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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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The Korean Institute of Communications and Information Sciences
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Volume & Issues
Volume 23, Issue 9A - Sep 1998
Volume 23, Issue 8 - Aug 1998
Volume 23, Issue 7 - Jul 1998
Volume 23, Issue 6 - Jun 1998
Volume 23, Issue 5 - May 1998
Volume 23, Issue 4 - Apr 1998
Volume 23, Issue 9 - 00 1998
Selecting the target year
The design for controllabel self-checking checker
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1149~1159
This paper presents the Controllable Self-Checking(CSC) Checker at which can be used the Fault-Tolerant System with the redundancy. According to the critical level of output(of system), especially, it can be instructed the time if it has to check the output or not. We adop the deterministic test, performed on-line, to detect the faults with a minimal test set. The results show the Parity 2-rail checker(P-TRC) which is designed much simpler than the checker has the higher fault coverage than the existent checker.
Design of inversion and division circuit over GF(
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1160~1164
In this paper, we propose a new algorithm for computing multiplicative inverses in
and design an inversion circuit and a division circuit using this algorithm. The algorithm used is based on Fermat's theorem. It takes around m/2 clock cycles. The hardware requirements of the inversion circuit and the division circuit using this algorithm are the same as traditional circuits except for the addition of multiplexers.
Binary pseudorandom sequences of period
with ideal autocorrelation generated by the polynomial
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1165~1172
In this paper, we present a construction for binary pseudorandom sequences of period
with ideal autocorraltion property using the polynomial
. We show that the sequence obtained from the polynomial becomes an m-sequence for certain values of d. We also find a few values of d which yield new binary sequences with ideal autocorrelation property when m is
, where k is a positive integer. These new sequences are represented using trace function and the results are tabulated.
A wireless MAC protocol for the integrated voice/data services
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1173~1183
This paper proposes an SS-PRMA protocol for the integrated voice and data services in the packet radio networks. In this protocol, the uplink logical channels are provided by combining the time slots and the spreding codes. SS-PRMA protocol contains some features of existing protocols such as PRMA, slotted ALOHA, and CDMA. In the proposed protocol, the voice terminals use a reservation mechanism, and the dta terminals use a slotted ALOHA scheme. The analysis and the simulation results show that most of the performances for the voice traffic can be achieved by employing a few distinct spreading codes and the data traffic throughput is closely related to the number of spreading code channels. Also it shows that the data traffic performance can be significantly improved by applying an FEC scheme to the data link layer.
Perfomence comprison of various input-buffered ATM switch architectures under random and bursty traffic
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1184~1195
In this paper, we compare vaious input-buffered ATM switch architectures in structures on input buffer and switching fabric, the resons for performance improvement and degradation, arbitration scheme and maximum throughput, and present comparative merits and demerits of each architecture under random and bursty traffic. We also analyze the prformance of combined architectures of windowing scheme, destination-queueing based input-port expansion schemeand output-port expansion scheme, and show that it is possible to achieve 100% throughput with combined scheme of destination-queueing based input-port expansion scheme and output-port expansio scheme when the number of output group is 2 and output port expansion ratio is 2.
Throughput analysis of the ARQ scheme in WLL link sublayer
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1196~1207
The link sublayer segmentizes a use data into several frames and transmits it through a wireless channel. In this case, the packet error probability and link throughput are affected by the frame size. And a portion of pure user data in a packet affects a link throughput. In this paper we analyze and simulate the retransmission scheme of the Wireless Local Loop(WLL) system and study the link throughput according to the payload size.
Design of flow control fucntion for ABR service in ATM networks
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1208~1221
We survey several issues for implementing the end-to-end flow control function for ABR service and propose a structure for implementation. In the proposed design, control parameters are calculated and maneuvered by software for easy implementation and efficiency adaptbility for the changes of parameters while the cells are emitted at the rate according to the allowed cell rate with the hardware implementation for real time processing. The proposed structure can cope with the changes of the specifications including the calculation of the control parameters and their application. Hence, the structure is expected to contribute to providing the ABR serice in the future ATM networks.
