The self-organizing nature of ad hoc networks is a good aspect in that terminals are not dependent on any infrastructure, that is, networks can be formed with decentralized and autonomous manner according to communication demand. However, this characteristic might affect the performance in terms of stability, reliability and so forth. Moreover, ad hoc networks face a scalability problem, which arise when the number of terminals in a network increases or a physical network domain expands, due to the network capacity limitation caused by the decentralized and the autonomous manner. Regarding this problem, some hierarchical and cluster-based routings have been proposed to effectively manage the networks. In this paper, we apply the concept of hierarchical routing and clustering to opportunistic routing, which can forward packets without using any pre-established path to achieve a path diversity gain with greater reachability. The simulation results show that the proposed method can achieve 11% higher reliability with a reasonable end-to-end delay in dense environments and 30% higher in large-scale networks.

A mobile ad hoc network (MANET) consists of mobile wireless terminals without using base stations. MANETs are expected to be utilized for various purposes such as traffic jam information announcements for vehicles and safety confirmation systems in disaster. Each MANET uses unique routing protocols that have been adapted for particular applications. Therefore, utilizing a common routing protocol for multiple MANETs is difficult. In this paper, we propose an Autonomous Clustering-based Inter-Domain Routing protocol to communicate between MANETs. Using the autonomous clustering, the proposed inter-domain routing scheme can change the network gateways between MANETs adaptively according to the network topology changes.

Route discovery process is a major mechanism in the most routing protocols in Mobile Ad Hoc Network (MANET). Routing overhead is one of the problems caused by broadcasting the route discovery packet. To reduce the routing overhead, the location-based routing schemes have been proposed. In this paper, we propose our scheme called Location-based Routing scheme with Adaptive Request Zone (LoRAReZ). In LoRAReZ scheme, the size of expected zone is set adaptively depending on the distance between source and destination nodes. Computer simulation has been conducted to show the effectiveness of our propose scheme. We evaluate the performances of LoRAReZ scheme in the terms of packet delivery fraction (PDF), routing overhead, average end-to-end delay, throughput, packet collision, average hop count, average route setup time, and power consumption. We compare those performance metrics with those of Location Aided Routing (LAR) and Location Aware Routing Protocol with Dynamic Adaptation of Request Zone (LARDAR) protocols. The simulation results show that LoRAReZ can provide all the better performances among those of LAR and LARDAR schemes.

This paper proposes T-CROM (Time-delayed Collaborative ROuting and MAC) protocol, that allows collaboration between network and MAC layers in order to extend the lifetime of MANETs in a resources-limited environment. T-CROM increases the probability of preventing energy-poor nodes from joining routes by using a time delay function that is inversely proportional to the residual battery capacity of intermediate nodes, making a delay in the route request (RREQ) packets transmission. The route along which the first-arrived RREQ packet traveled has the smallest time delay, and thus the destination node identifies the route with the maximum residual battery capacity. This protocol leads to a high probability of avoiding energy-poor nodes and promotes energy-rich nodes to join routes in the route establishment phase. In addition, T-CROM controls the congestion between neighbors and reduces the energy dissipation by providing an energy-efficient backoff time by considering both the residual battery capacity of the host itself and the total number of neighbor nodes. The energy-rich node with few neighbors has a short backoff time, and the energy-poor node with many neighbors gets assigned a large backoff time. Thus, T-CROM controls the channel access priority of each node in order to prohibit the energy-poor nodes from contending with the energy-rich nodes. T-CROM fairly distributes the energy consumption of each node, and thus extends the network lifetime collaboratively. Simulation results show that T-CROM reduces the number of total collisions, extends the network lifetime, decreases the energy consumption, and increases the packet delivery ratio, compared with AOMDV with IEEE 802.11 DCF and BLAM, a battery-aware energy efficient MAC protocol.

