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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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The Journal of Korean Institute of Communications and Information Sciences
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Volume 40, Issue 12 - Dec 2015
Volume 40, Issue 11 - Nov 2015
Volume 40, Issue 10 - Oct 2015
Volume 40, Issue 9 - Sep 2015
Volume 40, Issue 8 - Aug 2015
Volume 40, Issue 7 - Jul 2015
Volume 40, Issue 6 - Jun 2015
Volume 40, Issue 5 - May 2015
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On the Characteristics of MSE-Optimal Symmetric Scalar Quantizers for the Generalized Gamma, Bucklew-Gallagher, and Hui-Neuhoff Sources
Rhee, Jagan ; Na, Sangsin ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1217~1233
DOI : 10.7840/kics.2015.40.7.1217
The paper studies characteristics of the minimum mean-square error symmetric scalar quantizers for the generalized gamma, Bucklew-Gallagher and Hui-Neuhoff probability density functions. Toward this goal, asymptotic formulas for the inner- and outermost thresholds, and distortion are derived herein for nonuniform quantizers for the Bucklew-Gallagher and Hui-Neuhoff densities, parallelling the previous studies for the generalized gamma density, and optimal uniform and nonuniform quantizers are designed numerically and their characteristics tabulated for integer rates up to 20 and 16 bits, respectively, except for the Hui-Neuhoff density. The assessed asymptotic formulas are found consistently more accurate as the rate increases, essentially making their asymptotic convergence to true values numerically acceptable at the studied bit range, except for the Hui-Neuhoff density, in which case they are still consistent and suggestive of convergence. Also investigated is the uniqueness problem of the differentiation method for finding optimal step sizes of uniform quantizers: it is observed that, for the commonly studied densities, the distortion has a unique local minimizer, hence showing that the differentiation method yields the optimal step size, but also observed that it leads to multiple solutions to numerous generalized gamma densities.
Cooperative Spectrum Sensing Utilizing Sub-Nyquist Sampling in Cognitive Radio Networks
Jung, Honggyu ; Kim, Kwangyul ; Shin, Yoan ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1234~1238
DOI : 10.7840/kics.2015.40.7.1234
We propose cooperative spectrum sensing schemes based on sub-Nyquist sampling. As compressed sensing has recently attracted great attention, sparsity order estimation techniques also has been widely investigated. Thus, assuming that the sparsity order of channel occupancy can be obtained, we mathematically analyze the detection performance of sub-Nyquist sampling schemes according to various sampling rates and cooperative spectrum sensing schemes. Simulation results verify the performance of the proposed schemes.
Adaptive Channel Estimation Techniques for FDD Massive MIMO Systems
Chung, Jinjoo ; Han, Yonghee ; Lee, Jungwoo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1239~1247
DOI : 10.7840/kics.2015.40.7.1239
In frequency-division duplex (FDD) massive multiple-input multiple-output (MIMO) system, the computational complexity of downlink channel estimation is proportional to the number of antennas at a base station. Therefore, effective channel estimation techniques may have to be studied. In this paper, novel channel estimation algorithms using adaptive techniques such as Kalman and least mean square (LMS) filters are proposed in a channel model with temporal and spatial correlation.
Rain Attenuation Analysis for Designing UAV Data Link on Ku-Band
Lee, Jaeyoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1248~1256
DOI : 10.7840/kics.2015.40.7.1248
It is necessary to apply an exact data and a precise prediction model for a rain attenuation to design the link margin for a data link using Ku-band with the serious effect by rain. In this paper, we investigate the regional rainfall-rate distribution of Korea proposed in TTAK.KO-06.0122/R1 and compare it with the distribution provided by Rec. ITU-R PN.837-1 and Crane. And, the rain rate climate regions similar with the rainfall-rate distribution of Korea in Rec. ITU-R PN.837-1 and Crane model are selected. Finally, using Rec. ITU-R P.618-8 and Crane rain attenuation prediction model, we derive and analyze the rain attenuation for Ku-band frequency according to the time percentage of an average year and the distance of wireless communication link between unmanned aerial vehicle (UAV) and ground data terminal (GDT).
