• Journal of Korea Multimedia Society
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• v.14 no.12
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• pp.1572-1582
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• 2011

The rapid growth of UnderWater Acoustic Sensor Networks (UW-ASNs) has led researchers to enhance underwater MAC protocols against limitations existing in underwater environment. We propose the customized robust real-time packet inspection mechanism with addressing the problem of the search for the data packet loss and network performance quality analysis in UW-ASNs, and describe our experiences using this approach. The goal of this work is to provide a framework to assess the network real-time performance quality. We propose a customized and adaptive mechanism to detect, monitor and analyze the data packets according to the MAC protocol standards in UW-ASNs. The packet analyzing method and software we propose is easy to implement, maintain, update and enhance. We take input stream as real data packets from sniffer node in capture mode and perform fully analysis. We were interested in developing software and hardware designed tool with the same capabilities which almost all terrestrial network packet sniffers have. Experimental results confirm that the best way to achieve maximum performance requires the most adaptive algorithm. In this paper, we present and offer the proposed packet analyzer, which can be effectively used for implementing underwater MAC protocols.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12A
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• pp.1320-1328
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• 2007

In recent year, the popularity of WLAN has generated much interests on improvement and performance analysis of the IEEE 802.11 protocol. In this paper, we analyze two medium access methods of the IEEE 802.11 MAC protocol by investigating the MAC layer packet service times when arrival packet sizes have a general probability distribution. We use the M/G/1/K queueing model to analyze the throughput and the delay performance of IEEE 802.11 MAC protocol in a wireless LAN. We compare the performances of Basic access method and RTS/CTS access method. We take some numerical examples for the system throughput and the queue dynamics including the mean packet delay and packet blocking probability.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.2
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• pp.72-81
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• 2002

A new high-performance DSP architecture is proposed, which behaves as a coprocessor of a 32bit microcontroller. Because the proposed DSP architecture is a dual MAC(Multiply and Accumulate) DSP architecture, it can process efficiently a number of SOP(sum of product) operations used in many DSP applications. In order to efficiently perform other operations such as pure additions without any restriction, a MAC is composed of a multiplier and a ALU placed in parallel. In addition, it is a 3-way superscalar architecture, which can issue 3 instructions at a time. The benchmark results with 3 thor dual MAC DSPs show that the proposed DSP has the best performance. Futhermore, it is proven that the proposed DSP is more efficient in memory usage, although the performance is comparable in some algorithms such as Viterbi decoding and FFT butterfly.

• Journal of Korea Multimedia Society
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• v.14 no.2
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• pp.258-268
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• 2011

Underwater acoustic sensor networks can be used disaster prevention and environmental monitoring systems in underwater environments. Because, the underwater environment is different from the ground, the long propagation delay, low transfer rates and limited bandwidth characteristics should be considered. In this, paper will propose the MAC protocol that allocates time slot into each node according to priority policy through the period of contention-free slot reservation in underwater acoustic sensor networks in order to avoid collision and minimize energy consumption waste. We perform mathematical analysis to evaluate the performance of the proposed protocol with regard to the collision probability, the energy consumption by collision, throughput and channel utilization. We compare the proposed protocol with the conventional protocol, and the performance results show that the proposed protocol outperforms the conventional protocol.

• Journal of Broadcast Engineering
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• v.13 no.5
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• pp.696-706
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• 2008

In this paper we show the performance of the network-adaptive high-definition scalable video streaming using QWLAN board with IEEE 802.11e MAC monitoring and control. Realtime collected MAC parameters are used to determine which video data is extracted for the predicted available bandwidth. To achieve performance, extraction through R-D is proposed instead of the standard video packet extraction. It is shown through experiments that streaming video quality can be enhanced by fast adaptation to network conditions by using the proposed method.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.2
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• pp.111-118
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• 2008

In this paper a novel medium access control mechanism is investigated as a means to support real-time services. The primary goal is to provide constant-bit-rate voice call services to pairs of autonomous mobile nodes operating in ad hoc networks. Here, a time-slot reservation based MAC is considered to provide real-time voice calls and a new MAC called the time-slot reservation coordination function(TRCF) is presented. In addition to this isochronous type MAC protocol development, the proposed protocol is modeled using a Markov chain in order to predict its behavior. The performance of TRCF is analytically derived and the performance measures such as average wait time taken for a call connection and throughput are obtained.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.7
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• pp.1589-1598
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• 2014

To support the WBAN, IEEE 802.15 Task Group 6 announced standardized documents on technical requirements of the PHY and MAC. In the IEEE 802.15.6 MAC protocol, CSMA/CA(Carrier Sense Multiple Access with Collision Avoidance) algorithm is performed based on the eight-level priorities according to the type of traffics of the periodic data from medical sensor nodes. Several nodes, which detected the changed bio signals, transmit emergency data at the same time, so latency could be higher than emergency latency and energy consumption will increase. In this thesis, we proposed a CSMA/CA algorithm in WBAN to solve these problems. Simulations are performed using a Castalia based on the OMNeT++ network simulation framework to estimate the performance of the proposed superframe and algorithms. Performance evaluation results show that the packet transmission success rate and energy efficiency are improved by reducing the probability of collision using the proposed MAC protocol.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.8
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• pp.201-208
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• 2019

Intra-Body Communication (IBC) is a communication method using the human body as a communication medium. The fact that our human body consists of water and electrolyte allow such communication method could work and have strength in low-power. However, because the IBC directly affects to human body by using it as a medium, there was a lack of research in communication protocols of each communication layer. In this paper, we suggests MAC parameters which affects the performance of communication in human body channel, and propose new MAC protocol. Our results shows that our MAC is suitable for supporting high data rate applications with comparable radio duty cycle performance.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.76-89
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• 2014

In this paper, we propose a MAC(Media Access Control) protocol based on flexible RWT(RTS Waiting Time) for underwater mobile ad-hoc networks with a three-way handshaking mechanism. This protocol can solve a problem of collision between RTS(Request-To-Send) and CTS(Clear-To-Send) packets in existing MACA(Multiple Access with Collision Avoidance) protocol. This proposed MAC protocol is also an effective protocol which can apply to underwater mobile ad-hoc networks in a real field by using implementable technologies. We set flexible RTS Waiting Time called RWT, considering various characteristics of underwater environment. It is possible to support variable network size according to node mobility. Finally, we conduct a performance evaluation between proposed MAC protocol and existing MACA based MAC protocol through practical implementation and experiment. As a result, we verify the superiority of our proposed MAC protocol in terms of throughput, packet drop rate, average transmission time, energy consumption and channel utilization.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.6 s.324
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• pp.33-39
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• 2004

Design of efficient Medium Access Control (MAC) protocols with both high throughput performances is a major focus in distributed contention based MAC protocol research. In this paper, we propose an efficient contention based MAC protocol for wireless Local Area Networks, namely, the Developed Collision Resolution (DCR) algorithm. This algorithm is developed based on the following innovative ideas: to speed up the collision resolution, we actively redistribute the backoff timers for all active nodes; to reduce the average number of idle slots, we use smaller contention window sizes for nodes with successful packet transmissions and reduce the backoff timers exponentially fast when a fixed number of consecutive idle slots are detected. We show that the proposed DCR algorithm provides high throughput performance and low latency in wireless LANs.