• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4B
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• pp.338-344
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• 2002

This paper proposes a transient (predictive) connection admission control (CAC) scheme using the transient quality of service (QoS) measure for CDMA cellular systems with bursts On-Off sources. We need an approximate and bounded approach for real-time CAC applications. We derive the transient outage probability as the QoS measure using the Chernoff bound and the refuted large deviation approximation. Numerical results show that the predictive CAC is a promising approach for the multicell CDMA systems.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12A
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• pp.1806-1814
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• 2000

본 논문에서는 CDMA 계층구조 셀룰러 시스템에서 매크로 셀 기지국과 통신을 하는 고속 이동국과 마이크로 셀 기지국과 통신을 하는 저속 이동국의 비 그리고 소프트 핸드오프 영역 비에 따른 기지국이 받는 간섭전력과 시스템 용량을 구하였다. 매크로 셀 기지국과 통신을 하는 고속 이동국이 마이크로 셀 기지국과 통신을 하는 저속 이동국보다 많을수록 기지국이 받는 간섭전력은 증가하며 따라서 시스템 용량은 감소한다. 그러나 소프트 핸드오프 영역의 증가로 기지국이 받는 간섭전력은 감소하명 시스템 용량은 상당히 증가한다.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 1994.11a
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• pp.81-90
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• 1994

이동통신은 통화의 편리성을 제공하는 반면 통화도용의 가능성이 높아 이를 예방하기 위한 사용자 인증서비스가 필요하다. 본 논문에서는 국내 CDMA 이동통신 표준방식인 TIA/EIA/IS-95에서의 사용자 인증시스템을 분석한다. 그리고 실제 인증시스템에 적용 가능한 고속의 해쉬함수를 개발하고 이를 이용하여 인증시스템을 구현한다.

• Proceedings of the IEEK Conference
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• 2002.07a
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• pp.329-332
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• 2002

In this paper a common design method fur RF receivers of different CDMA standards is introduced. The method adopted a new equation, receiver noise equation, for the analysis of each standard. The test conditions for RF receivers in four different CDMA standards, CDMA cellular, PCS, WCDMA, and cdma2000 are analyzed based on the receiver noise equation. With the result of the analysis, the specifications fer RF receivers of different CDMA standards are derived.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.6
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• pp.220-229
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• 1996

We presetn sytem-level simulation methodology as well as environment setup established for CDMA digtial cellular mobile station in an effort to verify CDMA modem ASIC design. To make the system-level simulation feasible, behavioral modeling of a microcontroller was first carried out with VHDL. In addition, models written in C language were also developed to provide ASIC with realistic input data. Finally, the netlist of CDMA modem ASIC was loaded on the a hardware accelerator, which was interfaced with VHDL simulator, and ismulation was performed by excuting the actual CDMA call processing software. Simulation resutls thus obtained were confirmed by comparing them with the emulation resutls from the actual system constructed on hardware modeler. these methods were proved to be effective in both discovering in advance malfunctions when embedded in the system or design errors of ASIC and reducing simulation time by a factor of as much as 20 in case of simulation at gate-level.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6A
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• pp.397-404
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• 2003

In this paper, we have analyzed the level of cross-modulation noise required for CDMA mobile station and proposed a guideline for optimum design. From the analysis, the level of cross-modulation noise is determined by the system's noise figure(NF) and VCO's phase noise and there is a trade-off relationships between them. In addition, we have determined the value of LNA's IIP3 and duplexer's isolation to satisfy the above level in designing the system. Therefore, this paper will give a guideline for a selection of components in designing cdma2000 mobile station.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.4
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• pp.149-154
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• 2004

In this paper, Interference-Cancelled CDMA system using binary ZCD spreading codes is introduced. Proposed Interference-Cancelled CDMA system can be usefully used for the intra-cellular Interference-Cancelled wireless communication systems. Binary ZCD spreading code sets have various sequence period and family sizes and the ZCD properties of them are very effective for Interference-cancelled CDMA Systems. In this paper, we mathematically analyzed the system performance of our proposed Interference-Cancelled CDMA system in the AWGN channel and various interference environments such as MAI and MPI. Furthermore, using the BER performance simulation we certify the available interference cancellation properties of the proposed system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.12B
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• pp.2109-2119
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• 2000

In this paper, the Packet CDMA Reservation ALOHA protocol is proposed to support the multi-traffic services such as voice and videophone services with handoff calls, high-rate data and low-rate data services efficiently on the multi-rate transmission in uplink cellular systems. The frame structure, composed of the access slot and the transmission slot, and the proposed access permission probability based on the estimated number of contending users for each service are presented to reduce MAI. The assured priority to the voice and the videophone handoff calls is given through higher access permission probability. And through the proposed code assignment scheme, the voice service can be provided without the voice packet dropping probability in the CDMA/PRMA protocols. The code reservation is allowed to the voice and the videophone services. The low-rate data service uses the available codes during the silent periods of voice calls and the remaining codes in the codes assigned to the voice service to utilize codes efficiently. The high-rate data service uses the assigned codes to the high-rate data service and the remaining codes in the codes assigned to the videophone service. Using the Markov-chain subsystem model for each service including the handoff calls in uplink cellular systems, the steady-state performances are simulated and analyzed. After a round of tests for the examples, through the proposed code assignment scheme and the access permission probability, the Packet CDMA Reservation ALOHA protocol can guarantee the priority and the constant QoS for the handoff calls even at large number of contending users. Also, the data services are integrated efficiently on the multi-rate transmission.

• Journal of the Korean Operations Research and Management Science Society
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• v.26 no.4
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• pp.125-132
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• 2001

Traffic unbalance between uplink and downlink is one of the most notable characteristics in the next generation cellular mobile systems which provide multimedia services such as voice and video telephony, high-speed internet access, and mobile computing, etc. The CDMA/TDD system with unbalanced slot allocation between two links is a good solution for the traffic unbalance in this paper, we formulate the time slot and channel allocation problem for the CDMA/TDD systems in general multicell environments, which is to maximize the system capacity under the given traffic unbalance, and solve that problem by simulated annealing technique. Computational experiments show that the proposed scheme yields a good performance.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.5
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• pp.10-23
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• 1996

In this paper, the reverse link performance evaluation with synchronous CDMA is analyzed in the PCS system, which is the schem based on proposed method of KMT-PCS to increase the capacitance of cellular CDMA system. We make the baseband system model of CDMA reverse link, and then analyze system performance and subsystem techniques considering effect of channel and power control that are improtant factor influencing system performance in the PCS system. Based on this result, the paper presents primary technique analyses required at synchronous reverse link proposed by the KMT, which compose of initial synchronization range in initial synchronization step and control signal period in the synchronization maintenance step.