• Journal of Communications and Networks
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• 제12권2호
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• pp.140-149
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• 2010

Green communication is a new paradigm of designing the communication system which considers not only the processing performance but also the energy efficiency. Power control management is one of the approaches in green communication to reduce the power consumption in distributed communication system. In this paper, we propose improved power control schemes for mobile satellite systems with ancillary terrestrial components (ATCs). In order to increase system capacity and reduce the transmitting power of the user's equipment, we propose an efficient channel estimation method consisting of a modified open-loop power control (OLPC) and closed-loop power control (CLPC). The OLPC works well if the forward and reverse links are perfectly correlated. The CLPC is sensitive to round-trip delay and, therefore, it is not effective in a mobile satellite system. In order to solve the above problem, we added monitoring equipment to both the OLPC and CLPC to use information about transmitting power that has not yet been received by the receiver over the satellite/ATC channel. Moreover, we adapted an efficient pilot diversity of both OLPC and CLPC in order to get a better signal to interference plus noise ratio estimation of the received signal.

• International Journal of Computer Science & Network Security
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• 제23권10호
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• pp.169-178
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• 2023

Wireless sensor network is wieldy use for IoT application. The sensor node consider as physical device in IoT architecture. This all sensor node are operated with battery so the power consumption is very high during the data communication and low during the sensing the environment. Without proper planning of data communication the network might be dead very early so primary objective of the cluster based routing protocol is to enhance the battery life and run the application for longer time. In this paper we have comprehensive of twenty research paper related with clustering based routing protocol. We have taken basic information, network simulation parameters and performance parameters for the comparison. In particular, we have taken clustering manner, node deployment, scalability, data aggregation, power consumption and implementation cost many more points for the comparison of all 20 protocol. Along with basic information we also consider the network simulation parameters like number of nodes, simulation time, simulator name, initial energy and communication range as well energy consumption, throughput, network lifetime, packet delivery ration, jitter and fault tolerance parameters about the performance parameters. Finally we have summarize the technical aspect and few common parameter must be fulfill or consider for the design energy efficient cluster based routing protocol.

• 한국인터넷방송통신학회논문지
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• 제13권1호
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• pp.115-120
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• 2013

무선 센서 네트워크의 다양한 용도만큼 많은 취약점과 다양한 공격 가능성이 여러 논문에서 제기되고 있다. 여러 공격 중에서도 시빌(sybil) 공격은 공격 노드가 많은 수의 거짓 노드를 생성하여 네트워크에 잘 못된 정보를 보내는 공격이다. 사용자가 공격을 받았음을 인지하지 못하고 거짓 노드로부터 온 데이터를 사실로 오인하고 사용하게 되면 민감한 데이터일 경우 재앙이 될 수도 있다. 인증과 같은 암호화 기법으로 방어를 할 수 있지만 저전력, 저사양을 특징으로 하는 센서 노드에서는 구현이 곤란하다. 본 논문에서는 센서 네트워크에서 시빌 공격으로 생성된 거짓 노드를 탐지하는 기법을 제안한다. 제안 기법은 정상 노드의 군집과 거짓 노드의 군집 간에 네트워크가 약하다는 특징을 이용한다. 또한 센서 노드의 저전력을 고려하여 기존 에너지 고려 라우팅에 약간의 데이터를 추가함으로써 오버헤드를 최소화 하였다. 실험 결과를 통해 제안 기법이 기존 에너지 고려 라우팅에 비해 추가적인 에너지 소모가 극히 적으면서도 시빌 공격의 탐지를 90% 이상 할 수 있음을 보였다.

• Journal of Communications and Networks
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• 제17권5호
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• pp.453-462
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• 2015

Body area networks (BANs) have emerged as an enabling technique for e-healthcare systems, which can be used to continuously and remotely monitor patients' health. In BANs, the data of a patient's vital body functions and movements can be collected by small wearable or implantable sensors and sent using shortrange wireless communication techniques. Due to the shared wireless medium between the sensors in BANs, it may be possible to have malicious attacks on e-healthcare systems. The security and privacy issues of BANs are becoming more and more important. To provide secure and correct association of a group of sensors with a patient and satisfy the requirements of data confidentiality and integrity in BANs, we propose a novel enhanced secure sensor association and key management protocol based on elliptic curve cryptography and hash chains. The authentication procedure and group key generation are very simple and efficient. Therefore, our protocol can be easily implemented in the power and resource constrained sensor nodes in BANs. From a comparison of results, furthermore, we can conclude that the proposed protocol dramatically reduces the computation and communication cost for the authentication and key derivation compared with previous protocols. We believe that our protocol is attractive in the application of BANs.

• 센서학회지
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• 제26권6호
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• pp.408-413
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• 2017

In this paper, we newly developed a byte-inverted transmission method for flicker-free visible light communication (VLC). The VLC transmitter sends original data in the former half period of the clock, and inverted data and in the latter half period of the clock. The VLC receiver receives the original data in the in the former half period of the clock. In this system, we used 480Hz clock that was generated from the 60Hz power line. The average optical power of the LED array in the transmitter is constant, thus flicker-free, in the observation time longer than the period of the clock that is about 2ms. This period is shorter than the maximum flickering time period (MFTP) of 5ms that is generally considered to be safe. This configuration is very useful in constructing indoor wireless sensor networks using LED light because it is flicker-free and does not require additional transmission channel for clock transmission.

