Robust Distributed TOA-Based Localization for Multi-Hop MANET

This paper presents an intelligent early packet discard (I-EPD) for RTP-based video streaming over a multi-hop MANET (mobile ad hoc network). In a multi-hop MANET, the quality of transferring real-time video streams could be seriously degraded, since every intermediate node (IN) functionally like forwarding device does not possess large buffer and sufficient bandwidth. Even worse, a selected forwarding node could leave or power off unexpectedly which breaks the route to destination. Thus, a video packet temporarily buffered in ad hoc nodes may exceed its end-to-end jitter constraint when either a congested or failed link occurs; a stale video packet is useless even if it can reach destination after network traffic becomes smooth or failed route is reconfigured. In the proposed I-EPD, an IN can intelligently determine whether a buffered video packet should be discarded based on an estimated time constraint which is calculated from the RTP timestamps and the round trip time (RTT) measured by RTCP For the purpose of validation, we implement the I-EPD scheme on a Linux-based embedded system to demonstrate that with I-EPD buffer utilization on IN can be more effective and unnecessary bandwidth wastage can be avoided.

The TCP protocol exhibits poor performance in multi-hop Mobile Ad Hoc Networks (MANETs). The ultimate reason for this is that MANETs behave in a significantly different way from traditional wired networks (like the Internet) for which the TCP protocol was originally designed. In particular, route failures and route changes due to node mobility may be frequent events in MANETs. Furthermore, congestion phenomena in MANETs are essentially different from traditional wired networks. In this paper we propose a novel transport protocol for MANETs. Unlike other proposals, our protocol is not a modification of the TCP but is specifically tailored to the characteristics of the MANET environment. It is able to manage efficiently route changes and route failures. Furthermore, it includes a completely re-designed congestion control mechanism. Finally, it is designed in such a way to reduce as much as possible the number of useless retransmissions. This is extremely important since retransmissions consume energy.KeywordsAd Hoc NetworksMobilityTransport ProtocolsTCP

Reputed Packet Delivery Using Efficient Audit Misbehaviour Detection and Monitoring Method in Mobile Ad Hoc Networks

We propose a routing mechanism with distributed Call Admission Control (CAC) algorithms for Mobile Ad hoc Networks (MANET) based on IEEE 802.11e EDCA MAC protocol. A new flow can be admitted by the network only if it can find a path to sustain its traffic. Bloom filter is used here to detect the flows via each node, and the CAC routing decisions are made according to the number of flows of each node. Simulation results show that with our distributed CAC algorithm, the existing flows can be well protected in multi-hop MANET; the new added flows can make good use of the bandwidth resources without affecting the neighbor flows. Due to the space-efficient character of Bloom filter, it can be properly used in MANET, whose nodes have limited storage space and computational ability.

Clock synchronization is very important for power management protocol in a multi-hop MANET. However, since MANET is a network temporarily formed by a collection of mobile nodes without the aid of any centralized coordinator, clock synchronization is very difficult to achieve. Therefore, most of previous works on power efficiency assumed asynchronous clock. As a consequence, a mobile node will waste a lot of power and time waiting for forwarding a packet to its neighbors, due to the lack of information of wakeup times of its neighbors. In this paper, we propose a multi-hop time synchronization protocol, referred to as MTSP, for multi-hop MANETs based on IEEE 802.11 ad hoc mode. The MTSP consists of two phases: beacon window (BW) phase and synchronization (SYN) phase. In BW phase, several devices, which can directly communicate with each others, form a synchronization group. And each group selects the device with fastest timer as the leader node of the group. In SYN phase, leader nodes then synchronize with each other. Our simulation results show that MTSP is a distributed and effective multi-hop time synchronization protocol, especially for dense networks.KeywordsIEEE 802.11mobile ad hoc network (MANET)multi-hoptime synchronization

Trust and reputation systems play an important role in collaborative operations in mobile ad hoc networks. However, the security of trust and reputation system itself is threatened by the existence of selfish nodes. Selfish nodes can make passive attacks on the foundational process of trust and reputation system, the recommendation acquisition, through non cooperation of packet forwarding and recommendation rendering. Existing trust and reputation systems commonly suffer from vulnerability caused by the failure of recommendation acquisition which refers to the unsuccessful recommendation information obtaining from one node to another node. A credit-based mechanism is proposed to address this problem by offering credits as incentives to both intermediate nodes and recommendation render nodes. Furthermore, competition between selfish nodes is explored to prevent selfish nodes being paid excessive credits. Simulation results show that the proposed mechanism can effectively improve the success rate of recommendation acquisition and lower the total paid payoffs.