A practical approach for a lower bound of the number of wavelengths in WDM-based Optical transport networks
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1222~1228
Most of researchers have tried to find heuristic methods for near-optimal solutions of establishing light paths with minimum number of wavelengths in wavelengh-routed optical networks. In order to provide a performance measure for heuristic approaches, we propose a practical approach for a lower bound of the number of wavelengths which is required to provide full connections in WDM-based optical transport networks. This method is based on a path-flow formulation using K-shortest paths for each connection. Compared with a general link-flow formulation, the proposed method has much lower complexity and so needs much less calcuation tiem while it gives the same results as a general link-flow formulation in some sample networks.
Server network architectures for VOD service
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1229~1240
In this paper, we provide a design of DAVIC VOD service system with proxy servers which perform caching of video streams. Proxy servers are placed between a service provider system and service consumer systems. They provide video services to consumers on behalf of the service provider, therefore they reduce the loads of service providers and network. The operation of a proxy server depends on whether the requested program is in its storage. If this is the case, the prosy servere takes all the controls, but if the proxy does not have the program, it forwards the service request the proxy server takes all the controls, but if the prosy does not have the program, it forwards the service request to a service provider. While the service provider system provides the program to the consumer, the proxy copies and caches the program. The proxy server executes cache replacement, if necessary. We show by simultion that the LFU is the most efficiency caching replacement algorithm among the typical algorithms such as LRU, LFU, FIFO.
A multicast group shceduling algorithm for heterogeneous receivers
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1241~1248
The multicast scheme can improve the efficiency of multimedia retrieval service system, assuming that video transmission speed is faster than the playback rate and the store-and-play scheme. To best exploit the multicast benefits under bandwidth heterogeneous environment, we develop a multicast scheduling algorithm called MTS(Maximum Throughput Scheduling) which tries to maximize the amount of information transferred at each scheduling with subgrouping method. The MTS method compromises the multiple unicast method and the multicast method with lowest transmission rate. we compare the performance of MTS with that of MMS(Most Multicasting Scheduling) and EDS(Earliest Deadine Scheduling) via computer simulation. The performance results show that the MTS requires less number of service handlers to service the same number of subscribers.
An efficient channel assignment meghod for real-time service in the IEEE 802.11 wireless LAN system
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1249~1259
This paper proposes an efficient channel assignment method for real-time service in the IEEE 802.11 Wireless LAN system, and analyzes the supportability to real-time service and the channel utilzation of that through computer simulations. The improved MAC(Medium Access Control) protocol employing the proposed channel assignment method achieved good throughput over contention period as well as contention-free period by making real-time terminals transmit the information about their desiring value before starts of data transmissions. For performance evaluation of the proposed method, a simulation analyzing the variation of allocated bandwidths to terminals using real-time service and their buffer sizes wasexecuted. Real-time data traffics was modeled s 7-stae transition VBR sources, and asynchronous data traffics modeled as Poisson processes. In the simulation, the proposed method showed smaller variation of the bandwidth of each terminal and samller buffer size than the existing method, and also recorded good throughput over contention period.
Authentication protocol and subscriber anonymity for CDPD wireless data communication system
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1260~1269
We investigate here problems related to a subscriber authentication protocol in CDPD, and suggest an improved alternative. Associated with an anonymity of the subscriber, another method of generating the distributing alias is proposed other than the conventional approach initiated by an authentication server in this home network.
An improved frequency offset estimation technique for an OFDM system
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1270~1281
Frequency offset in an orthogonal frequency division multiplexing (OFDM) system is known to cause the inter-channel interference (ICI), amplitude and phase distortion of a received signal, resulting in a severe performance degradation of the total system. In this paper, we propose an improved pilot-based masimum likelihood frequency offset estimation technique, which uses the predefined sync-subchannels, and derive the error performance of the proposed frequency offset estimator analytically. The proposed technique improves the performance of the frequency offset estimator by adding up the frequency offset caused by coherent phase changes and averaging out the effect caused by random phase error. It is confirmed by computer simulations that the upper bound of error variance for the proposed frequency offset estimator analytically derived in this paper is correct, and that the proposed estimator has better performance than the previous ones in terms of error variance, tracking range, and time-varying characteristics of a channel.
Physical layer design of W-CDMA IMT-2000 system and performance analysis of key characteristics
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1282~1290
In this paper, the physical layer design of IMT-2000 system being developed by SK Telecom is introuduced. The outband signaling scheme and the two-pilot scheme are adopted for multimedia service and inter-cell asynchronous mode respectively. In addition, the synchronous transmission scheme is proposed to reduce the interference in the reverse link. The algorithm and simulation results of 'two-pilot scheme' for inter-cell asynchronous mode and 'reverse synchronous control' for synchronous transmission are presented.
