• Journal of the Institute of Electronics Engineers of Korea CI
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• v.47 no.6
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• pp.113-123
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• 2010

In this paper, an efficient network configuration method is proposed for mobile nodes in LR-WPAN (Low Rate Wireless Personal Area Network) based on the IEEE 802.15.4 standard. The proposed MSBS (mobile sensor beacon setup) method can be used to implement a joining procedure by which an improved processing rate can be achieved. This improvement is achieved by using BOP (Beacon only Period). In this method, the performance of mobile nodes is enhanced by using information on depth, traffic, and RSSI (Received Signal Strength Indication). By using the MSBS method, trusted data can be transferred and traffic overloads that occur at specific nodes can be prevented. The information obtained from the mobile nodes in wireless networks is analyzed using the proposed method, in order to study the performance of the method. Simulation results show that the MSBS method can be used to obtain an efficient network configuration according to the mobility of nodes in LR-WPAN.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.6
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• pp.2739-2742
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• 2012

6LoWPAN is a standard to enable IPv6 packets to be carried on top of low power wireless networks. It needs to achieve security in 6LoWPAN, which is being defined at the 6LoWPAN working group of the IETF. IPSec is already part of IPv6, which makes it a candidate to be directly employed or adapted for WSNs. Some results showed that the adoption of IPSec is viable, and also point towards the successful design and deployment of security architecture for WSNs. IPSec requires two communicating entities to share a secret key that is typically established dynamically with the IKE. However, there are some limitations to use IKE on wireless networks. In this article, we show requirements for being Efficient Key management Mechanism for IPSec on 6LoWPAN and analyze candidate protocols.

• Journal of the Korean Society for Railway
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• v.15 no.5
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• pp.454-458
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• 2012

The CBTC(Communication based Train Control) and WPAN(Wireless Personal Area Network) systems employed on 2.4GHz ISM band wireless networks provide complementary service within the same environment. Coexistence between the networks will be impaired if the mutual packets are uncertainty associated the timing or gaussian distance. This paper analyzes the impact of the mutual interference and proposed method to minimize the effect of the WPAN system signals on CBTC system. The performance analysis is illustrated by examining the symbol error rate versus signal to noise interference ratio in terms of carrier frequency offset. The method contributes to reduce the symbol error rate drastically. However it can't be a fundamental solution for the impact on the interference problem. It may be needed for railway only frequency after checking the problems of the current railway frequency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.3
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• pp.526-534
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• 2014

In this paper, for the WiMedia Distributed Medium Access Control (D-MAC) protocol based on UWB. performance degradation due to the Distributed Reservation Protocol (DRP) conflict problem caused by devices' mobility is analyzed. And a DRP relay protocol and a DRP conflict resolution (CR) are proposed to overcome the performance degradation at DRP conflicts. In order to give the loser device at DRP conflicts a chance to maintain resources, the proposed DRP relay protocol executed at each device helps the loser device reserve an indirect link maintaining the required resources via a relay node. Simulation results considering the mobile environment have indicated that the DRP relay combined with the CR prevent the throughput decrease even though mobility of devices increases.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.8 s.350
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• pp.25-34
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• 2006

In this paper DynaMoNET is suggested as a novel IPv6-based multi-homed mobile network architecture which is composed of nested mobile ad hoc networks dynamically coming together through wireless personal area networks. Each ad hoc network has a mobile router which may work as a root mobile router instead of fixed mobile routers in a DynaMoNET. A root mobile router provides the reliable Internet connectivity for the entire mobile network. This paper includes a innovative handover protocol for multi-homed mobile networks, network switchover algorithm considering multiple decision factors, root mobile router election process based on token-based algorithm fast root mobile router discovery algorithm and fault avoidance mechanism to support reliable Internet connectivity. Finally the system architecture of a mobile router is given in detail.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.95-105
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• 2010

IEEE 802.15.4 is the one of the protocols for radio communication in a personal area network. Since it aims to provide low cost and low power communication for ubiquitous communication, it requires high level of optimization in implementation. Recently, there have been many studies on the performance evaluation of IEEE 802.15.4 MAC protocol. According to the results of the studies, it is tendency that the transceiver is implemented to SoC type. On the implementation, the specific functions of MAC like CSMA-CA and MAC frame handling is designed to hardwired functions. In this paper, we implemented the protocol with hardwired low MAC (HL-MAC) and its state machine for the optimization from the physical layer and MAC layer. it has the characteristics of the small code size and the enhanced power consumption.

