A Cross Layer Routing Protocol for Multihop Cellular Networks

We propose a cross-layer routing protocol for a Code Division Multiple Access (CDMA) Multihop Cellular Network (MCN). In designing the routing protocol for MCN, multiple constraints are imposed on intermediate relay node selection and end-to-end path selection. The constraints on relay nodes include willingness for cooperation, sufficient neighbourhood connectivity and the level of interference offered on the path. Path constraints include end-to-end throughput and end-to-end delay. A facile incentive mechanism is presented to motivate the cooperation between nodes in call forwarding. In addition, we present a route resilience scheme in the event of dynamic call dropping. In particular, a fast neighbour detection scheme for route resilience is proposed. Instead of using periodic HELLO messages as in traditional ad-hoc routing, the proposed neighbour detection scheme adopts an explicit handshake mechanism to reduce neighbour detection latency. We conclude the paper by demonstrating the superior performance of the proposed routing protocol compared with the other well known routing algorithms.     

QoS routing based on multi-class nodes for mobile ad hoc networks

In this paper, we present a new quality of service (QoS) routing protocol for mobile ad hoc networks (MANETs). Most of the existing routing protocols assume homogeneous nodes in MANETs, i.e., all nodes have the same communication capabilities and characteristics. However, in many ad hoc networks, nodes are not the same. Some nodes have longer transmission range, larger transmission bandwidth, and are more reliable and robust than other nodes. We take advantage of the non-homogeneous property to design more efficient QoS routing protocol. And node location information is used to aid routing. We also develop a new algorithm to calculate end-to-end bandwidth for a given path. Our QoS routing protocol contains end-to-end bandwidth calculation and bandwidth reservation. QoS route is discovered and setup only when it is needed. Extensive simulation studies demonstrate the good performance of the QoS routing protocol.     

Local Coordination Based Routing and Spectrum Assignment in Multi-hop Cognitive Radio Networks

Although Cognitive Radio technology brings efficient spectrum usage and effective interference avoidance, it also brings new challenges to routing in multi-hop Cognitive Radio Networks. Firstly, spectrum assignment is required for each hop in routing; secondly, new delay is introduced during multi-frequency scheduling and frequency switching in each node; thirdly, the intersecting nodes serving multi-frequency traffic is easy to be bottleneck in neighborhood region. In this paper, we analysis and model the per-node delay and the path delay in multi-hop Cognitive Radio Network. Then we propose a framework of local coordination based routing and spectrum assignment to solve above problems, which consists of one protocol for routing path and one scheme for neighborhood region. A on-demand Routing and Spectrum Assignment Protocol is proposed to exchange the local spectrum information and interact with multi-frequency scheduling in each node. A local coordination scheme is presented to support flow redirection at an intersecting node and distribute heavy multi-frequency workload to its neighborhood. We prove the correctness and effectiveness of the protocol by thorough simulations, and find that the proposed solution provides good adaptability to varying spectrum distribution. The end-to-end delay when adaptive relay is cooperating with routing protocol outperforms traditional bare-routing solutions.     

Cyclic Prefix Update for OFDM Amplify-and-Forward Relay Systems

We consider half-duplex amplify-and-forward (AF) relaying for increasing network coverage and spectrum efficiency of an OFDM-based cellular system. Due to the fact that OFDM symbols are transmitted over two serial multipath channels (i.e., the source-relay link and the relay-destination link) via AF relaying, the time spread of the received signal at destination nodes is introduced by both source-relay and relay-destination channels. Consequently, cyclic prefix (CP) added at the source node should have a much longer length than that of one-hop OFDM transmission to avoid inter-symbol interference. However, the increased CP length leads to the reduced spectrum efficiency of OFDM communications. In this paper, we propose a novel CP update scheme for achieving efficient and reliable multi-hop transmission in OFDM-based AF relay systems. By enabling the additional CP discarding and CP re-adding functionalities to relay nodes, the proposed scheme significantly reduces the required CP length without causing extra loss in the bit error rate performance, and therefore improves achievable end-to-end throughput and spectrum utilization efficiency. Simulation results confirm the theoretical analysis and illustrate the effectiveness of the proposed scheme.     