User Selection Scheme Based on the Projection Matrix
Kim, Gibum ; Kim, Jinwoo ; Park, Hyuncheol ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1257~1265
DOI : 10.7840/kics.2015.40.7.1257
In this paper, we describe a greedy user selection scheme for multiuser multiple-input multiple-output (MIMO) systems. We propose a new metric which has significantly improved performance compared to the Frobenius norm metric. The approximation of projection matrix is applied to increase the accuracy of Frobenius norm of effective channel matrix. We analyze the computational complexity of two metrics by using flop counts, and also verify the achievable sum rate through numerical simulation. Our simulation result shows that the proposed metric can achieve the improved sum rate as the number of user antenna increases.
Recent Study on Interference Management for Full-Duplex Cellular Systems
Jeon, Sang-Woon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1266~1275
DOI : 10.7840/kics.2015.40.7.1266
This review paper introduces recent results on interference management for full-duplex cellular systems. Interference management techniques for uplink-downlink cellular networks are frist introduced, which are closely related to those for full-duplex cellular systems. Self-interference suppression method for full-duplex radios and the corresponding modeling of full-duplex cellular systems are then explained. Even if self-interference is perfectly suppressed, there exists a new source of interference between full-duplex users for full-duplex cellular systems. Therefore, management of such user-to-user interference is of crucially importance to improve the capacity of full-duplex cellular systems. Recently, new interference management techniques for achieving the optimal sum degrees of freedom of full-duplex cellular systems have been proposed. In this review paper, these optimal interference management techniques are mainly introduced.
Medium Access Control Protocols for Full-Duplex Communications in WLAN Systems: Approaches and Challenges
Kim, Wonjung ; Song, Taewon ; Kim, Taeyoon ; Pack, Sangheon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1276~1285
DOI : 10.7840/kics.2015.40.7.1276
Full-duplex communications have emerged as a key technology for next-generation wireless local area networks (WLANs). Although the key enabling technology for full-duplex communications is the self-interference cancellation (SIC) technique in the physical layer, the employment of full-duplex communications has huge potentials to substantially increase the throughput at the medium access control (MAC) layer. At the same time, full-duplex communications pose non-trivial challenges to the MAC protocol design. In this article, we first identify salient problems in supporting full-duplex communications in WLAN MAC protocols. After that, we survey the state-of-the art to address those problems and analyze their pros and cons. Finally, we present open research challenges to improve the effectiveness of full-duplex communications in WLANs.
Survey on MIMO Full-Duplex
Yang, Hyun Jong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1286~1292
DOI : 10.7840/kics.2015.40.7.1286
In this paper, a multi-input multi-output (MIMO) full-duplex system is addressed, where both the transmitter and receiver have multiple antennas. Fundamental problems of the MIMO full-duplex technique are discussed, and possible solutions are presented. In particular, the transceiver designs that have been reported in the literature are technically reviewed, and their problems are discussed investigating the feasibility of the full-duplex technique in commercialized systems such as LTE and WiFi.
Adaptive Multi-Antenna Channel Estimation Scheme for Uplink Multiuser Environments
Kim, Kyung Jun ; Choi, Kyung Jun ; Lee, Jinnyeong ; Kim, Kwang Soon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1293~1295
DOI : 10.7840/kics.2015.40.7.1293
In this letter, an adaptive multi-antenna channel estimation scheme is proposed for uplink multiuser environments such as LTE-A systems to accurately estimate time-varying channels within an affordable complexity. It is confirmed that the proposed channel estimator can achieve accurate channel tracking performance even when various time-varying channel environments and traffic patterns are provided.
Energy Saving Characteristics of OSPF Routing Based on Energy Profiles
Seo, Yusik ; Han, Chimoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1296~1306
DOI : 10.7840/kics.2015.40.7.1296
Nowadays the research of energy saving on the IP networks have been studied the various methods in many research institutes. This paper suggests the energy saving method in IP networks which have the various energy profiles, and analyzes its energy saving characteristics in detail. Especially this paper proposes the energy profile based OSPF routing method which have the selectable weighted value in OSPF metric and energy consumption in IP network. This paper analyzes the energy saving effects of the various situations to minimize the energy consumption using the various weighted value on the proposed scheme. The results show that the energy saving efficiency can get about 67% at in ingress input load
by using random energy profiles in IP networks. Although the number of hops is a slight increased due to routing the paths for the minimum energy consumption in the algorithm of this method, the increment hop number is limited the mean 1.4 hops. This paper confirms that the energy profile of core router has the large effects of energy saving than the energy profile of edge router, and the proposed method has the excellent energy saving characteristics in IP networks.
