• Journal of Advanced Navigation Technology
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• v.11 no.3
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• pp.274-280
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• 2007

An ultra-wideband signal is characterized by a radiated spectrum with wide bandwidth around a relatively low center frequency. In this paper, the bit error rate (BER), packet error rate (PER), and data throughput performance for an ultra-wideband system with M-ary correlation receiver are analyze in additive white Gaussian noise (AWGN) and co-channel interference channel. To evaluate the performance of UWB system, a set of UWB communication waveform as pulse position modulated (PPM) signals consisting of more than one UWB pulse is used. The M-ary PPM signals are defined to be equally correlated in order to simplify the system performance analysis. The analysis for system performance shows that the wireless channel error significantly degrades throughput performance and can be effectively increased by hybrid ARQ scheme. Also, an attempt for comparing the data throughput of ultra-wideband system on different performance improvement schemes and parameters has been made. From the performance evaluation process, it is shown that the effects of wireless channel and hybrid ARQ scheme for ultra wideband M-ary PPM system can be evaluated by means of a suitable combination of the PER, throughput vs. signal-to-noise power ratio per bit.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.1
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• pp.10-18
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• 2010

The polar transmitter is applied to the narrowband communication systems such as GSM (Global System for Mobile Communications), EDGE (Enhanced Data Rates for GSM Evolution), and GPRS (General Packet Radio Service). To apply polar transmitter for the wideband communication like OFDM (Orthogonal Frequency Division Multiplexing) where the high PAPR (Peak-to-Average Power Ratio) problem occurs, this paper proposes a windowed-sinc function based PAPR reduction scheme. The proposed algorithm mitigates the effect of excessive suppression due to successive peaks or relatively high peaks of the signal. The BER (Bit Error Rate) and EVM (Error Vector Magnitude) performances are measured for various window types and lengths. The simulation results demonstrate that the proposed algorithm achieves significant improvement in terms of BER and PAPR reduction performance with similar spectrum performance to the conventional peak windowing scheme.

• Journal of Korea Society of Industrial Information Systems
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• v.11 no.4
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• pp.32-39
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• 2006

MANET is a dynamically reconfigurable wireless network with no fixed infrastructure (base station, or AP). In order to provide the data service in MANET, we need an efficient routing protocol to deliver the data to the wanted destination at a mobile node. A method of routing protocols called reactive routing protocol has recently got attention because of their low routing overhead. But a method of flooding broadcasts the packet to all of its neighbors. For this reason, each of the node has high routing overhead to route and keep path discovery. Accordingly in this paper, I propose an adaptive flooding scheme using N-hop look-ahead in MANET, md an optimal N value of doing flooding the packet to limited area. Because of being basically ignorant about topological changes, each of the node did not spontaneously cope with path alteration. But an efficient flooding scheme applying N-hop look-ahead is more resilient to topology changes than traditional algorithms. And also with this efficient flooding scheme, the simulation results demonstrate excellent reduction of routing overhead.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.5B
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• pp.443-450
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• 2011

The Internet has become an essential part in our modern life by providing useful information. So, the volume of Internet traffic has been increasing rapidly, which emphasizes the importance of network traffic analysis for effective network operation and management. Signature based analysis have been commonly used, but it is shown that the increase of signatures due to the increase of applications causes the performance degradation of real-time traffic analysis on high-speed network links. In this paper, we propose OS fingerprinting method for real-time traffic analysis. The previous problems can be solved by utilizing the OS information. The OS fingerprinting method for real-time traffic analysis, proposed in this paper, conducts under passive mode, and improves the limitation of a previous method such as low completeness and accuracy. In this paper, we enlarged an input data to improve completeness, and used the User-Agent field in HTTP packet to extract various OS signatures. Also, we changed an input data from packet to flow to improve accuracy.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.704-711
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• 2003

Recently, the demands for real-time service and multimedia data are rapidly increasing. There are significant redundancies between header fields both within the same packet header and in consecutive packets belonging to the same packet stream. But there are many overheads in using the current UDP/IP protocol. Header compression is considered to enhance the transmission efficiency for small size of payload. By sending the static field information only once initially and by utilizing dependencies and predictability for other fields, the header size can be significantly reduced for most packets. This work describes an implementation for header compression of the headers of U/UDP protocols to reduce overhead on Ethernet network. Typical UDP/IP Header packets can be compressed down to 7 bytes and the header compression system is designed and implemented on the Linux environment. Using the designed Header compression system between a server and a client have the advantage of effective data throughput in network.