EAOMDV-MIMC: A Multipath Routing Protocol for Multi-Interface Multi-Channel Mobile Ad-Hoc Networks

Multipath routing has been proposed to improve performance of mobile ad-hoc networks (MANETs). However, due to: (1) nodes lacking of network interface and (2) route coupling, using multiple paths concurrently in conventional single channel MANETs rarely exhibit performance gain. To improve performance, an ad-hoc routing protocol (and its extension) that utilizes multiple homogeneous network interface is proposed in this paper. Unlike other related multi-channel routing protocols, channels are not assigned. Instead, nodes are allowed to make use of all available channels they are tuned to. In the base protocol, nodes estimate channel conditions by monitoring their network interface queues and distribute data packets to different channels and next-hops according to their conditions. In the extended protocol, estimated channel condition at a node is further propagated to neighboring nodes by piggybacking channel condition information in data packets. With overhearing, other nodes can retrieve this information to make better next-hop selections. Extensive simulation studies show that our protocol outperforms other related multi-channel routing protocols.     

Secure Distributed Routing Algorithm with Optimizing Energy Consumption for Cognitive Radio Networks

In cognitive radio networks, the non-cooperative behavior is an inherent security issue. Then it is important to guarantee the support of the cooperation among nodes. In this paper, first the distributed routing problems with optimizing energy use are translated into a 0–1 integer programming problem by analyzing the dynamical power interference among nodes. Secondly, the key allocation about end nodes is devised to realize the confidentiality about data transmission. Thirdly, a secure distributed routing algorithm (SDRA) with energy use is proposed to ensure the security on end-to-end communication. The simulation and analysis show that the energy use for the SDRA is lower than that of the spectrum and energy aware routing protocol. Moreover, the trust mechanism based on Bayesian theorem is more compatible than that of Beta function for distributed routing algorithm in the actual situation.     

A scalable joint routing and scheduling scheme for large-scale wireless sensor networks

The multihop configuration of a large-scale wireless sensor network enables multiple simultaneous transmissions without interference within the network. Existing time division multiple access (TDMA) scheduling schemes exploit gain based on the assumption that the path is optimally determined by a routing protocol. In contrast, our scheme jointly considers routing and scheduling and introduces several new concepts. We model a large-scale wireless sensor network as a tiered graph relative to its distance from the sink, and introduce the notion of relay graph and relay factor to direct the next-hop candidates toward the sink fairly and efficiently. The sink develops a transmission and reception schedule for the sensor nodes based on the tiered graph search for a set of nodes that can simultaneously transmit and receive. The resulting schedule eventually allows data from each sensor node to be delivered to the sink. We analyze our scheduling algorithm both numerically and by simulation, and we discuss the impact of protocol parameters. Further, we prove that our scheme is scalable to the number of nodes, from the perspectives of mean channel capacity and maximum number of concurrent transmission nodes. Compared with the existing TDMA scheduling schemes, our scheme shows better performance in network throughput, path length, end-to-end delay, and fairness index.     

Routing optimization method based on GPCR for vehicular Ad Hoc network

To improve the performance in sparse networks,local optimum,and routing loop in the greedy perimeter coordinator routing (GPCR) protocol,the weighted-GPCR (W-GPCR) protocol was proposed.The relationship between vehicle node routing and other parameters such as the Euclidean distance between node pairs,moving direction and density was profoundly analyzed,the composite parameter weighted model was established and the calculation method was designed for the existing routing problems,the weighted parameter ratio was selected adaptively in different scenarios,so as to obtain the optimal next-hop relay node.In order to verify the performance of the W-GPCR method,the proposed method was compared with the existing methods such as the traditional geographic perimeter stateless routing (GPSR) protocol,GPCR and so on,and the results show that the proposed method is superior to the package delivery ratio,end-to-end delay,and average hop count.     