New symbol timming algorithm for multi-level modulation scheme
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1291~1298
In this paper, a simple algorithm for detection of timing error of a synchronous, band-limited, multi-level data stream is proposed. The proposed algorithm can be applied to multi-level PAM, M-ary PSK, or M-ary QAM. The proposed algorithm for M-ary PSK requires only two samples per symbol for its operation, and it is based on the concept of transition logic table and transition level table. In orer to prove the steady-state operation of the proposed algorithm, its performance is evaluated and compared to BECM by Monte Carlo simulation method under Gaussian noise and fading noise channel environments. The comparison results confirm that the perforance of proposed algorithm is superior to that of BECM in jitter characteristics.
A blocking artifacts reduction algorithm using block boundary pixel difference characteristics
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1299~1309
In this paper, we propose a new approach for reducing the blocking artifact that is one of drawbacks of the block-based Discrete Cosine Transform (DCT) without introducing additional information or significant blurring. We modify the inter-block discontinuity minimization technique to preserve edges within a block as well as to reduce visible block boundaries. The homogeneity of each block is decided by the threshold value reated to Q-factor, which is included in a JPEG as well as MPEG streams. The quantization error is estimated by minimizing the discontinuity, which is weighted in proportion to block discontinuity and added to each pixel in the block to compensate block artifacts. The proposed algorithm reconstructs images which have less noticeable block boundaries from a subjective viewpoit without anyconstraints.
Investigation of miximum permitted error limits for second order sigma-delta modulator with 14-bit resolution
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1310~1318
Sigma-delta converter is frequently used for conyerting low-frequency anglog to digital signal. The converter consists of a modulator and a digital filer, but our work is concentrated on the modulator. In this works, to design second-order sigma-dalta modulator with 14bit resolution, we define maximumerror limits of each components (operational smplifier, integrator, internal ADC, and DAC) of modulator. It is first performed modeling of an ideal second-order sigma-delta modulator. This is then modified by adding the non-ideal factors such as limit of op-amp output swing, the finit DC gain of op-amp slew rate, the integrator gian error by the capacitor mismatch, the ADC error by the cmparator offset and the mismatch of resistor string, and the non-linear of DAC. From this modeling, as it is determined the specification of each devices requeired in design and the fabrication error limits, we can see the final performance of modulator.
Frequency determination for beam command in rotating phase and frequency scan radar systems
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1319~1324
The phase and frequency commands of a ratating radar system that utilizes frequency scanning to steer the beam in the azimuth direction and phase shifters in the elevation direction are derived in terms of the angles of the groung based coordinate system. The antenna type considered is slotted arrays that are easy to construct at such high microwave frequency as the X band. The frequency that has non-linear characteristics as a functio ofthe elevation angle is plotted and the derived frequency equation is aproximated to be a simple form to reduce the calculation time for real time multi-function radar systems. It is shown that the approximated frequency command is in good agreement with the exact one if the range of azimuth scanning is limited by
Joint video coding for multiple video program transmission based on rate-distortion estimation
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1325~1341
A conventional CBR channel is now capable of delivering several digitally compressed video programs due to recent advances in video compression, such as MPEG-2, and digital transmission technology. This paper presents a joint video coding scheme that is to maintain a constant sum of bit rates for all the programs but to allow the variable bit rate for individual program in the transimission environment mentioned above. Thus advantages of VBR video compression can be obtained. This paper contributes in two aspects. First, a rate-distortion estimation method for MPEG-2 video is proposed, which enavle us predict the amount of bits and the distortion generated from an encoded picture at a given quantization step size and vice versa. The most attractive features of the proposed rate-distortion estimation method are its accuracy and a computational complexity low enough to be applied to real-time video coding applications. Second, this paper presents an efficient and accurate joint rate control scheme using the rate-distortion estimation results and verifies its performance with experiments. The experimental results show that our coding scheme gives a significant gain even though a small number of video programs are coded jointly. For example, a stable picture quality is maintained among the video programs as well as within a program, and additional extra programs can be transmitted over the same channel bandwidth if the proposed joint video coding scheme is used.
