time routing protocol for mobile wireless sensor nodes in industrial environments, which offers superior quality of service in terms of delay time. We use geographic routing and information contained in the nodes routing table to extract location information. Then we calculate the node which is nearest to the target node to reduce hop counts and achieve fast data package transfers. It optimizes the packets forwarding hops, which in turn reduces the delay time effectively. We used OPNET to analyze our protocol and results indicate that this algorithm is useful and suitable for wireless sensor networks