Hybrid MANET–DTN and a New Algorithm for Relay Nodes Selection

In this paper, a new way to a selection of the secure relay nodes in hybrid MANET–DTN networks based on the cooperation between routing, trust and game theory mechanisms is introduced. The hybrid MANET–DTN enables delivering the data or messages in the situation when communication paths are disconnected or broken and also in the emergency situations. We focus on the situations when MANET routing protocol cannot establish the end-to-end connection between source and destination nodes. In this situation, it is necessary to select relay nodes, that will be able to transport data or messages between isolated islands of mobile terminals with limited connectivity to other terminals. The proposed algorithm enables to select the relay nodes, that will come into contact with other mobile nodes located in different network areas with regards to trust and game theory. The parameter trust is computed for all mobile nodes and relies on a parameter obtained during routing and data transport processes. The game theory provides a powerful tool to select one candidate from a number of possible nodes with respect to confidence and security. Moreover, we propose a new mechanism to compute and select the trusted node, that can be used for transportation of the secure data in this hostile and disconnected environment. In order to verify the functionalities of this mechanism, we implement this mechanism into the OPNET modeler simulation environment and introduce performance analysis.     

无线传感器网络中基于最优转发集的协作式编码传输协议

针对当前大多数据传输协议没有充分利用无线信道的广播特性这一问题,本文提出了基于网络编码的机会路由协议NCOR（Network Coding based Opportunistic Routing protocol）.首先,通过分析网络端到端传输代价,本文提出了最优转发集构造机制以最小化传输代价.此后,NCOR在转发集内执行节点协作式编码传输以保证传输可靠性.最后,理论分析了NCOR的传输可靠性结论.仿真实验表明NCOR可适用于不同的链路环境,且在保证可靠传输的同时,大幅降低了网络能耗.     

MR2_ODMRP: Improvement of End-to-End Transmission Delay in Wireless Multicast Routing

With recent advances in wireless technology, the importance of the capability to use multiple transmission rates and multiple radios has been widely recognized. In this paper, multi-rate and multi-radio (MR2) characteristics are exploited to improve end-to-end transmission delay for reliable multicasts. To achieve this goal, maximum potential rate based on multiple rates and radio based transmission delay with a different number of available radios are investigated in the construction of multicast routes. Multi-rate multi-radio on-demand multicast routing protocol (MR2_ODMRP), a protocol that makes ODMRP suitable for a MR2 environment, is proposed. An integer linear programming model is proposed to obtain the optimal tree as well as the rate and radios at each node of the tree for each multicast service. The solution is employed to evaluate the performance of the MR2_ODMRP. From the simulation, it is shown that the MR2_ODMRP produces nearly optimal solutions even in environments with a large number of nodes. It outperforms the ODMRP in wireless mesh networks. The end-to-end transmission delay is improved by a factor of four compared to the ODMRP.     

A routing protocol based on interference-aware and channel-load in multi-radio multi-channel ad hoc networks

Improving capacity and reducing delay are the most challenging topics in wireless ad hoc networks. Nodes that equip multiple radios working on different channels simultaneously permit effective utility of frequency spectrum and can also reduce interference. In this paper, after analyzing several current protocols in Multi-Radio Multi-Channel (MR-MC) ad hoc networks, a new multichannel routing metric called Integrative Route Metric (IRM) is designed. It takes channel load, interflow, and intra-flow interference into consideration. In addition, an MR-MC routing protocol based on Interference-Aware and Channel-Load (MR-IACL) is also presented. The MR-IACL can assign channels and routings for nodes according to channel load and interference degree of links, and optimize channel distribution dynamically to satisfy the features of topology changing and traffic frequent fluctuation during network running. The simulation results show that the new protocol outperforms others in terms of network throughput, end-to-end delay, routing overhead, and network lifetime.     