Application of the source superimposing method for multi scatterers analysis
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1342~1348
The major limitation of MOM solution has alaways been the computer CPU time and storage size, needed to carry out the impedance matrix computation. A new formulation technique using Sorce Superimposion method is presented in order to cut down computerstorage requirements and CPU time based on the equivalence principle and induction theorem. The numerical results are shown to give good agreement to those calculated by the conventional method and also application example is presented.
Implementation of a digital FM composite signal generator
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1349~1359
In this paper, presented is the result of a digital implementation of a FM stereo composite signal generator. The chip utilizing DDFS(Direct Digital Frequency Synthesizer architecture is implemented using
CMOS gate-array technology thereby replacing analog componentry. To verify the process of generating composite signals a conventional logic simulation method was used. The processed chip was mounted on an evaluation PCB to test and analyze to signals. According to the measurement result obtained by using a 12-bit DAC, the digital FM composite signal generator produces a 74DB spectrally pure signal over its entire tuning range, which is superior to that of analog counterpart by 14dB in it spectral reponse. And further enhancements of the spectral response is expected to be achieved by using a high resolution digital to analog converter, such as a 16-bit DAC. The resulting signals is superior to the signal of the analoy circuitry typically used, in major characteristics such as S/N ratios, accuracy, tuning stability, and signal seperation.
Implementation of TMN Agent for ATM switch : considering integration of agent into ATM switch
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1360~1371
There are many implementation methods according to models integrating TMN Agent into an ATM switch. In this paper, we evaluate the integrating models for integrating the Agent into an ATM switch in the aspects of the size of MIB(Management Information Base), the internal protocol profiles and the facility of implementation. Based on the evaluation, we choose an integrating model and implment the Agent. To ensure merit of the model, we propose an interface for exchanging management information between the Agent and an ATM switch. We also show the feasibility of our Agent system through some filed testes for the average processing time.
Modeling for DC characteristics of DFB-LD
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1372~1383
In this paper, modeling for DC and AC characteristics analysis of DFB-LD was performed considering effects of .lambda./4-shifted gratingandspatial hole burning within a laser diode cavity. From the simulation for DC characteristics, Light-Current curve, optical power distribution and carrier density distribution within the cavity can be obtained. The simulation for AC characteristics porovides IM response and the amplitude and phase and the amplitude and phase response of FM with excellent accuracy.
Analysis of a relative rate switch algorithm for the ABR service in ATM networks
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1384~1396
This paper ivestigates the performance of a relative rate (RR) switch algorithm for the rate-based available bit rate (ABR) flow control in asynchronous transfer mode (ATM) networks. A RR switch may notify the network congestion status to the source by suing the congestion indication (CI) bit or no increase (NI)bit in the backward RM (BRM) cells. A RR switch can be differently implemented according to the congestion detectio and notification methods. In this paper, we propose three implementation schemes for the RR switch with different congestion detection and notification methods, and analyze the allowed cell rate (ACR) of a source and the queue length of a switch in steady state. In addition, we derive the upper and lower bounds for the maximum and minimum queue lengths for each scheme respectively, and evaluate the effects of the ABR parameter values on the queue length. Furthermore, we suggest the range of the rage increase factor (RIF) and rate decrease factor (RDF) parameter values which can prevent buffer overflow and underflow at a switch.
Implementation and performance evaluation of SS No.7 in B-ISDN networks
The Journal of Korean Institute of Communications and Information Sciences, volume 23, issue 5, 1998, Pages 1397~1408
Service networks for the future communication networks will be combined by the B-ISDN networks. These service networks also will use SS No.7 as the signaling transport network for the control of user requriement service. Therefore, ITU-T recommended B-ISDN signaling layers for SS No.7 as a substitute for N-ISDN MTP signaling layer. In this paper, we propose the implementation structure and describe the characteristics and functions of each signaling layer of SS No.7, which are adapted to ATM switching system, and evaluate a performance. The structure of SSCOP transmission buffer using a linked list and an unit frame length is proposed for SAAL layer and the implementation structure and internal routing method according to the ATM switching system are also proposed for MTP-3b layer. Additionally, we propose the ISUP/B-ISUP level interworking structure using only associated mode, which are presented in the first stage of B-ISDN as the effective internatworking structure of SS No.7 for the circuit related signaling network between the existing N-ISDN networks and B-ISDN networks.