A Novel Scalable Multicast Mesh Routing Protocol for Mobile ad hoc Networks

In recent years the use of portable and wireless equipment is becoming more widespread, and as in many situations communication infrastructure might not be available, wireless networks such as Mobile Ad Hoc Networks (MANETs) are becoming increasingly important. A mobile ad hoc network is a collection of nodes that exchanges data over wireless paths. The nodes in this network are free to move at any time, therefore the network topology changes in an unpredictable way. Since there is no fixed infrastructure support in mobile ad hoc networks, each node functions as a host and a router. Due to mobility, continuous change in topology, limited bandwidth, and reliance on batteries; designing a reliable and scalable routing protocol for mobile ad hoc networks is a challenging task. Multicast routing protocols have been developed for routing packets in mobile ad hoc networks. Existing protocols suffer from overheads and scalability. As the number of senders, groups, and mobility speed increases, the routing overhead and the packet collision increases, and therefore the packet delivery ratio decreases. Thus none of the existing proposed multicast routing protocols perform well in every situation. In this study a novel multicast routing protocol for ad hoc networks is proposed. It is an efficient and scalable routing protocol, and named Network Sender Multicast Routing Protocol (NSMRP). NSMRP is a reactive mesh based multicast routing protocol. A central node called mesh sender (MS) is selected periodically from among the group(s) sender(s) to create one mesh in order to be used in forwarding control and data packets to all multicast group(s) member(s). One invitation message will be periodically flooded to all group(s) member(s) by MS to join the group(s). The proposed routing protocol is evaluated by simulation and compared with a well known routing protocol. The results are analyzed and conclusions are drawn

TDMAとDCFの組み合わせによるアドホックネットワーク上でのQoS通信の実現方式

　An ad hoc network does not rely on the fixed network infrastructure; it uses a distributed network management method. With the popularity of the smart devices, ad hoc network has received more and more attention, supporting QoS in ad hoc network has become inevitable. Many researches have been done for provision of QoS in ad hoc networks. These researches can be divided into three types.　The first type is contention-based approach which is the most widely used. IEEE 802.11e MAC (media access control) protocol belongs to this type which is an extension of IEEE 802.11 DCF(Distributed Coordination Function). It specifies a procedure to guarantee QoS by providing more transmission opportunities for high priority data. However, since IEEE 802.11eis designed based on the premise that access points are used, when the number of QoS flows increases, packet collisions could occur in multi-hop ad hoc network.　The second type is using TDMA-based approach. The TDMA approach can provide contention-free access for QoS traffics through the appropriate time slot reservation. The current TDMA approaches reserve time slots for both QoS traffics and best-effort traffics. However, it is difficult for TDMA as the only approach to allocating channel access time for best-effort traffics sincet he required bandwidth of the best-effort traffics changes frequently.　We propose a QoS scheme, which takes advantage of both contention-based approach and TDMA-based approach. In the proposed scheme, contention-based approach DCF provides easy and fair channel time for best-effort traffics, and TDMA approach serves the QoS traffics. A time frame structure is designed to manage the bandwidth allocation. A time frame is divided into two periods, specifically the TDMA periods and the DCF periods. The proportion of two periods is decided by QoS traffics. Therefore the QoS traffics are given absolutely higher priority than best-effort traffics. In order to guarantee the transmission of each QoS packet in TDMA period, a time slot assignment algorithm based on QoS data rate has been proposed. The proposed scheme also employs an admission control scheme, which rejects the new QoS user when the channel capacity is reached. In addition, we provide the configuration of the proposed scheme in the mobile environment. The procedures are designed for route changes and new-adding users. 　The proposed scheme is simulated in the QualNet simulator. In the static environment, the performance of the proposed scheme is evaluated in the case of a gradual increase in the number TCP flows and in the case of gradual increase in QoS data rate. Simulation results show that in the static environment the proposed scheme can not only provide effective QoS performance, but also can provide good support for best-effort flows. In the mobile environment, we simulated the performance of the proposed scheme at different moving speed (maximum is 5 Km/h) when the ARF (Auto Rate Fallback) is available. From the simulation results, in a specific mobile environment, the proposed scheme can support the QoS transmission well.電気通信大学201

HF-DSR: dynamic source routing for high frequency radio networks

HF-DSR is an ad hoc routing protocol designed to operate efficiently over high frequency (HF) radio networks. Ad hoc routing protocols allow networks to provide dynamic routing between endpoints. In contrast, static routing schemes require networks to be configured with potential routes in advance. As such, ad hoc routing mechanisms can compensate for unanticipated factors such as radio frequency (RF) interference or node mobility. HF-DSR is largely based on Dynamic Source Routing (DSR), a level 3 ad hoc networking protocol that emits network control information on demand. HF-DSR incorporates portions of DSR which minimize the quantity of control information transmitted. In this manner, as much network bandwidth as possible is conserved for user-initiated data transfers. During this project, an implementation of HF-DSR was developed to operate over the NATO standard STANAG 5066 data transfer protocol. A four node network was assembled using Microsoft Windows PCs, HF modems, HF radios, synchronous RS-232 interfaces, and Harris RF-6750W Wireless Gateways. Two different network topologies were constructed using the four nodes. Finally, HF-DSR route discovery and file transfer were exercised on both network topologies

