• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11C
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• pp.1083-1090
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• 2005

This paper presents the design of a video encoder for the device of need TV-OUT function. The designed video encoder satisfies the standard conditions of International Telecommunication Union-Radiocommunication (ITU-R) BT.470. ITU-R BT.470 can be classified as NTSC, PAL or SECAM. NTSC and PAL use Amplitude Modulation (AM) to transmit color difference signals and SECAM uses Frequency Modulation (FM). SECAM must have an antic-cloche filter but the filter recommended by ITU-R BT.470 is not easy to design due to sharpness of the frequency response. So formerly the filter was designed as analog. This paper proposes that the filter is designed as digital and the special quality of the filter is transformed easy to design. And the modulation method is modified to be identical with the result required at standard. The encoder can control power consumption by output mode to apply mobile phone, mobile devices, etc. The proposed encoder is experimentally demonstrated with ALTERA FPGA APEX20KE EP20K1000EBC652-3 device and SAMSUNG LCD-TV.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1357-1362
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• 2011

TV White Spaces (TVWS) are freed up after transition from analog television to Digital Television (DTV). Some wireless communications are allowable to operate in TVWSs, such unlicensed Wireless Fidelity (WiFi). Because TVWSs are located in the VHF and UHF bands, TVWSs can provide significantly better coverage and wall penetration inside buildings and other structures than the 2.4 GHz and 5 GHz WiFi frequencies currently in use. Therefore, this paper assumes that WiFi will be deployed in TVWSs. However, the interference impact of WiFi on DTV has to be taken into account. The interference probability in DTV receiver was evaluated by using Spectrum Engineering Advanced Monte-Carlo Analysis Tool (SEAMCAT). As a result, when 20 WiFi UEs are simultaneously operating at the maximum transmit power of 23 dBm and the guard band is 22 MHz, the protection distance should be at least 6 km to meet the interference probability of 5% in DTV receiver.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.11B
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• pp.1373-1382
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• 2011

Zigbee is communication technology most ideal because Zigbee support low power communication and wide expansion in wireless home network. However, Zigbee is not popular, because of Zigbee always has Hidden Node Problem and Transit Delay Problem. We propose new Beacon Frame structure to solve the two problem in Zigbee. New Beacon Frame structure reduces a Super Frame Duration and add a same space of a Control Frame Duration. We expect to solved method of Hidden Node Problem that exchange terminal information to using RTS/CTS. Also, We expect to solved method of Transit Delay Problem that put Beacon between Control Frame Duration and Super Frame Duration for synchronization. We confirm new Beacon Frame to solved two problem in OPNET simulation at Zigbee QoS Parameters. We measure Delay(sec) for solution degree of Transit Delay Problem, and measure Throughput(bits/sec) and Load (bits/sec) for solution degree of Hidden Node Problem.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.3A
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• pp.230-236
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• 2007

This paper presents a resource management mechanism for the mesh networking in IEEE 802.15.3 High-rate WPAN. IEEE 802.15 TGS is standardizing the MAC and PHY for mese networking. This task group researches the mechanism that are extension of network coverage without increasing transmit power of receive sensitivity, and studies the enhanced reliability via route redundancy. In this paper we propose the distributed resource management scheme that is fairly using the channel resource in the piconet without centralized piconet coordinator. Each DEV reserves the channel time and broadcasts its information. This scheme has unfairness for later associated DEV because of preoccupation of earlier associated DEVs. This paper presents the method that fairly allocates the channel time in MAC layer. And we evaluate the performance enhancement using simple simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.5A
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• pp.433-440
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• 2007

In this paper, we have proposed WiBro receiver structure employing joint adaptive antenna scheme at the base station (BS) and the mobile station (MS) and evaluated its performance. In WiBro system, the joint use of transmit beamforming at BS and receive beamforming at MS can improve the SINR significantly and increase the capacity compared to the conventional system. Moreover, power allocation level can be decreased because channel variation can be reduced by using the jointly updated weight. However, it needsthe calculation of the antenna weights in every subcarrier for performance improvement. This could imply an enormous computational burden. However, the computational complexity can be reduced significantly by using the same set of the antenna weights for the adjacent subcarriers instead of calculating antenna weights for every subcarrier. We have analyzed the impact of subcarrier grouping for weight calculation on the system performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.3
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• pp.161-163
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• 2014

