• Proceedings of the IEEK Conference
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• 2000.06d
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• pp.92-97
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• 2000

An AMR(Adaptive Multi-Rate) speech coding algorithm has been adopted as a standard speech codec for IMT-2000. It is based on the algebraic CELP, and consists of eight speech coding modes having the bit rate from 4.75 kbit/s to 12.2 kbit/s. It also contains the VAD(Voice Activity Detector), SCR (Source Controlled Rate) operation, and error concealment scheme for robustness in a radio channel. The bit rate of AMR is changed on a frame basis depending on the channel condition. In this paper, we introduced AMR speech coding algorithm and performed the real-time implementation using TMS320C6201, i.e., a Texas Instrument's fixed-point DSP. With the ANSI C source code released from ETSI and 3GPP, we convert and optimize the program to make it run in real time using the C compiler and assembly language. It is verified that the decoded result of the implemented speech codec on the DSP is identical with the PC simulation result using ANSI C code for test sequences. Also, actual sound input/output test using microphone and speaker demonstrates its proper real-time operation without distortions or delays.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.9
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• pp.63-69
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• 1998

In this paper, we propose a new Bit-Rate control algorithm based on bit usage matching to substitute encoded GOP(s) for new GOP(s) in MPEG-2 bitstream. It iteratively encodes current picture according to quantization value of previous picture and records bit-usage of each slice until nearly target bits are used. With target bits falling in two output bits, quantization value of slice should be changed to alleviate output bit error. We use recorded bit-usage information to decide which slices should be encoded with one quantization value and others with another. As every macroblock has different activity, we change macroblock quantization value using slice quantization value and activity value. The simulation results demonstrate that the fluctuation of the output bits can be kept within few-several tens of bits while maintaining the quality of the reconstructed pictures at a relatively stable level.

• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.229-232
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• 2000

AAL2는 ATM 망에서 Low bit Rate의 음성이나 데이터를 Real-Time으로 전송하기 위해 만들어진 표준안이다. IMT-2000 System에서는 ATM을 근간으로 시스템이 구성되며, 이동전화 가입자의 음성패킷이나 Low bit rate 데이터를 전송하기 위해 AAL2를 채택하였다. 본 논문에서는 IMT-2000 System에서 AAL2를 구현하기 위한 시스템의 구조와 실제AAL2를 구현한 예를 보인다.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.55-58
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• 1998

In this paper, we describe the design of the ATM adapter circuit in the BSC for IMT-2000 Network. This ATM adapter circuit can convert received ATM cell into TDM data in the BSC and vice versa. In the ATM adapter, we implemented both AAL1 and AAL5 functions to provide constant bit rate voice data and variable bit rate packet data servives, simultaneously.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1987.04a
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• pp.196-200
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• 1987

In this paper A NET-CUE System is designed and implemented for tramsmission of the network cuing informations with using data packet broad casting techniques. This system is composed with encoder and decoder. To show the performance of this system An eye height and bit error rate are cheched. The eye height is greater than 74% and The bit error rate is less than 4.6 * 10 The exper imental results show that this system provides a good quality of the operation.

• Journal of Communications and Networks
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• v.16 no.3
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• pp.301-304
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• 2014

This paper proposes accurate interference probability and bit error rate formulas for cognitive relay networks with underlay spectrum sharing and channel estimation error (CEE). Numerous results reveal that the CEE not only degrades the performance of secondary systems (SSs) but also increases interference power caused by SSs to primary systems (PSs), eventually unfavorable to both systems. A solution to further protect PSs from this effect through reducing the power of secondary transmitters is investigated and analyzed.

• Proceedings of the IEEK Conference
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• 2001.06a
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• pp.133-136
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• 2001

In this work, the problem of regulating and tracking available bit rate (ABR) traffic in ATM network. The issue of providing control signals to throttled sources at distant location from bottlenecked node is of particular interest. Network modeling and design of controller is outlined. To obtain optimal control, receding horizon control (RHC) theory is applied. Simulation results are presented in views of regulation and tracking problems with or without constraints.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.156-158
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• 2006

A super-regenerative receiver is designed and tested at 433 MHz ISM band, The designed receiver has the data rate of up to 200 kbps and a power consumption of 10 mW. We carried out the system performance test for the TX power of 0.1 mW and 1 m distance. The result of the bit-error rate test shows one bit error among the 4000 bits.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.11a
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• pp.310-313
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• 2011

This study investigates some schemes to estimate the coding efficiency of a video sequence. The texture complexity and motion are considered as two major parameters to decide the coding efficiency, and the methods to estimate the parameters are discussed. For a fixed values of PSNR, the bit rate of a video sequence is estimated using some schemes based on the estimated parameters, and compared with the bit rate by MPEG-4 AVC.

• Journal of information and communication convergence engineering
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• v.3 no.4
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• pp.176-178
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• 2005

This paper presents closed-form expressions for exact bit error rate of MSK and OQPSK systems employing an adaptive antenna array at base station to eliminate co-channel interference. The channels under consideration are AWGN and one-path flat Rayleigh fading with AWGN. Computer simulation is carried out to confirm the theoretical results.