RoMR: Robust Multicast Routing in Mobile Ad-Hoc Networks

Support for multicast services is crucial for mobile ad-hoc networks (MANETs) to become a viable alternative to infrastructured networks. Efficient multicasting in MANETs faces challenges not encountered in other types of networks such as the mobility of nodes, the tenuous status of communication links, limited resources, and indefinite knowledge of the network topology. This thesis addresses these challenges by providing a framework and architecture with proactive and reactive components to support multicasting in MANETs emphasizing reliability and efficiency of end-to-end packet delivery. The architecture includes the Robust Multicast Routing protocol (RoMR) to provide multicast services to multicast applications. RoMR's proactive component calculates multiple multicast trees based on the prediction of future availability of the links and the assumption that the trees will become disconnected over time. The reactive components respond to changes in the network topology due to the mobility of the nodes and to changes in the multicast group's membership. Sending redundant data packets over multiple paths further enhances the reliability at the cost of an increase in the use of network resources. RoMR uses approximations to Steiner trees during tree formation and forward error correction encoding techniques during packet transmission in order to counteract this increase. To avoid additional network traffic, trees are distributed only when the existing trees cannot be easily patched to accommodate changes in topology or group membership. The novelty of the proposed protocol stems from integrating techniques that have not previously been combined into a multicasting protocol and a unique method to calculate the relative weights of the links. In addition to the specifications of the protocol, a simulation framework was developed to test different implementations of the various components of RoMR. Simulations compared the performance of the basic version of RoMR to a version that ignored link weights, and to a link-state multicast protocol currently being considered by the Internet Engineering Task Force. A statistical analysis of the results showed that RoMR performed better overall, than the other two protocols

Routing in multi-hop Ad Hoc networks: an Experimental Approach

In this thesis we investigate the efficiency of routing protocols for Mobile Ad Hoc networks (MANETs) by adopting an experimental approach. MANET routing protocols have been mainly evaluated through simulations which often introduce simplifying assumptions (e.g., radio propagation model) and mask important real characteristics. To avoid these modeling approximations, it is necessary to complement simulation with experiments on real MANETs. This work provides a contribution in this direction reporting our experiences learned by these real measurements. By setting up MANET prototypes, firstly we investigate IEEE 802.11 behavior in single­hop MANETs, secondly we focus on an innovative analysis of routing protocols in multi­hop MANETs by varying scenarios. To the best of our knowledge, our medium­scale scenario composed of 23 nodes represents one of the largest MANET testbed. Our experimental results highlight that, in contrast with MANET community, by using proactive routing protocols the overall system gains in scalability, performance and efficiency. These results encourage us identifying in this last class Hazy Sighted Link State (HSLS) as a more suitable protocol. A further contribution of this thesis is hence to design, develop and test an enhanced version of HSLS, strengthened with a mechanism to guarantee the reliability of LSU packets without additional control overhead, and a module to support middleware-network interactions as proposed by the MobileMAN project (EUIST-FP5-FET-Open-IST-2001-38113)

The improvements in ad hoc routing and network performance with directional antennas

The ad hoc network has typically been applied in military and emergency environments. In the past decade, a tremendous amount of MAC protocols and routing protocols have been developed, but most of these protocols are designed for networks where devices equipped with omni-directional antennas. With fast development of the antenna technology, directional antennas have been proposed to improve routing and network performance in ad hoc networks. However, several challenges and design issues (like new hidden terminal problem, deafness problem, neighbor discovery problem and routing overhead problem) arise when applying directional antennas to ad hoc networks, consequently a great number of directional MAC and routing protocols have been proposed. In this thesis the implementation of directional antennas in ad hoc networks is studied from technical point of view. This thesis discusses the problems of utilizing directional antenna in ad hoc networks and reviews several recent proposed MAC algorithms and routing algorithms. The improvement of ad hoc routing and network performance with directional antennas compared with omni-directional antennas are evaluated based on simulations which are done with the QualNet simulator. The main finding of this study is that directional antennas always outperform omni-directional antennas in both static and mobility scenarios, and the advantage of directional antennas is more obvious when channel condition becomes worse or mobility level is larger. This thesis provides a survey of directional MAC and routing protocols in ad hoc networks. The result and principles obtained in this thesis are quite valuable for researchers working in this field. They can use it as reference for further researches. The theory parts of smart antenna technology and IEEE 802.11 MAC protocol can be considered as a technical introduction for beginners

A Study of Routing Protocols for Ad-Hoc Network Based on Named Data Networking

電気通信大学202