Many people have faced mortal risks due to sudden disasters such as earthquakes, fires, and terrorisms, etc. In disasters where most people become panic, it is important to grasp disaster positions immediately and to find out some appropriate evacuation routes. We previously proposed the specific evacuation support system named as Emergency Rescue Evacuation Support System (ERESS). ERESS is based on Mobile Ad-hoc network (MANET) and aims to reduce the number of victims in panic-type disasters. This system consists of mobile terminals with advanced disaster recognition algorithm and various sensors such as acceleration, angular velocity and earth magnetism. However, the former ERESS did not have the clear criteria to detect the disaster outbreak. In this paper, we propose a new disaster recognition algorithm by Support Vector Machine (SVM) which is a kind of machine learning. In this method, an ERESS mobile terminal learns the behaviors of its holder by SVM. The SVM acquires the decision boundary based on the sensing data of the terminal holder, and it is judged whether to be the emergency. We show the validity of the proposed method by panic-type experiments.

Establishing peer-to-peer (P2P) live streaming for mobile ad hoc network (MANET) requires an efficient scheme to deliver the real-time data in the infrastructure-less disaster environment. However, P2P membership management is difficult in the dynamic mobility and resource limited MANET. In this paper, we present a cross-layer design for P2P-MANET which integrates P2P DHT-based routing protocol and IPv6 routing protocol. Therefore, the proposed scheme can manage and recover the P2P overlay as well as selecting efficient routing path to multicast video streaming. The simulation results demonstrate that the proposed scheme performs relatively better than the layered approach or the off-the-shelf design in terms of the playback continuity and signaling overhead.

In the infrastructure-less disaster environment, the application of the peer-to-peer (P2P) group conference over mobile ad hoc network (MANET) can be used to communicate with each other when the rescue crews search the survivors but work separately. However, there still are several problems of in-time multimedia delivery in P2P-MANET: (1) MANET mobility influences the maintenance of P2P overlay. (2) P2P overlay is not proximal to MANET topology, this leads to the inefficient streaming delivery. (3) The unreliable wireless connection leads to the difficulty of multi-source P2P group conferencing. Therefore, P2P conferencing cannot work well on MANET. To overcome the above disadvantages, in this paper, we present a cross-layer P2P group conferencing mechanism over MANET, called RING (Real-time Intercommunication Network Gossip). The RING uses the ring overlay to manage peers and utilizes the cross-layer mechanism to force the ring overlay to be proximal to MANET topology. Therefore, RING can lead efficient in-time multimedia streaming delivery. On the other hand, the ring overlay can deal with peer joining/leaving fast and simply, and improves the delivery efficiency with the minimum signaling overhead. Through mathematical theory and a series of experiments, we demonstrate that RING is workable and it can shorten the source-to-end delay with minimal signaling overhead.

The future wireless mobile communication networks are expected to provide seamless wireless access and data exchange to mobile users. In particular, it is expected that the demand for ubiquitous data exchange between mobile users will increase with the widespread use of various wireless applications of the intelligent transportation system (ITS) and intelligent vehicles. Mobile ad hoc networks (MANETs) are one of the representative research areas pursuing the technology needed to satisfy the increasing mobile communication requirements. However, most of the works on MANET systems do not take into account the continuous and dynamic changes of nodal mobility to accommodate system design and performance evaluation. The mobility of nodes limits the reliability of communication between the source and the destination node since a link between two continuously moving nodes is established only when one node enters the transmission range of the other. To alleviate this problem, mobile relay has been studied. In particular, it is shown that relay selection is an efficient way to support nodal mobility in MANET systems. In this paper, we propose a mobility-based relay selection algorithm for the MANET environment. Firstly, we define the lifetime as the maximum link duration for which the link between two nodes remains active. Therefore, the lifetime indicates the reliability of the relay link which measures its capability to successfully support relayed communication when requested by the source node. Furthermore, we consider a series of realistic scenarios according to the randomness of nodal mobility. Thus, the proposed algorithm can be easily applied in practical MANET systems by choosing the appropriate node mobility behavior. The numerical results show that the improved reliability of the proposed algorithm's relayed communication is achieved with a proper number of mobile relay nodes rather than with the conventional selection algorithm. Lastly, we show that random mobility of the individual nodes enhances reliability of the network in a sparse network environment.

