Nam-Yeol Yun

Design and Implementation of the Test-bed for Underwater Acoustic Sensor Network Based on ARM9 Processor

Underwater acoustic communication, compared with Wireless Sensor Networks (WSNs) used in terrestrial environment, poses unique challenges due to the harsh underwater environment, such as limited bandwidth capacity, high and variable propagation delays, high bit error rates, and temporary losses connectivity caused by multipath and fading phenomena in spite of using a variety of applications in many areas. In this paper we specify to develop the baseboard using characteristics of ARM9 processor based on low power consumption to enhance the performance, to improve a variety of restrictions. And we describe the process of the underwater communication that demonstrates and designs test-bed of the underwater acoustic sensor network with a similar actual environment.

A Focus on Practical Assessment of MAC Protocols for Underwater Acoustic Communication with Regard to Network Architecture

Abstract Underwater acoustic communication is a rapidly growing research area nowadays and many related studies have already been conducted in recent decades. Underwater acoustic communication can be easily applied to many fields, such as oceanic data collection, undersea exploration, disaster prevention, underwater environmental monitoring, and tactical surveillance. However, there are many challenges associated with underwater communication, including bandwidth limitations, multi-path propagation, padding, long end-to-end propagation delay, high bit error, temporary loss of connectivity, and limited battery power. To overcome these problems, existing implementable MAC protocols need to be classified in terms of network topology. To improve network mobility, two kinds of network topologies, which include cluster-head-based and ad-hoc-based MAC protocols, are considered. In this paper, we summarize some selected MAC protocols and analyze their performance by comparing a number of factors. We obtain experimental results by developing and simulating the existing numerical models of each protocol practically using simulation tools.

A Focus on Comparative Analysis: Key Findings of MAC Protocols for Underwater Acoustic Communication According to Network Topology

Underwater acoustic communication can be applicable to many fields, such as oceanic data collection, undersea exploration and development, disaster prevention, underwater environmental monitoring and tactical surveillance. However, it has several challenges to design underwater acoustic sensor networks, for instance, limited bandwidth, multi-path, padding, long propagation delay, high bit error, temporary losses of connectivity and limited battery power. Nowadays many studies are being conducted to overcome abovementioned problems. In this paper, various MAC protocols for underwater acoustic communication are classified by network topology, one is cluster head based MAC protocols and the other one is ad-hoc based MAC protocols. In recent researches, there were not comparative analyses of MAC protocols for underwater acoustic communication according to network topology. So, we summarize and analyze these protocols through comparing each other with some factors. In the future, MAC protocols for underwater acoustic communication will be designed with consideration for each advantage of cluster head and ad-hoc MAC protocols, considering the mobility of nodes to improve underwater acoustic communication, which can be applied to lots of underwater applications.

A Smart Electronic Tagging System Based on Context Awareness and Machine-to-Machine Interworking

The existing electronic tagging system traces the location of a sex offender using triangulation by communicating with Global Positioning System (GPS) satellites and mobile phone base stations. The acquired location information is used to prevent the offenders from perpetrating repeat crimes. However, the battery resources of such a system are inadequate as it has to trace the location of the moving target in real time and consumes a large amount of battery power while communicating with GPS satellites and mobile phone base stations. In addition, the systems cannot infer the mental state of the targets or detect their alcohol consumption levels, which may be necessary for the prevention of a repeat crime. The purpose of this study is to connect the Ubiquitous System Network (USN), which consumes little electricity, and Android mobile platforms, which are commonly used for machine-to-machine communication. Thus, this system will legally facilitate the protection of minors by providing information only about the targets approach to certain facilities. In addition, the system uses an Android platform to process data measured by the USNs sensors, which can also detect alcohol intake and infer the mental state of the target, and then initiates the corresponding real-time context-awareness services.

Design and Performance Evaluation of Hierarchical Protocol for Underwater Acoustic Sensor Networks

ABSTRACTAs underwater environment monitoring system’s interest has increased, the research is proceeding about underwater acoustic sensor network. Underwater sensor network can be applicable to many fields, such as underwater environment monitoring, underwater resource exploration, oceanic data collection, military purposes, etc. It is essential to define the PHY-MAC protocol for revitalization of the underwater acoustic sensor network which is available utilization in a variety of fields. However, underwater acoustic sensor network has to implement by consideration of underwater environmental characteristics, such as limited bandwidth, multi-path, fading, long propagation delay caused by low acoustic speed. In this paper, we define frequency of adjusted PHY protocol, network topology, MAC protocol, PHY-MAC interface, data frame format by consideration of underwater environmental characteristics. We also present system configuration of our implementation and evaluate performance based on our implementation with test in real underwater field.

