Simulation and emulation are valuable techniques for the evaluation of algorithms and protocols used in mobile ad-hoc networks. However, these techniques always require the simplification of real-world properties such as radio characteristics or node mobility. It has been shown that this may lead to results and conclusions which do not reflect the behavior of ad-hoc networks in the real world. Various prototype implementations demonstrate that even simple protocols such as flooding do not behave as it was predicted by earlier simulation. To overcome this problem, real-world experiments are required. In this paper, we present a survey on existing real-world implementations of mobile ad-hoc networks. We report on the technology used for the implementations as well as on key findings from experiments conducted with these implementations.

A survey on real-world implementations of mobile ad-hoc networks

The Air Force Institute of Technology

Researchers have long faced a fundamental tension between the experimental realism of wireless testbeds on one hand, and the control and repeatability of simulation on the other hand. To overcome the stark tradeoff of these traditional alternatives, we are developing a wireless emulator that enables both realistic and repeatable experimentation by leveraging physical layer emulation.We discuss the design and implementation of a prototype wireless emulator, and show how this emulator can be leveraged to provide insight into wireless network and application behaviour. Our experience shows that, compared to simulation, our emulator-based approach provides us with a better understanding of real-world wireless network performance, and enables us to quickly deploy our research into an operational wireless network, while still allowing us to enjoy the benefits of a controlled experimental environment.

Using emulation to understand and improve wireless networks and applications

In wireless networking research, there has long existed a fundamental tension between experimental realism on one hand, and control and repeatability on the other hand. Hardware-based experimentation provides realism, but is tightly coupled to the physical environment and circumstances under which experiments are carried out. To overcome this, researchers have understandably embraced simulation as a means of evaluation. Unfortunately, wireless simulation is plagued with inherent inaccuracies. To overcome the stark tradeoff between the realism of hardware-based experimentation and the repeatability of simulation-based experimentation, we are developing a wireless emulator that enables both realistic and repeatable experimentation. Unlike previous emulators, our approach simultaneously achieves both a high degree of realism and fine-grained repeatability by leveraging physical layer emulation.

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Repeatable and realistic wireless experimentation through physical emulation

Mobile Ad hoc Network (MANET) is a collection of wireless mobile nodes that dynamically form a network temporarily without any support of central administration. Moreover, Every node in MANET moves arbitrarily making the multi-hop network topology to change randomly at unpredictable times. There are several familiar routing protocols like DSDV, AODV, DSR, etc...which have been proposed for providing communication among all the nodes in the network. This paper presents a performance comparison of proactive and reactive protocols DSDV, AODV and DSR based on metrics such as throughput, packet delivery ratio and average end-to-end delay by using the NS-2 simulator.

Performance Comparisons of Routing Protocols in Mobile Ad Hoc Networks

Many wireless ad hoc routing protocols have been proposed in the literature. Researchers are comparing and improving these protocols before standard routing protocols are defined. In this paper, we present a framework for wireless ad hoc routing protocols based on the concept of a relay node set (RNS). This framework facilitates the comparison, design, and improvement of wireless ad hoc routing protocols. We briefly present an analytical model for comparing protocols using this framework with packet overhead as the metric. We also apply the framework to show how to improve a routing protocol. Future work using the framework is also discussed.

/pdf/a-framework-for-wireless-ad-hoc-routing-protocols-1p9hf8x2dx.pdf

A framework for wireless ad hoc routing protocols

The integration of various network-level functions, including routing, management, and security, is critical to the efficient operation of a mobile ad hoc network. In this article we focus on network mobility (rather than node mobility), implying the movement of entire subnetworks with respect to one another, while individual users initially associated with one such subnetwork may also move to other domains. One example is a battlefield network that includes ships, aircraft, and ground troops. In this "network of networks", subnets (e.g. shipboard networks) may be interconnected via a terrestrial mobile wireless network (e.g., between moving ships). We discuss the design and implementation of a new ad hoc routing protocol, a suite of solutions for policy-based network management, and approaches for key management and deployment of IPsec in a MANET. These solutions, in turn, are integrated with real-time middleware, a secure radio link, and a topology monitoring tool. We briefly describe each component of the solution, and focus on the challenges and approaches to integrating these components into a cohesive system to support network mobility. We evaluate the effectiveness of the system through experiments conducted in a wireless ad hoc testbed.

/pdf/network-mobility-and-protocol-interoperability-in-ad-hoc-4n8xva6s69.pdf

Network mobility and protocol interoperability in ad hoc networks

Wireless mobile ad hoc networks differ from wired networks in that their topologies are highly dynamic and their links can have a relatively high bit error rate These properties make it difficult to conduct controlled, repeatable experiments with routing and other protocols in a wireless ad hoc network environment To address this problem, we have developed a switch that connects multiple unaltered hosts according to a controllable dynamic topology with a controllable bit error rate on the links The dynamic topology switch emulates a wireless mobile ad hoc network using standard Ethernet physical connections This allows researchers to experiment with routing and other protocols in a mobile ad hoc network (MANET) environment In this paper, we describe our dynamic topology switch and describe the validation of the switch We validate the switch by comparing control packet overhead for the optimized link state routing (OLSR) protocol measured using the switch and using the ns-2 simulator

A dynamic topology switch for the emulation of wireless mobile ad hoc networks

A method and apparatus are provided for transmitting and receiving data using an electric field. A first device determines whether a transmission path to a second device is formed through a part of a human body using an electric field. A connection is established with the second device through the transmission path by the first device, when the transmission path is formed through the part of the human body. Connection information for the second device is obtained through the transmission path by the first device. Data is transmitted from the first device to the second device using the obtained connection information of the second device.

Method for transmitting and receiving data using e-field in portable terminal and apparatus thereof

Blind broadcast in a wireless ad hoc network means any mobile node will rebroadcast all received broadcast messages. One node may receive the same copy of a message from more than one neighbor, so unnecessary overhead is introduced. A connected dominating set (CDS) can be used to reduce broadcast overhead. We propose a proactive link state routing protocol, integrated with CDS discovery algorithms, as a promising approach for routing in wireless ad hoc networks. This paper presents approximation algorithms to find a minimal CDS for a given network. A prototype of a proactive link state routing protocol integrated with CDS algorithms is introduced. Both simulation and analytical results indicate better performance than other algorithms.

J.S. Park

Papers

A framework for wireless ad hoc routing protocols

Network mobility and protocol interoperability in ad hoc networks

A dynamic topology switch for the emulation of wireless mobile ad hoc networks

Method for transmitting and receiving data using e-field in portable terminal and apparatus thereof

Minimal connected dominating set algorithms and application for a MANET routing protocol