• Journal of IKEEE
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• v.13 no.3
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• pp.7-17
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• 2009

WiMedia UWB technology is a fully distributed data communication technology developed for the application demanding a high data transmission rate in the wireless PAN area. In general, devices can send data either by reserving time slots or by using prioritized CSMA/CA. If the PCA protocol of prioritized CSMA/CA is used, they are suffered congestion as the number of devices increases. In this paper, we propose a Deterministic Access Protocol(DAP) in WiMedia WPANs. A DAP is a method to transmit data in the non-reserved DRP period without competition as each device informs the beacon order information in the beacon period and the queue information. In addition, the problem that the devices with a lower beacon slot number have more transmission opportunities is addressed by introducing the reference point. Simulation results are given to demonstrate that a DAP can improve the throughput and reduce the packet loss rate.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.10A
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• pp.823-829
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• 2011

Recently, wireless body area network (WBAN) has received much attention as an application for the ubiquitous healthcare system. In WBAN, each sensor nodes and a personal base station such as PDA have an energy constraint and computation overhead should be minimized due to node's limited computing power and memory constraint. The reliable data transmission also must be guaranteed because it handles vital signals. In this paper, we propose a systematic network coding scheme for WBAN to reduce the network coding overhead as well as total energy consumption for completion the transmission. We model the proposed scheme using Markov chain. To minimize the total energy consumption for completing the data transmission, we made the problem as a minimization problem and find an optimal solution. Our simulation result shows that large amount of energy reduction is achieved by proposed systematic network coding. Also, the proposed scheme reduces the computational overhead of network coding imposed on each node by simplify the decoding process.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.6 s.336
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• pp.41-52
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• 2005

In wireless networks there are various errors, caused by multi-path fading and interference between devices which lower the network Performance. Especially, performance of IEEE 802.IS.3 High-Rate WPAN (Wireless Personal Area Network) which is operated in ISM unlicensed frequency band is easily affected by channel errors. In this paper, we propose a scheduling algorithm which takes channel errors into consideration in scheduling asynchronous data traffic. The proposed scheduling algorithm can allocate CTA(Channel Time Allocation) proportionally in accordance with the requested channel time of each device. It also prevents waste of channel time by allocating CTA of the channel-error devices to other channel-error free devices. After recovering from the channel error, the devices are compensated as much as they conceded during channel error status. Simulation results show that the proposed scheduling algorithm is superior to the existing SRPT(Shortest Remain Processing Time) and RR(Round Robin) in throughput and fairness aspects.

• Journal of the Korea Society for Simulation
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• v.17 no.4
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• pp.89-97
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• 2008

In wireless personal area networks (WPANs), the successful design of channel time allocation algorithm is a key factor in guaranteeing the various quality of service (QoS) requirements for the stringent real-time constraints of multimedia services. In this paper we propose a channel time allocation algorithm for achieving a high quality transmission and high channel error tolerance of MPEG stream in the IEEE 802.15.3 high-rate wireless PANs. Our algorithm exploits the characteristics of MPEG stream. When a new MPEG stream arrives, a DEV models it by the traffic envelope and delivers the traffic envelope to the piconet coordinator (PNC) along with the channel time request. The PNC performs channel time allocation according to the envelope. Performance of the proposed scheme is investigated by simulation and analysis. Our results show that compared to conventional scheme, the proposed scheme is very effective and provides a good performance under typical channel error conditions.