Bluetooth Beacon Planing Considering Position Estimation Accuracy in Small and Isolated In-Door Environment
Ahn, Heejune ; Thuy, Tran Vinh ; Lee, Ye Hoon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1307~1312
DOI : 10.7840/kics.2015.40.7.1307
The recent adoption of Bluetooth LE technology in smart phones triggered commercial interest in RSSI-based positioning technology. Estimation error in RSSI measurement due to the antenna pattern, multipath fading, environmental noise has to be considered for designing beacon systems. The paper proposes an analysis method and beacon planning rules for a small and isolated indoor service area, based on probabilistic model of RSSI estimation error. As an practically important guide, the beacons have to be installed at the boundary of the service area to minimize the maximum position error, whereas the beacons have to be evenly distributed in the service space to minimize the average estimation error.
Performance Enhancement of AODV Routing Protocol Based on Interrupt Message and Backup Path Strategy in MANET
Lee, Yun-kyung ; Kim, Ju-gyun ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1313~1329
DOI : 10.7840/kics.2015.40.7.1313
In MANET, frequent route breaks lead to repeated route discovery process and this increases control packet overhead and packet drop. AODV-I improves performance of AODV by using the event driven approach which removes periodic Hello message. Unlike the Hello message, Interrupt message which is sent for each event can detect and predict the link failure because it allows node to know the status of the neighbor node. From this characteristics of Interrupt message, performance of AODV-I can be further improved by adding a processing procedures for each type of Interrupt message and it is also possible to improve AODV-I by adding the Backup path scheme because it originally has problems due to a single path of AODV. In this paper, we propose AODV-IB that combines improved Backup path scheme and Interrupt message approach of AODV-I in order to reduce transmission delay and the number of route discoveries. AODV-IB improves AODV-I by adding proper processing procedures for the link failure prediction and detection for each Interrupt message. We also implement improved Backup path strategy in AODV-IB by minimizing delay without additional Control packet. Simulation results, using the simulator QualNet 5.0, indicate that proposed AODV-IB performs better than AODV-I.
Combination of Token Bucket and AMP Schemes to Solve Buffer Underflow and Overflow of Video Streaming in Wireless Communication
Lee, Hyun-no ; Kim, Dong-hoi ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1330~1338
DOI : 10.7840/kics.2015.40.7.1330
In wireless communication network, the amount of packet data for the video streaming in the playout buffer of the receiver is changed with time according to network condition. If the amount of packet data is less than a specific buffer amount, the buffer underflow problem is generated. On the contrary, if the amount of packet data is more than a given buffer amount, the buffer overflow problem is occurred. When the playout of the video streaming is processed, these buffer underflow and overflow problems cause stop and skip phenomenons and then provide the discontinuity of playout. Therefore, to solve the buffer underflow and overflow problems of the video streaming in wireless communication network, This paper analyzes the combined effect of Token Bucket scheme, which controls the bursty traffic, and AMP(Adaptive Media Playout) scheme, which adaptively changes the playout speed of receiver. Through simulation, we found that the combination of Token Bucket and AMP schemes provides the superiority in terms of the occurrence number of buffer underflow and overflow, the stop duration time and the number of removed frames generated by underflow and overflow, and PSNR.
Performance Improvement of Traffic Identification by Categorizing Signature Matching Type
Jung, Woo-Suk ; Park, Jun-Sang ; Kim, Myung-Sup ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1339~1346
DOI : 10.7840/kics.2015.40.7.1339
The traffic identification is a preliminary and essential step for stable network service provision and efficient network resource management. While a number of identification methods have been introduced in literature, the payload signature-based identification method shows the highest performance in terms of accuracy, completeness, and practicality. However, the payload signature-based method's processing speed is much slower than other identification method such as header-based and statistical methods. In this paper, we first classifies signatures by matching type based on range, order, and direction of packet in a flow which was automatically extracted. By using this classification, we suggest a novel method to improve processing speed of payload signature-based identification by reducing searching space.