A packet control mechanism via a cross-layer feedback to reduce bursts of packet drops for transmission of video over mobile multihop ad-hoc networks is presented. With this approach, the application layer would be capable of controlling the packet transmission flow in accordance with the multihop characteristics of the routing layer.

This paper proposes a mathematical framework to model and analyze the energy consumption of routing protocols in multihop wireless networks such Mobile Ad Hoc Networks (MANETs) or Sensor Networks (WSNs) by taking into account the protocol parameters, the traffic pattern and the network characteristics defined by the medium channel properties, the dynamic topology behavior, the network diameter and the nodes density. Moreover, our framework allows to classify routing protocols by exploring the relationship between application requirements and wireless network features. To the best of our knowledge, there is no such proposed framework that provides in-depth an analytical investigation of above relationship. We apply this model to a Beacon-less routing protocol Pizza-Forwarding (PF) compared to well known routing protocols such as Optimized Link State Routing, Ad Hoc On Demand Distance Vector Routing, Greedy Perimeter Stateless Routing and a Simple Random Walk Routing in order to underline their behavior according to the network features and application requirements. Finally, we show that Beacon-less routing protocol should be a best candidate to save energy in WSNs.

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> Accurate localization of nodes in a sensor network is a crucial step before the sensor network can be utilized for various applications. This paper proposes a successive estimation method to self-localize the sensor nodes using time of arrival (TOA) measurements, through the aid of a few anchor nodes whose positions are known <emphasis emphasistype="italic">a priori</emphasis>. The successive nature of the proposed algorithm makes it attractive for distributed computation in a resource constrained environment. The proposed technique uses subsets of TOAs to obtain coarse sensor node estimates. Depending on available computation and transmission resources, the node positions are refined to improve their accuracies. The solution of the proposed node localization algorithm is algebraic and closed-form, which simplifies computation and avoids possible local convergence or divergence problems as in the traditional iterative approaches. A main benefit of the proposed algorithm is that although it is closed-form and performs successive estimation of the node locations, it is able to reach the CramÉr–Rao lower bound (CRLB) accuracy under white Gaussian measurement noise with sufficient SNR. This is confirmed by the theoretical analysis and corroborated by simulations. </para>

This paper presents a multi-node 2-Dimensional (2D) time-of-arrival (TOA) and direction-of-arrival (DOA) optimal fusion technique. This technique can be applied in ad-hoc networks, especially suitable for the application in the mobile ad-hoc networks (MANETs). In this work, positioning error in MANETs would be optimized via TOA-DOA joint estimation and fusion across multiple nodes. In the proposed MANET, we assume two categories of nodes: Those equipped with antenna arrays (base-nodes) and those equipped with omni-directional antennas (target-nodes). All nodes are capable of communicating with other nodes. Base-nodes are capable of positioning (TOA-DOA estimation) other nodes located in their coverage area. A fusion method is proposed to minimize the mean square of the positioning error of a target-node, when more than one base-node estimates its position. The fusion scheme is derived theoretically and compared with simulation results. This paper depicts the capability of the proposed 2D fusion algorithm to considerably reduce the positioning error. The proposed technique has important applications in GPS-denied environments

This paper evaluates the performance of a semidistributed multinode time-of-arrival (TOA) anddirection-of-arrival (DOA) fusion localization technique in terms of localization circular error probability (CEP). The localization technique is applicable in mobile ad hoc networks (MANETs) when global positioning system (GPS) is not available (GPS denied environments). The localization CEP of the technique is derived theoretically and verified via simulations. In addition, we theoretically derive the localization CEP of GPS-aided TOA fusion and GPS-aided DOA fusion techniques, which are also applicable in MANETs. Finally, we compare these three localization techniques theoretically and via simulations. The comparison confirms that in moderate scale MANETs, the multinode TOA-DOA fusion localization technique achieves the best performance; while in large scale MANETs, GPS-aided TOA fusion leads to the best performance.