In this letter, we investigate the performance impact of disjoint multiple paths on SCTP in the connected MANET under emergency situations. Disjoint multiple paths allow multi-homing of SCTP to be fully utilized in MANETs, but it may cause inappropriate SACK handling. Through simulations, we evaluate the impact in terms of throughput and energy efficiency.

A MANEMO node is an IP-based mobile node that has interface attachments to both a mobile network, using Network Mobility (NEMO), and a Mobile Ad Hoc Network (MANET). While communicating with a correspondent node in the Internet, the MANEMO node should use the best possible path. Therefore, as conditions change, a handover between NEMO and MANET is desirable. This paper describes the operation of a MANEMO handover when IEEE 802.11 is used. An analytical model illustrates that packet loss during a MANEMO handover may severely affect data and real-time applications. We therefore propose using buffering during the handover, by making use of the Power Save Mode in IEEE 802.11. In the proposed algorithm, a MANEMO node may rapidly switch between the two interfaces, eventually receiving packets delivered via the old network interface while initiating the Mobile IP/NEMO handover on the new interface. Performance results show that packet loss can be significantly reduced, with small and acceptable increases in signalling overhead and end-to-end delay.

In this paper, we propose a framework of connectivity analysis for aviation ad hoc networks on flight paths. First, a general analytical connectivity model for the common one-dimensional ad hoc network is newly developed. Then it is applied for modeling the connectivity of ad hoc networks among aircraft along flight paths where aircraft arrival process follows a Poisson distribution. Connectivity is expressed in terms of connectedness probability of two nodes in the network, connected distance, and network coverage extension factor. An exact closed form derivation of connectedness probability is proposed. The radical effect of mobility on the network connectedness of aircraft over a single flight path is analyzed. The network connectedness probability depends on node density and node distribution, which are derived from node arrival rate and node velocity. Based on these results, the proposed model is extended to the practical case of paths with multi-velocity air traffic classes. Using this model, the critical values of system parameters for the network of aircraft with certain connectivity requirements can be derived. It helps to evaluate network extension capability under the constraints of various system parameters.

Network Coding (NC) can improve the information transmission efficiency and throughput of data networks. Random Linear Network Coding (RLNC) is a special form of NC scheme that is easy to be implemented. However, quantifying the performance gain of RLNC over conventional Store and Forward (S/F)-based routing system, especially for wireless network, remains an important open issue. To solve this problem, in this paper, based on abstract layer network architecture, we build a dynamic random network model with Poisson distribution describing the nodes joining the network randomly for tree-based single-source multicast in MANET. We then examine its performance by applying conventional Store and Forward with FEC (S/F-FEC) and RLNC methods respectively, and derive the analytical function expressions of average packet loss rate, successful decoding ratio and throughput with respect to the link failure probability. An experiment shows that these expressions have relatively high precision in describing the performance of RLNC. It can be used to design the practical network coding algorithm for multi-hop multicast with tree-based topology in MANET and provide a research tool for the performance analysis of RLNC.

Mobile Ad Hoc Networks (MANETs) offer quick and easy network deployment in situations where it is not possible otherwise and they can be used to provide mobile users with a temporary infrastructure to use services in the absence of fixed infrastructure. Nodes in MANETs are free to move and organize themselves in an arbitrary fashion. The challenging task in such dynamic environments is how to improve the service availability. Replicating a service at some nodes distributed across the network is an effective strategy. However, service replication can considerably impact the system energy consumption. Since mobile devices have limited battery resources, a dynamic and efficient service replication is necessary to support such environments. In this paper, we propose a distributed service replication scheme for achieving high service availability with reasonable energy consumption for MANETs. The proposed method called HDAR (Highly Distributed Adaptive Service Replication) divides the whole network into disjoint zones of at most 2-hops in diameter and builds a dynamic replication mechanism which selects new replica zones depending on their service demand and the tradeoff between the communication and replication energy consumption costs. Through simulations, we confirmed that our approach can achieve higher service availability with reasonable energy consumption than existing methods.