• The KIPS Transactions:PartA
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• v.11A no.1
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• pp.81-88
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• 2004

In this paper, we designed the outer encoder/decoder for the terrestrial DMB that is an advanced digital broadcasting standard, implemented, and verified by using ALTERA FPGA. In the encoder part, it was created the parity bytes (16 bytes) from the input packet (188by1e) of MPEG-2 TS and the encoded data was distributed output by the convolutional interleaver for Preventing burst errors. In the decoder part, It was proposed the algorithm that detects synchronous character suitable to DMB in transmitted data from the encoder. The circuit complexity in RS decoder was reduced by applying a modified Euclid's algorithm. This system has a capability to correct error of the maximum 8 bytes in a packet. After the outer encoder/decoder algorithm was verified by using C language, described in VHDL and implemented in the ALTERA FPGA chips.

• The KIPS Transactions:PartC
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• v.11C no.2
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• pp.157-162
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• 2004

Recently, the growth of information infrastructure is getting fatter and faster. At the same time, the security accidents are increasing together. We have problem that do not handle traffic because we have the Intrusion Detection Systems in low speed environment. In order to overcome this, we need effective security analysis techniques that ran Processed data of high-capacity because high speed network environment. In this paper we proposed the Gigabit Intrusion Detection System for coordinated security function such as intrusion detection, response on the high speed network. We suggested the detection mechanism in high speed network environment that have pattern matching function based packet header and based packet data that is proceeded in system kernel area, we are shown that this mechanism was excellent until maximum 20 times than existing system in traffic processing performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11A
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• pp.1253-1262
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• 2004

The Data Over Cable System Interface Specification (DOCSIS) protocol enables the delivery of Internet Protocol(IP) traffic over Cable TV networks with significantly higher data rates. In this paper, we assessed the performance of the DOCSIS protocol using the OPNET. The simulation can be used to predict the upstream system throughput, mean access delay and channel utilization on varying packet size and transmission stream and wid/without concatenation, and it has shown that maximum system throughput is 4.6 Mbps for channel capacity of 5.12 Mbps and packet size of 1500 bytes. The mean access delay varies depending on the offered load, and it is assumed that the offered load does not exceed the capacity of the channel. Excess offered load causes service starvation according to the assigned priority.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.6
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• pp.1058-1069
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• 2015

In wireless sensor networks, geographic routing is known as an efficient method to transmit the data packet using the location information. Geographic routing relies on two techniques: greedy forwarding and face routing. Face routing helps to recover from greedy routing fail and is based on the planar graph in which does not cross each edge. However, the planarization causes frequently short transmission of data packet because it removes other edges except the shortest one. In other words, since the planarization removes the long edges, face routing could not exploit the efficient removed edges of communication graph. This problem brings about the excessive energy consumption of nodes. In this paper, we propose an energy efficient face routing protocol in wireless sensor networks. This proposed protocol searches the removed edges and transmits them via the edges. Simulation shows that the proposed protocol is more efficient in terms of energy consumption than the previous face routing.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.5
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• pp.147-154
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• 2015

Satellite broadcasting networks, like if you have if you have just received information that everyone must bring the required security attributes this earth should be done as encryption. In this paper, a satellite communication network AH additional security header in transport mode IPsec VPN by applying the SHA-256 and MD-5 authentication algorithm to authenticate the data portion Error rate and analyze the BER and Throughput. First, to generate a normal IP packet added to IPsec transport mode security header AH were constructed internal authentication data by applying the SHA-256 and MD-5 algorithm. Channel coder was applied to the Rate Compatible Punctured Turbo Codes, packet retransmission scheme Hybrid-ARQ Type-II and Type-III were used. Modulation method was applied to the BPSK, the wireless channel Markov channel (Rician 80%, Rayleigh 20% and Rician 90%, Rayleigh 10%) as an authentication algorithm according to the satellite channel state analyzed how they affect the error rate and Throughput.