We consider the device-to-device (D2D) communication underlaying multi-cell interference system, in which the cellular downlink (DL) resource is reused by K cells and two D2D transmission links within each cell. In this paper, it has been shown that the downlink intra-cell and inter-cell interference can be effectively handled by interference alignment (IA) technique, as long as the simultaneous D2D links are properly selected or power-controlled so that they may not incur interference to the base stations in the same and neighbor cells. In particular, we provides the IA technique that can achieve the theoretically maximum possible degree of freedom (DOF), demonstrating that a total of (K+1)M degrees of freedom (DOFs) can be achieved for K-cell interference system with two underlaying D2D links, where base stations, cellular UE's, and D2D UE's all have M transmit and receive antennas.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.3
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• pp.15-23
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• 2020

As the IoT industry expands, various application services based on location information of devices are released. In order to transmit the location information, various wireless communication technologies such as Bluetooth and Wi-Fi are used. However, these technologies have limited coverage, and cellular networks with relatively wide coverage have the disadvantage of paying for use. In this paper, we implemented our own location information system using LoRa, a low power long distance wireless communication technology. As a result, no cost is incurred and it has relatively wider coverage than other wireless communication technologies using LoRa technology. The implementation system enables LoRa communication based on IPv6 using CoAP and 6LoWPAN, and enables multiple devices to interwork with the existing Internet environment.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.47 no.12
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• pp.55-67
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• 2010

The electrical properties of a back drilled via-hole (BDH) without the open-stub and the plated through via-hole (PTH) with the open-stub, which is called the conventional structure, in a high-count multi~layered (HCML) printed circuit board (PCB) were investigated for a high-speed digital system, and a selected inner layer to transmit a high-speed signal was farthest away from the side to mount the component. Within 10 GHz of the broadband frequency, a design of experiment (DOE) methodology was carried out with three cause factors of each via-hole structure, which were the distance between the via-holes, the dimensions of drilling pad and the anti-pad in the ground plane, and then the relation between cause and result factors which were the maximum return loss, the half-power frequency, and the minimum insertion loss was analyzed. Subsequently, the empirical formulae resulting in a macro model were extracted and compared with the experiment results. Even, out of the cause range, the calculated results obtained from the macro model can be also matched with the measured results within 5 % of the error.

• The Journal of the Convergence on Culture Technology
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• v.3 no.3
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• pp.27-30
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• 2017

IoT could be applied to various areas because of the important role of sensor. The existing sensor communication method is to quickly transmit data by using clock and two data pins based on the I2C serial communication method. As the objects used are gradually light-weighted and the amount of data transmission is decreased, the simplification of hardware is more emphasized as an essential design element than the speed of transmission. This paper designed a circuit to send/receive data in series, and also realized arduino, by analyzing the existing communication method and then using a single pin for light-weight. The single pin serial communication could reduce power consumption, which is suitable for the sensor area using digital communication of IoT area.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.12
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• pp.1345-1352
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• 2014

Bus architecture of SoC has been replaced by NoC in recent years. Noc uses the multi-clock domains to transmit and receive data between neighbor network interfaces and they have same frequency, but a phase difference because of clock skew. So a synchronizer is used for a mesochronous frequency in interconnection between network interfaces. In this paper the metastability is defined and analyzed in a D latch and a D flip-flop to search the possibilities that data can be lost in the process of sending and receiving data between interconnects when a local frequency and a transmitted frequency have a phase difference. 180nm CMOS model parameter and 1GHz are used to simulate them in HSpice. The simulation results show that the metastability happens in a latch and a flip-flop when input data change near the clock edges and there are intermediate states for a longer time as input data change closer at the clock edge. And the next stage can lose input data depending on environmental conditions such as temperature, processing variations, power supply, etc. The simulation results are very useful to design a mescochronous synchronizer for NoC.