• Journal of the Korea Society of Computer and Information
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• v.14 no.10
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• pp.101-110
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• 2009

The 6LoWPAN(IPv6 Low-power Wireless Personal Area Network) performs IPv6 header compression, TCP/UDP/IGMP header compression, packet fragmentation and re-assemble to transmit IPv6 packet over IEEE 802,15.4 MAC/PHY. However, from the point of view of security. It has the existing security threats issued by IP packet fragmenting and reassembling, and new security threats issued by 6LoWPAN packet fragmenting and reassembling would be introduced additionally. If fragmented packets are retransmitted by replay attacks frequently, sensor nodes will be confronted with the communication disruption. This paper analysis security threats introduced by 6LoWPAN fragmenting and reassembling, and proposes a re-transmission mechanism that could minimize re-transmission to be issued by replay attacks. Re-transmission procedure and fragmented packet structure based on the 6LoWPAN standard(RFC4944) are designed. We estimate also re-transmission delay of the proposed mechanism. The mechanism utilizes timestamp, nonce, and checksum to protect replay attacks. It could minimize reassemble buffer overflow, waste of computing resource, node rebooting etc., by removing packet fragmentation and reassemble unnecessary.

• Journal of the Korea Society of Computer and Information
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• v.16 no.8
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• pp.77-84
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• 2011

In this paper we implement a 6LoWPAN protocol on the MICAz sensor platform, which could minimize packet re-transmission, and support security primitives for packet integrity and confidentiality. And we also present a performance evaluation of the implemented protocol calculated according to the cryptographic algorithms. In the re-transmission method, time stamp, nonce, and checksum are considered to protect replay attacks. As cryptographic algorithms, AES, 3DES, SHA2, and SHA1 are implemented. If transmission errors (thus, packet losses) and the number of hops are increase then, packet re-transmissions are increase exponentially from the experimental results. Also, the result shows that cryptographic operations take more time than packet re-transmission time.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.1
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• pp.1-14
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• 2010

It is recently issued scalability, mobility and external internet connection on Wire-less sensor network. The low power wireless sensor networks based on IPv6 technology 6LoWPAN technology is being standardized in the IETF. This paper for the 6LoWPAN environment based on the routing protocol LOAD, route cost applied the packet re-transmission rate which follows in Link Qualities price which uses at course expense and packet transmission Minimum route Cost routing protocol where does on the course wherethe smallest packet re-transmission becomes accomplished proposed. The technique which proposes compared and LOAD and AODV that about 13%, about 16% energy consumption is few respectively averagely, Energy of the entire network equally, used and energy effectiveness and improvement of network life time experiment led and confirmed.

• Journal of Advanced Navigation Technology
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• v.10 no.1
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• pp.1-6
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• 2006

In this paper, we have analyzed transmission time for WAP over CDMA using turbo code scheme. In order for SAR to improve the transfer capability, the transmission of messages have been simulated using a fragmentation that begins with the total package and incremental fragmentation for each layer using the WTP to define the resultant packet size and the level of fragmentation for each proceeding layer. This turbo code scheme decreases transmission time of RLP baseband packets by sending packets. From the results, we were able to obtain packet transmission time and optimal WTP packet size for WAP over CDMA in a Rician fading channel.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.2 no.2
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• pp.82-102
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• 2008

Packet losses tend to occur during short error bursts separated by long periods of relatively error-free transmission. There is also a significant spatial correlation in loss among the receiver nodes in a multicast session. To recover packet transmission errors at the transport layer, tree-based protocols construct a logical tree for error recovery before data transmission is started. The current tree construction scheme does not scale well because it overloads the sender node. We propose a scalable recovery tree construction scheme considering these properties. Unlike the existing tree construction schemes, our scheme distributes some tasks normally handled by the sender node to specific nodes acting as repair node distributors. It also allows receiver nodes to adaptively re-select their repair node when they experience unacceptable error recovery delay. Simulation results show that our scheme constructs the logical tree with reduced message and time overhead. Our analysis also indicates that it provides fast error recovery, since it can reduce the number of additional retransmissions from its upstream repair nodes or sender node.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.11
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• pp.5360-5376
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• 2017

In this paper, we study the cross-layer design for the AMC/HARQ-based wireless networks, and propose a new dynamic transmission-mode selection scheme to improve system spectrum efficiency. In the proposed scheme, dynamic thresholds for transmission-mode selection in each packet transmission and retransmission are jointly designed under the constraint of the overall packet error rate. Comparing with the existing schemes, the proposed scheme is inclined to apply higher modulation order at the first several (re)transmissions, which corresponds to higher-rate transmission modes thus higher average system spectrum efficiency. We also extend the cross-layer design to MIMO (Multi-input Multi-output) communication scenarios. Numerical results show that the proposed new dynamic transmission-mode selection scheme generally achieves higher average spectrum efficiency than the conventional and existing cross-layer design.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.553-556
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• 2005

It is analyzed that WAP packet transmission time to improve performance of WAP using SAR algorithm in Bluetooth channel. The order for SAR algorithm to improve the transfer capability, it is fragmented in WTP total messages that are coming down from upper layer and then the packets are sent one at time in baseband. And it is studied that transmission time for WAP over bluetooth according to DM1, DM3 or DM5 packet type using SAR algorithm in Bluetooth piconet environment. This SAR algorithm decreases WAP packet transmission time of L2CAP baseband packets by sending packet which are spanning multiple slots.

• Journal of Advanced Navigation Technology
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• v.6 no.2
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• pp.158-167
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• 2002

In this paper, it is analyzed that WAP packet transmission time to improve performance of WAP using SAR-QT algorithm in Bluetooth channel. The order for SAR-QT algorithm to improve the transfer capability, it is fragmented in WTP total messages that are coming down from upper layer and then the packets are sent one at time in baseband. And it is studied that transmission time for WAP over Bluetooth according to DMI, DM3 or DM5 packet type using SAR-QT algorithm in Bluetooth piconet environment. This SAR-QT algorithm decreases WAP packet transmission time of L2CAP baseband packets by sending packet that are spanning multiple slots. From the results, in WAP over Bluetooth channels, it is found out that WTP packet size ought to be increased to decrease transmission time of WAP packet. In addition, considering BER in wireless channel, optimal WTP packet size is achieved for WAP over Bluetooth in a Rician fading environment.

• Journal of Advanced Navigation Technology
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• v.6 no.1
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• pp.69-76
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• 2002

With the growth of data communication service by mobile devices, WAP is proposed to efficiently access the Internet contents by user request through wireless condition that has a high error rate and mobility. But, because a transmission speed of WAP is limited, it takes many times to transmit and to receive the data. This paper has studied the WAP packet transmission time using WTP-SAR algorithm. As a method that is to improve transfer capability of WAP, using SAR function in WTP, total message down from upper layer has been fragmented and packet is transmitted through RLP frame time slot. Then, we have analyzed the transmission time of WAP packet with variable RLP layer size on the wireless CDMA network for next generation systems. From the results, we could obtain the WAP packet transmission time and optimal WTP packet size.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1796-1798
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• 2002

Speech transmission is common in many communications systems. In this paper, a technique to reduce the total bits required for expressing the speech data is proposed for the purpose of a packet transmission. A novel coding method is derived based on the concept of finding common information in sequential speech samples. Computer simulations demonstrate that the proposed scheme reduces the total bits re- quired in PCM approximately by half.