CF-MAC Protocol for Voice Communication in Wireless Ad-Hoc Networks

Energy efficiency of the MAC protocol is a key design factor for wireless sensor networks (WSNs). Due to the importance of the problem, a number of energy efficient MAC protocols have been developed for WSNs. Preamble-sampling based MAC protocols (e.g., B-MAC and X-MAC) have overheads due to their preambles, and are inefficient at large wakeup intervals. SCP-MAC, a very energy efficient scheduling MAC protocol, minimizes the preamble by combining preamble sampling and scheduling techniques; however, it does not prevent energy loss due to overhearing; in addition, due to its synchronization procedure, it results in increased contention and delay. In this paper, we present an energy efficient MAC protocol for WSNs that avoids overhearing and reduces contention and delay by asynchronously scheduling the wakeup time of neighboring nodes. To validate our design and analysis, we implement the proposed scheme on the MicaZ platform. Experimental results show that AS-MAC considerably reduces energy consumption, packet loss and delay when compared with SCP-MAC.

The efficient use of energy is an important performance metric to extend the lifetime of wireless sensor networks. Since major energy consumption of node is due to its transceiver, the design of MAC protocol plays a vital role in sensor network design. In cluster based sensor networks, due to the different functions of member node and cluster head node, the usage of common MAC protocol results increased energy consumption. To overcome this problem, a novel energy efficient hybrid MAC protocol (EEHMAC) for cluster based wireless sensor networks is proposed in this paper. The proposed EEHMAC protocol uses E-TDMA (Energy efficient TDMA) for intra-cluster communication and FDMA (Frequency Division Multiple Access) for inter-cluster communication. IDS (Iterative Deepening Search) based Scheduling algorithm is used for assigning time slot and frequency slot to nodes. Nodes in EEHMAC follow the periodic duty cycle, which reduces the idle listening, and overhearing problems. Simulation results reveal that an average of 18% energy saving is achieved compared to LEACH (Low Energy Adaptive Clustered Hierarchy) protocol and 10% energy is saved in comparison with GH-MAC (Graph theory based Hybrid MAC) protocol. It is evident that delay of EEHMAC is reduced by 17% and throughput is increased by 15% under all traffic conditions. These results demonstrate that EEHMAC performs better than existing MAC protocols in terms of energy efficiency, delay and throughput.

Wireless ad-hoc networks are collections of wireless nodes having no predefined infrastructure. Most of the existing routing protocols for wireless ad-hoc networks use the shortest path or minimum distance path to the destination. However, the shortest path routing does not provide a good balance of the traffic load among all nodes. When many users utilize the shortest paths, some nodes become highly congested and become what is known as hotspots. These hotspots degrade the performance of wireless ad-hoc networks by creating long queuing and contention delays. This paper investigates the effects of shortest path routing on the network by varying different network parameters. A load distributed path routing is also proposed to enhance the performance of shortest path routing. Matlab simulations show that the load distributive routing provides 35% and 44% less contentions in a 20-node and 30-node network respectively, when compared to shortest path routing.

This work presents a TDMA based multi-channel MAC protocol called TMMAC for Ad Hoc Networks. TMMAC requires only a single half-duplex radio transceiver on each node. In addition to explicit frequency negotiation which is adopted by conventional multi-channel MAC protocols, TMMAC introduces lightweight explicit time negotiation. This two-dimensional negotiation enables TMMAC to exploit the advantage of both multiple channels and TDMA, and achieve aggressive power savings by allowing nodes that are not involved in communication to go into doze mode. Moreover, TMMAC dynamically adjusts its negotiation window size based on different traffic patterns, which further improves communication throughput and energy savings. In this paper, the performance of TMMAC is analyzed and evaluated. The evaluations show that TMMAC achieves up to 113% higher communication throughput while consuming 74% less per packet energy over the state-of-the-art multi-channel MAC protocols for single-transceiver wireless devices.

This paper considers the problem of self-diagnosis of wireless ad-hoc networks using the comparison approach. In this approach, a MANET consists of a collection of n independent heterogeneous mobile hosts interconnected via wireless links, and it is assumed that at most σ of these mobile hosts are faulty. In order to diagnose the state of the wireless ad hoc network, tasks are assigned to pairs of mobiles and the outcomes of these tasks are compared. The agreements and disagreements among mobiles are the basis for identifying the faulty mobiles. The comparison approach is believed to be one of the most practical diagnosis approaches. We describe a new distributed self-diagnosis protocol for wireless ad hoc networks that is able to identify hard and soft faults in a finite amount of time. We then analyze the time and communication complexities of wireless ad hoc networks and show that it performs better, from a communication complexity viewpoint, than the existing protocols.