Implementation of 10 Gb/s 4-Channel VCSELs Driver Chip for Output Stabilization Based on Time Division Sensing Method
Yang, Choong-reol ; Lee, Kang-yoon ; Lee, Sang-soo ; Jung, Whan-seok ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1347~1353
DOI : 10.7840/kics.2015.40.7.1347
We implemented a 10 Gb/s 4-channel vertical cavity surface emission lasers (VCSEL) driver array in a
CMOS process technology. To enhance high current resolution, power dissipation, and chip space area, digital APC/AMC with time division sensing technology is primarily adopted. The measured -3 dB frequency bandwidth is 9.2 GHz; the small signal gain is 10.5 dB; the current resolution is 0.01 mA/step, suitable for the wavelength operation up to 10 Gb/s over a wide temperature range. The proposed APC and AMC demonstrate 5 to 20 mA of bias current control and 5 to 20 mA of modulation current control. The whole chip consumes 371 mW of low power under the maximum modulation and bias currents. The active chip size is
Ultra Wide Area Wireless Backhaul Network System Based on Large Scale Array Antenna
Go, SeongWon ; Kim, Hyoji ; Lee, Ju Yong ; Cho, Dong-Ho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1354~1362
DOI : 10.7840/kics.2015.40.7.1354
Heterogeneous network technology is expected to be a core technology for 5G mobile communications. 5G mobile network would be composed of many base stations even have mobility, then the operator should connect base stations through the wireless backhaul technology. This paper presents Ultra Wide Area Wireless Backhaul Network System with massive array antenna. We conducted link budget analysis for Ultra Wide Area Wireless Backhaul Network and performance analysis of massive array antenna system through the transmission simulator based on beamforming technology. In wide area (
) wireless backhaul system composed of massive antenna, we achieved 5 bps/Hz average spectral efficiency with 1 W transmission power per beam.
Design of Modified H-slot Aperture-coupled Circular Polarization Microstrip Array Antenna
Park, Ki-dong ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1363~1368
DOI : 10.7840/kics.2015.40.7.1363
Aperture-coupled circular polarization microstrip array antenna is proposed in this paper. The proposed antenna is useful for 2.4GHz ISM band and its aperture shape is a modified H-slot. The optimal design parameters for the antenna structure is found by using electromagnetic analysis tool HFSS repeatedly. The HFSS simulation results, such as return loss, axial ratio, radiation pattern and gain of the proposed array antenna are compared with results of the single antenna. It is able to verify that the proposed array antenna is valuable enough to be used in various applications as well as 2.4GHz ISM band.
Dynamic Threshold-Based Multicast Scheme for N-Screen Services in Indoor and Ship Area Networks
Hur, Kyeong ; Lee, Seong Ro ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1369~1376
DOI : 10.7840/kics.2015.40.7.1369
A wireless bridge is essential to transmit control and managing information to sensors or instruments from a central integrated ship area network station. In this paper, a WiMedia Distributed-MAC(D-MAC) protocol is adopted for development of a seamless N-Screen wireless service in Indoor and Ship Area Networks. Furthermore, to provide the OSMU(One Source Multi Use) N-screen service through P2P streaming in the seamless D-MAC protocol, a Dynamic Threshold-based Multicast(DTM) technology is proposed and analyzed. For this technology, a new Hard/Soft Vertical Region(HVR-SVR) based time slot allocation and a multicast resource reservation scheme are combined. From simulation results, proposed DTM scheme expands the number of time slots available for unicast and multicast realtime N-Screen reservations with various service time interval requests. Furthermore, it enhances performances in vewpoints of realtime N-Screen data reservation conflict and throughput.
A Resource Management Scheme for Reliable Multimedia Data Transmission in Ship Area Networks
Kim, Jin-Woo ; Lee, Seong Ro ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1377~1384
DOI : 10.7840/kics.2015.40.7.1377
In this paper, a resource management scheme for preventing the video frame loss in the presence of network congestion is proposed. WiMedia protocol is suitable for the application that supports the real-time multimedia service in the ship area network since it supports high speed data transfer. However, network congestion causes the degradation of video quality, since WiMedia standard discards video frames regardless of importance of video frame. Therefore, a resource management scheme for WiMedia network is proposed in this paper. The proposed technique can intelligently treat the network congestion, and solve the degradation of video quality.
UHD Video Stitching Method for Enhanced User Experience
Gankhuyag, Ganzorig ; Hong, Eun Gi ; Kim, Giyeol ; Choe, Yoonsik ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1387~1394
DOI : 10.7840/kics.2015.40.7.1387
Along with the development of network transmission technology, the IPTV market is growing in fast pace. Additionally the UHD resolution broadcasting system along with user experience (UX) that provides better service to user has attracted attention recently since there are not enough research has been done with differentiated the UX that can enhance the UX yet. Therefore we proposed a low complexity syntax level image stitching implementation technique that run with multi-view services, which makes possibility to view multiple channel or video contents on the screen at the same time. Simulation results have demonstrated the liability and effectiveness of the proposed algorithm by showing that capability of generating more than 80 frames per second by stitching four Full-HD size videos into UHD frame.