A joint multi-carrier frequency offset (CFO) and multi- time of arrival (TOA) estimation algorithm for multiuser single-input multiple-output (SIMO) orthogonal frequency division multiplexing (OFDM) systems is proposed. With carefully designed pilots, multiple CFOs and TOAs of K users are separated jointly, dividing a complex 2K-dimensional estimation problem into 2K low-complexity mono-dimensional estimation problems. Two CFO estimation approaches, including a low-complexity closed-form solution and a high-accuracy null-subcarrier assisted accurate estimation approach, are proposed, where the integer and fractional parts of each CFO are estimated as a whole rather separately. Each TOA is estimated regardless of CFO by exploring the features of the inter-carrier interference matrix. The Cramer-Rao lower bounds (CRLBs) of multi-CFO and mutli-TOA estimation are derived for the first time for SIMO OFDM systems. Simulation results show that the proposed CFO and TOA estimators provide higher estimation accuracy than the existing approaches. They also achieve performances close to the CRLBs especially at high signal-to-noise-ratios (SNRs).

In this research, our aim is to construct an effective quality of service (QoS) routing scheme for mobile ad hoc networks (MANET) that provides the service to satisfy required quality by absorbing dynamic changes of network resources. In this paper, we propose an application-level QoS routing scheme for MANETs (ALRS) as a novel QoS routing, that includes following three significant features: (1) estimation of consumed bandwidth on each node using 2-hop neighbors' traffic information, (2) route construction combined with admission control on each application session using (1), and (3) route maintenance based on (1) and (2). ALRS realizes control of generated traffic in MANET effectively and enables to provide the service to satisfy required quality for dynamic changes of network resources. By using our proposed scheme, it is expected that the availability of bandwidth would greatly improve for high-load communication, such as multimedia application on MANET. From our simulation results, it has shown, that our proposed scheme, by effective suppression of traffic, increased delivery ratio up to 40%, without any deterioration of throughput compared to traditional method. Results show that our proposed scheme enables to provide the service to satisfy the required quality

Quality of service (QoS) and security have been considered as two competent units to govern and administer end-to-end traffic across network. A mobile ad hoc network (MANET) is a type of wireless communication, every node can act as a router or base station. Secure QoS-based routing is an important problem in MANET. A hierarchical key ranking (HKR) model is presented here for secure group communications in MANETs. To enhance the security, one-to-one random mapping is performed using hash-based message authentication code (HashMAC). Due to the dynamic nature and topological changes in MANET, group safeguarding is efficiently accomplished. For secure group communication and efficient QoS routing in MANET, a sector key (SK) is shared among group members to encrypt group messages which is obtained using secured message authenticated code (SMAC). The primary design is to include the group members in sector to vigorously contribute to the security of the multicast group, as a result dropping the communication and calculating load on the source. Experimental evaluation is done to estimate the performance of the proposed secure QoS routing and communication using hierarchical key ranking [SRHKR] in MANET in terms of delivery rate, security level, delay.

Worldwide Interoperability for Microwave Access (Wimax) is power station through which mobile network, commonly known as A Mobile Ad-hoc Network (MANET) is used by the people. A MANET can be described as an infrastructure-less and self-configure network with autonomous nodes. Participated nodes in MANETs move through the network constantly causing frequent topology changes. Designing suitable routing protocols to handle the dynamic topology changes in MANETs can enhance the performance of the network. In this regard, this paper proposes four algorithms for the routing problem in MANETs. First, we propose a new method called Classical Logic-based Routing Algorithm for the routing problem in MANETs. Second is a routing algorithm named Fuzzy Logic-based Routing Algorithm (FLRA). Third, a Reinforcement Learning-based Routing Algorithm is proposed to construct optimal paths in MANETs. Finally, a fuzzy logic-based method is accompanied with reinforcement learning to mitigate existing problems in FLRA. This algorithm is called Reinforcement Learning and Fuzzy Logic-based (RLFLRA) Routing Algorithm. Our proposed approaches can be deployed in dynamic environments and take four important fuzzy variables such as available bandwidth, residual energy, mobility speed, and hop-count into consideration. Simulation results depict that learning process has a great impact on network performance and RLFLRA outperforms other proposed algorithms in terms of throughput, route discovery time, packet delivery ratio, network access delay, and hop-count.