Adaptive GTS Allocation Scheme based on IEEE 802.15.4 for Underwater Acoustic Sensor Networks

This paper proposes a new media access control (MAC) protocol, Preamble-MAC (P-MAC). P-MAC is adaptive and dynamic MAC protocol based on Virtual Distance Level (VDL), which is the estimated, accumulated information of channel status and variation obtained through periodically monitoring underwater environment information such as long, unknown propagation delays and low bandwidth for underwater acoustic sensor networks.

A Reliable Error Detection Mechanism in Underwater Acoustic Sensor Networks

Underwater Acoustic Sensor Networks (UWASNs) are not secure due to various characteristics of underwater environments. The error rate is very high in underwater environment due to factors such as long propagation delay, fading, multi-path and noises. Moreover, malicious attacks to the network add one more threat to reliable data transport problems. With respect to terrestrial sensor network, UWASNs are very different in nature. Reliable and faster data communication is our main issue. As the signal has to travel inside a noisy wireless acoustic channel so the processing of the signal is also take to measure. Moreover, we know the error rate is always high in underwater, so detecting the error and correcting them is the main key to secure the communication among nodes. The energy efficiency as well as the performance of any mechanism depends on collusion free data transmission and reception among sensors. Data link layer plays a crucial part in the Media Access Control (MAC) operation by detecting errors. For secure communication it is necessary to detect the errors during the transmission and reception. Especially in data link layer, the error detection and correction used some techniques like Cyclic Redundancy Check (CRC), checksum, parity bit, Forward Error Correction (FEC) and different error-correcting codes like Humming code, Reed Solomon code, binary convolution code and others tailored made program. In UWASNs data throughput depends on the packet size and the MAC protocols, where different protocols perform differently. A valid packet size has a great effect on the network. The ideal packet sizes depend on the specific application and the pattern of message it generates. We have to use small size packets which do help faster communication and higher data throughput in UWASNs. In this paper, depends on our practical experience, instead of using any kind of FEC techniques, we used CRC-8 because the process of data transmission usually contains the risk of unwanted modification as the channel is open. Signals arrive to the physical layer at different power and delay due to acoustic effects. So packets need to recheck for reliable data communication in UWASNs.

The UMO (Underwater Moving Object) Firmware Design and Implementation Based on Underwater Acoustic Communication

UMO (Underwater Moving Object) based on underwater acoustic communication can be useful for underwater environment observation, catastrophe prevention, ocean resources exploration, ocean organism research, vessel sinking exploration, and etc. But, for controlling the UMO underwater acoustic communication has constraints due to limited transmission capacity, propagation delay, a lot of collisions occurred by multi-path propagation and of course, battery changing impossibility. So, it is essential to develop the firmware which will consider above-mentioned underwater acoustic communication limitations. In this paper, we consider constraints and problems of underwater acoustic communication. Recently years, we have constructed adaptive simplex communication firmware and we have upgraded it with half-duplex communication firmware. We have also built the test-bed theoretically similar to real underwater environment for real implementation and data monitoring which was gathered by the sensors.

Adaptive MAC scheme using queue information for underwater environmental monitoring system

Underwater acoustic communication can be applied to many fields, such as oceanic data collection, undersea exploration, disaster prevention, underwater environmental monitoring, and tactical surveillance. Underwater environmental monitoring system is one of basic technologies in these application fields. Therefore, there is a growing need for researching underwater monitoring systems. Underwater communication systems should be designed differently from terrestrial wireless systems because of the special characteristics of the underwater environment, such as bandwidth limitations, multi-path propagation, padding, long end-to-end propagation delay, high bit error, temporary loss of connectivity, and limited battery power. In this paper, we considered the throughput and energy efficiency for constructing an underwater environmental monitoring system. Further, we aimed to transmit high-priority data first. The proposed MAC (Media Access Control) protocol gives transmission opportunities according to priority, and the number of transmissions is scheduled depending on the value of the data. In addition, we compared the performance of the proposed MAC protocol with the TDMA (Time Division Multiple Access) protocol based on numerical analysis.

A Standard Error Detection Mechanism for Underwater Acoustic Sensor Networks

Underwater Acoustic Sensor Networks (UWASNs) have some constant factors like energy limitations and node mobility. Energy is a very crucial issue as any kind of recharging is not possible in underwater environment. Energy consumption in each section is important. Saving a small amount of energy helps the life span of the sensor nodes as well as the lifetime of the networks. Especially for static UWASNs, long-term non-time critical application energy efficiency is of major concern. Beside energy efficient protocol design, error control is important in communication as the issue of data integrity is becoming increasingly important. Allowable error rate and undetected error probability in a network is also calculated for noisy channel. Error control is a system design technique that can fundamentally change the trade-offs in a communication system design. An error detection mechanism with low power consumption is also important for saving energy. In this paper, we have tried to find out how we can save our precious energy during communication among sensor nodes and bio mimetic fish-robots. Especially in security and error checking operation in underwater environment based on different error detection and correction mechanisms.