认知无线多跳网中结合QoS查找的跨层多信道MAC协议

针对认知无线多跳网中频谱资源具有较大时变性及差异性的问题,设计了一种结合QoS查找的跨层多信道MAC协议。该协议将按需QoS查找与动态频谱分配跨层相结合,仅让参与传输的节点执行频谱分配并按QoS要求获取频谱资源。此外,协议使用频分双工收发机实现了对公共控制信道的不间断监听,并设计了一套支持不同数量收发机节点间混合通信的接入算法。大量仿真结果表明,该协议能有效保证对端到端传输的QoS要求的满足,并显著提高端到端吞吐量及时延。     

A simple void node and loop‐free three‐dimensional routing protocol for multi‐hop wireless networks

Wireless networks are now very essential part for modern ubiquitous communication systems. The design of efficient routing and scheduling techniques for such networks have gained importance to ensure reliable communication. Most of the currently proposed geographic routing protocols are designed for 2D spatial distribution of user nodes, although in many practical scenarios user nodes may be deployed in 3D space also. In this paper, we propose 3D routing protocols for multihop wireless networks that may be implemented in two different ways depending on how the routing paths are computed. When the routing paths to different user nodes from the base station in the wireless network are computed by the base station, we call it centralized protocol (3DMA‐CS). A distributed routing (3DMA‐DS) protocol is implemented when respective routing path of each user node to the base station is computed by the user node. In both of these protocols, the user (base station) selects the relay node to forward packets in the direction of destination, from the set of its neighbours, which makes minimum angle with the reference line drawn from user (base station) to the base station (user), within its transmission range. The proposed protocols are free from looping problem and can solve the void node problem (VNP) of multihop wireless networks. Performance analysis of the proposed protocol is shown by calculating end‐to‐end throughput, average path length, end‐to‐end delay, and energy consumption of each routing path through extensive simulation under different network densities and transmission ranges.     

Avoidance of multicast incapable branching nodes for multicast routing in WDM networks

In this article we study the multicast routing problem in all-optical WDM networks under the spare light splitting constraint. To implement a multicast session, several light-trees may have to be used due to the limited fanouts of network nodes. Although many multicast routing algorithms have been proposed in order to reduce the total number of wavelength channels used (total cost) for a multicast session, the maximum number of wavelengths required in one fiber link (link stress) and the end-to-end delay are two parameters which are not always taken into consideration. It is known that the shortest path tree (SPT) results in the optimal end-to-end delay, but it can not be employed directly for multicast routing in sparse light splitting WDM networks. Hence, we propose a novel wavelength routing algorithm which tries to avoid the multicast incapable branching nodes (MIBs, branching nodes without splitting capability) in the shortest-path-based multicast tree to diminish the link stress. Good parts of the shortest-path-tree are retained by the algorithm to reduce the end-to-end delay. The algorithm consists of tree steps: (1) a DijkstraPro algorithm with priority assignment and node adoption is introduced to produce a SPT with up to 38% fewer MIB nodes in the NSF topology and 46% fewer MIB nodes in the USA Longhaul topology, (2) critical articulation and deepest branch heuristics are used to process the MIB nodes, (3) a distance-based light-tree reconnection algorithm is proposed to create the multicast light-trees. Extensive simulations demonstrate the algorithm’s efficiency in terms of link stress and end-to-end delay.     

Up-Down Links Dualpath Greedy Routing Protocol for Wireless Sensor Networks

Greedy geographic routing is attractive in wireless sensor networks because of its efficiency and scalability. This paper presents an up-down links dualpath greedy routing (UDLDGR) protocol for wireless sensor networks. The routing protocol not only reserves the features of greedy forwarding algorithm, which is simple, efficient, but also uses different relay nodes to serve as routing nodes for up and down routing paths, makes the energy consumption more balanced. The greatest advantage of UDLDGR is it trades off only small cost for the source node to obtain two different transmission paths information. The multipath strengthens the network reliability, such as load balancing and robustness to failures. Our simulation results show that UDLDGR can improve system lifetime by 20–100% compared to single path approaches.     

