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.

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.

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.

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 a multi-hop mobile ad-hoc network, broadcasting is an elementary operation to support many applications. Broadcasting by flooding may cause serious redundancy, contention, and collision in the network, which is referred to as the broadcast storm problem. Many broadcasting schemes have been proposed to give better performance than simple flooding in mobile ad-hoc network. How to decide whether rebroadcast or not also poses a dilemma between reachability and efficiency under different host densities. In this paper, we propose an enhanced broadcasting scheme, which can reduce rebroadcast packets without loss of reachability. Simulation results show that the proposed scheme offers better reachability and efficiency than other previous schemes.

We propose an efficient reachability estimation scheme for group membership services in mobile ad hoc networks (MANETs). The periodical message exchange-based scheme, i.e., a typical reachability estimation scheme, requires message exchanges even when the reachability status does not change. It is presumed that the reachability between nodes is maintained while the nodes move around in a limited range. The proposed scheme exploits a virtual grid for the course-grained estimation. A region in the virtual grid can be used to represent the movement range which does not change the reachability. Each node calculates how long it will stay in a region, and issues the duration information only when it gets out of the current region.

Video multicast over wireless medium has gained increasing popularity in a wide range of applications, such as video-on-demand and group video conferencing. With mobile ad hoc networks emerging as a promising solution for future ubiquitous communications, supporting reliable video multicast over mobile ad hoc networks is a timely research topic. In this paper we tackle this issue by using multiple tree multicast routing protocol. Specifically, we introduce an extension to the Multicast Ad Hoc On-demand Distance Vector (MAODV) routing protocol to construct two optimally disjoint trees in a single routine. The extended protocol is called Multiple Tree Multicast Ad Hoc On-demand Distance Vector (MT-MAODV) routing protocol. In order to distribute the video evenly and independently between these disjoint trees, the Multiple Description Coding (MDC) scheme is used for video coding. Simulation shows that the proposed protocol demonstrates video multicast with better quality than the conventional video multicast using a single tree only.

It is predicted that there will be a high demand for video applications in future wireless networks including wireless ad hoc networks. However, supporting video applications over mobile ad hoc networks is more complicated than with other networks due to the lack of support from a preinstalled infrastructure. In this paper, we tackle this problem by adopting the concept of multipoint-to-point video transmission used in wire-line networks. A novel framework designed with features to accommodate the characteristics of ad hoc networks is presented. There are two key features in our proposal. First, Multiple Description Coding (MDC) scheme is used for video coding to reduce the redundancy by avoiding the transmission of duplicate video frames. Second, the routing protocol is expanded to include finding disjoint routes from video sources to the receiver so that a single link breakage or a single intermediate node failure affects transmission from only the minimum number of nodes. Furthermore, the use of disjoint routes also enables the workload to be distributed more evenly within the network. A simulation study was carried out using NS-2 to demonstrate the performance of the proposed mechanism. We show that the proposed mechanism outperforms conventional point-to-point transmission, especially under conditions of high mobility.

In this paper, we propose SDRP: a new service discovery protocol combined with routing policies in MANETs. The protocol is performed upon a distributed network. We describe a service by a unique ID number and use a group-cast routing policy in advertisement and request. In addition, the nodes included in the reply path also cache the advertisement information. We compare SDRP with both Flood and MAODV in terms of overload, and average delay. Simulation results show SDRP can spend less response time and accommodate even high mobility network environments.