Many people have suffered and died due to a lot of large-scale disasters such as earthquake, fire, and terrorism, etc. In disasters where most evacuators become panic, two things are necessary for their immediate evacuation. The first is to estimate the location of the disaster occurrence. The second is to construct an evacuation support system that searches for safe and efficient evacuation routes. In this paper, we propose Emergency Rescue Urgent Communication -- Evacuation Support System (EUC-ESS) based on Mobile Ad-hoc networks (MANET) composed of many mobile terminals. Using experiments and computer simulations, we show that this system would support evacuators in determining appropriate routes for survivors.

Recently, the importance of data sharing structures in autonomous distributed networks has been increasing. A wireless sensor network is used for managing distributed data. This type of distributed network requires effective information exchanging methods for data sharing. To reduce the traffic of broadcasted messages, reduction of the amount of redundant information is indispensable. In order to reduce packet loss in mobile ad-hoc networks, QoS-sensitive routing algorithm have been frequently discussed. The topology of a wireless network is likely to change frequently according to the movement of mobile nodes, radio disturbance, or fading due to the continuous changes in the environment. Therefore, a packet routing algorithm should guarantee QoS by using some quality indicators of the wireless network. In this paper, a novel information exchanging algorithm developed using a hash function and a Boolean operation is proposed. This algorithm achieves efficient information exchanges by reducing the overhead of broadcasting messages, and it can guarantee QoS in a wireless network environment. It can be applied to a routing algorithm in a mobile ad-hoc network. In the proposed routing algorithm, a routing table is constructed by using the received signal strength indicator (RSSI), and the neighborhood information is periodically broadcasted depending on this table. The proposed hash-based routing entry management by using an extended MAC address can eliminate the overhead of message flooding. An analysis of the collision of hash values contributes to the determination of the length of the hash values, which is minimally required. Based on the verification of a mathematical theory, an optimum hash function for determining the length of hash values can be given. Simulations are carried out to evaluate the effectiveness of the proposed algorithm and to validate the theory in a general wireless network routing algorithm.

Next generation network characteristics increase the complexity in the design and provision of advanced services, making inappropriate the selection of traditional approaches. Future networks are becoming larger in scale, more dynamic and more heterogeneous. In order to cope with these requirements, services are expected to adapt to environmental conditions and require minimum human intervention. In this paper a new model for providing autonomous and decentralized services is proposed, especially focusing on mobile ad hoc networks (MANETs). Using a newly proposed four-layered approach, service development may be realized independently from the underlying physical network. In a reference implementation, it is demonstrated that it is possible to set up an overlay network that hides any network changes from the service layer. Multiple mechanisms have been adapted in order to efficiently -- in terms of message exchanges and convergence time -- operate over an ad hoc environment. Finally, it is demonstrated that a specific service could operate over a dynamic network with multiple failures.