Spatial Multiplexing Using Open-Loop Precoding in Maritime Communication Environment with Channel Correlation and LOS
Jang, Jungyup ; Lee, Seong Ro ; Kim, Dong Ho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1397~1404
DOI : 10.7840/kics.2015.40.7.1397
Recently, high data rate transmission is required in maritime communication. In this paper, we consider multiple input multiple output (MIMO) spatial multiplexing (SM). However, the performance of SM is severly degraded due to spatial channel correlation and line-of-sight (LOS) component. In the maritime communication, the MIMO channel correlation and LOS are critical due to the lack of scatteres around the transmitter and/or the receiver. When the feedback of channel information is available, precoding can enhance the error performance by exploiting the channel information. However, it is difficult to derive closed-form solution considering both the correlation and LOS. In this paper, we present open-loop precoding-based spatial multiplexing transmission method by showing that the effect of performance for the correlation and LOS. It is shown that the open-loop precoding can mitigate the performance degradation due to the LOS as well as the correlation. Consequently, we expect that the proposed open-loop precoding can be adopted to the maritime communication system.
Hierarchical Modulation Scheme for 3D Stereoscopic Video Transmission Over Maritime Channel Environment
You, Dongho ; Lee, Seong Ro ; Kim, Dong Ho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1405~1412
DOI : 10.7840/kics.2015.40.7.1405
Recently, Due to the rapid growth of broadcasting communication and video coding technologies, the demands for immersive media contents based on 3D stereoscopic video will increase steadily. And the demands must ultimately provide the contents for users which are in wireless channel such as vehicle, train, and ship. Thus, in this paper, we transmit the 3D stereoscopic video over the maritime Rician channel that direct wave is more dominant than reflective wave. Besides, we present unequel error protection (UEP) by applying hierarchical 4/16-QAM to V+D(Video plus Depth) format which can represent 3D stereoscopic video. We expect our system to provide seamless broadcasting service for users with poor reception condition.
A Performance Analysis of Phase Comparison Monopulse Algorithm for Antenna Spacing and Antenna Array
Sim, Heon-Kyo ; Jung, Min-A ; Kim, Seong-Cheol ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1413~1419
DOI : 10.7840/kics.2015.40.7.1413
Monopulse RADAR is the radar which detects the range of the target using a single transmitted signal. In this paper, using 9.41GHz X-band radar, the research for the phase comparison monopulse algorithm used in the marine environment is conducted. In addition, by applying the phase comparison monopulse algorithm, we calculate the RMSE for the various antenna spacings and the positions of the target. Based on that result, we compare the performance of the phase comparison monopulse algorithm in the uniform linear array with that in the non-uniform linear array. Finally, the differences in performance among the MUSIC algorithm, Bartlett method and the proposed phase comparison monopulse algorithm are analyzed.
Network Coding and Relay Selection for a Bidirectional Ship-to-Ship Relay Communication System
Do, Thinh Phu ; Jeong, Hyun Woo ; Jung, Min-A ; Kim, Yun Hee ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1420~1423
DOI : 10.7840/kics.2015.40.7.1420
This letter considers a ship-to-ship communication system in which two ships exchange their information with the help of multiple relay ships. For the system, we propose a novel relay scheme that allows relay ships to select a method between analog network coding (ANC) and digital network coding (DNC) adaptively based on channel state information. We also provide a relay selection criterion in supporting the proposed adaptive network coding. The simulation results show that the proposed scheme outperforms the conventional scheme employing only the ANC or only the DNC.
Downlink System Level Simulator for Enhanced Inter-Cell Interference Coordination in Maritime Heterogeneous Networks
Hwang, Taemin ; Nam, Yujin ; Jeong, Min-A ; So, Jaewoo ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1424~1432
DOI : 10.7840/kics.2015.40.7.1424
As the wireless communication technologies are being studied for application to maritime communication networks in a fusion of marine industries and IT technology, interference coordination techniques have been studied in the maritime heterogeneous networks. In this paper, we develop a simulator for measuring, verifying and evaluating performance of a maritime heterogeneous network. Unlike other previous simulators, the developed simulator applies enhanced inter-cell interference coordination (eICIC) that are being introduced in the 3GPP Release 10 for mitigating the cross-tier interference between ships. Furthermore, we investigate the effects of almost blank subframes (ABS) and cell range expansion (CRE) on the throughput of small cells in maritime heterogeneous networks by using the developed simulator.
