• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.13 no.5
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• pp.249-258
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• 2013

In multi-hop ad hoc networks, multi-interface multi-channel architecture is being noticing as methodology to improve the effective bandwidth and end-to-end throughput, But since existing routing metrics designed for networks based on single-interface exactly can not reflects the nature of networks based on multi-interface multi-channel, we are not expected the effect of throughput improvement. there had been proposal of MCR that discover high throughput by using metrics such as channel diversity and interface switching cost. however, MCR have an problem that is degraded it's performance in congested networks, because it not reflects the impact of traffic load. in this paper, we propose MAMCR metric, which select high throughput paths under congested conditions by combination MCR with channel access time metric, and conform it's the effect of performance improvement by ns-2 simulation.

• Journal of KIISE:Information Networking
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• v.37 no.4
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• pp.301-306
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• 2010

We propose the control channel access scheme for multi-interface multi-hop cognitive radio (CR) environment having a cluster structure. Due to the difficulty of obtaining common channels across the entire CR network, most multi-interface multi-hop CR networks put the control channel outside the CR bandwidth and dedicate one network interface to it in order to exchange the control information such as the activation of licensed users. However, this will be the waste of the network interface. Our focus is how to alternate between the control and the data channel without multichannel hidden node problem under the cluster structure where CR nodes connect with neighbors through multiple data channels. By using simulation, we evaluate the performance of the proposed scheme. The results show that the proposed scheme achieves higher network throughput than the dedicated scheme where one network interface card should dedicate to the control channel and cannot be used for data transmission.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.36-39
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• 2011

In this paper, performance of EMI interface and multi-channel wireless impedance sensor node is evaluated for SHM on bolted connection. To achieve the objective, following approaches are implemented. Firstly, an interface washer is designed to monitor loosened bolt through the variation in EMI of interface washer due to change in preload in bolt. Secondly, a multi-channel wireless impedance sensor node based on Imote2 platform is designed for automated and cost-efficient impedance-based SHM on bolted connections. Finally, performance of the multi-channel wireless impedance sensor node and the interface washer are experimentally validated for a lab-scale bolted connection model. A damage monitoring method using RMSD index of EMI signatures is utilized to examine the strength of each individual bolted connection.

• Journal of Information Technology Services
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• v.11 no.2
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• pp.291-306
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• 2012

Recently, Wireless Mesh Network (WMN) technology recently has been used in various industries. Especially, a number of multi-channel assignment schemes have been presented to improve the throughput of IEEE 802.11-based multi-hop WMN. However, performance of the conventional multi-channel assignment schemes is not enough to satisfy the industry requirements. We, thus, should study more about the multi-channel assignment scheme in order to enhance the performance. This paper proposes a novel channel assignment scheme that employs Multi-channel and Multi-Interface in the WMN. The proposed scheme can obtain the traffic information of the network and the efficient channel assignment result without any message exchanges. We verify the efficiency of the proposed scheme through the mathematical modeling and the real-world experiments. The results show that the proposed scheme improves the throughput of the network compared with the conventional schemes.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.4
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• pp.1005-1014
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• 2010

When reader collect tags, we found that they tend to get together to specific interface in Multi-Interface Multi-Channel 2.4GHz Active RFID system. To solve this problem, we designed the LP-Combind and AP-Balanced protocol for load distribution between interfaces, then verified its superiority of the performance through the simulation. There are three problems to implement designed protocols in hardware of firmware-level. first, tag selects randomly the channel of reader and reader need the method which can change the channel of tags. second, reader has the synchronization problem between reader and tag. third, reader has problem that MCU of reader have to operate simultaneously dual interface. To slove this problems, we designed the message and implemented method for tag channel change and the protocol in order to adjust synchronization between reader and tag, Therefore, we compared and analyzed the performance of protocols by experiment. If LP windows size is same, the performance of LP-Combined protocol and AP-Balanced protocol which lower collision probability by its load distribution is more outstanding than single interface protocol performance.