The usage of light-weight mobile devices is increasing rapidly, leading to demand for more telecommunication services. Consequently, mobile ad hoc networks and their applications have become feasible with the proliferation of light-weight mobile devices. Many protocols have been developed to handle service discovery and routing in ad hoc networks. However, the majority of them did not consider one critical aspect of this type of network, which is the limited of available energy in each node. Cluster Based Routing Protocol (CBRP) is a robust/scalable routing protocol for Mobile Ad hoc Networks (MANETs) and superior to existing protocols such as Ad hoc On-demand Distance Vector (AODV) in terms of throughput and overhead. Therefore, based on this strength, methods to increase the efficiency of energy usage are incorporated into CBRP in this work. In order to increase the stability (in term of life-time) of the network and to decrease the energy consumption of inter-cluster gateway nodes, an Enhanced Gateway Cluster Based Routing Protocol (EGCBRP) is proposed. Three methods have been introduced by EGCBRP as enhancements to the CBRP: improving the election of cluster Heads (CHs) in CBRP which is based on the maximum available energy level, implementing load balancing for inter-cluster traffic using multiple gateways, and implementing sleep state for gateway nodes to further save the energy. Furthermore, we propose an Energy Efficient Cluster Based Routing Protocol (EECBRP) which extends the EGCBRP sleep state concept into all idle member nodes, excluding the active nodes in all clusters. The experiment results show that the EGCBRP decreases the overall energy consumption of the gateway nodes up to 10% and the EECBRP reduces the energy consumption of the member nodes up to 60%, both of which in turn contribute to stabilizing the network.

In OLSR (Optimized Link State Routing Protocol), the multipoint relay mechanism has been introduced to minimize routing overhead for flooding control traffic. In order to achieve as low a routing overhead as possible, the selection of MPRs (multipoint relays) is designed to limit the overall number of such relays in the network. OLSR provides the shortest paths in terms of hops; however, it does not take into account the QoS (quality of service) requirements. Therefore, QOLSR (Quality OLSR), which adds a QoS extension to the OLSR, has been proposed. Although QOLSR provides the best QoS path, its selection process does not consider the number of MPRs, which causes an increase in the routing overhead. In this paper, we focus on the selection process of MPRs in link state QoS routing protocol. We propose three heuristics for high-efficiency selections: MIMS, MQES, and MCIS. The basic approach of these selections is to determine a smaller set of MPRs that provide better QoS paths between any two nodes. The main objective in doing so is to maximize the QoS effect while limiting the routing overhead. In addition, we evaluate the performance of the routing protocols with the proposed selections by simulation. The results indicate that MIMS and MCIS achieve high-efficiency selection; as compared to QOLSR, MIMS reduces the maintenance cost by 30%, while the throughput of the resultant path is decreased by 13%, and MCIS reduces the cost by 21% without any decrease in the throughput.

This paper proposes a scheme to select an appropriate gateway based on multiple metrics such as remaining energy, mobility or speed, and number of hops in Mobile Ad Hoc Network (MANET) and the infrastructure network integration. The Multiple Criteria Decision Making (MCDM) method called Simple Additive Weighting (SAW) is used to rank and to select the gateway node. SAW method calculates the weights of gateway node candidates by considering these three metrics. The node with the highest weight will be selected as the gateway. Simulation results show that our scheme can reduce the average energy consumption of MANET nodes, and improve throughput performance, gateway lifetime, Packet Delivery Ratio (PDR) of the MANET and the infrastructure network.

Ad-Hoc networks are collections of mobile nodes communicating using wireless media without any fixed infrastructure. Minimal configuration and quick deployment make Ad-Hoc networks suitable for emergency situations like natural disasters or military conflicts. The current Ad-Hoc networks can only support either high mobility or high transmission rate at a time because they employ static approaches in their routing schemes. However, due to the continuous expansion of the Ad-Hoc network size, node-mobility and transmission rate, the development of new adaptive and dynamic routing schemes has become crucial. In this paper we propose a new routing scheme to support high transmission rates and high node-mobility simultaneously in a big Ad-Hoc network, by combining a new proposed packet-pheromone-based approach with the Hint Based Probabilistic Protocol (HBPP) for congestion avoidance with dynamic path selection in packet forwarding process. Because of using the available feedback information, the proposed algorithm does not introduce any additional overhead. The extensive simulation-based analysis conducted in this paper indicates that the proposed algorithm offers small packet-latency and achieves a significantly higher delivery probability in comparison with the available Hint-Based Probabilistic Protocol (HBPP).