A link contact duration-based routing protocol in delay-tolerant networks

Delay Tolerant Networks (DTNs) provide message delivery services to users via intermittently connected nodes. In DTNs, routing is one of the most challenging issues since end-to-end connectivity between nodes may not be available most of the time. Although many routing protocols for DTNs have been proposed, they do not achieve satisfactory performance, since they exploit only some of the network characteristics. In this paper, we present a new DTN routing protocol, called the Link Contact Duration-based Routing Protocol (LCD). Like existing protocols, LCD uses the disconnect duration of a link between two nodes to find the routing path with the shortest end-to-end delay. In addition, LCD uses the contact duration of a link and the number of buffered messages to deliver as many messages as possible in a short time. Our simulation results show that LCD has better performance than existing DTN routing protocols.     

An Energy-Aware Routing Protocol for Mobile Ad Hoc Networks Based on Route Energy Comprehensive Index

The design of energy-aware routing protocols has always been an important issue for mobile ad hoc networks (MANETs), because reducing the network energy consumption and increasing the network lifetime are the two main objectives for MANETs. Hence, this paper proposes an energy-aware routing protocol that simultaneously meets above two objectives. It first presents Route Energy Comprehensive Index (RECI) as the new routing metric, then chooses the path with both minimum hops and maximum RECI value as the route in route discovery phase, and finally takes some measures to protect the source nodes and the sink nodes from being overused when their energies are low so as to prolong the life of the corresponding data flow. Simulation results show that the proposed protocol can significantly reduce the energy consumption and extend the network lifetime while improve the average end-to-end delay compared with other protocols.     

A framework for post-disaster communication using wireless ad hoc networks

Disaster management system requires timely delivery of large volumes of accurate messages so that an appropriate decision can be made to minimize the severity. When a disaster strikes, most of the infrastructure for communication gets uprooted. As a result, communication gets hampered. A well designed Internet of things (IoT) can play a significant role in the post-disaster scenario to minimize the losses, and save the precious lives of animals and human beings. In this paper, we have proposed a framework for post-disaster communication using wireless ad hoc networks. The framework includes: (i) a multi-channel MAC protocol to improve the network throughput, (ii) an energy aware multi-path routing to overcome the higher energy depletion rate at nodes associated with single shortest path routing, and (iii) a distributed topology aware scheme to minimize the transmission power. Above proposals, taken together intend to increase the network throughput, reduce the end-to-end delay, and enhance the network lifetime of an ad hoc network deployed for disaster response. A multi-channel MAC protocol permits the transmission from hidden and exposed nodes without interfering with the on-going transmission. We have compared the proposed framework with an existing scheme called Distressnet [1]. Simulation results show that the proposed framework achieves higher throughput, lower end-to-end delay, and an increased network longevity.     

Efficient on-demand routing for mobile ad hoc wireless access networks

In this paper, we consider a mobile ad hoc wireless access network in which mobile nodes can access the Internet via one or more stationary gateway nodes. Mobile nodes outside the transmission range of the gateway can continue to communicate with the gateway via their neighboring nodes over multihop paths. On-demand routing schemes are appealing because of their low routing overhead in bandwidth restricted mobile ad hoc networks, however, their routing control overhead increases exponentially with node density in a given geographic area. To control the overhead of on-demand routing without sacrificing performance, we present a novel extension of the ad hoc on-demand distance vector (AODV) routing protocol, called LB-AODV, which incorporates the concept of load-balancing (LB). Simulation results show that as traffic increases, our proposed LB-AODV routing protocol has a significantly higher packet delivery fraction, a lower end-to-end delay and a reduced routing overhead when compared with both AODV and gossip-based routing protocols.