• Journal of the Korea Society for Simulation
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• v.18 no.1
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• pp.1-7
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• 2009

In this paper, we obtain the optimal number of interfaces/channels in wireless mesh networks by simulation. The simulation study is done in static multi-channel multi-interface environment. When many nodes use a single interface and channel and contend for the channel, collisions of RTS/CTS results in network performance degradation. To avoid such degradation and reduce interferences between the adjacent nodes, use of multi-interface/channel is considered. 802.11a and 802.11b systems offer 12 and 3 orthogonal channels respectively and multi-interface/channel scheme could be applied. But rare research about the optimal number of interfaces/channels has been studied. Therefore, in this paper, simulation study for the optimal number of interfaces/channels in wireless mesh network is made.

• Journal of KIISE:Information Networking
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• v.36 no.2
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• pp.118-129
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• 2009

The ISO 18000-7 Active RFID standard, a single channel system operating in the 433Mhz, faces technical difficulties in supporting some recently introduced application demands because of its low transmission rates and radio interference between readers. We propose a new multi-channel active RFID system operating in the 2.4Ghz. The special feature of the proposed system is that a reader makes use of multiple interfaces to improve its performance like a multi-core processor. However if only a small part of interfaces are actually used, the performance improvement would not meet the expectation. To overcome this problem, a new multi-channel multi-interface active RFID protocol, which balances communication loads among all available interfaces, is necessary. 3 protocols, named as "Aggregated", "LP-Combined", "AP-Balanced", are proposed. Through simulation, we compare them for various conditions by changing number of tags, number of interfaces, tag data size. AP-Balanced shows the best performance and its performance increases almost linearly as the number of interface increases, which meets our expectation.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.1
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• pp.16-27
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• 2012

In multi-interface multi-channel(MIMC) based tactical ad hoc networks, QoS support for required operational capacity is one of the main challenging issues for multi-hop transmissions. To support QoS in such a harsh environment, we propose a novel MAC scheme to minimize multi-hop as well as per-hop delay. The current IEEE 802.11 MAC protocols should contend to reserve the channel resource at every hop by each sender. The every-hop channel contention results in a degradation of end-to-end delay for multi-hop transmissions. The basic idea of our scheme is to make a "multi-hop reservation" at the MAC layer by using the modified RTS frame. It contains additional information such as destination information, packet priority, and hop count, etc. In addition, we differentiate the contention window area according to the packet priority and the number of hops to deliver packets in the predefined allowed latency. Our scheme can minimize the multi-hop delay and support the QoS of the critical data in real time(i.e., VoIP, sensing video data, Video conference between commanders). Our simulation study and numerical analysis show that the proposed scheme outperforms the IEEE 802.11 MAC.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.951-956
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• 2007

This paper suggests a high-speed control method which is suitable for multi-joint robots using a real-time stand-alone controller for general-purpose. The fast processing controller consists of a PCI Interface Board and 2-axe PWM drivers. The PCI Interface Board consists of 32-channel PWM output ports, 32-channel Encoder Counters, 32-channel A/D Converters and 48-channel Digital I/O ports, and all the I/O data transmissions are completed within 1ms. And The 2-axe PWM driver can be redesigned easily in order to embed in each link. Experimental implementations show that the high-speed control method can be used for the real-time control which is essential to controlling of multi-body robots such as humanoid robots. Especially, it is efficient for realizing the model-based motion control in demand of much calculation time by the high I/O communication speed.

• Journal of Korea Society of Digital Industry and Information Management
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• v.6 no.3
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• pp.103-109
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• 2010

Total performance is improved by minimizing the channel interference between links in wireless mesh networks (WMNs). The paper refines on the CB-CA [1] to be suitable for multi-radio multi-channel (MRMC) WMNs. The CB-CA is the cluster-based channel assignment algorithm for one radio three channel WMN based on IEEE 802.11b/g. The CB-CA does not perform the channel scanning and the channel switching between the cluster heads (CHs) and the edge gateway nodes (EGs). However, the use of co-channel for links between CHs and EGs brings the problem of channel interference among many nodes. We propose and evaluate an improved CB-CA algorithm to solve this problem in MRMC WMNs. The proposed algorithm discriminates between transmission channel and receive channel and assigns channels to each interface randomly and advertises this information to neighbor clusters in order to be assigned no-interference channel between clusters. Therefore, the proposed algorithm can minimize the interference between clusters and also improve QoS, since it can use multiple interfaces and multiple channels.