• 센서학회지
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• 제25권5호
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• pp.303-309
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• 2016

In this paper, we introduce a new method for controlling the illumination of LEDs in visible light communication (VLC) by changing the duty cycle of Manchester code. When VLC data were transmitted in Manchester code, the average optical power of the LEDs was proportional to the duty cycle. In experiments, we controlled the illumination of a $3{\times}3$ LED array from 10% to 90% of its peak value by changing the duty cycle of the Manchester code. The synchronizing clocks required for encoding and decoding the Manchester code were supplied by pulse generators that were connected to a 220 V power line. All pulse generators made the same pulses with a repetition frequency of 120 Hz, and they were synchronized with the full-wave rectified voltage of the power line. This scheme is a very simple and useful method for constructing indoor wireless sensor networks using LED light.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권1호
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• pp.239-260
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• 2023

The underwater acoustic wireless communication networks are generally formed by the different autonomous underwater acoustic vehicles, and transceivers interconnected to the bottom of the ocean with battery deployed modems. Orthogonal frequency division multiplexing (OFDM) has become the most popular modulation technique in underwater acoustic communication due to its high data transmission and robustness over other symmetrical modulation techniques. To maintain the operability of underwater acoustic communication networks, the power consumption of battery-operated transceivers becomes a vital necessity to be minimized. The OFDM technology has a major lack of peak to average power ratio (PAPR) which results in the consumption of more power, creating non-linear distortion and increasing the bit error rate (BER). To overcome this situation, we have contributed our symmetry research into three dimensions. Firstly, we propose a machine learning-based underwater acoustic communication system through long short-term memory neural network (LSTM-NN). Secondly, the proposed LSTM-NN reduces the PAPR and makes the system reliable and efficient, which turns into a better performance of BER. Finally, the simulation and water tank experimental data results are executed which proves that the LSTM-NN is the best solution for mitigating the PAPR with non-linear distortion and complexity in the overall communication system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권5호
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• pp.2243-2257
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• 2019

A heterogeneous cellular network (HCN) is useful to increase the spectral and energy efficiency of wireless networks and to reduce the traffic load from the macro cell. The performance of the secondary user equipment (SUE) is affected by interference from the eNodeB (eNB) in a macro cell. To decrease the interference between the macro cell and the small cell, allocating resources properly is essential to an HCN. This study considers the scenario of a software-defined heterogeneous cellular network and performs the resource allocation process. First, we show the system model of HCN and formulate the optimization problem. The optimization problem is a complex process including power and frequency resource allocation, which imposes an extremely high complexity to the HCN. Therefore, a hierarchical resource allocation scheme is proposed, which including subchannel selection and a particle swarm optimization (PSO)-based power allocation algorithm. Simulation results show that the proposed hierarchical scheme is effective in improving the system capacity and energy efficiency.

• 한국산학기술학회논문지
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• 제12권6호
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• pp.2754-2759
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• 2011

정보통신과 RFID/USN의 발전으로 인하여 유/무선망의 통합이 일반화되어가고 있다. 이러한 시점에서 무선환경에서 데이터 통신을 위한 프로토콜로서 WAP이 사용되고 있다. 이러한 WAP에서 안전한 통신을 위하여 개발된 WTLS는 인터넷 프로토콜인 TCP/IP에서 사용되는 TLS를 무선환경에 맞도록 최적화한 것이다. 그러나 WTLS는 WAP 보안문제, 종간 문제, 소비전력등의 문제점을 가지고 있다. 그러므로 본 논문에서는 WTLS의 단점들을 없애고자 WTLS에 사용되는 암호알고리즘을 제안하였다. 제안된 알고리즘은 단일형태가 아닌 혼합형 알고리즘을 사용하기 때문에 계산상의 복잡도를 줄여 소비전력 및 보안문제를 해결할 수 있다.

• 대한전자공학회논문지TC
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• 제43권1호
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• pp.19-24
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• 2006

무선 센서 네트워크는 사람이 접근할 수 없는 곳에서 감시와 정보 수집과 같은 다양한 응용분야를 가진다. 무선 센서 네트워크의 주된 연구는 에너지 소모의 감소와 데이터의 신뢰성이다. 전방향 오류 정정(FEC)을 이용한 시스템은 FEC를 사용하지 않은 시스템 보다 적은 전송 전력으로 목표하는 데이터의 신뢰성을 제공한다. 본 논문에서는 무선 센서 네트워크를 위한 FEC로 다양한 부호율(0.53, 0.81, 0.91)을 가지는 LDPC부호의 사용을 제안한다. 또한 채널로 AWGN채널에 노드 간의 간섭을 고려한다. 제안한 시스템은 낮은 SNR에서 높은 신뢰도를 가지는 데이터 전송뿐만 아니라 데이터 전송 전력의 감소를 가진다.