An Unambiguous Correlation Function to Improve Tracking Performance for Binary Offset Carrier Signals
Woo, Sunghyuk ; Chae, Keunhong ; Lee, Seong Ro ; Yoon, Seokho ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1433~1440
DOI : 10.7840/kics.2015.40.7.1433
In this paper, we propose an unambiguous correlation function to improve tracking performance for binary offset carrier (BOC) signals. Specifically, we divide a BOC sub-carrier into multiple rectangular pulses, and analyze that the BOC autocorrelation function is made up of the sum of several partial correlation functions. Then, we obtain two sub-correlation functions by combining two partial correlation functions and propose a novel unambiguous correlation function with no side-peak which can be regulated its width based on the combination of the sub-correlation functions and partial correlation functions. From numerical results, it is confirmed that the proposed correlation function provides a tracking performance improvement over the conventional correlation functions in terms of the tracking error standard deviation.
A Channel Scheduling Scheme for Interference Avoidance in Wireless USB Systems
Kim, Jin-Woo ; Park, Kyung Woo ; Oh, Il-Whan ; Kim, Kyung-Ho ; Lee, Seong Ro ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1441~1449
DOI : 10.7840/kics.2015.40.7.1441
Wireless universal serial bus (WUSB) is the USB technology merged with WiMedia PHY/MAC. WUSB can be applied to wireless persanal area network (WPAN) applications as well as PAN applications like wired USB. Because numerous WUSB networks operate independently for each application, data conflict can occur between adjacent networks. To avoid data conflict, the resource in a different time zone can be utilized. However, if devices in a network increase, available resources in the network decrease, and then the lack of resources necessary to provide service can occur. To solve this problem, we propose interference avoidance scheme for WUSB systems.
Measurements on the Propagation Path Loss Exponent at Maritime VHF Channel Using Single Carrier Signal
Kim, Seung-Geun ; Kim, Sea-Moon ; Yun, Changho ; Lim, Yong-Kon ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1450~1456
DOI : 10.7840/kics.2015.40.7.1450
The received signal strengths according to the propagation distance between a transmitting shore station with a 53 m antenna hight and a receiving ship station with about 6m antenna hight from 700 m upto about 20 km are measured at ship's moving velocity of
using a single carrier signal at 150.0625MHz. In this paper, the path loss exponents at the propagation distance from 700 m to 20km are estimated via minimum-mean-square-error method using the measurements of the received signal strength, and the mean of the estimated path loss exponent become 3.79. The estimated propagation path loss exponents is similar to that calculated based on the field-strength values from 2 km to 20 km in Annex 2 of ITU-R P.1546-4, which is measuring results at maritime VHF at 100 MHz carrier frequency. Therefore, the estimated propagation path loss exponent shall be used as the expected path loss exponents for summer in costal area of South Sea of Korea.
Optimization of Resource Allocation for Inter-Channel Load Balancing with Frequency Reuse in ASO-TDMA-Based VHF-Band Multi-Hop Data Communication System
Cho, Kumin ; Lee, Junman ; Yun, Changho ; Lim, Yong-Kon ; Kang, Chung G. ;
The Journal of Korean Institute of Communications and Information Sciences, volume 40, issue 7, 2015, Pages 1457~1467
DOI : 10.7840/kics.2015.40.7.1457
Depending on the type of Tx-Rx pairs, VHF Data Exchange System (VDES) for maritime communication is expected to employ the different frequency channels. Load imbalance between the different channels turns out to be a critical problem for the multi-hop communication using Ad-hoc Self-Organizing TDMA (ASO-TDMA) MAC protocol, which has been proposed to provide the connectivity between land station and remote ship stations. In order to handle the inter-channel load imbalance problem, we consider a model of the stochastic geomety in this paper. After analyzing the spatial reuse efficiency in each hop region by the given model, we show that the resource utility can be maximized by balancing the inter-channel traffic load with optimal resource allocation in each hop region.