A peer-to-peer file search and download protocol for wireless ad-hoc networks

This paper presents an overlay based Byzantine tolerant broadcast protocol for wireless ad-hoc networks. The use of an overlay results in a significant reduction in the number of messages. The protocol overcomes Byzantine failures by combining digital signatures, gossiping of message signatures, and failure detectors. These ensure that messages dropped or modified by Byzantine nodes will be detected and retransmitted and that the overlay will eventually consist of enough correct processes to enable message dissemination. An appealing property of the protocol is that it only requires the existence of one correct node in each one-hop neighborhood. The paper also includes a detailed performance evaluation by simulation.

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The Ad-Hoc networks are autonomous and infrastructure-less networks that provide flexibility to network nodes to connect and disconnect at any time. Routing protocol is a crucial part in the changeable topology network. DSDV, DSR and AODV are the most typical basic protocols for wireless Ad-Hoc networks. In this paper, it interprets and compares these three typical routing protocols using NS-2 simulator. It analyzes these three protocols in several aspects such as packet loss rate, route cost, average end-to-end delay and packet delivery fraction through simulations using Network Simulator in varying network conditions including the number of nodes, maximum moving speed of mobile node, maximum number of connections, node pause time, data rate and node moving range. Performance analysis of simulation results shows that each protocol has its own best suitable scene, so one can choose the optimal protocol under different scenarios according to the simulation results.

Abstract—We focus on a popular message dissemination pro-tocol for wireless ad-hoc networks, GOSSIP3. Our contribution is twofold. First, we perform an extensive experimental evaluation of GOSSIP3 under fully utilized wireless channel and across diverse node densities. We identify the parameters of GOSSIP3 that need special configuration for the protocol to operate optimally. Second, we devise a self-configuration algorithm for GOSSIP3 that allows the protocol to work optimally for any network. We demonstrate through simulations that our protocol significantly outperforms the default configuration of GOSSIP3. I.

Complete-exchange multicasting is quite useful for numerous applications. We explicate a load-balanced complete-exchange multicast protocol (LCM), based on passive clustering, for wireless ad-hoc networks. From a logical viewpoint, LCM constructs multiple cluster structures to balance the traffic loads among all group members. It further avoids overloading of nodes or traffic congestion on the route. In LCM, an innovative scheme is devised to deal with the scenario in which a node plays different roles for different cluster structures. Simulation results show that LCM not only preserves all the advantages of passive clustering, but also performs very efficiently in complete-exchange multicasting. Consequently, LCM is really a feasible solution for load-balanced complete-exchange multicasting, especially for dense networks.

Development of applications and protocols for wireless ad-hoc networks has always been a challenge. Spe- cific characteristics such as frequent topology changes due to nodes moving around, popping up or being turned off, need to be considered from the earliest stages of develop- ment. Since testing and evaluation using genuine wireless devices is both expensive and highly impractical, other tools need to be used in the development phase. Simulators give a very detailed model of lower layers' behaviors, but code often needs to be completely rewritten in order to be used on actual physical devices. Emulators present a trade-off be- tween real test beds and simulators, providing a virtual wireless network at the lowest layers, and yet allowing real code to be run on the higher layers. In this paper, we pre- sent such an emulation platform, called NEMAN, that al- lows us to run a virtual wireless network of hundreds of nodes on a single end-user machine. NEMAN has shown to be an important and very useful tool during development of different applications and protocols for our project, includ- ing a key management protocol and a distributed event noti- fication service.

We introduce WRP-Lite, which is a table-driven routing protocol that uses non-optimal routes, and compare its performance with the performance of the dynamic source routing (DSR) protocol, which is an on-demand routing protocol for wireless ad-hoc networks. We evaluate the performance of WRP-Lite and DSR for varying degree of mobility and traffic in a 20-node network. The performance parameters are end-to-end delay, control overhead, percentage of packets delivered, and hop distribution. We show that WRP-Lite has much better delay and hop performance while having comparable overhead to DSR.

Ad hoc mobile networks are composed of mobile nodes communicating through wireless medium, without any fixed backbone infrastructure. In these networks, Congestion occurs in any intermediate nodes when data packets travel from source to destination and they incur high packet loss and long delay, which cause the performance degradations of a network. This paper presents the early detection congestion and control routing protocol for wireless Ad-hoc networks called as EDAODV. EDAODV detects congestion at a node level by calculating queue_status value and finding congestion status. Based on a congestion status, EDAODV utilizes the non-congested predecessor and successor nodes of a congested node and initiates route finding process bi-directionally to find alternate non-congested path between them for transmitting data. The process finds more non-congested alternate paths and chooses a best single path for transmitting data.

A novel low power medium access protocol energy efficient MAC (EE-MAC) for wireless sensor network is proposed in this paper. EE-MAC targets for improving energy efficiency, delay performance and packet delivery ratio by considering various load conditions of the network. This protocol is based on the hybrid of TDMA and FDMA approaches. The novel idea behind EE-MAC is that it uses the priority concept with hybrid MAC scheduling in order to achieve its objectives. The performance of EE-MAC is obtained through simulations for various packet sizes, traffic loads, and different scenarios which show significant improvements in packet delivery ratio, energy efficiency, and delay compared to existing protocols.